TABLE 1.

Percent nucleotide identity in packaging signal regions, P99 (H3N2) versus NL (H1N1)^a

Segment	% nucleotide identity	PS length (UTR + coding) (nt)
		3′	5′
PB2	89.7	177	184
PB1	96.9	174	193
PA	89.8	174	208
HA	50.0	136	136
NP	87.5	195	174
NA	56.6	150	200
M	90.1	275	270
NS	83.3	200	200

^aRegions analyzed are conservative estimates of packaging signal (PS) lengths, based on data compiled by Hutchinson et al. (57). Data in bold indicate the segments examined in the present study.