Presentations from the May 21-23 HIV Vaccine Trials Network (HVTN) Meeting

The HVTN has made available the Powerpoint files of presentations from their recent meeting in DC. [1]

Of particular interest, Surojit Sarkar from Emory presents data indicating that – as suggested by the longitudinal data from trials of Merck’s HIV vaccine – CD8 T cell responses induced by Ad5 vectors do no contract in the way that typically occurs during the development of protective memory T cell responses, and that this is associated with the persistence of the vector. [2]

As a result, Ad5-induced CD8 T cell responses appear functionally compromised and display poor proliferative capacity and protective efficacy in Sarkar’s murine studies.

David Watkins also contrasts the breadth of T cell responses that he observes in macaque vaccine studies (6-18 CD8 T cell epitopes) with those observed in the Merck vaccine efficacy trial (3 CD8 T cell epitopes), and several other presenters discuss strategies for improving the number of epitopes targeted by HIV-specific T cell responses. Based on a prior comment to this blog by Ian York, it is to be hoped that members of relevant NIH study sections are being educated about the potential importance of improving the breadth of vaccine-induced T cell responses in humans. [3, 4]