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. 2011 Jun 9;7(6):e1002081. doi: 10.1371/journal.ppat.1002081

Figure 6. The amino acid at position 89 in HA2 influences neutralization to HA2.

Figure 6

(A) Sequence comparison of HA2 from Bris/59/07 and NCD/20/99. The differing residues in the HA2 are indicated (grey). (B) The 89L mutation, but not the 146N mutation in HA2 of Bris/59/07, conferred similar levels of neutralization to Bris/59/07 HA-pseudotypes as compared to NCD/20/99 HA-pseudotypes, using sera from the NJ/76 vaccine trials that have neutralization titers to NCD/20/99, but not to wild-type Bris/59/07. (C) The 89L mutation, but not the 146N mutation in Bris/59/07 HA2, conferred similar levels of neutralization to Bris/59/07 HA-pseudotypes as compared to chimeric HA-pseudotypes with Mex/4108/09 HA2, using the contemporary sera cohort from samples that have neutralization titers to Mex/4108/09 HA2 (determined in Figure 5A), but not to wild type Bris/59/07. The dotted lines in both panels B and C represent the neutralization titer of 160, which has been proposed as a correlate of seroprotection in microneutralization assays involving replicating influenza virus [4]. Protective titers for neutralization of HA-pseudotypes have not been determined. Data are shown as means +/− SD and reflect two or more independent experiments with each sample run in duplicate. Bris: Bris/59/07; Mex: Mex/4108/09; NCD: NCD/20/99.