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Introduction
Viral arthritis and tenosynovitis caused by avian orthoreovirus (ARV) have been known for more than 40 years (Petek and others 1967, Walker and others 1972). The agent was isolated and characterised in numerous outbreaks of tenosynovitis, mainly in broilers (Jones 2008).
However, in the last 20 years, only very few cases were reported (Dobson and Glisson 1992, Hemzani and others 1996, de Gussem and others 2010), and in none of them molecular methods were applied to characterise the virus and to link such data with the appearance of the virus in combination with flock data.
ARV is classified in the Orthoreovirus genus within the Reoviridae family (Attoui and others 2012). Recent studies based on phylogenetic analysis of the immunogenic σC protein (Wickramasinghe and others 1993) indicated the existence of many variants which have been classified in distinct clusters within the ARV (Kant and others 2003, Liu and others 2003, Goldenberg and others 2010). New isolates of ARV seem to differ from the well described strains used in commercial vaccines (Lublin and others 2011). Vaccination of broiler breeders is essential to protect progenies against infection via maternally derived antibodies (Eidson and others 1979), although the full effect is only given when progenies are challenged with homologous serotypes (Rau and others 1980, Wood and others 1986).
Here we report outbreaks of viral tenosynovitis in central and western France even though parent stocks were vaccinated according to well known procedures. Birds from five hatcheries were involved. Data of broiler breeder flocks and their progenies are presented; the virus isolates are characterised serologically and genetically. The aim of this study was to link data from breeders with those of broiler flocks which would allow conclusions for future strategies to prevent reovirus-induced tenosynovitis.
Material and methods
Flocks data and clinical observations
Numerous cases of tenosynovitis appeared in different geographic regions in France. In order to investigate these outbreaks, data from 17 broiler flocks and the corresponding parent flocks were used. Data from flocks included genetics, hatcheries and vaccinations of the breeders. To estimate the economic losses, performance of an ARV infected flock was compared with the average performance of the three last flocks of the same farm.
ELISA titres in breeders and progeny were measured during routine flock monitoring....