viral antigens were first observed in cell extracts by elisa 4 hours after infection , and infectious virions and haemagglutinin 2 hours later , but whereas maximum titres of infectious virus and haemagglutinin were found 10 hours after infection , the elisa titre continued to rise until 24 hours after infection , which suggested that virus structural proteins were being accumulated in the cells after most of the progeny virions had been released .
C0042769
infectious virus
C0009450
infection