Volume 16, Issue 1: 2026 - Article 217

Abstract
Newcastle disease (ND) virus is a highly pathogenic virus affecting avian species. ND is considered economically important because of the high morbidity and mortality associated with the disease in birds. While ND impairs the immunity of birds, little is known about how long the immunosuppression lasts across the bird’s life time. The present study evaluated the effects of early velogenic Newcastle disease virus (vNDV) infection (at a younger age) on their immune response to vaccination as older layer chickens. A total of 310 pullet chickens were randomly assigned to three groups: 80 unvaccinated unchallenged (UU), 150 unvaccinated challenged (UC), and 80 vaccinated challenged (VC) pullets. On day 2 post-hatch, pullets in VC group were given LaSota vaccine. On day 10 post-hatch, chicks in the UC and VC groups were experimentally challenged with 0.1 ml of vNDV Kudu 113 strain inoculum via intramuscular injection. On day 21 post-challenge (PC), ten chicks were randomly sampled from each group and housed separately. Chickens in all the groups were vaccinated with the ND LaSota vaccine and re-vaccinated 42 days after the initial vaccination. Serum samples were collected weekly and tested for Newcastle disease virus haemagglutination inhibition antibodies. Results showed antibody titres of the VC and UC groups were significantly (p < 0.05) higher than that of the UU group all through the study. The antibody titre levels in all the groups (UU, VC and UC) demonstrated a typical lymphoid response to the NDV vaccine: no impairment was recorded with regards to the early virus challenge. These results suggest that early infection of pullet chicks with the NDV, as done in this study, does not lead to lasting immunosuppression in layer chickens.

Keywords: Pullet chicks; Newcastle disease virus infection; Young age; Vaccination response; Antibody titres; Serology.

How to cite this article:
Onyema I, Ezeasor C, Omeke JN, Ikenna-Ezeh NH, Nnorum CO, Eze DC and Ezema WS (2026). Effects of early Newcastle disease (ND) virus infection of chicken pullets on their antibody response to ND virus challenge and ND vaccinations later in the life of the layer chickens. Journal of Veterinary and Applied Sciences, 16(1): 1333 – 1339.

*Correspondence: E-mail:     ifeanyi.onyema@unn.edu.ng     Phone: +2348063707010

Effects of early Newcastle disease (ND) virus infection of chicken pullets on their antibody response to ND virus challenge and ND vaccinations later in the life of the layer chickens

Ifeanyichukwu Onyema ¹ *, Chukwunonso Ezeasor ¹, Jacinta N. Omeke ¹, Nkechi H. Ikenna-Ezeh ², Chelsea O. Nnorum ¹, Didacus C. Eze ² and Wilfred S. Ezema ^1
1 Department of Veterinary Pathology, Faculty of Veterinary Medicine, University of Nigeria Nsukka, Enugu State, Nigeria.
² Department of Veterinary Microbiology & Immunology, Faculty of Veterinary Medicine, University of Nigeria Nsukka, Enugu State, Nigeria.

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