Failure to detect human immunodeficiency virus type 1 superinfection in 28 HIV-seroconcordant individuals with high risk of reexposure to the virus.

We have examined the occurrence of HIV-1 superinfection in 14 HIV-seroconcordant couples (i.e., partners were independently infected with different HIV-1 strains) with high risk of reexposure to the virus. Phylogenetic analyses based on pol and env global sequences obtained from more than 100 longitudinal plasma samples (corresponding to a period of 1-4 years) failed to detect HIV-1 superinfection in this cohort of patients. Our results suggest that despite recent reports of HIV-1 reinfection, chronic HIV infection seems to confer protection against superinfection with a second HIV-1 strain.