Efficacy of two diagnostic tests for the detection of infectious bursal disease viruses in chicken from different types of bursal samples

Infectious Bursal Disease (IBD) is an economically important irreversible immunosuppressive disease of young birds. The present study was designed to confirm the efficacy of two common diagnostic tests for the detection of Infectious Bursal Disease Virus (IBDV) from the three types of bursal samples collected from a recent outbreak in layer and broiler chickens of Gazipur district, Bangladesh. This study compared the degree of sensitivity between Ouchterlony Double Immunodiffusion Test (ODIT) and Reverse Transcription Polymerase Chain Reaction (RT-PCR) for the detection of IBD viral antigen from the bursal samples. A total of 180 field bursal samples (80 broiler and 100 from layer chicken) from suspected IBDV infected dead chickens were collected from 50 different poultry farms. Bursal homogenates were used to detect IBDV using ODIT and RT-PCR. Three types of bursal samples, hemorrhagic bursa (90), edematous bursa (78) and atrophied bursa (12) were selected for the detection of viral antigen. A panel of anti-sera and IBDV specific primer for VP2 gene was used for RT-PCR. The data demonstrated that, out of 180 field samples, 164 (91%) were positive by RT-PCR and 120 (67%) were positive by ODIT. Haemorrhagic bursas were more sensitive compared to oedematous bursas while no virus was detected from the samples of atrophied bursa. This study demonstrated that, RT-PCR was more sensitive and effective diagnostic tool compared to that of ODIT.   Key words: Infectious bursal disease virus (IBDV), ouchterlony double immunodiffusion test (ODIT), reverse transcription polymerase chain reaction (RT-PCR), bursa, broiler, layer.