Virologic Findings in Selected Free-Range Mule Duck Farms at High Risk for Avian Influenza Infection

Abstract

Prevalence of avian influenza infection in free-range mule ducks (a cross between Muscovy [Cairina moschata domesticus] and Pekin ducks [Anas platyrhychos domesticus]) is a matter of concern and deserves particular attention. Thus, cloacal swabs were collected blindly from 30 targeted mule flocks at 4, 8, and 12 wk of age between October 2004 and January 2005. They were stored until selection. On the basis of a positive H5 antibody detection at 12 wk of age with the use of four H5 antigens, the samples from eight flocks were selectively analyzed. Positive samples were first screened with a matrix gene-based real-time reverse transcriptase-polymerase chain reaction assay before virus isolation. Eight avian influenza subtypes (H5N1, H5N2, H5N3, H6N2, H6N8, and H11N9) and three avian paramyxovirus type 1 viruses were isolated. All 11 are characterized as low pathogenicity (LP) and avirulent, respectively, by in vivo tests and, when relevant, nucleotide sequencing of the hemagglutinin (or fusion [F]) protein cleavage site. Regarding H5 isolates, all of their eight genes belong to the avian lineage and some particular genetic traits were determined. H5 genes were fully sequenced and phylogenetically analyzed; they all belong to the Eurasian lineage, lack additional glycosylation sites, and do not cluster, suggesting separate introductions from the wild reservoir. None were grouped with the Asian isolates. The N1 gene (H5N1 isolate) was very close genetically to an Italian LP-H7N1 gene. Antigenic relationships between these H5 isolates and others were assessed comparatively by crossed hemagglutination inhibition tests. All these data are very useful to control the evolution of H5 viruses at the genetic and antigenic level to better understand the source of new outbreaks (new introductions from wild birds or the result of spread among poultry) and to assess the immunity afforded by available vaccines. These data are useful also to update antigens for avian influenza survey and to choose the most suitable vaccine in the case of preventive vaccination of ducks.

Phylogeny and genotyping of recent avian low-pathogenic H5 subtype influenza viruses from French ducks

“…The deletion of 19 aa observed in the NA of 03426 was previously reported by Cherbonnel et al (2007) and is typical of an adaptation of viruses to terrestrial poultry (Matrosovich et al, 1999). This NA was closely related to that of the Italian strains isolated in 1997, and these NAs clustered in a single group, based on a significant bootstrap value (99 %), which suggests that they had a common ancestor with a non-deleted N2.…”

“…They are designated 02166, 03426, 05057b, 05066b, 06436, 06964, 061054, 070090b, 080032 and 080036, respectively (Table 1). The additional virus sequences, with respect to Cherbonnel et al (2007), have been deposited at GenBank under the accession numbers CY046117 to CY046186.…”

“…The second subgroup contained two French viruses (05066b and 03426), a contemporary Italian isolate A/turkey/Italy/1258/05 LPAIV (H5N2) and A/duck/Mongolia/54/01 LPAIV (H5N2). According to current HA phylogeny, the gene from 02166 did not belong to any of the previous subgroups, but according to the arbitrary cut-off conditions (explained in Methods), formed a group with a single French virus A/ duck/France/05056a/2005 H5N2 (Cherbonnel et al, 2007).…”

“…Although the characteristics of asian H5 LPAIV have been previously described , the genetic characteristics of H5 LPAIV from European domestic ducks have been little documented, even though serological surveys have shown these species (Pekin, Muscovy and the mule hybrid) to be frequently infected by H5 viruses in Europe (Hesterberg et al, 2008). Some characteristics, based on partial sequencing and antigenic study of four H5 LPAIV from domestic ducks, have already been reported (Cherbonnel et al, 2007). We have taken this study further by analysing 10 whole genomes of the H5 subtype of LPAIV isolated in France from decoy ducks (two isolates), commercial ducks (seven isolates), and chickens (one isolate) for 7 years, between 2002 and 2008.…”

Risk factors of primary introduction of highly pathogenic and low pathogenic avian influenza virus into European poultry holdings, considering at least material contaminated by wild birds and contact with wild birds

“…In addition to the phylogenetic data, presence of wild birds in the proximity of the effected holdings was also reported as further evidence for some of the analysed outbreaks (Bouwstra et al, 2015b;Gall-Recule et al, 2008;Therkildsen et al, 2011). Other sources of evidence presented to support the incrimination of contact with wild birds as the source of introduction were: proximity (epidemiological evidence) (Cecchinato et al, 2010;Cherbonnel et al, 2007;Conraths et al, 2016;Iglesias et al, 2010;Manvell et al, 2008;Marche et al, 2014;Probst et al, 2012;Ward et al, 2008a;Ward et al, 2009b) or phylogenetic inference, where virus was only isolated from the affected poultry holdings and compared with sequences reported in databases such as GenBank (Alexander et al, 2010;Bragstad et al, 2007;Bragstad et al, 2005;Corrand et al, 2012;Handberg et al, 2010;Hanna et al, 2015;Marche et al, 2014;Marinova-Petkova et al, 2016;Parker et al, 2014;Reid et al, 2011;Starick et al, 2008;Szeleczky et al, 2009;Terregino et al, 2007) (Table 5). …”