In humans, H1N1pdm09 infection in the elderly (>70 years old) induced antibodies with broader epitope recognition in both the internal genes and the HA1 receptor binding domain (RBD) than for the younger age groups (0 to 69 years).
In this study, we compared antigenic (hemagglutination inhibition (HI) assay) and molecular (sequencing of the hemagglutinin (HA1) gene) characterization of influenza isolates collected in the Province of Québec (Canada) during the last three flu seasons (1997-2000).
A total of 548, 2,123, and 1,336 sequences of the HA1 genes of influenza A virus subtypes H1 and H3 and influenza B virus, respectively, collected during 2003 to 2006 from an island-wide surveillance network were determined.
Direct polymerase chain reaction (PCR) amplifications of cDNA and subsequent nucleotide sequence analysis of part of the HA-1 gene of the original infecting influenza B strain and the nasal wash material from an infected volunteer were performed.
We conclude that bacterially expressed recombinant HA1 proteins can be produced rapidly and used to generate SRID potency reagents shortly after new influenza strains with pandemic potential are identified.
In this study, we investigate 20,152 general-population serum samples from southern Vietnam collected between 2009 and 2013 from which we report antibody titers to the influenza virus HA1 protein using a continuous titer measurement from a protein microarray assay.