Old biopsy brings new insight to HIV-1 evolution

Human immunodeficiency virus type 1 (HIV-1) diversified in west-central Africa long before the recognized AIDS pandemic, according to a genetics study published in this week’s issue of Nature.

The origin of the current AIDS pandemic has been a subject of great speculation since AIDS was first described in 1981. Now Michael Worobey from the University of Arizona, USA, and his international team has investigated a new source of ‘old’ genetic material that offers fresh insights into the evolution of pandemic AIDS viruses.

The team analyzed viral sequences from a paraffin-embedded lymph node biopsy specimen collected in 1960 from a woman in what is now Kinshasa, Democratic Republic of Congo. They compared this against a viral sequence from 1959, which is the oldest known HIV-1 case and the only other pre-1976 HIV-1 viral sequence available to date.

The team’s results suggest that these viruses evolved from a common ancestor circulating in the African population near the beginning of the twentieth century. They also suggest there is a link between rapid urbanization and the emergence of this area as an epicenter for the HIV/AIDS pandemic — with the rise of cities in this region contributing to the initial establishment and the early spread of HIV-1.

There are many more paraffin-embedded HIV-1-infected specimens in the archival banks of west-central African hospitals that could provide a vast source of clinical material for viral genetic analyses. Resurrecting more viral sequences from early African HIV-1 cases could offer further insights, because this virus evolves rapidly — up to a million times faster than that of animal DNA — substantial amounts of sequence change occur in a matter of decades, note Paul M. Sharp of the University of Edinburgh, UK, and Beatrice H. Hahn of the University of Alabama at Birmingham, USA, in a related News and Views article.

Also in this week’s issue of Nature, a Review article by Dan Barouch of the Harvard Medical School summarizes the challenges and prospects of prophylactic HIV-1 vaccines, and calls for a renewed and coordinated commitment to basic research, preclinical studies and clinical trials. A Commentary by Ruslan Medzhitov of Yale University and Dan Littman of New York University also supports the call for a rethink of HIV-vaccine development. Medzhitov and Littman suggest that, to date, immunology approaches have been less than scientific and would benefit from improving our understanding of the immune system.