Sequence analysis of novel H1N1 HA isolates shows limited variation in the predicted neutralization epitope.

Alignment of hemagglutinin protein from novel H1N1 isolates deposited in the NCBI Influenza Virus Resource was performed using the multiple sequence alignment application within the database. 1000 full length HA sequences contained in the database on November 11, 2009 were analyzed for variation in HA2 residues previously shown to be contacted by neutralizing antibodies binding to the stem region [13], [17].