A stronger immune response occurs in women who have been infected with two different strains of HIV by two different sexual partners than in women infected with one strain of HIV, a new study finds.
This type of dual infection is called HIV "superinfection".
The finding that a mixture of different HIV strains may be one way to trigger a more powerful immune system antibody response may prove useful in efforts to develop an HIV vaccine in the fight against Aids, according to the researchers at the Fred Hutchinson Cancer Research Center in Seattle.
How the study was done
The researchers tracked the immune activity of 12 superinfected women in Kenya for five years. Compared to singly infected women, the superinfected women had about 70% more neutralising antibodies (agents the immune system uses to fight invaders) and their antibodies' ability to neutralise HIV was almost 50% stronger.
The study appears online in the journal PLoS Pathogens.
"We found that women who had been infected twice not only had more potent antibody responses, but some of these women had 'elite' antibody activity, meaning that they had a broad and potent ability to neutralise a wide variety of strains of HIV over a sustained period of time," senior author Julie Overbaugh said.
Only about 1 percent of HIV-infected people are "elite neutralisers," the authors noted.
"Individuals who become superinfected with a second virus from a different partner represent a unique opportunity for studying the antibody response and may provide insights into the process of developing broad neutralising antibodies that could inform HIV-vaccine design," Overbaugh said.
It is estimated that more than 1.1 million Americans have HIV and someone becomes newly infected about every 10 minutes, according to the US Department of Health and Human Services.
Many experts consider an HIV vaccine to be the best way to offer long-term protection against HIV but efforts to develop such a vaccine have achieved only limited success.
The New Mexico AIDS Education and Training Center has more about HIV/AIDS vaccination.
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