ORCID Profile
0000-0002-1290-191X
Current Organisation
The University of Hong Kong
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Publisher: Springer Science and Business Media LLC
Date: 15-07-2020
DOI: 10.1038/S41467-020-17280-8
Abstract: The sudden deterioration of patients with novel coronavirus disease 2019 (COVID-19) into critical illness is of major concern. It is imperative to identify these patients early. We show that a deep learning-based survival model can predict the risk of COVID-19 patients developing critical illness based on clinical characteristics at admission. We develop this model using a cohort of 1590 patients from 575 medical centers, with internal validation performance of concordance index 0.894 We further validate the model on three separate cohorts from Wuhan, Hubei and Guangdong provinces consisting of 1393 patients with concordance indexes of 0.890, 0.852 and 0.967 respectively. This model is used to create an online calculation tool designed for patient triage at admission to identify patients at risk of severe illness, ensuring that patients at greatest risk of severe illness receive appropriate care as early as possible and allow for effective allocation of health resources.
Publisher: MDPI AG
Date: 19-07-2021
DOI: 10.3390/V13071400
Abstract: The induction of a specific antibody response has long been accepted as a serological hallmark of recent infection or antigen exposure. Much of our understanding of the influenza antibody response has been derived from studying antibodies that target the hemagglutinin (HA) protein. However, growing evidence points to limitations associated with this approach. In this review, we aim to highlight the issue of antibody non-responsiveness after influenza virus infection and vaccination. We will then provide an overview of the major factors known to influence antibody responsiveness to influenza after infection and vaccination. We discuss the biological factors such as age, sex, influence of prior immunity, genetics, and some chronic infections that may affect the induction of influenza antibody responses. We also discuss the technical factors, such as assay choices, strain variations, and viral properties that may influence the sensitivity of the assays used to measure influenza antibodies. Understanding these factors will hopefully provide a more comprehensive picture of what influenza immunogenicity and protection means, which will be important in our effort to improve influenza vaccines.
Publisher: Springer Science and Business Media LLC
Date: 09-02-2022
DOI: 10.1007/S00705-022-05383-0
Abstract: Coronavirus disease 2019 (COVID-19) is an acute respiratory infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Other coronaviruses (CoVs) can also infect humans, although the majority cause only mild respiratory symptoms. Because early diagnosis of SARS-CoV-2 is critical for preventing further transmission events and improving clinical outcomes, it is important to be able to distinguish SARS-CoV-2 from other SARS-related CoVs in respiratory s les. Therefore, we developed and evaluated a novel reverse transcription quantitative polymerase chain reaction (RT-qPCR) assay targeting the genes encoding the spike (S) and membrane (M) proteins to enable the rapid identification of SARS-CoV-2, including several new circulating variants and other emerging SARS-like CoVs. By analysis of in vitro -transcribed mRNA, we established multiplex RT-qPCR assays capable of detecting 5 × 10° copies/reaction. Using RNA extracted from cell culture supernatants, our multiple simultaneous SARS-CoV-2 assays had a limit of detection of 1 × 10° TCID 50 /mL and showed no cross-reaction with human CoVs or other respiratory viruses. We also validated our method using human clinical s les from patients with COVID-19 and healthy in iduals, including nasal swab and sputum s les. This novel one-step multiplex RT-qPCR assay can be used to improve the laboratory diagnosis of human-pathogenic CoVs, including SARS-CoV-2, and may be useful for the identification of other SARS-like CoVs of zoonotic origin.
Publisher: Springer Science and Business Media LLC
Date: 18-10-2023
Publisher: AME Publishing Company
Date: 08-2020
DOI: 10.21037/JTD-20-2363
Publisher: Springer Science and Business Media LLC
Date: 20-07-2020
Publisher: World Health Organization, Western Pacific Regional Office
Date: 05-12-2013
Publisher: Research Square Platform LLC
Date: 11-08-2023
DOI: 10.21203/RS.3.RS-3234133/V1
Abstract: As influenza A virus (IAV) infection establishes a more erse immunological memory to different viral proteins compared to vaccination, we hypothesize that this could skew antibody responses to immunizing antigens after infection. To explore this, we generated mouse models that possess either an IAV hemagglutinin (HA)- or neuraminidase (NA)-biased immunological memory by simultaneously or, sequentially-inoculating them with cocktails of isogenic viruses bearing four antigenically-distinct HA (H3v) or NA (N2v), that spans the IAV H3N2 human circulation history. Cocktail priming elicited comparable antibody responses to all immunizing antigens, whilst responses in sequentially-inoculated mice were antigen-dependent. We then challenged the mice with two H3N2 strains of opposing virulence and antigenic distance and examined the post-infection antibody landscapes. In both models, antibody increases after the two challenges occurred to antigenically-related, and not against antigenically-distant, HAs or NAs for which baseline titers were low. H3-imprinted mice seroconverted to challenge NA, but not HA, and vice versa. In primed mice, the antibody response was directed to the viral target with low pre-existing immunity, despite high titers of protective antibodies and no signs of symptomatic infections, while immune-naïve mice seroconverted to both HA and NA. Our findings show that the dynamics of antibody responses to HA and NA after infection can be altered by pre-existing immunity, i.e the “antibody ceiling effect” does not imply no-response, simply a "misdirected" response, to an antigenically-related antigen or an alternate viral protein. These results have implications on our seroepidemiological studies as well as our understanding of immune correlates of protection in populations with different influenza immune histories.
