Project description:Background and Aims: Viral clearance during acute hepatitis C virus (HCV) infection is associated with the induction of potent antiviral T-cell responses. Since dendritic cells (DC) are essential in the activation of primary T-cell responses our goal was to analyze gene expression in DC from patients during acute HCV infection. Methods: By using microarrays, gene expression was compared in resting and activated peripheral blood plasmacytoid (pDC) and myeloid (mDC) DC from acute HCV resolving patients (AR) and from those who become chronically infected (ANR), as well as in HCV chronically infected patients (CHR) and healthy seronegative individuals (CTRL). Results: For pDC, a high number of upregulated genes related to different functions and processes was found in AR patients, irrespective of DC stimulation. However, for mDC, most evident differences were detected after DC stimulation, again corresponding to upregulated genes in AR patients. Differences between AR and ANR were also observed when comparing their DC with those from CHR patients and CTRL individuals. Most differences corresponded to metabolism-associated genes, with upregulation in AR patients of genes belonging to pathways associated with DC activation and cytokine responses. Conclusion: Our results show that upregulation of relevant genes in DC during acute HCV infection may determine viral clearance, suggesting that dysfunctional DC may be responsible for the lack of efficient T-cell responses which lead to chronic HCV infection. Gene expression was compared in resting and activated peripheral blood plasmacytoid (pDC) and myeloid (mDC) DC from acute HCV resolving patients (AR) and from those who become chronically infected (ANR), as well as in HCV chronically infected patients (CHR) and healthy seronegative individuals (CTRL)
Project description:Hepatitis A virus (HAV) is a hepatotropic human picornavirus that has been associated only with acute infection. Its pathogenesis is not well understood since there have been few recent studies in animal models using modern methodologies. We characterized HAV infections in three chimpanzees, quantifying viral RNA by qRT-PCR and examining critical aspects of the innate immune response including intrahepatic interferon-stimulated gene expression. We compared these infection profiles with similar studies of chimpanzees infected with hepatitis C virus (HCV), a hepatotropic flavivirus that frequently causes persistent infection. Surprisingly, HAV-infected animals exhibited very limited induction of type I interferon-stimulated genes in the liver compared to chimpanzees with acute resolving HCV infection, despite similar levels of viremia and 100-fold greater quantities of viral RNA in the liver. Minimal ISG15 and IFIT1 responses peaked 1-2 weeks after HAV challenge, then subsided despite continuing high hepatic viral loads. An acute inflammatory response at 3-4 weeks correlated with the appearance of virus-specific antibodies, and both apoptosis and proliferation of hepatocytes. Despite this, HAV RNA persisted in the liver for months, remaining present long after its clearance from serum and feces and revealing dramatic differences in the kinetics of clearance in the three compartments. Viral RNA was detected in the liver for significantly longer (35 to >48 weeks) than HCV RNA in animals with acute resolving HCV infection (10-20 weeks). Collectively, these findings suggest that early HAV infection is far stealthier than HCV infection and represents a distinctly different paradigm in viral-host interactions within the liver. Chimpanzee liver was biopsied during an acute HAV infection. Chimp 1 and 2 had two baseline samples. Chimp 3 used the baselines from chimps 1 and 2. Chimp 1 had 8 samples during the HAV acute infection. Chimp 2 had 9 samples during the HAV acute infection. Chimp 3 had 4 samples during the HAV acute infection.
Project description:Background and Aims: Viral clearance during acute hepatitis C virus (HCV) infection is associated with the induction of potent antiviral T-cell responses. Since dendritic cells (DC) are essential in the activation of primary T-cell responses our goal was to analyze gene expression in DC from patients during acute HCV infection. Methods: By using microarrays, gene expression was compared in resting and activated peripheral blood plasmacytoid (pDC) and myeloid (mDC) DC from acute HCV resolving patients (AR) and from those who become chronically infected (ANR), as well as in HCV chronically infected patients (CHR) and healthy seronegative individuals (CTRL). Results: For pDC, a high number of upregulated genes related to different functions and processes was found in AR patients, irrespective of DC stimulation. However, for mDC, most evident differences were detected after DC stimulation, again corresponding to upregulated genes in AR patients. Differences between AR and ANR were also observed when comparing their DC with those from CHR patients and CTRL individuals. Most differences corresponded to metabolism-associated genes, with upregulation in AR patients of genes belonging to pathways associated with DC activation and cytokine responses. Conclusion: Our results show that upregulation of relevant genes in DC during acute HCV infection may determine viral clearance, suggesting that dysfunctional DC may be responsible for the lack of efficient T-cell responses which lead to chronic HCV infection.
