Basic Sciences Plenary: The Tempo and Mode of SIV and HIV Outbreaks
Dr. Michael Worobey
The CAHR 2010 Basic Sciences Track Plenary seminar was presented by Dr. Michael Worobey, Associate Professor at Arizona State University. His talk provided a detailed introduction to viral sequence-based phylogenic methods and their utility to examine the evolutionary history of HIV and SIV. In particular, a ‘molecular clock’ approach using known dates of sample collection and predicted rates of HIV evolution allowed Dr. Worobey to estimate that transmission of HIV into the human population likely occurred in the early 1900’s in Africa, and that subsequent spread of HIV to North America occurred via Haiti in the 1960’s – well before the identification of HIV/AIDS in the early 1980’s. A similar analysis of SIV sequences indicated that this virus has co-evolved with non-human primates for at least 200,000 years (or likely much longer). This observation suggests that sufficient time has passed to allow SIV to reach an evolutionary equilibrium, which might help to explain the general lack of pathology associated with infection in its natural host. Dr. Worobey highlighted the impact of societal changes on the rate of HIV transmission, wherein the birth of cities in Western and Central Africa appeared to be a major contributor. If human social/behavioural changes have indeed played a key role in establishing and maintaining the HIV epidemic, Dr. Worobey’s work suggests that targeting these issues may be our most immediate means to stem the tide of HIV/AIDS in a meaningfully way.