Gabriel Vasquez, MD
Nominated From: University of Washington
Research Site: Centro de Investigaciones Tecnologicas Biomedicas y Medioambientales
Research Area: HIV
Primary Mentor: Alison Roxby, MD
Research Project
Baseline Ad26 Neutralizing Antibodies and Intensity of Vaccine-Induced Seropositivity (VISP) among Former Mosaico Participants in Peru: A Pilot Recall Study
This pilot recall study evaluates whether preexisting Ad26 neutralizing antibody (NAb) titers are associated with the intensity and persistence of vaccine-induced seropositivity (VISP) among former Mosaico participants in Peru. Approximately 40 vaccinated adults without HIV will be recalled for standardized HIV diagnostic testing, including fourth-generation screening and supplemental algorithms, recording semi-quantitative signal-to-cutoff (S/CO) values as a proxy for VISP intensity. Archived baseline (and Month-7, if available) Ad26 NAb titers from Mosaico will be linked to current VISP measures. Primary analyses will test the association between baseline Ad26 titers and S/CO, adjusting for time since last dose and key covariates. Findings will characterize biological drivers of VISP variability, inform diagnostic and counseling guidance, and justify a larger, multi-site study.
Research Significance
Vaccine-induced seropositivity (VISP) affects virtually all recipients of Ad26-based HIV vaccines and can lead to false-positive HIV diagnoses with major clinical, social, and legal consequences. No published study has examined whether preexisting Ad26 immunity modulates VISP intensity or duration. This pilot study addresses that gap directly, generating data that will improve participant counseling, optimize diagnostic algorithms, and inform the design of future HIV vaccine trials.
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