Funding for this research was provided by:
National Institute of Allergy and Infectious Diseases (HHSN272201400006C, AI007417, HHSN272201400007C)
NIH Office of the Director (OD011089)
National Institute of Child Health and Human Development (CA09110)
Received: 8 January 2018
Accepted: 30 May 2018
First Online: 17 July 2018
: Not applicable.
: All authors read and approved the final draft.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.