Nat. Biotechnol. 32, 684–692 (2014); published online 22 June 2014; corrected after print 14 January 2015
In the version of this article initially published, the concentration of the V-region primers in the Online Methods section was given as 0.6 μM. The correct concentration is 0.06 μM. The error has been corrected in the HTML and PDF versions of the article.