Rotavirus-specific breast milk antibody in two populations and possible correlates of interference with rhesus rotavirus vaccine seroconversion.

Milk was collected from 56 New York and 70 Venezuelan mothers participating in Rhesus rotavirus (RRV) pediatric vaccine trials. Plaque reduction neutralization antibody (PRNA) to RRV (VP7:3, VP4:RRV) and human P rotavirus (VP7:3, VP4:P) and epitope-blocking antibody to one RRV VP4 and VP7 epitope were determined. Controlling for postpartum age, more Venezuelan milk samples had detectable RRV and P PRNA, RRV VP4 epitope-blocking antibody (P less than or equal to .001), and higher RRV and P PRNA geometric mean titers (P = .01) than New York samples. Using a logistic regression model, both milk and infants' serum preimmunization RRV PRNA titers had a negative effect on seroconversion (P = .008 and .02, respectively). Only 25% (2/8) infants fed milk containing greater than or equal to 1:160 RRV PRNA seroconverted compared with 83% (5/6) fed milk containing less than 1:160 RRV PRNA (P = .1). Of milk samples containing greater than or equal to 1:160 RRV PRNA, seven (88%) of eight had greater than fourfold neutralizing activity against RRV versus P (P = .035), suggesting that VP4-specific milk antibodies may interfere with RRV seroconversion.