Project description:This is a within-host hepatitis B viral mathematical model for hepatitis B in the acute phase of infection. The model incorporates hepatocytes, hepatitis B virus, immune system cells and cytokine dynamics using a system of ordinary differential equations.
Project description:The woodchuck model of hepatitis B virus (HBV) infection displays many characteristics of human infection and has particular value for characterizing the host immune responses during the development of chronic infection. Using the newly developed custom woodchuck microarray platform, we compared the intrahepatic transcriptional responses of neonatal woodchucks with self-limiting and progressing persistent infection with woodchuck hepatitis virus (WHV). This revealed that WHV does not induce intrahepatic gene expression during the early acute stage of infection (8 weeks), suggesting it is a “stealth” virus. At the mid-acute phase of infection (14 weeks), resolution was associated with induction of a prominent cytotoxic T cell signature, with perforin and other markers of immune-mediated cytotolytic response being strongly expressed. Strikingly, this was accompanied by high level expression of PD-1 and various other inhibitory T cell receptors, which likely act to minimize liver damage by cytotoxic T cells during viral clearance. Conversely, self-limiting infection was not associated with a strong interferon-α/β (IFN-α/β) transcriptional response, while the IFN-γ signaling response (as measured by expression of CXCL9) in the mid-acute phase was comparable to that in chronically infected adult animals. Nevertheless, viperin and other antiviral genes were differentially expressed during resolving infection, suggesting that a subset of interferon-stimulated genes (ISGs) may play a role in the control of WHV replication. Conclusion: This study identifies new immune pathways associated with the clearance of hepadnavirus infection and reveals novel targets with potential for the treatment of chronic hepatitis B.
Project description:The woodchuck model of hepatitis B virus (HBV) infection displays many characteristics of human infection and has particular value for characterizing the host immune responses during the development of chronic infection. Using the newly developed custom woodchuck microarray platform, we compared the intrahepatic transcriptional responses of neonatal woodchucks with self-limiting and progressing persistent infection with woodchuck hepatitis virus (WHV). This revealed that WHV does not induce intrahepatic gene expression during the early acute stage of infection (8 weeks), suggesting it is a M-bM-^@M-^\stealthM-bM-^@M-^] virus. At the mid-acute phase of infection (14 weeks), resolution was associated with induction of a prominent cytotoxic T cell signature, with perforin and other markers of immune-mediated cytotolytic response being strongly expressed. Strikingly, this was accompanied by high level expression of PD-1 and various other inhibitory T cell receptors, which likely act to minimize liver damage by cytotoxic T cells during viral clearance. Conversely, self-limiting infection was not associated with a strong interferon-M-NM-1/M-NM-2 (IFN-M-NM-1/M-NM-2) transcriptional response, while the IFN-M-NM-3 signaling response (as measured by expression of CXCL9) in the mid-acute phase was comparable to that in chronically infected adult animals. Nevertheless, viperin and other antiviral genes were differentially expressed during resolving infection, suggesting that a subset of interferon-stimulated genes (ISGs) may play a role in the control of WHV replication. Conclusion: This study identifies new immune pathways associated with the clearance of hepadnavirus infection and reveals novel targets with potential for the treatment of chronic hepatitis B. Neonatal woodchucks of both genders were infected at 3 days of age with the same WHV7P1 inoculum containing 5 x 106 WID50 of WHV strain WHV7-11. Custom microarrays were generated from sequences obtained in transcriptome sequencing of woodchuck liver and PBMCs, and were used to examine liver gene expression in animals which eventually become chronically infected with WHV (8 weeks, n=5; 14 weeks, n=9), animals that eventually resolve WHV infection (8 weeks, n=10;14 weeks, n=7) and uninfected animals (8 weeks, n=5;14 weeks,n=5).
