Infecção por reovirus aviário em frangos de corte no brasil: caracterização molecular de isolados e avaliação clínica, patológica e sorológica
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Data
2022-01-06
Autores
Schaefer, Gustavo
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Universidade Estadual Paulista (Unesp)
Resumo
Neste estudo, os sinais clínicos, exame patológico post-mortem, sorologia, isolamento viral e caracterização molecular de isolados de vírus foram direcionados para confirmar a ocorrência de infecção por Reovírus Aviário (ARV) em amostras de frangos de corte com artrite e tenossinovite criados em quatorze granjas distribuídas em unidades de avicultura em três estados brasileiros (Bahia - BA, Minas Gerais - MG e São Paulo - SP). Foram encontradas lesões macroscópicas e microscópicas características, como inchaço das articulações metatarsais e tenossinovite aguda a crônica, apresentando marcadas reações inflamatórias e hemorrágicas. A soroconversão entre pintos de um dia e frangos de abate foi detectada em frangos em unidades avícolas dos estados de MG e SP, enquanto altos títulos médios de anticorpos anti-ARV em ambas as idades foram detectados em granjas de BA. Quatorze isolados de ARV foram detectados por RT-qPCR e a análise de sequenciamento parcial de seu gene σC mostrou alta identidade com alguns isolados brasileiros recentes de ARV, mas esses vírus tinham alta variabilidade em relação às cepas de vacinas ARV e a filogenia os classificou em três grupos genéticos distintos: I (Subgrupo Ib), III e V. A variabilidade nos resíduos de aminoácidos deduzidos da proteína σC identificada nesses isolados de ARV resultou em mudanças relevantes na estrutura da proteína secundária e ocorreu predominantemente nos sítios antigênicos previstos desta proteína, incluindo aqueles que são críticos para neutralização de vírus. No geral, os resultados indicam que esses isolados de ARV com diferenças relevantes no gene σC e na proteína do capsídeo estão envolvidos na etiologia da artrite e tenossinovite que afeta frangos dessas granjas no Brasil e, devido à sua variabilidade genética e antigênica, eles podem não ser eficazes controlada por vacinas comerciais contra ARV contendo cepas de referência do agrupamento genético I.
In this study, clinical signs, post-mortem pathology examination, serology, viral isolation and molecular characterization of virus isolates were addressed to confirm the occurrence of Avian Reovirus (ARV) infection in samples from broilers with arthritis and tenosynovitis reared in fourteen poultry farms distributed in poultry farming units in three Brazilian states (Bahia - BA, Minas Gerais - MG and São Paulo - SP). Characteristic macroscopic and microscopic lesions were found, such as swelling of metatarsal joints and acute to chronic tenosynovitis showing marked inflammatory and hemorrhagic reactions. Sero-conversion between day-old chicks and broilers at slaughter was detected for broilers in poultry farming units from MG and SP states, while high anti-ARV mean antibody titers at both ages were detected in poultry farms from BA. Fourteen ARV isolates were detected by RT-qPCR and the partial sequencing analysis of their σC gene showed high identity with some recent Brazilian ARV isolates, but these viruses had high variability regarding ARV vaccine strains and the phylogeny classified them into three distinct genetic clusters: I (Sub-cluster Ib), III and V. The variability in deduced amino acid residues of σC protein identified in these ARV isolates resulted in relevant changes in secondary protein structure and occurred predominantly in predicted antigenic sites of this protein including those that are critical for virus-neutralization. Overall, the results indicate that these ARV isolates carrying relevant differences in σC gene and capsid protein are involved in the etiology of arthritis and tenosynovitis affecting broilers from these poultry farms in Brazil and due to their genetic and antigenic variability, they may not be effectively controlled by commercial vaccines against ARV containing references strains of genetic cluster I.
In this study, clinical signs, post-mortem pathology examination, serology, viral isolation and molecular characterization of virus isolates were addressed to confirm the occurrence of Avian Reovirus (ARV) infection in samples from broilers with arthritis and tenosynovitis reared in fourteen poultry farms distributed in poultry farming units in three Brazilian states (Bahia - BA, Minas Gerais - MG and São Paulo - SP). Characteristic macroscopic and microscopic lesions were found, such as swelling of metatarsal joints and acute to chronic tenosynovitis showing marked inflammatory and hemorrhagic reactions. Sero-conversion between day-old chicks and broilers at slaughter was detected for broilers in poultry farming units from MG and SP states, while high anti-ARV mean antibody titers at both ages were detected in poultry farms from BA. Fourteen ARV isolates were detected by RT-qPCR and the partial sequencing analysis of their σC gene showed high identity with some recent Brazilian ARV isolates, but these viruses had high variability regarding ARV vaccine strains and the phylogeny classified them into three distinct genetic clusters: I (Sub-cluster Ib), III and V. The variability in deduced amino acid residues of σC protein identified in these ARV isolates resulted in relevant changes in secondary protein structure and occurred predominantly in predicted antigenic sites of this protein including those that are critical for virus-neutralization. Overall, the results indicate that these ARV isolates carrying relevant differences in σC gene and capsid protein are involved in the etiology of arthritis and tenosynovitis affecting broilers from these poultry farms in Brazil and due to their genetic and antigenic variability, they may not be effectively controlled by commercial vaccines against ARV containing references strains of genetic cluster I.
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Palavras-chave
Artrite, Frango, Brasil, Infecção