Hepatitis B Viral Strain Unique to Chimpanzees

It has become evident to scientists that a particular strain of the hepatitis B virus (HBV) is unique to wild and captive populations of chimpanzees. Although chimpanzees have long been used as an experimental model organism to study infection and transmission of HBV from humans, they were not believed to be natural hosts for the virus. Furthermore wild-caught chimpanzees that were positive for hepatitis B surface antigen, an indicator of chronic infection, were assumed to have contracted the virus solely via injection of human serum; an illegal practice performed in Africa following capture to improve chimpanzee endurance during extended periods of travel.

Researchers have sequenced the genomes of HBV from chimpanzees and humans with chronic infection by using important gene technology including PCR-amplification, gel electrophoresis and DNA sequencing using advanced computer software. As a result of such gene technology scientists have been able to reject their previous claim that HBV is not indigenous to chimpanzee populations. The DNA of chimpanzee HBV and human HBV are in fact considerably different in their nucleotide sequences and derived amino acid sequences to be regarded as separate viral strains.

This discovery has important implications for veterinarians and medical doctors in the health and well-being of people who are in direct contact with chimpanzees as transmission can occur via blood or body fluid contact. Although the frequency of HBV infection in chimpanzees remains unknown, caretakers in zoos and wildlife refuges should take all appropriate precautions including inoculation to largely reduce the risk of contracting the virus.

Posted by Geoff Nicolson
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References:
Primary Reference

Margolis, H., Purcell, R. (2000). “Identification of hepatitis B virus indigenous to chimpanzees.” Proc Natl Acad Sci USA 97(4): 1661–1664.

Secondary Reference

Vartanian, J., Henry, M. (2002). “Identification of a Hepatitis B Virus Genome in Wild Chimpanzees from East Africa Indicates a Wide Geographical Dispersion among Equatorial African Primates.” Journal of Virology pp. 11155-11158.

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