Inactivated Seasonal Influenza Vaccines Increase Serum Antibodies to the Neuraminidase of Pandemic Influenza A(H1N1) 2009 Virus in an Age‐Dependent Manner

Abstract

Pre-existing antibodies to the hemagglutinin of pandemic A (H1N1) 2009 influenza virus (pH1N1) positively correlates with age. The impact of contemporary seasonal influenza vaccines on establishing immunity to other pH1N1 proteins is unknown. We measured serum antibodies to the neuraminidase of pandemic H1N1 (pNA) in adults prior to and after vaccination with seasonal trivalent inactivated influenza vaccines. Serum antibodies to pNA were observed in all age groups; however, vaccination elevated pNA antibodies in predominately the elderly. Therefore, contemporary seasonal vaccines likely contribute to reduction of pH1N1 associated disease in older individuals.

Molecular Basis for Broad Neuraminidase Immunity: Conserved Epitopes in Seasonal and Pandemic H1N1 as Well as H5N1 Influenza Viruses

“…In addition to the cross-reactivity/protection observed in the mouse model (15)(16)(17)36), there is evidence that seasonal influenza vaccination increased antibody responses to the NA of 09pdm H1N1 in the elderly (40) and there is measurable NA-specific cross-reactivity between ferret serum against 09pdm H1N1 and H5N1 viruses (14). The presence of conserved group B, E, and F epitopes is likely the molecular basis for such cross-reactivity and heterologous protection.…”

The 2009 pandemic H1N1 virus induces anti-neuraminidase (NA) antibodies that cross-react with the NA of H5N1 viruses in ferrets

“…The conventional test tube NI assay described in the WHO manual was improved in a number of steps as described by Sandbulte et al[20, 32]. First, the use of the PCR tubes and PCR thermocycler is more convenient and safer than using test tubes.…”

Effect of Priming with H1N1 Influenza Viruses of Variable Antigenic Distances on Challenge with 2009 Pandemic H1N1 Virus

“…The burden of disease was largely in children and young adults, with up to 50% of this population showing evidence of infection (44), compared to 10% of the adult population (11,44). Several investigations have attempted to determine why severe disease and hospitalization associated with 2009 pH1N1 infection predominated in younger age groups (5,8,24,27,37,40,42).…”