Evaluation of serological tests for the diagnosis of Mycoplasma gallisepticum and Mycoplasma synoviae infections in broiler chickens with respiratory ailments

The pathogenic avian mycoplasmas, such as Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS) are responsible for causing significant economic losses to the poultry industry. The present study was aimed at serodiagnosis of MG and MS infection in broiler chicken flocks using serum plate agglutination test (SPAT), indirectenzyme linked immunosorbent assay (i-ELISA) and Dot-ELISA, followed by measuring the relative diagnostic efficacy of SPAT and Dot-ELISA in reference to i-ELISA. The blood samples (n68) collected from the broiler chicken aging 46 weeks affected with respiratory tract infection from poultry farms located in Mathura district of Uttar Pradesh, India were used in the study. Initially, SPAT was used to detect MG and MS antibodies in collected sera. In SPAT, 36.76 and 72.06 sera were found positive for MG and MS antibodies, respectively. Later, the samples were screened using laboratory standardized i-ELISA and Dot-ELISA. The culture of MG (NCBI accession no. KX759104.1) and MS (NCBI accession no. KY486506.1) isolates were used to prepare antigens to standardize i-ELISA and Dot-ELISA. Using i-ELISA, the seropositivity of MG and MS antibodies in collected sera was found to be 85.29 and 80.88, respectively. However, seropositivity of MG and MS antibodies using Dot-ELISA was found to be 66.18 and 77.94, respectively. The i-ELISA was used as gold standard test to compare the diagnostic efficacy of SPAT and Dot-ELISA. The relative diagnostic sensitivity, specificity and kappa values for the detection of MG and MS using SPAT was found to be 43.10, 100, 0.1822 and 86.09, 100, 0.7574, respectively. However, the relative diagnostic sensitivity, specificity and kappa values for the detection of MG and MS using Dot-ELISA was found to be 77.59, 100, 0.2524 and 96.36, 100, 0.9102, respectively. The present study reports that i-ELISA and Dot-ELISA should be used along with SPAT for accurate detection of avian mycoplasmas infection in poultry flocks affected with respiratory tract infection.