Prokaryotic expression and purification of HA1 and HA2 polypeptides for serological analysis of the 2009 pandemic H1N1 influenza virus

Hemagglutinin (HA) is an important influenza virus surface antigen that is highly topical in influenza research. In the present study, the genes encoding the HA1 and HA2 proteins from the 2009 pandemic influenza virus H1N1 (A/California/04/2009(H1N1)) were cloned into a prokaryotic expression plasmid pCold-TF, and soluble fusion proteins containing H1N1 HA1 and HA2 were produced by transformed Escherichia coli. Western blot assays were used to examine the immunoreactivity of the recombinant proteins using polyclonal and monoclonal antibodies derived against the whole virus A/California/04/2009(H1N1). Recombinant protein immunoreactivity was also analyzed qualitatively by ELISA and hemagglutination inhibition using human serum samples. These results will aid future immunological and serological studies of the 2009 pandemic H1N1 virus HA.