RESUMO
Senecavirus A (SVA) is a picornavirus that is endemic in swine, causing a vesicular disease clinically indistinguishable from other vesicular diseases, like foot-and-mouth disease. The widespread viral circulation, constant evolution, and economic losses caused to the swine industry emphasize the need for measures to control the agent. In this study, we evaluated the immunogenicity of a whole-virus-inactivated vaccine using a representative contemporary Brazilian SVA strain in Balb/ByJ mice. The animals were vaccinated with two doses by an intramuscular route. The humoral response induced by the vaccination was evaluated by an in-house ELISA assay for IgG detection. The cellular response was assessed by flow cytometry after in vitro SVA stimulation in splenocyte cultures from vaccinated and non-vaccinated groups. Protection against SVA was assessed in the experimental groups following an oral challenge with the homologous virus. The vaccination induced high levels of IgG antibodies and the proliferation of CD45R/B220+sIgM+, CD3e+CD69+, and CD3e+CD4+CD44+CD62L- cells. These results indicate the immunogenicity and safety of the vaccine formulation in a murine model and the induction of humoral and cellular response against SVA.
RESUMO
Avian poxvirus (APV) is an enveloped double-stranded DNA virus that affects many domestic and wild birds worldwide. APVs are classified into three clades (A to C), represented by fowlpox (FP) virus (clade A), canarypox virus (clade B), and psittacinepox virus (clade C), although two additional clades (D and E) have been proposed. In this study, a tumorlike skin lesion found in a domestic fowl was submitted for molecular diagnosis of Avipoxvirus by PCR and sequencing. The phylogenetic analysis revealed that the amplified segment of the corelike 4b protein and polymerase genes clustered in clade E. The APVs in clade E were previously reported from outbreaks in Hungary (flock of turkeys) and in Mozambique (layer chickens), associated with a possible vaccine failure to protect against clade E viruses. To our knowledge, this report is the first identification of clade E in this country, providing new information about host range and genetic diversity of APVs in Brazil, and may represent a potential risk of FP disease outbreaks in commercial poultry.
Reporte de caso- Identificación del Avipoxvirus clado E en Brasil. El poxvirus aviar (APV) es un virus de ADN bicatenario envuelto que afecta a muchas aves domésticas y silvestres en todo el mundo. Los poxvirus aviares se clasifican en tres clados (A, B y C), representados por el virus de la viruela aviar (FP) (clado A), el virus de la viruela del canario (clado B) y el virus de la viruela de los psitácidos (clado C), aunque dos clados adicionales (D y E) han sido propuestos. En este estudio, una lesión cutánea similar a un tumor encontrada en una gallina doméstica fue sometida a diagnóstico molecular de Avipoxvirus por PCR y secuenciación. El análisis filogenético reveló que el segmento amplificado de los genes de la proteína del centro 4b y de la polimerasa se agruparon en el clado E. Los poxvirus aviares en el clado E se reportaron previamente de brotes en Hungría (parvada de pavos) y en Mozambique (gallinas de postura), asociados con una posible falla de la vacuna para proteger contra los virus del clado E. De acuerdo con el conocimiento de los autores, este informe es la primera identificación del clado E en este país, brindando nueva información sobre el rango de hospedadores y la diversidad genética de poxvirus aviares en Brasil, y puede representar un riesgo potencial de brotes de viruela aviar en aves comerciales.