Publisher: MDPI AG
Date: 12-01-2022
Abstract: Subtype H3N2 influenza A viruses (A(H3N2)) have been the dominant strain in some countries in the Western Pacific region since the 2009 influenza A(H1N1) pandemic. Vaccination is the most effective way to prevent influenza however, low vaccine effectiveness has been reported in some influenza seasons, especially for A(H3N2). Antigenic mismatch introduced by egg-adaptation during vaccine production between the vaccine and circulating viral stains is one of the reasons for low vaccine effectiveness. Here we review the extent of this phenomenon, the underlying molecular mechanisms and discuss recent strategies to ameliorate this, including new vaccine platforms that may provide better protection and should be considered to reduce the impact of A(H3N2) in the Western Pacific region.
Publisher: Springer Science and Business Media LLC
Date: 24-01-2018
DOI: 10.1007/S00705-018-3730-0
Abstract: Gene segments from avian H1N1 influenza A viruses have reassorted with other influenza viruses to generate pandemic strains over the past century. Nevertheless, little effort has been invested in understanding the characteristics of avian H1N1 influenza viruses. Here, we present the genome sequence and a molecular and virological characterization of an avian influenza A virus, A/wild bird/Korea/SK14/2014 (A/SK14, H1N1), isolated from migratory birds in South Korea during the winter season of 2014-2015. Full-genome sequencing and phylogenetic analysis revealed that the virus belongs to the Eurasian avian lineage. Although it retained avian-receptor binding preference, A/SK14 virus also exhibited detectable human-like receptor binding and was able to replicate in differentiated primary normal human bronchial epithelial cells. In animal models, A/SK14 virus was moderately pathogenic in mice, and virus was detected in nasal washes from inoculated guinea pigs, but not in direct-contact guinea pigs. Although A/SK14 showed moderate pathogenicity and no evidence of transmission in a mammalian model, our results suggest that the dual receptor specificity of A/SK14-like virus might allow for a more rapid adaptation to mammals, emphasizing the importance of further continuous surveillance and risk-assessment activities.
Publisher: MDPI AG
Date: 06-04-2021
DOI: 10.3390/V13040624
Abstract: Hemagglutinin and neuraminidase, which constitute the glycoprotein spikes expressed on the surface of influenza A and B viruses, are the most exposed parts of the virus and play critical roles in the viral lifecycle. As such, they make prominent targets for the immune response and antiviral drugs. Neuraminidase inhibitors, particularly oseltamivir, constitute the most commonly used antivirals against influenza viruses, and they have proved their clinical utility against seasonal and emerging influenza viruses. However, the emergence of resistant strains remains a constant threat and consideration. Antivirals targeting the hemagglutinin protein are relatively new and have yet to gain global use but are proving to be effective additions to the antiviral repertoire, with a relatively high threshold for the emergence of resistance. Here we review antiviral drugs, both approved for clinical use and under investigation, that target the influenza virus hemagglutinin and neuraminidase proteins, focusing on their mechanisms of action and the emergence of resistance to them.
Publisher: Elsevier BV
Date: 11-2004
DOI: 10.1016/J.VIROL.2004.08.029
Abstract: Outbreaks of dengue due to dengue virus type 1 (DENV-1) occurred almost simultaneously in 2001 in Myanmar and at multiple sites almost 10,000 km away in the Pacific. Phylogenetic analyses of the E protein genes of DENV-1 strains recovered from Asia and the Pacific revealed three major viral genotypes (I, II, and III) with distinct clades within each. The majority of strains from the Pacific and Myanmar, and a number of other Asian strains fell into genotype I. Genotype II comprised a smaller set of Asian and Pacific strains, while genotype III contained viruses from erse geographical localities. These analyses suggested that the continuing outbreak of dengue in the Pacific has been due to multiple, direct, introductions of dengue viruses from a variety of locations in Asia followed by local transmission. There was no evidence that the introduction of these viruses into the Pacific was associated with any adaptive changes in the E protein of the viruses.
Publisher: American Society for Microbiology
Date: 06-2015
DOI: 10.1128/JVI.02537-14
Abstract: A balance between the functions of the influenza virus surface proteins hemagglutinin (HA) and neuraminidase (NA) is thought to be important for the transmission of viruses between humans. Here we describe two pandemic H1N1 viruses, A/swine/Virginia/1814-1/2012 and A/swine/Virginia/1814-2/2012 (pH1N1 low -1 and -2, respectively), that were isolated from swine symptomatic for influenza. The enzymatic activity of the NA of these viruses was almost undetectable, while the HA binding affinity for α2,6 sialic acids was greater than that of the highly homologous pH1N1 viruses A/swine/Pennsylvania/2436/2012 and A/swine/Minnesota/2499/2012 (pH1N1-1 and -2), which exhibited better-balanced HA and NA activities. The in vitro growth kinetics of pH1N1 low and pH1N1 viruses were similar, but aerosol transmission of pH1N1 low -1 was abrogated and transmission via direct contact in ferrets was significantly impaired compared to pH1N1-1, which transmitted by direct and aerosol contact. In normal human bronchial epithelial cells, pH1N1 low -1 was significantly inhibited by mucus but pH1N1-1 was not. In Madin-Darby canine kidney cell cultures overlaid with human or swine mucus, human mucus inhibited pH1N1 low -1 but swine mucus did not. These data show that the interaction between viruses and mucus may be an important factor in viral transmissibility and could be a barrier for interspecies transmission between humans and swine for influenza viruses. IMPORTANCE A balance between the functions of the influenza virus surface proteins hemagglutinin (HA) and neuraminidase (NA) is thought to be important for transmission of viruses from swine to humans. Here we show that a swine virus with extremely functionally mismatched HA and NAs (pH1N1 low -1) cannot transmit via aerosol in ferrets, while another highly homologous virus with HA and NAs that are better matched functionally (pH1N1-1) can transmit via aerosol. These viruses show similar growth kinetics in Madin-Darby canine kidney (MDCK) cells, but pH1N1 low -1 is significantly inhibited by mucus in normal human bronchial epithelial cells whereas pH1N1-1 is not. Further, human mucus could inhibit these viruses, but swine mucus could not. These data show that the interaction between viruses and mucus may be an important factor in viral transmissibility and could be a species barrier between humans and swine for influenza viruses.
