C-terminal 6x His-tagged influenza hemagglutinin HA trimeric (A/Beijing/32/92) (H3N2) (aa 17-529) protein (GenBank Accession#: ACF41856). Over 95% are trimeric fraction collected from column chromatography. A trimerization domain sequence has been introduced into the C-terminal of HA to stabilize the formation of trimer HA.