Kris Krawczynski

Infectivity of Hepatitis C Virus in Plasma After Drying and Storing at Room Temperature

OBJECTIVE To determine effect of environmental exposure on the survival and infectivity of hepatitis C virus (HCV). METHODS Three aliquots of chimpanzee plasma containing HCV and proven infectious HCV inoculum were dried and stored at room temperature, 1 aliquot for 16 hours, 1 for 4 days, and 1 for 7 days. A chimpanzee (CH247) was sequentially inoculated intravenously with each of these experimental inocula, beginning with the material stored for 7 days. Each inoculation was separated by at least 18 weeks of follow-up to monitor for infection. The concentration of HCV RNA was measured and quasi species were sequenced for each experimental inoculum and in serum samples from CH247. RESULTS Evidence of HCV infection developed in CH247 only after inoculation with the material stored for 16 hours. No infection occurred after inoculation with the material stored for 7 days or 4 days. Compared with the original infectious chimpanzee plasma, the concentration of HCV RNA was 1 log lower in all 3 experimental inocula. The same predominant sequences were found in similar proportions in the original chimpanzee plasma and in the experimental inocula, as well as in serum samples from CH247. CONCLUSION HCV in plasma can survive drying and environmental exposure to room temperature for at least 16 hours, which supports the results of recent epidemiologic investigations that implicated blood-contaminated inanimate surfaces, objects, and/or devices as reservoirs for patient-to-patient transmission of HCV. Healthcare professionals in all settings should review their aseptic techniques and infection control practices to ensure that they are being performed in a manner that prevents cross-contamination from such reservoirs.

Both innate and adaptive immunity mediate protective immunity against hepatitis C virus infection in chimpanzees

Understanding the immunological correlates associated with protective immunity following hepatitis C virus (HCV) reexposure is a prerequisite for the design of effective HCV vaccines and immunotherapeutics. In this study we performed a comprehensive analysis of innate and adaptive immunity following HCV reexposure of two chimpanzees that had previously recovered from HCV‐JFH1 infection. One of the chimpanzees, CH10274, became protected from active viremia by repeated challenges with homologous HCV‐JFH1 and developed neutralizing antibodies, but was later infected with high‐level viremia by a heterologous challenge with the HCV H77 virus that persisted for more than 1 year. The other chimpanzee, CH10273, was protected from a similar, heterologous H77 challenge without any evidence of neutralizing antibodies. Peripheral HCV‐specific T‐cell responses were present in both chimpanzees after challenges and, interestingly, the overall magnitude of response was lower in uninfected CH10273, which, however, exhibited a more robust CD8+ T‐cell response. CH10273 showed higher hepatic expression of CD8 and CD56 (natural killer) markers than CH10274 did shortly after inoculation with H77. The heightened T‐cell response was associated with an enhanced hepatic production of interferons (both type I and II) and interferon‐stimulated genes (ISGs) in CH10273. Therefore, protection or clearance of HCV reinfection upon heterologous rechallenge depends on the activation of both intrahepatic innate and cellular immune responses. Furthermore, our results suggest that serum neutralizing antibodies may contribute to early control of viral replication and spread after homologous HCV rechallenges but may not be sufficient for a long‐term protective immunity. Conclusion: Our study shows that protective immunity against HCV reinfection is orchestrated by a complex network of innate and adaptive immune responses. (HEPATOLOGY 2011;)

Immunopathogenesis of hepatitis E virus infection.

The course of hepatitis E virus infection (HEV) can vary substantially between different individuals. Although most infections take a clinically silent asymptomatic course, a few patients may develop severe hepatitis that can progress to fulminant hepatic failure. In addition, cases of chronic hepatitis E have been described in immunosuppressed patients. The detailed mechanisms leading to different clinical outcomes of HEV infection are only partially understood. Both viral factors including the HEV genotype and the dose of the infectious inoculum, as well as host factors such as stage of liver disease, pregnancy or distinct genetic polymorphisms determine the course of HEV infection. Recent studies were able to associate T-cell responses, activation of the interferon system and viral evolution with severity or chronicity of hepatitis E. We here summarize the emerging data on the immunopathogenesis of HEV infection.

