Superinfection

  • Cases of HIV superinfection have been definitively established, but there is limited evidence about their frequency.
  • Some cases have been associated with CD4 cell declines or transmitted drug resistance, but superinfection does not appear to have a widespread compromising effect on the health of people with HIV.

Superinfection occurs when an HIV-positive person is re-infected with a strain of HIV they do not already have. This new version of HIV may be drug-resistant. Cases of HIV superinfection have been definitively established, sometimes showing a loss of response to antiretroviral therapy after superinfection.1 2 3 Superinfection with wild-type virus can also occur when drug-resistant virus is already present.4

However, superinfection may not be a common event among people taking antiretroviral therapy. One study found no evidence of superinfection among 15 sexually active HIV-positive couples over at least two years. Another analysis of protease and reverse transcriptase sequences from 3155 San Francisco patients, most of whom were taking HIV therapy, failed to show any evidence of superinfection.5 6

A study of 49 long-term HIV-positive couples who do not use condoms when they have sex with each other also found no evidence of HIV superinfection. Instead there was a clear relationship between long-term frequent exposure to their partner’s virus and a strong immune response to that virus, suggesting that repeated exposures eventually build immunity against superinfection.7

A study of 78 recently infected individuals in San Francisco and Los Angeles has reported an annual rate of superinfection of 5% among people not taking antiretroviral therapy. Superinfection occurred between five and 13 months after the estimated date of initial infection.8 Superinfection sped disease progression: within six months, viral loads increased by an average of 1.6 log10 and CD4 cell counts decreased by an average of 132 cells/mm3.

In another instance, superinfection led to the rapid onset of AIDS (within three and a half years) and death (within six years) despite an initial good immune response.9

However two Dutch studies showed that people experiencing viral load increases, either when not on treatment10 or while taking combination therapy11 only rarely do so because of superinfection.  

A 2005 report suggests that superinfection may be more common during the early stage of HIV disease when the immune response to the virus is not well developed.12 Most case reports also reflect superinfections acquired in the first few years after primary infection.

However, in 2007 a Seattle man on treatment who had had an undetectable viral load for over a decade appeared to have a case of superinfection.13 Moreover a five-year prospective study of 36 Kenyan sex workers identified seven cases of superinfection, including two acquired more than four years after primary infection.14

Superinfection with a different subtype leading to recombinant viruses has been documented,15 as has superinfection leading to the existence of two circulating subtypes in an individual.16

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References

  1. Jost S et al. A patient with HIV-1 superinfection. N Engl J Med 347: 731-736, 2002
  2. Booth C et al. Divergent pol sequences as markers of HIV-1 superinfection in a case of recurrent acute seroconversion illness. Fourth European Drug Resistance Workshop, Monte Carlo, abstract 101, 2006
  3. Smith DM et al. HIV drug resistance acquired through superinfection. AIDS 19: 1251-1256, 2005
  4. Koelsch KK et al. Clade B HIV-1 superinfection with wild-type virus after primary infection with drug-resistant clade B virus. AIDS, 17: F11-F16, 2003
  5. Chakraborty B et al. Evaluating HIV-1 superinfection in cell culture, the SCID-hu Thy/Liv model and HIV-infected individuals with high risk of re-exposure to the virus. Antivir Ther 7: S47, 2002
  6. Shafer RW et al. Failure to detect HIV-1 re-infection based on serial protease and reverse transcriptase sequences during 1239 patient years observation. Antivir Ther 7: S149, 2002
  7. Willberg CB et al. Immunity to HIV-1 is influenced by continued natural exposure to exogenous virus. PLoS Pathogens 4 (10): e1000185, 2008
  8. Smith D et al. Incidence of HIV superinfection following primary infection. Eleventh Conference on Retroviruses and Opportunistic Infections, San Francisco, abstract 21, 2004
  9. Gottlieb G et al. HIV-1 superinfection in a rapid disease progressor: rapid replacement of the initial strain with the superinfecting virus by natural selection. Eleventh Conference on Retroviruses and Opportunistic Infections, San Francisco, abstract 454, 2004
  10. Jurrianns S et al. A sudden increase in viral load is infrequently associated with HIV-1 superinfection. J Acquir Immune Defic Syndr 47(1): 69-73, 2008
  11. Bezemer D et al. Combination antiretroviral therapy failure and HIV super-infection. AIDS 22(2):309-11, 2008
  12. Grant R et al. High frequency of apparent HIV-1 superinfection in a seroconverter cohort. Twelfth Conference on Retroviruses and Opportunistic Infections, Boston, abstract 287, 2005
  13. Buskin SE et al. Transmission cluster of highly drug-resistant HIV-1 among 9 men who have sex with men in Seattle/King County, WA, 2005 – 2007. J Acquir Immune Defic Syndr 49: 205-212, 2008
  14. Piantadosi A et al. Chronic HIV-1 infection frequently fails to protect against superinfection. PLoS Pathog 3(11): e177 doi: 10.1371/journal.ppat. 0030177, 2007
  15. Fang G et al. Recombination following superinfection by HIV-1. Antivir Ther 8: S202, 2003
  16. Yerly S et al. Prevalence of co- and super-infection in IVDUs. Antivir Ther 8: S203, 2003
This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.