HIV-1 vaccines may not be as reliable against superinfection as once thought

Nov 19 2007

Natural HIV-1 infection does not always elicit a protective immune response, according to a new study published November 16 in PLoS Pathogens.

The team of researchers from Washington University, the Fred Hutchinson Cancer Research Center of Seattle, and the University of Nairobi show how HIV-1 vaccines may not be as reliable against superinfection as once thought.

Superinfection of HIV-1 occurs when an individual infected with one strain of HIV-1 acquires a second strain. Currently there are over 20 published cases of HIV-1 superinfection, most of which have been focused on individuals who have been carefully monitored during their infection. These cases prove that an HIV-1 vaccine may not always protect against infection by a different strain. But because there have been reports of selected individuals, it has been unclear how commonly HIV-1 re-infection occurs.

To address this question, Dr. Julie Overbaugh and her research team investigated the incidence of HIV-1 superinfection in 36 high-risk women followed roughly five years after their initial infection.

Seven cases of superinfection were found; five of them occurring over a year past initial infection. Additionally, three of the seven cases displayed a virus from the same HIV-1 genetic subtype.

This study suggests that immune responses found in natural HIV-1 infection, which fail to provide protection against re-infection, may not be the best path to an effective HIV-1 vaccine.