Funding for this research was provided by:
Alfred P. Sloan Foundation (APSF-2012-10-05)
National Institutes of Health (5R01AI092531)
Received: 5 October 2017
Accepted: 6 June 2018
First Online: 20 June 2018
Ethics approval and consent to participate
: All samples were collected after signed guardian consent was obtained, as outlined in our protocol to the ethical research board of the University of Pittsburgh (IRB PRO12100487). This consent included sample collection permissions and consent to publish study findings.
: Consent was obtained to publish study findings (IRB PRO12100487).
: The authors declare that they have no competing interests.
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