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PLoS Pathog. 2008 Oct;4(10):e1000185. doi: 10.1371/journal.ppat.1000185. Epub 2008 Oct 24.

Immunity to HIV-1 is influenced by continued natural exposure to exogenous virus.

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1
Division of Experimental Medicine, Department of Medicine, University of California San Francisco, San Francisco, California, USA. Chris.Willberg@ndm.ox.ac.uk

Abstract

Unprotected sexual intercourse between individuals who are both infected with HIV-1 can lead to exposure to their partner's virus, and potentially to super-infection. However, the immunological consequences of continued exposure to HIV-1 by individuals already infected, has to our knowledge never been reported. We measured T cell responses in 49 HIV-1 infected individuals who were on antiretroviral therapy with suppressed viral loads. All the individuals were in a long-term sexual partnership with another HIV-1 infected individual, who was either also on HAART and suppressing their viral loads, or viremic (>9000 copies/ml). T cell responses to HIV-1 epitopes were measured directly ex-vivo by the IFN-gamma enzyme linked immuno-spot assay and by cytokine flow cytometry. Sexual exposure data was generated from questionnaires given to both individuals within each partnership. Individuals who continued to have regular sexual contact with a HIV-1 infected viremic partner had significantly higher frequencies of HIV-1-specific T cell responses, compared to individuals with aviremic partners. Strikingly, the magnitude of the HIV-1-specific T cell response correlated strongly with the level and route of exposure. Responses consisted of both CD4(+) and CD8(+) T cell subsets. Longitudinally, decreases in exposure were mirrored by a lower T cell response. However, no evidence for systemic super-infection was found in any of the individuals. Continued sexual exposure to exogenous HIV-1 was associated with increased HIV-1-specific T cell responses, in the absence of systemic super-infection, and correlated with the level and type of exposure.

PMID:
18949024
PMCID:
PMC2562513
DOI:
10.1371/journal.ppat.1000185
[Indexed for MEDLINE]
Free PMC Article
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