The neutralization antibody titer of 1:4 was recognized as the positive criterion ,
8 sera samples were detected to be positive ,
The neutralization antibody titer of 1:4 was recognized as the positive criterion , 8 sera samples were detected to be positive , and the positive rate was 12.9 % .
The neutralization antibody titer of 1:4 was recognized as the positive criterion , 8 sera samples were detected to be positive , and the positive rate was 12.9 % .