CD4 T-cell responses directed towards A/H5N1-derived haemagglutinin peptides increase in patients with seasonal influenza A virus infection

Abstract

Objectives: Recent outbreak of influenza A/H5N1 viral infections in birds and mammals worldwide prompted renewed concerns over an emerging H5N1-related influenza pandemic in the generally immunologically-naive global population. Cross-reactive CD4+ T cells between A/H1N1 and A/H5N1 subtypes targeting internal and surface influenza proteins have been identified in humans, indicating some protection against severe and fatal A/H5N1 infection. Methods: To detect T-cell responses towards H1 and H5 viruses, we stimulated PBMCs from patients hospitalised with seasonal influenza A viruses, alongside healthy individuals, with overlapping peptide pools spanning hemagglutinin (HA) and neuraminidase (NA..