Funding for this research was provided by:
National Institute of Allergy and Infectious Diseases (HHSN272200900007C,U19AI110819)
Received: 23 April 2018
Accepted: 11 December 2018
First Online: 7 January 2019
Ethics approval and consent to participate
: Not applicable.
: Not applicable. All figures are created for this manuscript.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.