When HIV spread afar
- Department of Biology, Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA 16802; and Fogarty International Center, National Institutes of Health, Bethesda, MD 20892
Since the first cases of AIDS were described in the United States in 1981, the origin of this devastating disease has intrigued scientists and the general public alike. This fascination is reflected in the numerous theories put forth for the emergence of HIV, the most infamous of which involves the alleged use of HIV-contaminated oral polio vaccine in Africa during the late 1950s (1). Thankfully, a steady stream of virological data and phylogenetic analyses now means that the oral polio vaccine theory has rightly been assigned to the back shelves of science fiction (2). The article by Gilbert et al. in this issue of PNAS (3) similarly uses an elegant combination of virology and phylogeny to shed light on another key moment in the history of HIV: its spread from an origin in Africa to the Americas.
Haiti: Sink or Source?
From the earliest days of AIDS reporting, it was clear that the Caribbean nation of Haiti was particularly significant in this epidemic. Indeed, HIV/AIDS was initially found to be relatively frequent in persons of Haitian origin, and some Haitian isolates of HIV-1 fell on relatively deep branches in phylogenetic trees, suggesting that the virus took an early foothold in that country. Until now, however, the connection among Africa, Haiti, and industrialized nations like the United States has largely remained the stuff of speculation. By deploying an impressive armory of phylogenetic techniques, Gilbert et al. (3) provide the first solid evidence for the role of Haiti in the emergence and evolution of HIV.
Like many RNA viruses and retroviruses, HIV-1 is genetically very diverse, falling into a series of phylogenetically defined clades, or subtypes, that have differing geographic distributions, as well as an ever-expanding set of intersubtype recombinants. The focus …
*E-mail: ech15{at}psu.edu
