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HIV Superinfection May Boost Viral Load but Does Not Worsen Disease Progression


Superinfection with a second strain of HIV may lead to a more rapid increase in plasma HIV RNA levels, but apparently does not contribute much to CD4 T-cell loss or disease progression, according to a study published in the September 24 edition of AIDS.

Superinfection refers to becoming infected with a second or subsequent strain of a pathogen after initial infection. Over the course of the epidemic, studies have produced conflicting findings about the effects -- and even the existence -- of HIV superinfection.

Keshet Ronen and Julie Overbaugh from the Fred Hutchinson Cancer Research Center and colleagues conducted a prospective study of a cohort of high-risk women in Mombasa, Kenya -- a group previously found to have an HIV superinfection rate of 3% per year.

This analysis included 144 women with HIV-1, of whom 21 experienced superinfection during follow-up between 1993 and 2008. The researchers collected clinical and laboratory data at quarterly intervals, comparing viral load and CD4 counts over time between women with single infection and those with superinfection.


  • Superinfected women showed a significantly more rapid rate of viral load increase compared to those with a single strain.
  • There was a borderline association between superinfection and faster CD4 cell decline, but the difference did not reach statistical significance.
  • There was no significant difference in time to clinical progression to a CD4 count below 200 cells/mm3, needing to start antiretroviral therapy (based on older CD4-based initiation thresholds), or death.
  • In an adjusted analysis, superinfected women had lower baseline viral load before superinfection occurred, and there was a trend toward increased viral load at the time of superinfection.

"These data suggest that superinfection is associated with accelerated progression in laboratory measures of HIV-1 disease, but has a limited impact on the occurrence of clinical events," the study authors concluded. "Our observation that superinfected individuals have lower baseline viral load prior to superinfection suggests that there may be host or viral determinants of susceptibility to superinfection."



K Ronen, BA Richardson, SM Graham, J Overbaugh et al. HIV-1 superinfection is associated with an accelerated viral load increase but has a limited impact on disease progression. AIDS 28(15):2281-2286. September 24, 2014.