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Volume 6 Supplement 3

AIDS Vaccine 2009

P04-16. Orally exposed uninfected individuals have systemic anti-HIV response correlating with partner's viral load


We have previously shown that this cohort of exposed uninfected individuals (EU) of men who have sex with men (MSM) display HIV-1 neutralizing capacity in their salivary IgA1 (AIDS 2009). To investigate whether oral HIV-1 exposure mounts also a systemic anti-HIV-1 response, we have here investigated consecutive samples of plasma (unfractioned and IgA1 purified) for neutralizing capacity, and whether the response correlates with exposure measured by viral load in the HIV-positive partners.


Plasma were collected from EU (n = 25) every 6 months during 2 years and from low-risk controls (n = 22). IgA1-purification was performed with jacaline. Neutralization was tested in a PBMC-based neutralization assay using three primary HIV-1 isolates. Self-reported questionnaires described routes of HIV-1-exposure, and clinical records determined viral load in HIV-positive partners.


At study start, plasma samples from 7/25 EU could neutralize 2 of 3 tested HIV-1 isolates. None of the 22 low-risk controls could neutralize any HIV-1 isolate (p = 0.01). 6/7 EU retained their neutralization capacity during continuous exposure, although 3/6 EU only neutralized one of the three HIV-1 isolates at time of last sampling. Of importance, the neutralization capacity among EU correlated with a significantly higher viral load in the respective partners compared to partners of non-neutralizing EU. Purified IgA1 was shown to mediate neutralization in 6/7 samples whereas none of the IgA1-depleted plasma samples could neutralize HIV-1.


Orally exposed uninfected MSM can mount an anti-HIV-1 response in plasma, here shown to correlate with the viral load in the HIV-positive partner.

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Open Access This article is published under license to BioMed Central Ltd. This is an Open Access article is distributed under the terms of the Creative Commons Attribution 2.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Hasselrot, K., Bratt, G., Hirbod, T. et al. P04-16. Orally exposed uninfected individuals have systemic anti-HIV response correlating with partner's viral load. Retrovirology 6 (Suppl 3), P44 (2009).

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