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AIDS. 2017 Sep 10;31(14):2007-2016. doi: 10.1097/QAD.0000000000001577.

The effect of oral preexposure prophylaxis on the progression of HIV-1 seroconversion.

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aVaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center bDepartment of Laboratory Medicine cDepartment of Global Health dDepartment of Epidemiology eDepartment of Medicine fDepartment of Pediatrics, University of Washington, Seattle, Washington gDivision of Global Health Protection, Center for Global Health, CDC, Atlanta, Georgia, USA hDepartments of Medical Microbiology and Internal Medicine, University of Manitoba, Winnipeg, Manitoba, Canada iDepartment of Microbiology and immunology, Indiana University, Indianapolis, Indiana, USA.



To investigate whether oral preexposure prophylaxis (PrEP) alters timing and patterns of seroconversion when PrEP use continues after HIV-1 infection.


Retrospective testing of the timing of Fiebig stage HIV-1 seroconversion in the Partners PrEP Study, a randomized placebo-controlled clinical trial of PrEP conducted in Kenya and Uganda.


Specimens from 138 seroconverters were collected every 3 months and when HIV-1 infection was suspected based on monthly rapid HIV-1 tests. Progression of seroconversion was compared between randomized groups (PrEP versus placebo) and per-protocol groups (placebo versus PrEP participants with detectable tenofovir during the seroconversion period) using laboratory assessment of Fiebig stage. Delay in site-detection of seroconversion and association with PrEP drug-regimen resistant virus were assessed using logistic regression. Analysis of time to each Fiebig stage used maximum likelihood estimation with a parametric model to accommodate the varying lengths of HIV-infection intervals.


There was a significant increase in delayed site detection of infection associated with PrEP (odds ratio = 3.49, P = 0.044). Delay in detection was not associated with increased risk of resistance in the PrEP arm (odds ratio = 0.93, P = 0.95). Estimated time to each Fiebig stage was elongated in seroconverters with evidence of ongoing PrEP use, significantly for only Stage 5 (28 versus 17 days, P = 0.05). Adjusted for Fiebig stage, viral RNA was ∼2/3 log lower in those assigned to PrEP compared with placebo; no differences were found in Architect signal to cut-off at any stage.


Ongoing PrEP use in seroconverters may delay detection of infection and elongate seroconversion, although the delay does not increase risk of resistance.

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