Genetic and subunit vaccines based on the stem domain of the Equine influenza hemagglutinin provide homotypic protection against heterologous strains

IBAÑEZ, LORENA ITATI; CALDEVILLA, CECILIA; PAREDES ROJAS, YESICA; MATTION, NORA

VACCINE

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 2018 vol. 36 p. 1592 - 1598

0264-410X

H3N8 influenza virus strains have been associated with infectious disease in equine populations throughout the world. Although current vaccines for equine influenza stimulate a protective humoral immune response against the surface glycoproteins, disease in vaccinated horses has been frequently reported, probably due to poor induction of cross-reactive antibodies against non-matching strains. This work describes the performance of a recombinant protein vaccine expressed in prokaryotic cells (ΔHAp) and of a genetic vaccine (ΔHAe), both based on the conserved stem region of influenza hemagglutinin (HA) derived from A/equine/Argentina/1/93 (H3N8) virus. Sera from mice inoculated with these immunogens in different combinations and regimes presented reactivity in vitro against highly divergent influenza virus strains belonging to phylogenetic groups 1 and 2 (H1 and H3 subtypes, respectively), and conferred robust protection against a lethal challenge with both the homologous equine strain (100 %) and the homosubtypic human strain A/Victoria/3/75 (H3N2) (70 - 100 %). Animals vaccinated with the same antigens but challenged with the human strain A/PR/8/34 (H1N1), belonging to the phylogenetic group 1, were not protected (0 - 33%). Combination of protein and DNA immunogens showed higher reactivity to non-homologous strains than protein alone, although all vaccines were permissive for lung infection.