Development of replication-competent viral vectors for HIV vaccine delivery

Purpose of Review: To briefly describe some of the replication-competent vectors being investigated for development of candidate HIV vaccines focusing primarily on technologies that have advanced to testing in macaques or have entered clinical trials. Recent Findings: Replication-competent viral vectors have advanced to the stage at which decisions can be made regarding the future development of HIV vaccines. The viruses being used as replication-competent vector platforms vary considerably, and their unique attributes make it possible to test multiple vaccine design concepts and also mimic various aspects of an HIV infection. Replication-competent viral vectors encoding simian immunodeficiency virus or HIV proteins can be used to safely immunize macaques, and in some cases, there is evidence of significant vaccine efficacy in challenge protection studies. Several live HIV vaccine vectors are in clinical trials to evaluate immunogenicity, safety, the effect of mucosal delivery, and potential effects of preexisting immunity. Summary: A variety of DNA and RNA viruses are being used to develop replication-competent viral vectors for HIV vaccine delivery. Multiple viral vector platforms have proven to be well tolerated and immunogenic with evidence of efficacy in macaques. Some of the more advanced HIV vaccine prototypes based on vesicular stomatitis virus, vaccinia virus, measles virus, and Sendai virus are in clinical trials.