The National Institutes of Allergy and Infectious Diseases (NIAID) announced today that a preventive HIV vaccine candidate developed by NIAID’s Vaccine Research Center (VRC) is progressing into a phase II trial. The 480-person study will be conducted by the HIV Vaccine Trials Network (HVTN) and is dubbed HVTN 204. The vaccine being evaluated is a “prime-boost” approach involving initial priming immunizations with DNA vaccines carrying gag, pol, nef and env genes from HIV-1 followed by a boosting immunization with an adenovirus-based vaccine vector (very similar to the one used by the Merck HIV vaccine candidate described below) that also carries same genes (apart from possibly nef – last time we heard technical issues were precluding the inclusion of this gene). One novel twist to the vaccine – stressed heavily in NIAID’s press release – is that both the DNA and adenovirus components include multiple env genes, one each from HIV subtypes A, B and C. VRC director Gary Nabel is quoted as saying: "This is the first Phase II study of a vaccine candidate that is broadly relevant to the global AIDS pandemic because it combines components of HIV strains found throughout the world.” It is worth noting that only efficacy studies can tell us whether there is any advantage to this putatively broad relevance when it comes to the primary goal of the vaccine: protecting against HIV infection.
Background information on this vaccine approach can be found in TAG’s report from last year’s Office of AIDS Research Advisory Committee (OARAC) meeting on HIV vaccines. An update including new data that was presented at the 2005 Keystone meeting can be found in the IAVI Report.
UPDATE: A couple of links related to the manufacturers of the two vaccine components:
Vical makes NIAID's DNA vaccine (the company had a similar deal with Merck, but Merck dropped the DNA "prime" from their approach due to poor immunogenicity) while GenVec makes the adenovirus vector. GenVec's announcement actually came out last week, preempting today's NIAID release by mentioning the phase II trial plans.