Publisher: American Association of Avian Pathologists (AAAP)
Date: 06-2015
Publisher: Elsevier BV
Date: 11-2014
Publisher: MDPI AG
Date: 26-03-2018
Publisher: Oxford University Press (OUP)
Date: 03-11-2017
Publisher: American Society for Microbiology
Date: 07-2013
DOI: 10.1128/CMR.00097-12
Abstract: The challenges in successful vaccination against influenza using conventional approaches lie in their variable efficacy in different age populations, the antigenic variability of the circulating virus, and the production and manufacturing limitations to ensure safe, timely, and adequate supply of vaccine. The conventional influenza vaccine platform is based on stimulating immunity against the major neutralizing antibody target, hemagglutinin (HA), by virus attenuation or inactivation. Improvements to this conventional system have focused primarily on improving production and immunogenicity. Cell culture, reverse genetics, and baculovirus expression technology allow for safe and scalable production, while adjuvants, dose variation, and alternate routes of delivery aim to improve vaccine immunogenicity. Fundamentally different approaches that are currently under development hope to signal new generations of influenza vaccines. Such approaches target nonvariable regions of antigenic proteins, with the idea of stimulating cross-protective antibodies and thus creating a “universal” influenza vaccine. While such approaches have obvious benefits, there are many hurdles yet to clear. Here, we discuss the process and challenges of the current influenza vaccine platform as well as new approaches that are being investigated based on the same antigenic target and newer technologies based on different antigenic targets.
Publisher: Wiley
Date: 12-07-2020
DOI: 10.1111/IRV.12783
Publisher: Springer Science and Business Media LLC
Date: 07-06-2019
Publisher: Springer Science and Business Media LLC
Date: 05-04-2013
Abstract: Colonization of the nasopharynx by Streptococcus pneumoniae is considered a prerequisite for pneumococcal infections such as pneumonia and otitis media. Probiotic bacteria can influence disease outcomes through various mechanisms, including inhibition of pathogen colonization. Here, we examine the effect of the probiotic Lactobacillus rhamnosus GG (LGG) on S. pneumoniae colonization of human epithelial cells using an in vitro model. We investigated the effects of LGG administered before, at the same time as, or after the addition of S. pneumoniae on the adherence of four pneumococcal isolates. LGG significantly inhibited the adherence of all the pneumococcal isolates tested. The magnitude of inhibition varied with LGG dose, time of administration, and the pneumococcal isolate used. Inhibition was most effective when a higher dose of LGG was administered prior to establishment of pneumococcal colonization. Mechanistic studies showed that LGG binds to epithelial cells but does not affect pneumococcal growth or viability. Administration of LGG did not lead to any significant changes in host cytokine responses. These findings demonstrate that LGG can inhibit pneumococcal colonization of human epithelial cells in vitro and suggest that probiotics could be used clinically to prevent the establishment of pneumococcal carriage.
Publisher: Research Square Platform LLC
Date: 31-01-2023
DOI: 10.21203/RS.3.RS-2434849/V1
Abstract: Highly pathogenic avian influenza (HPAI) H5N1 activity has intensified globally since 2021, replacing the dominant clade 2.3.4.4 H5N8 virus. H5N1 viruses have spread rapidly to four continents, causing increasing reports of mass mortality in wild birds and poultry. The ecological and virological properties required for future mitigation strategies are unclear. Using epidemiological, spatial and genomic approaches, we demonstrate changes in the source of resurgent H5 HPAI and reveal significant shifts in virus ecology and evolution. Outbreak data indicates key resurgent events in 2016/17 and 2020/21 that contributed to the panzootic spread of H5N1 in 2021/22, including an increase in virus diffusion velocity and persistence in wild birds. Genomic analysis reveals that the 2016/17 epizootics originated in Asia, where HPAI H5 reservoirs are documented as persistent. However, in 2020/21, 2.3.4.4b H5N8 viruses emerged in domestic poultry in Africa, featuring several novel mutations altering the HA structure, receptor binding, and antigenicity. The new H5N1 virus emerged from H5N8 through reassortment in wild birds along the Adriatic flyway around the Mediterranean Sea. It was characterized by extensive reassortment with low pathogenic avian influenza in domestic and wild birds as it spread globally. In contrast, earlier outbreaks of H5N8 were caused by a more stable genetic constellation, highlighting dynamic changes in HPAI H5 genomic evolution. These results suggest a shift in the epicenter of HPAI H5 beyond Asia to new regions in Africa, the Middle East, Europe, and North and South America. The persistence of HPAI H5 with resurgence potential in domestic birds indicates that elimination strategies remain a high priority.
