Table 5. Representation of 9 H1N1 T cell epitope sequences with single amino acid substitutions from the most frequent sequences (≥ 80% conservation) among all influenza A 1977–2006 strains and H1N1 strains 2007–2009.

Protein	A/New York/348/2003 H1N1 ELISpot positive peptide§	1977–2006 Influenza A*	2007 human H1N1″	2008 human H1N1̂	2009 human H1N1+
PB1	---------------K-	86	-	-	99
	37 GYTMDTVNRTHQYSERG 53	13	99	84	-
	-----------R---K-	#	-	-	1
	-----------H-----	#	-	16	-
	----------I------	89	1	-	-
	507 MELPSFGVSGVNESADM 523	10	99	100	100
	----------------L	86	-	-	99
	560 RCHRGDTQIQTRRSFEI 576	11	100	100	-
	------A---------L	0.04	-	-	1
	----S------------	84	-	-	100
	650 GPAKNMEYDAVATTHSW 666	12	99	97	-
	-----I-----------	0.68	-	3	-
	----T------------	0.42	1	-	-
	-----------I-----	87	-	-	96
	656 EYDAVATTHSWVPKRNR 672	11	100	100	-
	-----------T-----	0.76	-	-	4
	-----------K-----	85	-	-	100
	680 RGILEDEQMYQRCCNLF 696	10	98	87	-
	--V--------------	0.23	1	10	-
	----------L------	#	-	3	-
PB2	-------------Q---	89	-	-	100
	434 LLRHFQKDAKVLFLNWG 450	7	97	100	-
	---------R-------	0.03	1	-	-
	----------I------	0.03	1	-	-
	-----------V-----	90	-	-	99
	536 MWEINGPESVLINTYQW 552	8	100	100	1
	-----V-----------	84	-	-	99
	542 PESVLINTYQWIIRNWE 558	8	99	100	1

§Highly conserved aa of 1977–2006 influenza A subtypes are boldface.

*3175 PB1 and 3144 PB2 human H1N1, H3N2, H1N2, H5N1, and avian H5N1 and other avian subtypes sequences circulating between 1977 and 2006 were extracted from NCBI GenBank and GenPept databases as of September 2006. Sequences representing less than 1% were not included unless they were also represented in the 2007–2009 strains.

All human PB1 and PB2 H1N1 sequences from 2007 to 2009 were extracted from the Influenza Virus Resource on Jun 17, 2009.

+168 PB1 and 171 PB2 human H1N1 2009 sequences.

^31 PB1 and 31 PB2 human H1N1 2008 sequences.

″314 PB1 and 314 PB2 human H1N1 2007 sequences.

#New sequence representation not found in the 1977–2006 influenza A subtypes sequences.