Bioassay for influenza A and B nucleoprotein

摘要

The present invention relates to nucleoprotein (NP) genes of the influenza A and B viruses which were constructed from virion RNA and subsequently expressed in Spodoptera frugiperda (S19) cells using the baculovirus vector, Autographa californica nuclear polyhedrosis virus (AcNPV). Western blot analysis of lysates prepared from S19 cells infected with the recombinant viruses confirmed that the baculovirus- expressed NP antigens were reactive with monoclonal antibodies specific for either type A or B NP and with anti-NP antibodies in human serum samples. Electrophoretic analysis indicated that the expressed influenza NP antigens comigrated with NP purified from influenza A or B virions and that the recombinant NP antigens represented greater than 10% of total protein in infected cells. Dilutions of clarified S19 cell lysates were used as antigens in a standard enzyme immunoassay format to detect serum antibody specific for influenza A or B viruses. The results from assays using the baculovirus-expressed NP antigens showed good correlation with the results obtained using bacterially-expressed NP antigen as well as complement fixation. Therefore, baculovirus-expressed NP antigens can be used in reproducible and routine assays for the serodiagnosis of influenza virus infections as an alternative to the more burdensome complement fixation or hemagglutination tests.