Characterization of the noncoding regions of the 1918 influenza A H1N1 virus.

The terminal noncoding region (NCR) sequences of the eight gene segments of the influenza A/Brevig Mission/1/1918 (H1N1) virus were determined by rapid amplification of cDNA ends (RACE). Chimeric viruses encoding the open reading frames of the 1918 virus but flanked by either the wild-type 1918 NCR sequences or the NCR sequences of two other H1N1 virus strains, A/WSN/1933 and A/New York/312/2001, were produced. No growth differences between the NCR variant 1918 influenza viruses were noted.