T-cell vaccines that elicit effective immune responses against HCV in chimpanzees may create greater immune pressure for viral mutation

A prime/boost vaccine strategy that transfects antigen-presenting cells using ligand-modified immunoliposomes to efficiently deliver plasmid DNA, followed by boosting with non-replicating recombinant adenovirus was used in chimpanzees to generate HCV-specific memory T-cells. Three chimpanzees (two vaccines, one control) were immunized with immunoliposomes complexed with DNA expressing NS3-NS5B or complexed with empty vector. Animals were boosted with adenovirus expressing NS3-NS5B, or non-recombinant adenovirus (control). Using liposome delivery we were able to obtain specific HCV responses following DNA priming in the chimpanzees. This data and mouse immunization studies confirm this as a more efficient delivery system than direct intramuscular inoculations with naked DNA. Subsequent to the adenovirus boost significant increases in peripheral HCV-specific T-cell responses and intrahepatic IFN-gamma and CD3varepsilon mRNA were also observed in the two vaccinated animals. Following challenge (100 CID(50)) both vaccinated animals showed immediate and significant control of viral replication (peak titers 3.7x10(4) and 9x10(3)IU/mL at weeks 1 and 2), which coincided with increases in HCV-specific T-cell responses. Viral kinetics in the control animal were comparable to historical controls with exponential increases in titer during the first several weeks. One vaccinated animal developed a low-level persistent infection (2x10(3)IU/mL) which correlated with a decrease in HCV-specific T-cell responses. Circulating virus isolated from both vaccinated animals showed approximately 2-fold greater nonsynonymous mutation rates compared to controls and the nonsynonymous/synonymous mutation rate ratio was indicative of positive selection. These data suggest that although T-cell vaccines can induce immune responses capable of controlling HCV, they also induce high levels of immune pressure for the potential selection of escape mutants.

Histopathology and detection of hepatitis C virus in liver

The discovery of the hepatitis C virus (HCV) made it possible to delineate the pathological features of HCV infection in the liver and to compare them with the numerous published descriptions of the pathology of parenterally transmitted non-A, non-B hepatitis. Not surprisingly, the two proved to be very similar. Study of the pathogenesis and immunopathology of HCV infection, however, has been hampered by the apparently small amounts of viral proteins present in hepatocytes and other liver cells. Nearly a decade after discovery of the virus there is still no entirely satisfactory method, suitable for routine diagnostic use, for demonstrating the location of the virus. Detection of viral RNA in liver and other organs has therefore played a significant part in investigation of the pathophysiology of HCV infection. Both the histological features and detection of the virus by immunostaining, in situ hybridisation and tissue polymerase chain reaction (PCR) will be discussed in this review.

Kinetics of miR-122 Expression in the Liver during Acute HCV Infection

The relationships among micro RNA-122 (miR-122) expression in the liver, hepatitis C virus (HCV) replication and hepatic damage were analyzed in three chimpanzees observed for 180 days after inoculation with HCV genotype 1a. Levels of miR-122 in the liver and serum were measured by real-time RT PCR in serial liver biopsies and serum samples. Hepatic miR-122 levels were normalized separately for each of three chimpanzees with small RNAs and microRNAs that are endogenous to the liver and are stably expressed. Two- to 4-fold rise in hepatic miR-122 levels was observed at the onset of HCV infection (the first 4 weeks) when HCV titers in the liver and serum increased rapidly in all three chimpanzees in concordance with in vitro data indicating the miR-122 significance for HCV replication. Between 10 to 14 weeks after inoculation, when hepatic and serum HCV RNA titers exceeded 3 logs and alanine aminotransferase (ALT) activity was elevated, hepatic miR-122 levels were in decline. Cumulative data derived from all three chimpanzees from 180 days of observation documented an inverse (negative) correlation between hepatic miR-122 and HCV RNA in the liver and serum and positive correlation between level of serum miR-122 and HCV replication. Subsequent rise of miR-122 level during HCV clearance and ALT normalization suggested a tri-phasic occurrence of the relationship among hepatic miR-122 expression, HCV replication and hepatic destruction, which was the most apparent in one chimpanzee but less evident in two other animals. In vivo kinetics of hepatic and serum miR-122, HCV replication and hepatic destruction reflects complexities of the virus-host interaction during the acute phase of HCV infection.

