Clonal Proliferation Of Hepatocytes And Progression Of Liver Disease In Chronic Hepatitis B Virus Infection
Funder
National Health and Medical Research Council
Funding Amount
$420,558.00
Summary
Infection with the hepatitis B virus (HBV) can lead to either acute resolving, or chronic HBV infection. Chronic HBV infections are often associated with severe liver disease, and increased risk of liver cancer and occur worldwide in 350 million people. HBV infects hepatocytes, the major cell of the liver. Early during infection 100% of hepatocytes are infected. However, this percentage declines over time to 10-50% or less. The reasons for this are unknown. We suggest that changes in the liver c ....Infection with the hepatitis B virus (HBV) can lead to either acute resolving, or chronic HBV infection. Chronic HBV infections are often associated with severe liver disease, and increased risk of liver cancer and occur worldwide in 350 million people. HBV infects hepatocytes, the major cell of the liver. Early during infection 100% of hepatocytes are infected. However, this percentage declines over time to 10-50% or less. The reasons for this are unknown. We suggest that changes in the liver cell population occur because of the immune response against infected hepatocytes. We hypothesize that the immune response kills infected hepatocytes and provides and growth advantage to hepatocytes that can no longer be infected with HBV. This leads to the clonal proliferation of HBV-negative hepatocytes that over time become the major cell population in the liver. We will study human liver tissue using molecular techniques to detect the HBV DNA that integrates randomly into cell DNA during HBV infection. We will then determine the copy number of specific integrated virus-cell junctions as a measure of hepatocyte proliferation. Sections of fixed liver will also be examined for changes in histology and frequency of HBV infection. These studies will determine if foci of HBV-negative hepatocytes are clonal. This finding would suggest that a major role of the immune system in the development of liver cancer is to restrict the genetic pool of hepatocytes. We hypothesise that liver cancer beings with a very specific survival advantage for hepatocytes that lack HBV replication and antigen expression, and that proliferation of these cells expands the pool of potentially altered HCC precursor cells.Read moreRead less
Though vaccination has had a major impact on the number of persons becoming infected, chronic infection with the hepatitis B virus (HBV) still remains a major worldwide problem, with 350 million people chronically infected. The existence of HBV vaccine escape mutants and the fact that 5% of vaccinees fail to respond implies that HBV will remain a significant public health problem for the foreseeable future. Current treatments for chronic HBV infection have a low success rate (~20%) and patients ....Though vaccination has had a major impact on the number of persons becoming infected, chronic infection with the hepatitis B virus (HBV) still remains a major worldwide problem, with 350 million people chronically infected. The existence of HBV vaccine escape mutants and the fact that 5% of vaccinees fail to respond implies that HBV will remain a significant public health problem for the foreseeable future. Current treatments for chronic HBV infection have a low success rate (~20%) and patients with chronic infection are expected to die prematurely due to chronic liver disease or primary liver cancer. Interestingly, exposure to HBV can lead to either acute resolving or chronic HBV infection. Like chronic infections, acute infections involve spread of virus to virtually every hepatocyte, followed by rapid clearance of the virus mediated by the host immune response. Our immediate aim is to study the resolution of acute HBV infections to determine how the stable intracellular viral genome, covalently closed circular DNA (cccDNA), is cleared from the nucleus of infected hepatocytes. Our broad long-term aim is to develop new and effective treatments for chronic HBV infection based on a better understanding of how acute HBV infections are resolved by the host. Based on our previous work we believe that clearance of cccDNA requires hepatocyte death, together with compensatory proliferation of other infected hepatocytes. We will perform detailed studies in duck hepatitis B virus (DHBV) infected ducks to determine if hepatocyte death and compensatory proliferation are essential to clear the infection, or if mechanisms exist for clearance that do not involve cell destruction.Read moreRead less
Molecular Evolution And Rapid Typing Of Enteroviruses By Molecular Methods
Funder
National Health and Medical Research Council
Funding Amount
$44,934.00
Summary
Human enteroviruses (HEVs) are common human pathogens associated with a wide spectrum of symptoms ranging from asymptomatic infection to serious illness, especially in infants and the immunocompromised. They are responsible for large outbreaks of diseases. We will develop rapid molecular typing methods for enteroviruses, including reverse line blot hybridization and rolling circle amplification. Meanwhile, we will analyze molecular evolution of important enteroviruses over time.