FIG 5.

The N-terminal 305 residues of Aichi NP are directly involved in determining influenza virus virion morphology. (A) Amino acid differences between WSN and Aichi NPs. (B) Schematic diagram of chimeric NP proteins. Chimeric NP WA includes the N-terminal 305 residues from WSN and the rest of the sequence from Aichi. Chimeric NP AW contains the N-terminal 305 from Aichi and the rest of the sequence from WSN. (C) MDCK cells were infected with recombinant WSN-AichiM1 viruses expressing NP WA or NP AW at an MOI of 1 for 18 h as indicated. Cell surfaces were stained for viral proteins with anti-H1N1 goat serum followed by Alexa Fluor 488 anti-goat IgG.