Hepatitis C virus clearance correlates with HLA-DR expression on proliferating CD8+ T cells in immune-primed chimpanzees.

Vaccination of chimpanzees against hepatitis C virus (HCV) using T‐cell‐based vaccines targeting nonstructural proteins has not resulted in the same levels of control and clearance as those seen in animals reexposed after HCV clearance. We hypothesized that the outcome of infection depends on the different subtypes of activated T cells. We used multicolor flow cytometry to evaluate activation (CD38+/HLA‐DR+) and proliferation (Ki67+/Bcl‐2‐low) profiles of CD4+ and CD8+ T cells in peripheral blood before and after challenge in chimpanzees vaccinated using DNA/adenovirus, mock‐vaccinated, and chimpanzees that had spontaneously cleared infection (rechallenged). The frequencies of activated or proliferating CD8+ T cells peaked at 2 weeks postchallenge in the vaccinated and rechallenged animals, coinciding with reductions in viral titers. However, the magnitude of the responses did not correlate with outcome or sustained control of viral replication. In contrast, proliferation of the CD8+ T cells coexpressing HLA‐DR either with or without CD38 expression was significantly higher at challenge in animals that rapidly cleared HCV and remained so throughout the follow‐up period. Conclusion: Our data suggest that the appearance of proliferating HLA‐DR+/CD8+ T cells can be used as a predictor of a successfully primed memory immune response against HCV and as a marker of effective vaccination in clinical trials. (Hepatology 2014;59:803–813)

Hepatitis C Virus Infection—Pathobiology and Implications for New Therapeutic Options

Despite progress in therapeutic approaches for the elimination of hepatitis C, chronic hepatitis C virus infection remains an important cause of liver disease. Therapeutic intervention with the currently available interferon-based treatment regimens is quite successful, but treatment is difficult to tolerate and is contraindicated in many patients. A better understanding of the HCV biology, immunopathology, and liver disease will help to design better therapeutic strategies. The American Association for the Study of Liver Diseases sponsored a single-topic conference on hepatitis C virus infection on March 4 and 5, 2005, to enhance our current knowledge in the areas of basic and clinical research related to antiviral and immunomodulatory therapies in hepatitis C disease. The faculty consisted of 23 invited experts in the field of viral hepatitis. The program was divided into four sections including: (a) replicative mechanisms and models; (b) viral-host interactions; and (c) antiviral drug development and new strategies; and (d) back to the bedside—current issues. This report summarizes each of the presentations sections.

Recombinant hepatitis E virus vaccine: a successful Phase II trial in a disease-endemic region

Evaluation of: Shrestha MP, McNair Scott R, Joshi DM et al. Safety and efficacy of a recombinant hepatitis E vaccine. N. Engl. J. Med. 356, 895–903 (2007). A recombinant hepatitis E (rHEV) vaccine was evaluated for safety and efficacy in healthy adults susceptible to HEV infection randomly assigned to receive three doses of vaccine (898 subjects) or placebo (896 subjects). Vaccine efficacy in prevention of clinically overt hepatitis E was 95.5% after dose three until the end of the study (median: 804 days, primary end point of the study) and 85.7% 14 days after dose two until dose three (secondary end point). The proportion of subjects with adverse events (general symptoms and injection site findings) was similar among subjects receiving rHEV vaccine or placebo. The rHEV vaccine was proven safe and highly efficacious in preventing clinically overt hepatitis in a high-risk population.