Publisher: AME Publishing Company
Date: 03-2020
Publisher: European Respiratory Society (ERS)
Date: 08-04-2020
DOI: 10.1183/13993003.00562-2020
Abstract: During the outbreak of coronavirus disease 2019 (COVID-19), consistent and considerable differences in disease severity and mortality rate of patients treated in Hubei province compared to those in other parts of China have been observed. We sought to compare the clinical characteristics and outcomes of patients being treated inside and outside Hubei province, and explore the factors underlying these differences. Collaborating with the National Health Commission, we established a retrospective cohort to study hospitalised COVID-19 cases in China. Clinical characteristics, the rate of severe events and deaths, and the time to critical illness (invasive ventilation or intensive care unit admission or death) were compared between patients within and outside Hubei. The impact of Wuhan-related exposure (a presumed key factor that drove the severe situation in Hubei, as Wuhan is the epicentre as well the administrative centre of Hubei province) and the duration between symptom onset and admission on prognosis were also determined. At the data cut-off (31 January 2020), 1590 cases from 575 hospitals in 31 provincial administrative regions were collected (core cohort). The overall rate of severe cases and mortality was 16.0% and 3.2%, respectively. Patients in Hubei (predominantly with Wuhan-related exposure, 597 (92.3%) out of 647) were older (mean age 49.7 versus 44.9 years), had more cases with comorbidity (32.9% versus 19.7%), higher symptomatic burden, abnormal radiologic manifestations and, especially, a longer waiting time between symptom onset and admission (5.7 versus 4.5 days) compared with patients outside Hubei. Patients in Hubei (severe event rate 23.0% versus 11.1%, death rate 7.3% versus 0.3%, HR (95% CI) for critical illness 1.59 (1.05–2.41)) have a poorer prognosis compared with patients outside Hubei after adjusting for age and comorbidity. However, among patients outside Hubei, the duration from symptom onset to hospitalisation (mean 4.4 versus 4.7 days) and prognosis (HR (95%) 0.84 (0.40–1.80)) were similar between patients with or without Wuhan-related exposure. In the overall population, the waiting time, but neither treated in Hubei nor Wuhan-related exposure, remained an independent prognostic factor (HR (95%) 1.05 (1.01–1.08)). There were more severe cases and poorer outcomes for COVID-19 patients treated in Hubei, which might be attributed to the prolonged duration of symptom onset to hospitalisation in the epicentre. Future studies to determine the reason for delaying hospitalisation are warranted.
Publisher: No publisher found
Date: 2014
Publisher: Springer Science and Business Media LLC
Date: 25-05-2016
DOI: 10.1038/SREP26742
Abstract: Current anti-influenza therapy depends on administering drugs soon after infection, which is often impractical. We assessed whether combinations of oseltamivir (a neuraminidase inhibitor) and T-705 (a nonspecific inhibitor of viral polymerases) could extend the window for treating lethal infection with highly pathogenic A(H5N1) influenza virus in mice. Combination therapy protected 100% of mice, even when delayed until 96 h postinoculation. Compared to animals receiving monotherapy, mice receiving combination therapy had reduced viral loads and restricted viral spread in lung tissues, limited lung damage and decreased inflammatory cytokine production. Next-generation sequencing showed that virus populations in T-705–treated mice had greater genetic variability, with more frequent transversion events, than did populations in control and oseltamivir-treated mice, but no substitutions associated with resistance to oseltamivir or T-705 were detected. Thus, combination therapy extended the treatment window for A(H5N1) influenza infection in mice and should be considered for evaluation in a clinical setting.
Publisher: American Society for Microbiology
Date: 31-12-2014
Abstract: Avian species are reservoirs of influenza A viruses and could harbor viruses with significant pandemic potential. We examined the antibody and cellular immune responses to influenza A viruses in field or laboratory workers with a spectrum of occupational exposure to avian species for evidence of zoonotic infections. We measured the seroprevalence and T cell responses among 95 in iduals with various types and degrees of prior field or laboratory occupational exposure to wild North American avian species using whole blood s les collected in 2010. Plasma s les were tested using endpoint enzyme-linked immunosorbent assay (ELISA) and hemagglutination (HA) inhibition (HAI) assays to subtypes H3, H4, H5, H6, H7, H8, and H12 proteins. Detectable antibodies were found against influenza HA antigens in 77% of in iduals, while 65% of in iduals tested had measurable T cell responses (gamma interferon [IFN-γ] enzyme-linked immunosorbent spot assay [ELISPOT]) to multiple HA antigens of avian origin. To begin defining the observed antibody specificities, Spearman rank correlation analysis showed that ELISA responses, which measure both head- and stalk-binding antibodies, do not predict HAI reactivities, which measure primarily head-binding antibodies. This result suggests that ELISA titers can report cross-reactivity based on the levels of non-head-binding responses. However, the strongest positive correlate of HA-specific ELISA antibody titers was receipt of seasonal influenza virus vaccination. Occupational exposure was largely uncorrelated with serological measures, with the exception of in iduals exposed to poultry, who had higher levels of H7-specific antibodies than non-poultry-exposed in iduals. While the cohort had antibody and T cell reactivity to a broad range of influenza viruses, only occupational exposure to poultry was associated with a significant difference in antibody levels to a specific subtype (H7). There was no evidence that T cell assays provided greater specificity for the detection of zoonotic infection. However, influenza vaccination appears to promote cross-reactive antibodies and may provide enhanced protection to novel influenza viruses. IMPORTANCE Annual vaccinations are necessary to ameliorate influenza disease due to drifted viral variants that emerge in the population. Major shifts in the antigenicity of influenza viruses can result in immunologically distinct viruses that can cause more severe disease in humans. Historically, genetic reassortment between avian, swine, or human influenza viruses has caused influenza pandemics in humans several times in the last century. Therefore, it is important to design vaccines to elicit broad protective responses to influenza infections. Because avian influenza viruses have an important role in emerging infections, we tested whether occupational exposure to birds can elicit immune responses to avian influenza viruses in humans. Instead of a specific occupational exposure, the strongest association of enhanced cross-reactive antibody responses was receipt of seasonal influenza vaccination. Therefore, in iduals with preexisting immune responses to seasonal human influenza viruses have substantial cross-reactive antibody and T cell responses that may lead to enhanced protection to novel influenza viruses.
