A clinical trial of an HIV-1 vaccine, RV144, undertaken in Thailand in 2009, had surprising results. In some patients, vaccination led to a decreased risk of HIV-1 infection but in other patients the infection risk increased but not compared with placebo.
After investigation, researchers have elucidated the reasons for these distinct responses. They analysed the genetic variants of the human leukocyte antigen (HLA) class II immune proteins in 760 trial participants. It was found that the HLA DQB1*06 allele (and presence of IgA antibodies) negated any protective effect of the vaccine.
Conversely, the HLA DPB1*13 allele (and presence of IgG antibodies) decreased susceptibility after vaccination
Differences in vaccine-induced responses elicited by individuals with HLA-DPB1*13 should be further examined to determine the mechanism of protection of the vaccine, the authors conclude in
Science Translational Medicine
(online, 15 July 2015)
Correction: This article was updated on 24 July 2015 at 13:01 (BST) to correctly state that risk of infection did not increase compared with placebo and that the HLA DQB1*06 allele (and presence of IgA antibodies) increased risk of HIV-1 infection and not suceptibility to HIV infection after vaccination as originally published. The image caption was also changed to say that HIV infection was less likely, not more likely, in some patients after vaccination owing to the presence of a genetic variant.
 Prentice HA, Ehrenberg PK, Rolland M et al . HLA class II genes modulate vaccine-induced antibody responses to affect HIV-1 acquisition. Sci Transl Med 2015;7:296ra112. doi:10.1126/scitranslmed.aab4005.