Correction to: Nature Medicine https://doi.org/10.1038/nm.4082, published online 18 April 2016.

Following publication of this article, the authors were made aware of image duplications in Fig. 1c and Supplementary Figs. 2a, 7b and 8a. New images have been taken to correct the errors; original and updated figures are shown in the Supplementary Information accompanying this amendment.

Supplementary information is available in the online version of this amendment.