Publisher: Elsevier BV
Date: 04-2021
Publisher: AME Publishing Company
Date: 07-2018
Publisher: Elsevier BV
Date: 03-2011
DOI: 10.1016/J.VIROL.2010.12.050
Abstract: The transmembrane domains (TMDs) of dengue virus type-1 M protein (DENV-1M) were reported to form cation-selective channels in artificial lipid bilayers. We further explored this observation using the two-electrode voltage cl (TEVC) method on the Xenopus laevis oocytes expressing DENV PrM and M proteins. Using myc epitope tagged M proteins, M was first shown to adopt its predicted native topology in mammalian cells when expressed on its own. The recombinant proteins were then successfully expressed on the surface of Xenopus oocytes. Using influenza A M2 (Inf A/M2) protein as a control, we measured the conductance of oocytes expressing DENV proteins under hyperpolarized or low-pH conditions. Inf A/M2 showed pH-dependent, amantadine-sensitive channel activity that was consistent with previously published reports. However, no activity was detected for DENV proteins. We conclude that DENV PrM and M proteins do not show pH-activated ion channel activity.
Publisher: Springer Science and Business Media LLC
Date: 08-06-2017
DOI: 10.1038/S41541-017-0017-5
Abstract: Conventional inactivated avian influenza vaccines have performed poorly in past vaccine trials, leading to the hypothesis that they are less immunogenic than seasonal influenza vaccines. We tested this hypothesis by comparing the immunogenicity of the H5N1 and H7N9 vaccines (avian influenza vaccines) to a seasonal trivalent inactivated influenza vaccine in naïve ferrets, administered with or without the adjuvants MF59 or AS03. Vaccine immunogenicity was assessed by measuring neutralizing antibody titers against hemagglutinin and neuraminidase and by hemagglutinin -specific IgG levels. Two doses of unadjuvanted vaccines induced low or no HA-specific IgG responses and hemagglutination-inhibiting titers. Adjuvanted vaccines induced comparable IgG-titers, but poorer neutralizing antibody titers for the H5 vaccine. All adjuvanted vaccines elicited detectable anti- neuraminidase -antibodies with the exception of the H5N1 vaccine, likely due to the low amounts of neuraminidase in the vaccine. Overall, the H5N1 vaccine had poorer capacity to induce neutralizing antibodies, but not HA-specific IgG, compared to H7N9 or trivalent inactivated influenza vaccine.
Publisher: Oxford University Press (OUP)
Date: 18-07-2017
Publisher: MDPI AG
Date: 18-11-2021
DOI: 10.3390/PATHOGENS10111505
Abstract: Guangdong province, located in South China, is an important economic hub with a large domestic migrant population and was among the earliest areas to report COVID-19 cases outside of Wuhan. We conducted a cross-sectional, age-stratified serosurvey to determine the seroprevalence of antibodies against SARS-CoV-2 after the emergence of COVID-19 in Guangdong. We tested 14,629 residual serum s les that were submitted for clinical testing from 21 prefectures between March and June 2020 for SARS-CoV-2 antibodies using a magnetic particle based chemiluminescent enzyme immunoassay and validated the results using a pseudovirus neutralization assay. We found 21 s les positive for SARS-CoV-2 IgG, resulting in an estimated age- and sex-weighted seroprevalence of 0.15% (95% CI: 0.06–0.24%). The overall age-specific seroprevalence was 0.07% (95% CI: 0.01–0.24%) in persons up to 9 years old, 0.22% (95% CI: 0.03–0.79%) in persons aged 10–19, 0.16% (95% CI: 0.07–0.33%) in persons aged 20–39, 0.13% (95% CI: 0.03–0.33%) in persons aged 40–59 and 0.18% (95% CI: 0.07–0.40%) in persons ≥60 years old. Fourteen (67%) s les had pseudovirus neutralization titers to S-protein, suggesting most of the IgG-positive s les were true-positives. Seroprevalence of antibodies to SARS-CoV-2 was low, indicating that there were no hidden epidemics during this period. Vaccination is urgently needed to increase population immunity to SARS-CoV-2.
Publisher: Wiley
Date: 25-08-2020
DOI: 10.1111/IRV.12798
Publisher: American Society for Microbiology
Date: 04-2013
DOI: 10.1128/JVI.02346-12
Abstract: Several novel anti-influenza compounds are in various phases of clinical development. One of these, T-705 (favipiravir), has a mechanism of action that is not fully understood but is suggested to target influenza virus RNA-dependent RNA polymerase. We investigated the mechanism of T-705 activity against influenza A (H1N1) viruses by applying selective drug pressure over multiple sequential passages in MDCK cells. We found that T-705 treatment did not select specific mutations in potential target proteins, including PB1, PB2, PA, and NP. Phenotypic assays based on cell viability confirmed that no T-705-resistant variants were selected. In the presence of T-705, titers of infectious virus decreased significantly ( P 0.0001) during serial passage in MDCK cells inoculated with seasonal influenza A (H1N1) viruses at a low multiplicity of infection (MOI 0.0001 PFU/cell) or with 2009 pandemic H1N1 viruses at a high MOI (10 PFU/cell). There was no corresponding decrease in the number of viral RNA copies therefore, specific virus infectivity (the ratio of infectious virus yield to viral RNA copy number) was reduced. Sequence analysis showed enrichment of G→A and C→T transversion mutations, increased mutation frequency, and a shift of the nucleotide profiles of in idual NP gene clones under drug selection pressure. Our results demonstrate that T-705 induces a high rate of mutation that generates a nonviable viral phenotype and that lethal mutagenesis is a key antiviral mechanism of T-705. Our findings also explain the broad spectrum of activity of T-705 against viruses of multiple families.
