Comparison of B lymphocyte responses in broiler chickens vaccinated with electron beam or formalin inactivated Staphylococcus aureus

Authors: PERERA, RUVINDU - University Of Arkansas; SANTAMARIA, JOSSIE - University Of Arkansas; BECK, CHRYSTA - University Of Arkansas; ERF, GISELA - University Of Arkansas; ALRUBAYE, ADNAN - University Of Arkansas; Jesudhasan, Palmy

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 11/15/2024
Publication Date: 1/28/2025
Citation: Perera, R., Santamaria, J.M., Beck, C.N., Erf, G.F., Alrubaye, A., Jesudhasan, P. 2025. Comparison of B lymphocyte responses in broiler chickens vaccinated with electron beam or formalin inactivated Staphylococcus aureus. Abstract. The International Poultry Scientific Forum, January 27-28, 2025.

Interpretive Summary: Staphylococcus aureus is one of the foodborne pathogens and poultry meat is one the sources for human infections. In order to control S. aureus in chickens, we wanted to vaccinate electron beam (eBeam)-inactivated S. aureus and test the effect of the vaccine in reducing the colonization of S. aureus. We vaccinated broiler chickens embryos on day18. We had 6 different treatment groups with 5 chickens/group. We had formalin-killed (FK)-SAu as a control to compare the effect of eBeam-inactivated vaccine Blood samples were collected at specific time intervals post-in ovo vaccination. We conducted ELISA and flow cytometry analyses to find out the immune response to the vaccination. The results indicate that higher plasma levels of SAu-specific IgM and IgA after the in ovo eBeam SAu vaccination may reflect better protection at mucosal surfaces.

Technical Abstract: Chicken meat is a common source of foodborne Staphylococcus aureus (SAu) infection and a major cause of bacteremia and infective endocarditis in humans as well as septicemia and arthritis in chickens. Hence, SAu poses significant health hazards and severe economic losses due to meat condemnation. Lethal electron Beam (eBeam) treatment inactivates bacteria by disintegrating nucleic acids while preserving surface epitopes that endow antigenicity and immunogenicity in hosts. Our objective was to compare local and systemic B cell responses in broiler chickens vaccinated with eBeam inactivated (eB)- or formalin-killed (FK)-SAu. Endotoxin-free PBS was the vaccine (sham) control. This study had 6 treatment (trt) groups with 5 chickens/group, where each vaccine trt was divided into two groups (Group A and B; i.e., A-eB, A-FK, A-sham, B-eB, B-FK, B-sham). Group A received the vaccine/sham treatments in ovo. At 34d of age, intradermal (i.d.) injections of respective trt into the pulps of growing feathers (GFs) were conducted to elicit booster- and primary-immune responses in groups A and B, respectively. Blood was collected at specific time intervals post-in ovo vaccination (Phase 1) from Group A chickens for immunofluorescent (IF) staining and B cell analyses by flow cytometry, and to compare relative levels of plasma SAu-specific antibodies by ELISA. Following i.d. GF injections (Phase 2), blood was similarly sampled and analyzed from both groups. Additionally, in Phase 2, GFs were collected at various times p.i. to assess local, primary and booster B cell presence in pulps by IF staining of pulp cell suspensions and flow cytometry. Two-way ANOVA was conducted to test effects of treatment, time, and their interactions followed by Bonferroni post hoc tests. Statistical significance was set at P<0.05. eB vaccine resulted in higher SAu-specific IgM and IgA levels early in Phase 1, while in Phase 2, all groups had similar circulating levels of SAu-specific IgM, IgG and IgA antibodies and B cells. FK vaccine resulted in higher levels of B cells in GF-pulps at 24 h p.i. in both the primary and booster responses. In conclusion, the higher plasma levels of SAu-specific IgM and IgA after the in ovo eBeam SAu vaccination may reflect better protection at mucosal surfaces.