The Infectious bursal disease virus (IBDV), rapidly destroy immature B lymphocytes in bursa of fabricous and cause the immunosuppression and high mortality in broiler chicken. Therefore, present study was conducted to investigate the viral antigen in lymphoid tissues of experimentally infected broiler chicken and specific antigen negative (SAN) chicks through immunohistochemistry (IHC) and reverse transcriptase polymerase chain reaction (RT-PCR). For this purpose, two hundred broiler chicks were reared and divided into 4 groups (A, B, C and D), fifty birds in each group. The birds in group A were commercial broiler chicks having maternal derived antibodies and group B containing SAN chicks. The groups A and B were challenged with IBDV field isolate. While the group C and D was unchallenged control. On 3^rd, 5^th, 9^th and 14^th day post infection (pi), Lymphoid organs Bursa of Fabricius, spleen and thymus and non lymphoid organs kidney and liver were collected for histopathology, IHC and viral genome detection by RT-PCR. At day 3 of pi, viral antigen observed in lymphoid cells of follicles of bursa and thymus, marked leukocytic infiltration occurred with bursal oedema and hyperemia. Virus was constantly found at 5^th day post infection until day 14^th, in the primary lymphoid tissues and characterized in acute inflammation. The hypervariable region of viral antigen, VP 2 gene was detected in bursa, thymus, spleen, kidney and liver tissues in challenged groups A and B through RT-PCR by using specific primers of 743bp. The virus antigen detection from tissues reduced with increasing antibody titer. It is concluded, the IBDV antigen detection rate in primary lymphoid organs was high as virus targets the lumphocytes and macrophages. Immunohistochemistry and RT-PCR are more specific and sensitive methods for detection of IBD viral antigen.

To Cite This Article: Zahid B, Aslam A, Anjum R, Imran S, Irshad I, Ara C and Sadia H, 2018. Study on tissue tropism and molecular detection of VP2 gene of infectious bursal disease virus in experimentally infected broiler tissues. Pak Vet J, 38(3): 291-295. http://dx.doi.org/10.29261/pakvetj/2018.054