RESUMO
Turkey coronavirus (TCoV) causes diarrhoea in young turkey poults but little is known about its prevalence in the field. To address this, a portion of the S1 region of the spike glycoprotein of TCoV carrying relevant B cell epitopes (amino acid positions 54-395) was cloned and expressed in Escherichia coli. This protein was purified and used to develop an indirect ELISA for detection of antibodies against TCoV. Using experimentally derived positive and negative turkey serum samples this ELISA showed high sensitivity (95%) and specificity (92%) for TCoV. To further evaluate the potential of the ELISA, 360 serum samples from commercial turkey farms in Ontario were tested for TCoV-specific antibodies using the recombinant TCoV ELISA. High seroprevalence of TCoV was found with 71.11% of breeders and 56.67% of meat turkeys testing seropositive. Although there was significant positive correlation with a TCoV-N protein-based ELISA, there was little to no correlation with the whole IBV antigen-based ELISA when field sera were tested for antibodies against TCoV.
Assuntos
Anticorpos Antivirais/sangue , Coronavirus do Peru/imunologia , Ensaio de Imunoadsorção Enzimática/veterinária , Glicoproteínas de Membrana/imunologia , Proteínas Recombinantes , Proteínas do Envelope Viral/imunologia , Animais , Anticorpos Antivirais/análise , Clonagem Molecular , Enterite Transmissível dos Perus/sangue , Enterite Transmissível dos Perus/epidemiologia , Enterite Transmissível dos Perus/virologia , Ensaio de Imunoadsorção Enzimática/métodos , Glicoproteínas de Membrana/genética , Ontário/epidemiologia , Doenças das Aves Domésticas/sangue , Doenças das Aves Domésticas/epidemiologia , Doenças das Aves Domésticas/virologia , Estudos Soroepidemiológicos , Glicoproteína da Espícula de Coronavírus , Perus , Proteínas do Envelope Viral/genéticaRESUMO
Turkey coronavirus (TCoV) causes diarrhea in young turkey poults, but little is known about its prevalence in the field. To address this, the complete nucleocapsid gene was cloned and expressed in Escherichia coli. Expressed nucleocapsid gene produced two distinct proteins (52 and 43 kDa); their specificity was confirmed by Western blotting using two different monoclonal antibodies. Recombinant N protein was purified and used as an antigen to develop an enzyme-linked immunosorbent assay (ELISA) for the serological detection of TCoV that was then validated using experimentally derived turkey serum. The N-based ELISA showed (97%) sensitivity and (93%) specificity for TCoV, which was significantly higher than an infectious bronchitis coronavirus-based commercial test for TCoV. To assess the utility of this recombinant ELISA, 360 serum samples from turkey farms in Ontario, Canada, and 81 serum samples from farms in Arkansas were tested for TCoV-specific antibodies. A high seroprevalence of TCoV was found in turkeys from the Ontario farms with 73.9% of breeders and 60.0% of meat turkeys testing seropositive using the N-based ELISA. Similarly, a high field prevalence was found in the turkeys from Arkansas, for which 64.2% of the serum samples tested seropositive.
