Abstract
Fifty-four fecal samples taken from broiler chickens from 1 to 45 days of age, and of pullets from 10 to 13 weeks of age, original from eight different poultry regions in the state of Minas Gerais, Brazil, were collected from March 2008 to January 2010 for avian Orthoreovirus (ARV) and avian Rotavirus (AvRV) analyses. For the assay of ARV, RNA was immediately extracted (Trizolâ) and transcribed into cDNA for assaying in a nested-PCR with ARV-specific primers. For AvRV, polyacrylamide gel electrophoresis (PAGE) was performed with RNA extracts obtained by phenol-chloroform extraction. CAV was additionally investigated through a nested-PCR of thymus and spleen. Results found 5.55% positive for ARV and 9.25% for AvRV. Also, CAV and ARV genomes were detected in co-infection, in a highly prostrated and claudicating chicken flock. No ARV or AvRV infections were detected in pullets. Material of a clinically affected flock was inoculated into SPF embryos, resulting in embryonic hemorrhage, whitish foci in the chorio-allantoic membrane and death. Sequencing of ARV amplicons and isolate cDNA grouped local strains with the ARV S1133 strain, historically used in live vaccines, suggesting the continued circulation of this vaccine virus strain in intensive poultry regions. Detection rates for ARV and AvRV, as well as the presence of CAV, were additionally indicative of failing biosecurity strategies for the intensive poultry regions examined.
Highlights
Orthoreovirus and Rotavirus are genera of Reoviridae, which in chickens and other species are usually involved in enteritis, stunted and poorer growth, reduced productive performance and higher mortality rates (McFerran et al, 1983; Andral et al, 1985; Gouch et al, 1988; Decaesstecker et al, 1988; Martins et al, 2009)
avian Orthoreovirus (ARV) and avian Rotavirus (AvRV) were detected in the broiler industry in Minas Gerais (Table 1)
Failed or lack of biosecurity, intensification and proximity of flocks of broiler chickens, may have a role in the detected occurrence of ARV and AvRV, as samples were obtained from chickens of densely broiler populated areas, and susceptible floor raised flocks may facilitate fecal-oral infection (Rosenberger, 2003)
Summary
Orthoreovirus and Rotavirus are genera of Reoviridae, which in chickens and other species are usually involved in enteritis, stunted and poorer growth, reduced productive performance and higher mortality rates (McFerran et al, 1983; Andral et al, 1985; Gouch et al, 1988; Decaesstecker et al, 1988; Martins et al, 2009). Infected hatchlings and young develop the gastro-intestinal signs which will result in poor growth and lower performance, and survivors may develop arthritis (Van der Heide et al, 1975). For the diagnosis of ARV, specific nested-polymerase chain reaction (PCR) protocols have been described for amplifying a region of the S1gene encoding the σC protein (Liu et al, 1997) region best suited for demonstrating diversity ((Shiff et al, 2007). Nested PCR reactions reduce or eliminate nonspecificity and increase sensitivity for ARV detection (Liu et al, 1997)
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