Acute
HCV infection often has no clinical symptoms, and therefore often goes detected
at this early stage. HIV positive people, however,
typically receive periodic monitoring of liver enzyme (ALT and AST) levels to
check for antiretroviral drug
liver toxicity. These elevations can also signal a recent HCV infection.
About
one-quarter of HIV negative people with acute HCV infection spontaneously clear
the virus without treatment. But coinfection
with HIV appears to impair immune response against HCV, according to a study
published in the June 1, 2008, Journal of Infectious Diseases.
Mark
Danta - who has been documenting the acute HCV outbreak in the U.K. - and an international
team of colleagues conducted a study comparing HIV positive and HIV negative individuals
with recently acquired hepatitis C.
The researchers identified 55 HIV positive
men with acute HCV infection; 8 HCV monoinfected individuals served as control
subjects. Blood samples from 14 of the HIV-HCV coinfected patients and all 8 HCV
monoinfected subjects were analyzed for HCV-specific T-cell responses against
a range of HCV antigens using interferon-gamma ELISpot and proliferation assays.
Genetic variation of the HCV E1/E2 region and selection pressure on the virus
were measured in 8 coinfected patients using cloned sequences over time.
Results
•
52
HIV-HCV coinfected individuals (95%) developed persistent chronic HCV infection,
compared with 65% of HCV monoinfected control subjects.
•
HIV-HCV
coinfected patients had significantly higher HCV RNA levels than those with HCV
monoinfection.
•
Coinfected
patients also had weaker immune responses against HCV than those with HCV alone.
•
HIV-HCV
coinfected individuals exhibited significantly reduced interferon-gamma ELISpot
responses compared with HCV monoinfected subjects (1/10 vs 5/8, respectively).
•
This
difference in response was especially evident against HCV non-structural proteins.
•
Among
coinfected patients, increased HCV genetic diversity was observed between the
first and subsequent time points, with no evidence for positive selection in the
E1/E2 region sequenced.
Conclusion
Based
on these findings, the study authors concluded that, "HIV coinfection is
associated with increased rates of HCV persistence and a lack of critical CD4
T-cell responses, with no evidence of immune selection pressure during early HCV
infection."
They added that, "Loss of key cellular immune responses
against HCV during acute disease may contribute to the failure of early host control
of HCV in [HIV-HCV] coinfected patients."
Centre for Hepatology,
Department of HIV Medicine, Department of Primary Care and Population Sciences,
and Department of Infection, Royal Free and University College Medical School,
London, UK; Nuffield Department of Clinical Medicine and Department of Zoology,
University of Oxford, Oxford, UK; Medical Research Centre, John Radcliffe Hospital,
Oxford, UK; Department of Infectious Diseases and Tropical Medicine, S. Bortolo
Hospital, Vicenza, Italy; St. Vincent's Clinical School, University of New South
Wales, Sydney, Australia; Department of Medicine II, University of Freiburg, Freiburg,
Germany.
6/06/08
Reference M Danta, N Semmo, P Fabris,
and others. Impact of HIV on host-virus interactions during early hepatitis C
virus infection. Journal of Infectious Diseases 197(11): 1558-1566. June
1, 2008.
Over
the past several years, researchers in the U.K., Europe, and Australia have reported
several outbreaks of apparently 
