Nat. Biotechnol. 32, 397 (2014); doi:10.1038/nbt.2907; published online 8 May 2014; corrected after print 5 June 2014

In the version of this article initially published, AAV1 was incorrectly identified as AAV9. It was not noted that the Surrey Clinical Research Centre is at the University of Surrey. The phase 1 clinical trial is for a gene transfer, not a gene therapy, and will test whether levels of AAV1 encoding, not expressing, PG9 will neutralize HIV in cell culture. Finally in the third from last paragraph, the question posed is “will vector-mediated gene transfer drive expresssion” not “will AAV9 drive expression.” These errors have been corrected in the HTML and PDF versions of the article.