Peripheral blood lymphocytes subpopulations and immune response of chicks to inactivated Newcastle disease virus given by nebulization

Newcastle disease (ND) is the most serious infectious disease of poultry causing substantial losses to the poultry industry. Vaccination programs against ND include the use of live vaccines administrated mainly mass by spray or aerosol, but vaccinal reaction often appears. Inactivated vaccines are applied for revaccination and require individual application. The present study was carried out to examine the possible induction of immune response following immunization of newly hatched chicks with inactivated La Sota NDV vaccine by ultrasonic nebulizer Sonovacr 095. Additionally, group of chicks was immunized with the same inactivated antigen in mixture with Parapoxvirus ovis as an immune response modifier (IRM) in order to test its immunostimulating activity. Immune response to inactivated NDV was estimated by HI test in week intervals up to 42nd day of age, and by survival after challenge infection. Nevertheless, inactivated antigen didn’ t induce specific antibodies response, which could be detected by HI test, but chickens remained fully protected after challenges (70-100%). Additionally, the changes of leukocytes subpopulation in peripheral blood were analyzed by means of flow cytometry using specific monoclonal antibodies for chicken CD45, Ia, Bu-1 and IgA cell surface molecules. Significant increase (p<0.05) in B cells subpopulations (phenotypes Bu-1+, Bu-1+Ia+, Bu-1+IgA+) was observed 3 days post immunization in vaccinated groups. Further investigations should include the use of more effective immunomodulator and different (higher) dose of inactivated antigen. Results achieved indicate the possible use of inactivated NDV antigen in specific immunoprotection of newly hatched chicks.