US researchers have suggested that a five-part investigational vaccine may protect monkeys from HIV-like virus to 55 percent.
Adding three more targets to the investigational vaccine for a total of five, more than half of the vaccinated animals were protected from simian-human immunodeficiency virus infection.
According to researchers from Duke University Medical Center in Durham, the vaccine added three more targets to a human vaccine candidate that showed a promise.
The team used a more-is-better approach in monkeys that appeared to improve vaccine protection from an HIV-like virus.
"The vaccine regimen tested in the Thai trial, known as RV144, had a 31 percent efficacy and is the only HIV investigational vaccine regimen to have demonstrated even modest protection from HIV infection," said senior study author Barton F. Haynes.
"In this study in monkeys, we increased that level of protection to 55 percent by using a pentavalent (five-part) vaccine," Haynes added.
The researchers -- including Bette T. Korber of the Los Alamos National Laboratory, who led the vaccine design -- started from the foundation used in the RV144 human vaccine trial in Thailand, adding targets that elicited antibody responses to regions of the HIV envelope.
Those antibodies were fairly easy to induce, Haynes said.
By adding the three additional regions of the viral envelope to the investigational vaccine, the researchers improved the level of protection afforded to animals exposed to a difficult-to-neutralise strain of the simian virus, which is comparable to HIV.
"Vaccine protection using this model of virus infection in primates is possible," said lead study author Todd Bradley.
"This is a proof-of-concept that provides a strategy to improve upon the first HIV vaccine regimen that provided limited protection in people," Bradley stated.
The study is published online in the journal Nature Communications.
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