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PLoS One. 2018 Nov 14;13(11):e0205139. doi: 10.1371/journal.pone.0205139. eCollection 2018.

First-in-human randomized controlled trial of an oral, replicating adenovirus 26 vector vaccine for HIV-1.

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Center for Virology and Vaccine Research, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States of America.
Harvard Medical School, Boston, Massachusetts, United States of America.
Ragon Institute of MGH, MIT and Harvard, Cambridge, Massachusetts, United States of America.
University of Rochester Medical Center, School of Medicine and Dentistry, Rochester, New York, United States of America.
International AIDS Vaccine Initiative, New York, New York, United States of America.
Batavia Biosciences B.V., Leiden, The Netherlands.



Live, attenuated viral vectors that express HIV-1 antigens are being investigated as an approach to generating durable immune responses against HIV-1 in humans. We recently developed a replication-competent, highly attenuated Ad26 vector that expresses mosaic HIV-1 Env (rcAd26.MOS1.HIV-Env, "rcAd26"). Here we present the results of a first-in-human, placebo-controlled clinical trial to test the safety, immunogenicity and mucosal shedding of rcAd26 given orally.


Healthy adults were randomly assigned to receive a single oral dose of vaccine or placebo at 5:1 ratio in a dosage escalation of 10^8 to 10^11 rcAd26 VP (nominal doses) at University of Rochester Medical Center, Rochester, NY, USA. Participants were isolated and monitored for reactogenicity for 10 days post-vaccination, and adverse events were recorded up to day 112. Rectal and oropharyngeal secretions were evaluated for shedding of the vaccine. Humoral and cellular immune responses were measured. Household contacts were monitored for secondary vaccine transmission.


We enrolled 22 participants and 11 household contacts between February 7 and June 24, 2015. 18 participants received one dose of HIV-1 vaccine and 4 participants received placebo. The vaccine caused only mild to moderate adverse events. No vaccine-related SAEs were observed. No infectious rcAd26 viral particles were detected in rectal or oropharyngeal secretions from any participant. Env-specific ELISA and ELISPOT responses were undetectable. No household contacts developed vaccine-induced HIV-1 seropositivity or vaccine-associated illness.


The highly attenuated rcAd26.MOS1.HIV-Env vaccine was well tolerated up to 10^11 VP in healthy, HIV-1-uninfected adults, though the single dose was poorly immunogenic suggesting the replicative capacity of the vector was too attenuated. There was no evidence of shedding of infectious virus or secondary vaccine transmission following the isolation period. These data suggest the use of less attenuated viral vectors in future studies of live, oral HIV-1 vaccines.


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Conflict of interest statement

The authors Christopher Yallop and Menzo Havenga are employees of Batavia Biosciences B.V., Leiden, The Netherlands. This employment does not alter the authors’ adherence to PLOS ONE policies on sharing data and materials.

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