Publisher: American Society for Microbiology
Date: 15-01-2017
DOI: 10.1128/JVI.00868-16
Abstract: Neuraminidase (NA) is a sialidase expressed on the surface of influenza A viruses that releases progeny viruses from the surface of infected cells and prevents viruses becoming trapped in mucus. It is a homotetramer, with each monomer consisting of a transmembrane region, a stalk, and a globular head with sialidase activity. We recently characterized two swine viruses of the pandemic H1N1 lineage, A/swine/Virginia/1814-1/2012 (pH1N1 low -1) and A/swine/Virginia/1814-2/2012 (pH1N1 low -2), with almost undetectable NA enzymatic activity compared to that of the highly homologous A/swine/Pennsylvania/2436/2012 (pH1N1-1) and A/swine/Minnesota/2499/2012 (pH1N1-2) viruses. pH1N1-1 transmitted to aerosol contact ferrets, but pH1N1 low -1 did not. The aim of this study was to identify the molecular determinants associated with low NA activity as potential markers of aerosol transmission. We identified the shared unique substitutions M19V, A232V, D248N, and I436V (N1 numbering) in pH1N1 low -1 and pH1N1 low -2. pH1N1 low -1 also had the unique Y66D substitution in the stalk domain, where 66Y was highly conserved in N1 NAs. Restoration of 66Y was critical for the NA activity of pH1N1 low -1 NA, although 19M or 248D in conjunction with 66Y was required to recover the level of activity to that of pH1N1 viruses. Studies of NA stability and molecular modeling revealed that 66Y likely stabilized the NA homotetramer. Therefore, 66Y in the stalk domain of N1 NA was critical for the stability of the NA tetramer and, subsequently, for NA enzymatic activity. IMPORTANCE Neuraminidase (NA) is a sialidase that is one of the major surface glycoproteins of influenza A viruses and the target for the influenza drugs oseltamivir and zanamivir. NA is important as it releases progeny viruses from the surface of infected cells and prevents viruses becoming trapped in mucus. Mutations in the globular head domain that decrease enzymatic activity but confer resistance to NA inhibitors have been characterized however, the importance of specific mutations in the stalk domain is unknown. We identified 66Y (N1 numbering), a highly conserved amino acid that was critical for the stability of the NA tetramer and, subsequently, for NA enzymatic activity.
Publisher: Frontiers Media SA
Date: 18-06-2019
Publisher: American Society for Microbiology
Date: 17-03-2020
DOI: 10.1128/JVI.01385-19
Abstract: Data on the immunologic responses to neuraminidase (NA) is lacking compared to what is available on hemagglutinin (HA) responses, despite growing evidence that NA immunity can be protective and broadly cross-reactive. Understanding these NA responses during natural infection is key to exploiting these properties for improving influenza vaccines. Using two community-acquired influenza cohorts, we showed that the induction of both HA and NA antibodies after infection is influenced by age and subtypes. Such response dynamics suggest the influence of immunological memory, and understanding how this process is regulated will be critical to any vaccine effort targeting NA immunity.
Publisher: Springer Science and Business Media LLC
Date: 17-03-2017
DOI: 10.1038/SREP44727
Abstract: Because of the pathogenicity and low incidence of avian influenza virus infections in humans, the immune correlates of protection for avian influenza vaccines cannot be determined from clinical studies. Here, we used the ferret model to address this for an avian influenza H5N1 vaccine. Using oil-in-water adjuvants, we generated groups of ferrets with undetectable (geometric mean titer [GMT] 10), low (GMT = 28.3), or high (GMT 761.1) hemagglutination-inhibition (HAI) titers to the A/Viet Nam/1203/2004 (H5N1) virus. Ferrets were then challenged with the wild-type virus and disease severity and immunologic parameters were studied. The severity of infection and symptom profile were inversely associated with pre-challenge HAI titers in a dose-dependent manner. A vaccinated ferret with no detectable HAI-antibodies but high flu-specific IgG-antibody titers mounted rapid functional antibodies after infection and experienced milder disease compared to other ferrets in the group. Compared to naïve ferrets, all vaccinated ferrets showed improved cellular immunity in the lungs and peripheral blood. High number of IFNγ + CD8- T cells in the airways was associated with early viral clearance. Thus, while neutralizing antibodies are the best correlate of protection, non-neutralizing antibodies can also be protective. This should be taken into consideration in future avian influenza vaccine trials.
Publisher: Mary Ann Liebert Inc
Date: 09-2007
Abstract: Outbreaks involving dengue viruses (DENV) of the same genotype occur in a cyclical pattern in Malaysia. Two cycles of outbreaks involving dengue virus type 2 (DENV-2) of the same genotype occurred in the 1990s in the Klang Valley, Malaysia. Sera of patients from the first outbreak and sera of mice inoculated with virus from the same outbreak had poorer neutralization activity against virus of the second outbreak. Conversely, patient sera from the second outbreak showed higher neutralization titer against virus of the early outbreak. At subneutralizing concentrations, sera of mice immunized with second outbreak virus did not significantly enhance infection with viruses from the earlier outbreak. Amino acid substitution from valine to isoleucine at position 129 of the envelope protein (E), as well as threonine to alanine at position 117 and lysine to arginine at position 272 of the NS1 protein, differentiated viruses of the two outbreaks. These findings highlight the potential influence of specific intragenotypic variations in eliciting varied host immune responses against the different DENV subgenotypes. This could be an important contributing factor in the recurring homogenotypic dengue virus outbreaks seen in dengue-endemic regions.
