Genetic influences

  • A range of genetic, or host, factors appear to affect an individual’s risk of infection.

A genetic variation (CCR5 delta 32) that reduces the frequency of CCR5 receptor molecules on CD4 cells has been shown to protect against infection (CCR5 is a co-receptor that HIV must use to gain entry to a cell – if the co-receptor is not present the virus cannot infect the cell).1 This variation is present in around 10 to 15% of Caucasians and 2% of African-Americans, but is virtually non-existent in people of Asian or African origin, and appears to have become more widespread in Caucasians as a result of the resistance it conferred against bubonic plague. People who, due to genetic inheritance, have higher levels of the chemokine known as RANTES that normally binds to CCR5 are also less likely to become infected, presumably because RANTES is frequently blocking the site that HIV needs to bind to.2 

Conversely, people with low levels of the gene that produces another chemokine that binds to CCR5 are more likely to become infected with HIV.3

More detailed information on the CCR5 co-receptor is available in NAM's HIV Treatments Directory.

References

  1. Liu R et al. Homozygous defect in HIV-1 coreceptor accounts for resistance of some multiply-exposed individuals to HIV-1 infection. Cell 86: 367-377, 1996
  2. McDermott DH et al. Chemokine RANTES promoter polymorphism affects risk of both HIV infection and disease progression in the Multicenter AIDS Cohort Study. AIDS 14: 2671-2678, 2000
  3. Gonzalez E et al. The influence of CCL3L1 gene-containing segmental duplications on HIV-1/AIDS susceptibility. Science 307: 1434-1440, 2005
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 It may have been superseded by more recent developments.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.