TYPE Original Research PUBLISHED 26 July 2022 DOI 10.3389/fvets.2022.947522 OPEN ACCESS EDITED BY Kun Li, Nanjing Agricultural University, China REVIEWED BY Awais Ghaffar, University of Calgary, Canada Abdul Rahman Omar, Putra Malaysia University, Malaysia *CORRESPONDENCE Iqra Zaheer dr.iqzaheer@gmail.com Wei Chen cwei010230@163.com SPECIALTY SECTION This article was submitted to Veterinary Infectious Diseases, a section of the journal Frontiers in Veterinary Science RECEIVED 18 May 2022 ACCEPTED 30 June 2022 PUBLISHED 26 July 2022 CITATION Zaheer I, Chen W, Khan A, Elokil A, Saleemi MK, Zaheer T and Khan MZ (2022) Immunopathological comparison of in ovo and post-hatch vaccination techniques for infectious bursal disease vaccine in layer chicks. Front. Vet. Sci. 9:947522. doi: 10.3389/fvets.2022.947522 COPYRIGHT © 2022 Zaheer, Chen, Khan, Elokil, Saleemi, Zaheer and Khan. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. Immunopathological comparison of in ovo and post-hatch vaccination techniques for infectious bursal disease vaccine in layer chicks Iqra Zaheer 1 *, Wei Chen 2 *, Ahrar Khan 3 , Abdelmotaleb Elokil 4 , Muhammad Kashif Saleemi 1 , Tean Zaheer 5 and Muhammad Zargham Khan 1 1 Department of Pathology, University of Agriculture, Faisalabad, Pakistan, 2 Institute of Animal Science, Guangdong Academy of Agricultural Sciences, Animal Nutrition and Feed Science in South China, Ministry of Agriculture and Rural Affairs, State Key Laboratory of Livestock and Poultry Breeding, Key Laboratory of Guangdong Public Laboratory of Animal Breeding and Nutrition, Guangdong Key Laboratory of Animal Breeding and Nutrition, Guangzhou, China, 3 Department of Animal Science & Technology, Shandong Vocational Animal Sciences and Veterinary College, Weifang, China, 4 Department of Animal Production, Faculty of Agriculture, Benha University, Benha, Egypt, 5 Department of Parasitology, University of Agriculture, Faisalabad, Pakistan This study was designed to compare immunopathological effects of in ovo vaccination with post-hatch vaccination against IBD in White Leghorn chicks. A total of 189 embryonated eggs were divided into six groups. At day 18 of incubation, groups A–C were administered in ovo with 228E, Winterfield 2512:10/3 and 2512/90:10/2.7, respectively, group D (post-hatch vaccination) and group E as shamed control (for quality evaluation of in ovo vaccination technique), and group F as control. The results showed that antibody titers against IBD detected by ELISA on days 2, 17, and 28 were significantly higher in all in ovo groups as compared to control groups E and F. On day 17, all vaccinated groups (in ovo and post-hatch vaccinated) showed no significant differences in antibody titers among themselves; however, at day 28, only the post-hatch group showed significantly higher antibody titers followed by in ovo vaccinated groups. The cell-mediated immunity determined by PHA-P assay was significantly higher in all vaccinated groups than the non-vaccinated groups. No clinical signs of IBD infection were observed in any of the vaccinated groups. There was only increase in bursa size of groups vaccinated with intermediate plus strains (groups A, C, and D) at day 28. The histopathology showed that all the treatment groups had mild lesions induced by IBD virus in bursa. This study concluded that in ovo vaccination with live IBD vaccines provides protective immunity to the chickens even in the presence of IBD-specific MDA; therefore, the onset of immunity was much earlier than the post-hatch vaccination and in ovo groups also maintained protective immunity against IBD for longer time. KEYWORDS IBD, in-ovo, vaccine, immunopathology, layers Frontiers in Veterinary Science 01 frontiersin.org