either or both or the internal matrix and nucleoprotein antigens were expressed from 2 to 6 hours after infection , with maximum expression after 2 hours , and the strain-specific and common antigenic determinants of haemagglutinin were observed on the cell surface from 4 hours after infection , and reached a maximum 8 to 10 hours after infection .
C0003320
antigens
C0003316
antigenic