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Date of Graduation

5-2026

Description

In poultry production, chickens are routinely vaccinated with live herpesvirus vaccines for protection from lymphoma causing Marek’s disease virus. However, information on the immune responses to these vaccines is limited. This study examined cellular and antibody responses to primary and secondary vaccinations with herpesvirus of turkey (HVT). Six unvaccinated 9-wk-old, and six HVT-vaccinated (s.c. at hatch) 19-wk-old, layer pullets received a first (V1) or a second (V2) HVT vaccination, respectively, by intradermal injection of HVT-vaccine into the pulp of growing feathers (GFs; 10 µL/GF; 16 GFs/bird). GFs were collected before (0h), and at 0.25, 1, 2, 3, 5, 7, and 10d post-pulp-injection (p.i.) and, blood, at 0, 3, 5, 7, 10, 14, 21, and 28d p.i. To assess leukocyte profiles in GF-pulps, cell suspensions were prepared for immunofluorescent staining and leukocyte population analysis by FACS. ELISA was used to measure plasma levels of HVT-specific IgM and IgG. GF and blood data were analyzed by 2-way ANOVA and 2-way repeated measures ANOVA, respectively, to test effects of vaccine, time, and their interactions, followed by Tukey’s HSD tests when appropriate (P≤0.05 for all tests). Both V1 and V2 recruited leukocytes, primarily lymphocytes, by 1d p.i. (P≤0.05) with peak levels (% pulp cells) observed by 3d that were higher (P≤0.001) with V1 (54%) than with V2 (24%) and declined gradually to near 0h levels by 10d. Heterophils and macrophages peaked (4% each; P≤0.05) at 0.25d with both V1 and V2. However, V1 and V2 differed greatly in recruitment of T- and B-cells, with V1 recruiting much higher levels at 3, 5, and 7d (P≤0.05). While CD4+ T cells dominated the T cell response to V1, with elevated levels from 3 to 10d, CD8+ T cells were the most abundant T cells responding to V2, with peak levels on 1 to 3d p.i. (P≤0.05). Plasma HVT-IgM levels were elevated (P≤0.05) on 10 and 28d post V1 but did not change post V2. Similarly, HVT-IgG levels increased steadily post V1 (P≤0.05), reaching near maximal levels by 14d, while V2 did not stimulate a further increase. The temporal, qualitative, and quantitative differences in leukocyte presence at the site of HVT injection post V1 versus V2, suggest development of cell mediated immunity in response to HVT vaccination.

Publication Date

2025

Document Type

Book

Degree Name

Bachelor of Science in Agriculture

Degree Level

Undergraduate

Department

Poultry Science

Advisor/Mentor

Erf, Gisela

Disciplines

Medicine and Health Sciences

Keywords

Health

Differences in cellular and humoral immune responses to a primary and secondary immunization with herpesvirus of turkey (HVT) vaccine in layer pullets

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