June 19, 2012
A new study in Uganda suggests that people infected with HIV can pick up a second strain more commonly than might be expected. However, other people with HIV who continue risky behavior apparently resist such superinfections, a difference scientists are hoping could prove useful to vaccine research.
"A superinfection occurs when an individual is initially infected with a strain or strains of HIV. And then at some point later on, after that person has developed an initial immune response to their first infecting strain, at that later time point they come into contact through risky behavior with a second viral strain and then are superinfected with that second strain," said Dr. Andrew Redd, lead author of the study.
"What we found in our study was that when we looked at a general population of heterosexuals in Uganda, we found that it actually isn't as rare as what we thought," Redd said. "From what we can tell, individuals who get superinfected respond to treatment just fine, and it lowers their viral load and they get healthier." Superinfection with a strain already antiretroviral-resistant "would be a major problem" but "doesn't seem to be a huge risk so far," he said.
Of people who are somehow protected against superinfection despite taking risks, "One question would be what natural immune response to their initial infection is protecting them from the superinfection," said Redd. "And if we can figure that out, that may give us a very interesting avenue to pursue for HIV vaccine research." Current vaccine strategies that attempt to "recreate the natural immune response may be insufficient to protect an individual from infection," he said.
[PNU editor's note: The study, "The Rates of HIV Superinfection and Primary HIV Incidence in a General Population in Rakai, Uganda," was published in the Journal of Infectious Diseases (2012;doi:10.1093/infdis/jis325).]