|BUBLOT, MICHEL - Merial Sas Research & Development|
|PRITCHARD, NIKKI - Merial, Ltd|
|AUDONNET, JEAN-CHRISTOPHE - Merial Sas Research & Development|
|YAO, JIANSHENG - Sanofi-Aventis Us, Inc|
Submitted to: World Veterinary Poultry Association
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/2015
Publication Date: 9/7/2015
Citation: Bublot, M., Pritchard, N., Audonnet, J., Yao, J., Swayne, D.E. 2015. Gene dependent level of protection induced by fowlpox recombinant expressing the hemagglutinin H7, the matrix M1, and/or the neuraminidase N1 avian influenza subtype [abstract]. Abstracts of the International Congress of the World Veterinary Poultry Association. CDROM.
Technical Abstract: A fowlpox recombinant (rFP) expressing the hemagglutinin (HA) from A/turkey/Ireland/1378/83 [H5N8] was previously shown to induce protection against a wide panel of highly pathogenic avian influenza (HPAI) H5 subtypes strains. The goal of the presented work was to evaluate if similar broad protection could be induced by rFP expressing HA from H7 subtypes. The rFP expressing the HA gene from A/Chicken/Victoria/1/85 [H7N7] (ck/Vic/85) was shown to clinically protect specific pathogen free (SPF) chickens against A/chicken/Pakistan/1369-CR2/95 [H7N3] but not against A/turkey/Italy/4580/99 [H7N1] (tk/Ita/99) HPAI challenges. New rFP expressing the HA gene from low pathogenic avian influenza (LPAI) A/Turkey/Italy/4426/00 [H7N1] (tk/Ita/00) or A/Turkey/Virginia/66/02 [H7N2] (tk/VA/02), both HA and Matrix 1 (M1) genes from tk/Ita/00, or the neuraminidase (NA) gene from tk/Ita/00 were generated and tested by the sub-cutaneous route in one day-old SPF chicks for efficacy against tk/Ita/99 HPAI challenge performed 3 weeks later. The rFP expressing tk/Ita/00 HA induced the best level of clinical protection (90%) which was not increased by M1 co-expression. The level of protection induced by rFP-NA (tk/Ita/00) was much lower (20%) than by rFP-HA (tk/Ita/00). SPF chickens vaccinated with rFP expressing HA from more distant strains (ck/Vic/85 or tk/VA/02) were poorly protected (20%). The co-administration of rFP-HA (ck/Vic/85) and rFP-NA (tk/Ita/00) did not improve protection (10%). Altogether, these data indicate the poor cross-protection against HPAI H7 subtype induced by rFP-HA. The M1 and NA genes did not improve the protection induced by HA alone. HPAI H7 subtype protection induced by rFP-HA may require a higher match between the HA gene of the vaccine and the challenge virus compared to H5 subtype.