HCV/Hepatitis C Re-Infection

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HCV/Hepatitis C Re-Infection

People Re-infected with Hepatitis C Are More Likely to Spontaneously Clear Virus, Indicating Partial Immunity

SUMMARY: Individuals who experience spontaneous clearance of an initial hepatitis C virus (HCV) infection are more likely to clear the virus again without treatment if they become re-infected.

This finding, reported in the January 2010 issue of Gastroenterology, demonstrates that the immune system can develop some degree of natural immunity against HCV, but protection is not complete.

By Liz Highleyman

http://www.hivandhepatitis.com/hep_c/news/2010/012610_b.html

Unlike diseases that are only contracted once because the body develops protective immunity, HCV infection can occur again after spontaneous clearance or successful treatment. It is not certain, however, how often this occurs or whether the immune system provides some level of protection against re-infection.

Osburn from s Hopkins and colleagues followed a group of active injection drug users (IDUs) -- a group with ongoing exposure to HCV -- who had spontaneously controlled an initial infection to determine whether primary control conferred protection against future chronic infection (persisting more than 6 months). The study included 22 active IDUs who had cleared a primary HCV infection for at least 60 days. Participants were monitored monthly to check for re-infection, defined as the detection of a new HCV infection. Immune protection was assessed based on the magnitude and duration of viremia (detectable virus in the blood) following re-infection and generation of T-cell and neutralizing antibody responses. ResultsHCV re-infection occurred in 11 IDUs -- or 50% of study participants -- who previously spontaneously controlled primary HCV infection.

83% of re-infected patients demonstrated spontaneous viral clearance the second time -- much higher that the approximately 25% of people who naturally clear an initial infection.The duration and maximum level of viremia during subsequent episodes of re-infection were significantly lower than those seen during initial infection in the same individuals.In contrast to chronic infection, HCV re-infection was associated with a significant increase in the breadth of T-cell responses.

Neutralizing antibodies against HCV "pseudoparticles" were detected in 60% of re-infected participants during acute infection; in contrast, cross-reactive neutralizing antibodies are rarely detected in people who progress to chronic infection.

Based on these results, the investigators concluded, "HCV re-infection is associated with a reduction in the magnitude and duration of viremia (compared with the initial infection), broadened cellular immune responses, and generation of cross-reactive humoral responses.""These findings are consistent with development of adaptive immunity that is not sterilizing but protects against chronic disease," they added.

These results are important because if HCV infection can trigger production of T-cell and/or neutralizing antibody responses, it is more likely that an effective vaccine could be developed.Department of Medicine & Department of Oncology, s Hopkins Medical Institutions, Baltimore, MD; Department of Infectious Diseases, Southwest Hospital, Third Military Medical University, Chongqing,

China.1/26/10

ReferenceWO Osburn, BE Fisher, KA Dowd, and others. Spontaneous Control of Primary Hepatitis C Virus Infection and Immunity against Persistent Reinfection. Gastroenterology 138

(1): 315-324 (Abstract). January 2010.

http://www.hivandhepatitis.com/hep_c/news/2010/012610_b.html

http://Hepatitis Cnewdrugs.blogspot.com/2010/01/hcvhepatitis-c-re-infection.html