Lack of susceptibility of Chacma baboons (Papio ursinus orientalis) to hepatitis C virus infection.

The main reason to ascertain whether baboons are susceptible to infection with hepatitis C virus (HCV) is the need to replace chimpanzees, which are endangered, as an animal model for undertaking research into the biology and host-virus interactions of HCV, and for developing a vaccine against this virus. A second reason is that baboons are a possible source of xenografts for human liver transplantation. We inoculated serum containing HCV into four Chacma baboons and monitored them for 52 weeks for evidence of infection. Serum was tested for antibody to HCV, HCV RNA, and aminotransferase concentrations at 2-week intervals for 26 weeks and thereafter at 4-week intervals. Liver tissue was examined at 28 and 52 weeks for histopathological changes and viral RNA, and at 52 weeks for viral particles using electron microscopy. Reverse transcription-polymerase chain reaction assay was used to detect HCV RNA, and the results were confirmed by Southern hybridization. Serum aminotransferase concentrations remained within the normal range and liver histology was normal during the follow-up period. Passive transmission of anti-HCV to the baboons was observed during the first 4 weeks. HCV RNA was not detectable in any serum or liver sample and electron microscopy failed to reveal viral particles in liver tissue. In conclusion, we did not find Chacma baboons to be susceptible to infection with HCV, although we cannot deny that in an immunosuppressed liver transplant recipient, infection of a baboon xenograft might occur. Another animal model for HCV infection must be sought.

Molecular epidemiology of hepatitis C virus infection at Ga-Rankuwa Hospital.

Different hepatitis C virus (HCV) genotypes may be associated with viral load, severity of liver disease, hepatocellular carcinoma, geographical location and sensitivity to interferon. In this study the prevalence of HCV-RNA and distribution of HCV genotypes was investigated in anti-HCV-positive patients admitted to Ga-Rankuwa Hospital during 1994 and 1995. One hundred and forty-nine sera from three groups of anti-HCV-positive patients (N = 78) were analysed. These included: (i) patients with various liver diseases; (ii) patients admitted to the renal unit; and (iii) a miscellaneous group of patients for whom HCV antibody screening was requested. Twenty-six patients (33%) tested positive for viral RNA. Restriction fragment length polymorphism (RFLP) analysis of these patients showed that HCV genotypes 1, 2 and 5 were present. Type 2 (35%) was the dominant genotype in the region served by Ga-Rankuwa Hospital. In a large proportion of viral RNA-positive patients (27%), the polymerase chain reaction product could not be digested with one of the sets of enzymes, and therefore could not be classified into genotypes 1 to 6. Further studies are now in progress to enhance our current knowledge of the epidemiology of HCV infection.