Humoral and cell mediated immune responses in turkeys to an indigenous turkey pox virus

Alka Singh, B.B. Dash, J.M. Kataria, S. Dandapat , S. Arthur and K. Dhama
Division of Avian Diseases, IVRI, Izatnagar, U.P.-243 122

The humoral and cell mediated immune responses in turkeys was studied after an experimental infection with an indigenous turkey poxvirus (TPV). It was found that the immunity developed in turkeys as early as two weeks of post-infection and lasted for seven months longer. The cell mediated immunity (CMI) developed earlier than humoral immunity. The turkeys once affected with the turkey poxvirus were not likely to be affected again, indicating development of strong immunity. The CMI response against the TPV isolate was determined by lymphocyte transformation test (LTT) by measuring the stimulation indices (SI) of peripheral blood mononuclear cells of infected turkeys using MTT dye at different intervals from 2 nd to 10 th wk post-infection period. The SI in control group was found to be lower than the infected turkeys. The humoral immune response in turkeys was studied by employing the agar gel precipitation test (AGPT) and serum neutralization test (SNT) at weekly intervals after the infection. In case of AGPT it was found that the precipitating antibodies were detectable up to 7 th wk of infection. The neutralization index (NI) was determined by employing SNT using inactivated serum samples collected from turkeys at weekly intervals from 2 nd to 10 th wk post-infection period. The turkeys were found to bear neutralizing antibodies with NI of more than 2.0 throughout the period of observation. It was observed that the indigenous turkey poxvirus is a potent immunogen, which elicits optimum humoral and CMI responses in turkeys against the turkey poxvirus infection.

Source : IPSACON-2005

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