Identification of a new reovirus causing substantial losses in broiler production in France, despite routine vaccination of breeders

Abstract

Numerous cases of tenosynovitis appeared in France causing high morbidity in free-range and standard broilers. The main clinical findings were lameness, stunting and non-uniform bodyweights. Although the natural mortality was low, the economic losses due to birds that had to be removed from the flock prematurely, downgrading of carcases and lower average weights at slaughter were substantial. Postmortem examinations, bacteriological, virological and serological examination confirmed the aetiology of avian orthoreovirus (ARV)-induced tenosynovitis. The isolated ARVs were analysed serologically and genetically. Sequencing of σC RT-PCR products and phylogenetic analysis revealed a new type of ARV. The virus was not neutralised in serum neutralisation test using monovalent sera from vaccinated chickens. Together with the flock data, epidemiology of these recent reovirus outbreaks in France was reconstructed. It is concluded that these reovirus isolates differ serologically and genetically from the well described reovirus isolates used in commercial vaccines which were not capable of preventing the disease. The outbreaks resulted in substantial losses in broilers from vaccinated breeders.

Phylogenetic analysis, genomic diversity and classification of M class gene segments of turkey reoviruses

“…The suitable nucleotide cut-off value (85%) is depicted by vertical solid line. Sellers et al, 2013;Troxler et al, 2013). Based on virus neutralization test, these variants of CRVs and TARVs were found to be antigenically different and did not cross neutralize (Rosenberger et al, 2013b).…”

“…Based on virus neutralization test, these variants of CRVs and TARVs were found to be antigenically different and did not cross neutralize (Rosenberger et al, 2013b). In addition, commercially available CRV vaccines were found to be ineffective against these new CRV variants (Sellers et al, 2013;Troxler et al, 2013). The occurrence of these two events simultaneously in two different host species I I I 1 TARV-O 'Neil USA/MN VA 2011 I I I 2 TARV-MN1 USA/MN VA 2011 I I I 1 TARV-MN2 USA/MN VA 2011 I II I 1 TARV-MN3 USA/MN VA 2011 I I I 1 TARV-MN4 USA/MN VA 2011 I III I 3 TARV-MN5 USA/WI VA 2011 I I I 1 TARV-MN6 USA/NC VA 2011 I I I 1 TARV-MN7 USA/SD VA 2012 I I I (chickens and turkeys) raises the question on the source of these arthritis-associated reoviruses.…”

“…All three breeds developed swelling of hock joint at 3-4 weeks of age, but tenosynovitis lesions were only observed in commercial Ross-1 broilers. Recently, Troxler et al (2013) analyzed sigma C protein sequences of 21 CRVs from 17 broiler farms and five hatcheries in France and succeeded in predicting a common origin of the virus as well as its horizontal and vertical transmission based on the distribution involving hatcheries and broiler breeder flocks. In future, screening of breeder and commercial turkey flocks for TRV strains and broilers for CRV strains and their complete genome sequencing may help to differentiate these viruses and help predict the source of infection.…”

“…Recently, CRV variants have been isolated from cases of lameness and tenosynovitis in 2.5-8 week old commercial broiler chickens in Europe and North America. Most of the commercially available vaccines are not effective against these variants (Rosenberger et al, 2013a;Sellers et al, 2013;Troxler et al, 2013).…”

Genomic characterization of a turkey reovirus field strain by Next-Generation Sequencing

“…Other research studies indicated that highly pathogenic ARV variants were capable of infecting not only unvaccinated broiler chickens, but also vaccinated broiler breeders (Dandar et al, 2013; Rosenberger et al, 2013; Troxler et al, 2013). In this paper, we report the complete genome sequence of a PA field strain (Reo/PA/Turkey/22342/13), isolated from TARV infected turkeys showing severe arthritis and lameness in a commercial turkey flock at 14 weeks of age, by using Next-Generation Sequencing (NGS) with the Illumina MiSeq.…”