Comparative study on conventional and real-time PCR assays for rapid and specific detection of Mycoplasma gallisepticum infection in poultry

Abstract

Mycoplasma gallisepticum (MG) has been reported to cause significant economic losses to the poultry industry. In this study, real-time TaqMan and conventional MG PCR assays were standardized for rapid and specific detection of pathogen and its efficacy were compared. A total of 146 pooled tissue samples comprising trachea, lungs and air sacs were collected from dead birds having history of respiratory tract infections. Each sample (tissues of 4–5 dead birds) represented different poultry flocks located in Haryana and Rajasthan states of India. The analysis of samples was carried out using primers of 16 S rRNA for conventional and lipoprotein gene for real-time MG PCR assays. In conventional PCR, 48/146 (32.87%) tissue samples were found positive for MG. However, real-time PCR showed higher positivity (58/146; 39.72%) as compared to conventional PCR. Considering the conventional PCR as a gold standard, sensitivity (100%), specificity (89.8%) & positive (0.81) and negative (1.0) predictive values of the standardized real-time PCR was calculated. However, Cohen's kappa statistic (k = 0.85) showed a 'strong' agreement between two PCR assays. The study revealed that screening of samples using more than one molecular technique is helpful for determining true burden of the disease.

Keywords

• Conventional PCR
• Mycoplasma gallisepticum
• Real-time PCR
• Poultry