Publisher: American Thoracic Society
Date: 15-02-2014
Publisher: Oxford University Press (OUP)
Date: 23-02-2015
Publisher: Oxford University Press (OUP)
Date: 17-07-2018
Publisher: Cold Spring Harbor Laboratory
Date: 18-12-2022
DOI: 10.1101/2022.12.18.520670
Abstract: Highly pathogenic avian influenza (HPAI) H5N1 activity has intensified globally since 2021, replacing the dominant clade 2.3.4.4 H5N8 virus. H5N1 viruses have spread rapidly to four continents, causing increasing reports of mass mortality in wild birds and poultry. The ecological and virological properties required for future mitigation strategies are unclear. Using epidemiological, spatial and genomic approaches, we demonstrate changes in the source of resurgent H5 HPAI and reveal significant shifts in virus ecology and evolution. Outbreak data indicates key resurgent events in 2016/17 and 2020/21 that contributed to the panzootic spread of H5N1 in 2021/22, including an increase in virus diffusion velocity and persistence in wild birds. Genomic analysis reveals that the 2016/17 epizootics originated in Asia, where HPAI H5 reservoirs are documented as persistent. However, in 2020/21, 2.3.4.4b H5N8 viruses emerged in domestic poultry in Africa, featuring several novel mutations altering the HA structure, receptor binding, and antigenicity. The new H5N1 virus emerged from H5N8 through reassortment in wild birds along the Adriatic flyway around the Mediterranean Sea. It was characterized by extensive reassortment with low pathogenic avian influenza in domestic and wild birds as it spread globally. In contrast, earlier outbreaks of H5N8 were caused by a more stable genetic constellation, highlighting dynamic changes in HPAI H5 genomic evolution. These results suggest a shift in the epicenter of HPAI H5 beyond Asia to new regions in Africa, the Middle East, Europe, and North and South America. The persistence of HPAI H5 with resurgence potential in domestic birds indicates that elimination strategies remain a high priority.
Publisher: American Society for Microbiology
Date: 11-2015
DOI: 10.1128/JVI.01514-15
Abstract: Human infections with avian influenza viruses are a serious public health concern. The neuraminidase (NA) inhibitors (NAIs) are the frontline anti-influenza drugs and are the major option for treatment of newly emerging influenza. Therefore, it is essential to identify the molecular markers of NAI resistance among specific NA subtypes of avian influenza viruses to help guide clinical management. NAI-resistant substitutions in NA subtypes other than N1 and N2 have been poorly studied. Here, we identified NA amino acid substitutions associated with NAI resistance among influenza viruses of N3, N7, and N9 subtypes which have been associated with zoonotic transmission. We applied random mutagenesis and generated recombinant influenza viruses carrying single or double NA substitution(s) with seven internal genes from A/Puerto Rico/8/1934 (H1N1) virus. In a fluorescence-based NA inhibition assay, we identified three categories of NA substitutions associated with reduced inhibition by NAIs (oseltamivir, zanamivir, and peramivir): (i) novel subtype-specific substitutions in or near the enzyme catalytic site (R152W, A246T, and D293N, N2 numbering), (ii) subtype-independent substitutions (E119G/V and/or D and R292K), and (iii) substitutions previously reported in other subtypes (Q136K, I222M, and E276D). Our data show that although some markers of resistance are present across NA subtypes, other subtype-specific markers can only be determined empirically. IMPORTANCE The number of humans infected with avian influenza viruses is increasing, raising concerns of the emergence of avian influenza viruses resistant to neuraminidase (NA) inhibitors (NAIs). Since most studies have focused on NAI-resistance in human influenza viruses, we investigated the molecular changes in NA that could confer NAI resistance in avian viruses grown in immortalized monolayer cells, especially those of the N3, N7, and N9 subtypes, which have caused human infections. We identified not only numerous NAI-resistant substitutions previously reported in other NA subtypes but also several novel changes conferring reduced susceptibility to NAIs, which are subtype specific. The findings indicate that some resistance markers are common across NA subtypes, but other markers need to be determined empirically for each subtype. The study also implies that antiviral surveillance monitoring could play a critical role in the clinical management of influenza virus infection and an essential component of pandemic preparedness.
Publisher: Wiley
Date: 04-12-2014
DOI: 10.1111/ACEL.12178
Publisher: Wiley
Date: 07-2023
DOI: 10.1111/IRV.13172
Abstract: Age‐associated immune changes and pre‐existing influenza immunity are hypothesized to reduce influenza vaccine effectiveness in older adults, although the contribution of each factor is unknown. Here, we constructed influenza‐specific IgG landscapes and determined baseline concentrations of cytokines typically associated with chronic inflammation in older adults (TNF‐α, IL‐10, IL‐6, and IFN‐γ) in 30 high and 29 low influenza vaccine responders (HR and LR, respectively). In a background of high H3 antibody titers, vaccine‐specific H3, but not H1, antibody titers were boosted in LRs to titers comparable to HRs. Pre‐vaccination concentrations of IL‐10 were higher in LRs compared with HRs and inversely correlated with titers of pre‐existing influenza antibodies. Baseline TNF‐α concentrations were positively correlated with fold‐increases in antibody titers in HRs. Our findings indicate that baseline inflammatory status is an important determinant for generating post‐vaccination hemagglutinin‐inhibition antibodies in older adults, and IgG responses can be boosted in the context of high pre‐existing immunity.
Publisher: Proceedings of the National Academy of Sciences
Date: 25-01-2016
Abstract: Influenza pandemics occur several times per century, causing millions of deaths. For one of the myriad of zoonotic influenza viruses to do so, a virus containing a hemagglutinin (HA) surface antigen previously unseen by most humans must evolve the necessary, albeit largely unknown, properties for sustained respiratory spread between people. During entry, the prototypic viral fusion protein HA binds receptors and is triggered irreversibly by low pH in endosomes to cause membrane fusion. These studies link a fundamental property, activation energy of a fusion protein measured as its pH of activation (acid stability), to the ability of zoonotic influenza viruses to cause a human pandemic. Monitoring HA stability is expected to enhance prepandemic surveillance and control of emerging influenza viruses.
Publisher: Wiley
Date: 08-03-2012
DOI: 10.1016/J.FEBSLET.2012.02.047
Abstract: The dengue virus membrane (M) protein is a key component of the mature virion. Here, we characterised the cellular behaviour of M using a recombinant protein construct to understand its inherent properties. Using confocal microscopy, we showed that M and its intracellular precursor, prM, localised to the endoplasmic reticulum. M protein was also detected on the cell surface and secreted, suggesting that M can enter the secretory pathway. In addition, cross-linking studies showed that M can form dimers and tetramers. These findings suggest that M behaves as a secretory protein analogous to the major envelope protein E.
