Origins of HIV

摘要

Social, economic, and political changes during the last 100 years have resulted in unprecedented contact and global movement among human populations. Under these conditions, the transmission of an animal virus to a human host (zoonotic transmission) enables the rapid spread of a virus beyond the geographic range of its original animal host. The most serious viral epidemic resulting from zoonotic transmission is AIDS caused by the human immunodeficiency viruses (HIVs). Exactly when simian immunodeficiency viruses (SIVs) were transmitted from nonhuman primates to humans and began to diversify, resulting in the emergence of HIVs, is still under investigation. Establishing the date of emergence of HIVs is imperative to elucidating how transmission occurred and to finding ways to prevent zoonotic transmissions in the future. Now, on page 1789 of this issue, Kor-ber et al. use a phylogenetic analysis, in combination with known sampling dates, to estimate the year of origin for the HIV-1 M ("main") group of viruses, the principal cause of the AIDS pandemic.