Autor Contributions
H L and J.L. had the concept, designed the study, and made critical
revision of the manuscript for important intellectual content. X.Y. made
statistical analysis and drafted the manuscript. Q.D., J.L and Y.L.
performed the ELISA test. H.W., Y Z. and P.L. performed the
neutralizations experiments. Y.L. and X.Q. helped to acquire and analyze
data.