Publisher: Springer Science and Business Media LLC
Date: 2010
Publisher: Springer Science and Business Media LLC
Date: 12-2012
DOI: 10.1038/NBT.2439
Publisher: Springer Science and Business Media LLC
Date: 22-02-2021
DOI: 10.1186/S13073-021-00847-5
Abstract: Since early February 2021, the causative agent of COVID-19, SARS-CoV-2, has infected over 104 million people with more than 2 million deaths according to official reports. The key to understanding the biology and virus-host interactions of SARS-CoV-2 requires the knowledge of mutation and evolution of this virus at both inter- and intra-host levels. However, despite quite a few polymorphic sites identified among SARS-CoV-2 populations, intra-host variant spectra and their evolutionary dynamics remain mostly unknown. Using high-throughput sequencing of metatranscriptomic and hybrid captured libraries, we characterized consensus genomes and intra-host single nucleotide variations (iSNVs) of serial s les collected from eight patients with COVID-19. The distribution of iSNVs along the SARS-CoV-2 genome was analyzed and co-occurring iSNVs among COVID-19 patients were identified. We also compared the evolutionary dynamics of SARS-CoV-2 population in the respiratory tract (RT) and gastrointestinal tract (GIT). The 32 consensus genomes revealed the co-existence of different genotypes within the same patient. We further identified 40 intra-host single nucleotide variants (iSNVs). Most (30/40) iSNVs presented in a single patient, while ten iSNVs were found in at least two patients or identical to consensus variants. Comparing allele frequencies of the iSNVs revealed a clear genetic differentiation between intra-host populations from the respiratory tract (RT) and gastrointestinal tract (GIT), mostly driven by bottleneck events during intra-host migrations. Compared to RT populations, the GIT populations showed a better maintenance and rapid development of viral genetic ersity following the suspected intra-host bottlenecks. Our findings here illustrate the intra-host bottlenecks and evolutionary dynamics of SARS-CoV-2 in different anatomic sites and may provide new insights to understand the virus-host interactions of coronaviruses and other RNA viruses.
Publisher: American Society for Microbiology
Date: 15-04-2015
DOI: 10.1128/JVI.00078-15
Abstract: Highly pathogenic H5N1 avian influenza viruses are associated with severe disease in humans and continue to be a pandemic threat. While vaccines are available, other approaches are required for patients that typically respond poorly to vaccination, such as the elderly and the immunocompromised. To produce a therapeutic agent that is highly efficacious at low doses and is broadly specific against antigenically drifted H5N1 influenza viruses, we developed two neutralizing monoclonal antibodies and combined them into a single bispecific Fc fusion protein (the Fc dual-affinity retargeting [FcDART] molecule). In mice, a single therapeutic or prophylactic dose of either monoclonal antibody at 2.5 mg/kg of body weight provided 100% protection against challenge with A/Vietnam/1203/04 (H5N1) or the antigenically drifted strain A/Whooper swan/Mongolia/244/05 (H5N1). In ferrets, a single 1-mg/kg prophylactic dose provided 100% protection against A/Vietnam/1203/04 challenge. FcDART was also effective, as a single 2.5-mg/kg therapeutic or prophylactic dose in mice provided 100% protection against A/Vietnam/1203/04 challenge. Antibodies bound to conformational epitopes in antigenic sites on the globular head of the hemagglutinin protein, on the basis of analysis of mutants with antibody escape mutations. While it was possible to generate escape mutants in vitro , they were neutralized by the antibodies in vivo , as mice infected with escape mutants were 100% protected after only a single therapeutic dose of the antibody used to generate the escape mutant in vitro . In summary, we have combined the antigen specificities of two highly efficacious anti-H5N1 influenza virus antibodies into a bispecific FcDART molecule, which represents a strategy to produce broadly neutralizing antibodies that are effective against antigenically erse influenza viruses. IMPORTANCE Highly pathogenic H5N1 avian influenza viruses are associated with severe disease in humans and are a pandemic threat. A vaccine is available, but other approaches are required for patients that typically respond poorly to vaccination, such as the elderly and the immunocompromised. The variability of the virus means that such an approach must be broad spectrum. To achieve this, we developed two antibodies that neutralize H5N1 influenza viruses. In mice, these antibodies provided complete protection against a spectrum of H5N1 influenza viruses at a single low dose. We then combined the two antibodies into a single molecule, FcDART, which combined the broad-spectrum activity and protective efficacy of both antibodies. This treatment provides a novel and effective therapeutic agent or prophylactic with activity against highly pathogenic H5N1 avian influenza viruses.
Publisher: Cold Spring Harbor Laboratory
Date: 25-03-2023
DOI: 10.1101/2023.03.25.534227
Abstract: Prior studies have identified genetic, infectious, and biological associations with immune competence and disease severity however, there have been few integrative analyses of these factors and study populations are often limited in demographic ersity. Utilizing s les from 1,705 in iduals in 5 countries, we examined putative determinants of immunity, including: single nucleotide polymorphisms, ancestry informative markers, herpesvirus status, age, and sex. In healthy subjects, we found significant differences in cytokine levels, leukocyte phenotypes, and gene expression. Transcriptional responses also varied by cohort, and the most significant determinant was ancestry. In influenza infected subjects, we found two disease severity immunophenotypes, largely driven by age. Additionally, cytokine regression models show each determinant differentially contributes to acute immune variation, with unique and interactive, location-specific herpesvirus effects. These results provide novel insight into the scope of immune heterogeneity across erse populations, the integrative effects of factors which drive it, and the consequences for illness outcomes.
Location: Egypt
Location: United States of America
No related grants have been discovered for Sook-San Wong.