Old Tissue Specimen Aids Historical Search for HIV Infection
HIV-1 infection probably emerged in sub-Saharan Africans during the early 20th century and possibly the late 19th century. This latest, and earliest, estimate of the emergence of HIV-1 in humans is based on a comparison of the genetic sequences from 2 of the oldest, known HIV-1 samples: one (ZR59) from a 1959 plasma sample from a Kinshasa man (in the Democratic Republic of the Congo) and another (DRC60) that was recently found in a 1960 preserved lymph node from a Kinshasa woman. An international group of investigators published their evolutionary assessment of HIV-1, based on these 2 viral samples, in this week's Nature.
Investigators at the University of Arizona obtained access to more than 800 paraffin-embedded human-tissue specimens from the 1958-1962 archives of the Department of Anatomy and Pathology at the University of Kinshasa and screened 27 blocks by means of RT-PCR for HIV-1 sequences. One specimen, a section of lymph node from 1960, contained HIV-1 RNA.
Genetic sequences of this newly discovered HIV-1 sample, DRC60, were then compared with those of ZR59 and found to be divergent enough to indicate several decades of independent evolution. The investigators performed molecular-clock analyses, which demonstrated that the most recent, common ancestor of ZR59 and DRC60 likely dated to the early 20th century—specifically 1908, with a probable date range of 1884-1924.
Not coincidentally, this was the era of colonial growth in sub-Saharan Africa, which included a population expansion in Kinshasa and similar towns. The belief is that cross-species transmission of HIV-1, from wild chimpanzees, occurred in this general geographic area by means of human predation—now approximately 100 years ago.
A Nature report indicates that the investigators will continue to mine the remaining archived specimens from Kinshasa in an attempt to further define the beginning of human HIV-1 infection.
Emergence of HIV-1 in Africans predates the comic serial Tintin in the Congo (1931).