Project description:Most individuals exposed to hepatitis C virus (HCV) become persistently infected while a minority spontaneously eliminate the virus. Although early immune events influence infection outcome, the cellular composition, molecular effectors, and timeframe of the host response active shortly after viral exposure remain incompletely understood. Employing specimens collected from people who inject drugs (PWID) with high risk of HCV exposure, we utilized RNA-Seq to characterize immune function in peripheral blood before, during, and after acute HCV infection resulting in spontaneous resolution. Our results provide a detailed description of innate immune programs active in peripheral blood during acute HCV infection, which include prominent type I interferon and inflammatory signatures. Innate immune gene expression rapidly returns to pre-infection levels upon viral clearance. This innate response coincides with a decrease in B cell transcriptional signatures. These results represent the first longitudinal transcriptomic characterization of human immune function in acute HCV infection and identify several dynamically regulated features of the complex response to natural HCV exposure.
Project description:Hepatitis A virus (HAV) is a hepatotropic human picornavirus that has been associated only with acute infection. Its pathogenesis is not well understood since there have been few recent studies in animal models using modern methodologies. We characterized HAV infections in three chimpanzees, quantifying viral RNA by qRT-PCR and examining critical aspects of the innate immune response including intrahepatic interferon-stimulated gene expression. We compared these infection profiles with similar studies of chimpanzees infected with hepatitis C virus (HCV), a hepatotropic flavivirus that frequently causes persistent infection. Surprisingly, HAV-infected animals exhibited very limited induction of type I interferon-stimulated genes in the liver compared to chimpanzees with acute resolving HCV infection, despite similar levels of viremia and 100-fold greater quantities of viral RNA in the liver. Minimal ISG15 and IFIT1 responses peaked 1-2 weeks after HAV challenge, then subsided despite continuing high hepatic viral loads. An acute inflammatory response at 3-4 weeks correlated with the appearance of virus-specific antibodies, and both apoptosis and proliferation of hepatocytes. Despite this, HAV RNA persisted in the liver for months, remaining present long after its clearance from serum and feces and revealing dramatic differences in the kinetics of clearance in the three compartments. Viral RNA was detected in the liver for significantly longer (35 to >48 weeks) than HCV RNA in animals with acute resolving HCV infection (10-20 weeks). Collectively, these findings suggest that early HAV infection is far stealthier than HCV infection and represents a distinctly different paradigm in viral-host interactions within the liver.
Project description:The natural history of chronic hepatitis B virus (HBV) infection could be divided in different phases by transaminase and HBV replication levels. However, it remains unknown how the intrahepatic transcriptomes in patients are correlated with the clinical phases. Here, we determined the intrahepatic transcriptomes of chronic hepatitis B patients and examined the role of specific groups of genes, including immune-related genes, in the control of hepatitis B virus infection. The transcriptomes of 83 chronic hepatitis B patients (22 immune tolerant, 50 immune clearance, and 11 inactive carrier state) were analyzed by performing microarray analysis of liver biopsies.KEGG pathway analysis showed that immune response genes and interferon-stimulated genes were up-regulated in the immune clearance phase. Although immune tolerant patients and inactive state carriers had significantly different serum viral loads, the hepatic transcriptomes of the two groups were largely similar and only significantly differed in the expression of 109 genes (p < 0.01). Thus, we hypothesized that some of the 109 genes may be involved in HBV control and identified genes of interest by performing systematic screening using specific siRNAs. We showed that silencing candidate genes such as EVA1A resulted in significantly increased viral replication. Conversely, overexpression of candidate genes suppressed virus replication. Conclusions: The immune related pathways were up-regulated in the immune clearance phase but not in the inactive carrier phase. A number of host genes unrelated to immune pathways were expressed in the inactive carrier phase and these may participate in the control of hepatitis B virus replication, resulting in low viral replication. This dataset is part of the TransQST collection.
Project description:The aim of this study was to compare murine immune responses, particularly CD8+ T cell activation, in acute infection of either Ross River virus (RRV) or lymphocytic choriomeningitis virus (LCMV). LCMV induces a strong CD8+ T cell response that is required for viral clearance. RRV induces CD8+ T cells that only affect viral clearance in certain tissue and do not contribute to prevention of viral RNA persistence in lymphoid and joint-associated tissue. We sequenced cells from the draining lymph node at 5 days post infection to assess activation states of CD8+ T cells at this timepoint.