Serological surveillance reveals patterns of exposure to H5 and H7 influenza A viruses in European poultry

Abstract

Influenza A viruses of H5 and H7 subtype in poultry can circulate subclinically and subsequently mutate from low to high pathogenicity with potentially devastating economic and welfare consequences. European Union Member States undertake surveillance of commercial and backyard poultry for early detection and control of subclinical H5 and H7 influenza A infection. This surveillance has moved towards a risk‐based sampling approach in recent years; however, quantitative measures of relative risk associated with risk factors utilized in this approach are necessary for optimization. This study describes serosurveillance for H5 and H7 influenza A in domestic and commercial poultry undertaken in the European Union from 2004 to 2010, where a random sampling and thus representative approach to serosurveillance was undertaken. Using these representative data, this study measured relative risk of seropositivity across poultry categories and spatially across the EU. Data were analysed using multivariable logistic regression. Domestic waterfowl, game birds, fattening turkeys, ratites, backyard poultry and the ‘other’ poultry category holdings had relatively increased probability of H5 and/or H7 influenza A seropositivity, compared to laying‐hen holdings. Amongst laying‐hen holdings, free‐range rearing was associated with increased probability of H7 seropositivity. Spatial analyses detected ‘hotspots’ for H5 influenza A seropositivity in western France and England, and H7 influenza A seropositivity in Italy and Belgium, which may be explained by the demographics and distribution of poultry categories. Findings suggest certain poultry category holdings are at increased risk of subclinical H5 and/or H7 influenza A circulation, and free‐range rearing increases the likelihood of exposure to H7 influenza A. These findings may be used in further refining risk‐based surveillance strategies and prioritizing management strategies in influenza A outbreaks.

Glycosylation deletion of hemagglutinin head in the H5 subtype avian influenza virus enhances its virulence in mammals by inducing endoplasmic reticulum stress

“…Glycosylation on HA stem sites mainly functions on maintaining the HA structure (Wagner, Heuer, Wolff, Herwig, & Klenk, 2002;Zhang et al, 2015) or cleavage (Yin et al, 2017), and glycosylation on the head sites mainly influences virus binding affinity (Wang et al, 2009) or assists in escaping from immune detection of antibody (Liao et al, 2010;Zost et al, 2017). Recently, the H5 subtype AIV has drastically evolved and alterations in its glycosylation sites have become increasingly complex (Gu et al, 2019;Hillman et al, 2019;Li et al, 2019;Qu et al, 2019;Wille et al, 2019).…”

Development and evaluation of a monoclonal antibody-based competitive ELISA for the detection of antibodies against H7 avian influenza virus

“…Effective prevention and control of H7 outbreaks require active global serological surveillance in poultry. For early detection and control of subclinical H7 infection, extensive serological surveillance programs in poultry have been carried out by the European Union [21]. Moreover, full-scale vaccination campaigns have been enforced throughout China to prevent H7 outbreaks in poultry since 2017.…”