The HIV two-step

Primate research published in Nature this past week provided conflicting evidence on the efficacy of primate versions of two HIV vaccines from Merck & Co. Inc. One report showed that an adenovirus vaccine was able to offer clinical control to more than 90% of monkeys when given before viral challenge. Yet an accompanying article showed that SHIV mutations caused viral escape from a monkey in which a similar vaccine had previously controlled the infection.

In one study, MRK et al. showed that of 21 monkeys vaccinated with vectors expressing the SIV (simian immunodeficiency virus) gag polypeptide, only two developed AIDS-like symptoms after SHIV (HIV-SIV hybrid) challenge. In contrast, 13 of 14 control monkeys developed AIDS-like symptoms. ...