Local Inflammatory and Systemic Antibody Responses Initiated by a First Intradermal Administration of Autogenous Salmonella-Killed Vaccines and Their Components in Pullets

Jossie M Santamaria; Chrysta N Beck; Gisela F Erf

doi:10.3390/vaccines12101159

Local Inflammatory and Systemic Antibody Responses Initiated by a First Intradermal Administration of Autogenous Salmonella-Killed Vaccines and Their Components in Pullets

Vaccines (Basel). 2024 Oct 11;12(10):1159. doi: 10.3390/vaccines12101159.

Authors

Jossie M Santamaria¹, Chrysta N Beck¹, Gisela F Erf¹

Affiliation

¹ Department of Poultry Science, Center of Excellence for Poultry Science, University of Arkansas System Division of Agriculture, Fayetteville, AR 72701, USA.

Abstract

Vaccination strategies are used to manage Salmonella in chickens. Salmonella-killed vaccines are considered safer since they are inactivated. However, little is known regarding the cellular immune activities at the site of vaccine administration of Salmonella-killed vaccines. The growing feather (GF) cutaneous test has been shown to be an effective bioassay to monitor local tissue/cellular responses. We assessed local and systemic antibody responses initiated by intradermal injection of Salmonella-killed vaccines into GF-pulps of 14-15-week-old pullets. Treatments consisted of two autogenous Salmonella-killed vaccines (SV1 and SV2), S. Enteritidis (SE) lipopolysaccharide (SE-LPS), and the water-oil-water (WOW) emulsion vehicle. GF-pulps were collected before (0 h) and at 6, 24, 48, and 72 h post-GF-pulp injection for leukocyte population analysis, while heparinized blood samples were collected before (0 d) and at 3, 5, 7, 10, 14, 21, and 28 d after GF-pulp injections to assess plasma levels (a.u.) of SE-specific IgM, avian IgY (IgG), and IgA antibodies using an ELISA. Injection of GF-pulps with SV1, SV2, or SE-LPS, all in a WOW vehicle, initiated inflammatory responses characterized by the recruitment of heterophils, monocytes/macrophages, and a few lymphocytes. The WOW vehicle emulsion alone recruited more lymphocytes than vaccines or SE-LPS. The SV1 and SV2 vaccines stimulated Salmonella-specific IgM and IgA early, while IgG levels were greatly elevated later during the primary response. Overall, SV1 and SV2 stimulated a heterophil and macrophage-dominated local inflammatory- and SE-specific humoral response with an isotype switch from IgM to IgG, characteristic of a T-dependent primary antibody response. This study provides comprehensive information on innate and adaptive immune responses to autogenous Salmonella-killed vaccines and their components that will find application in the management of Salmonella in poultry.

Keywords: Salmonella vaccines; antibody response; emulsion; lipopolysaccharide; local cellular immune response; pullets.

Grants and funding

The research reported in this article was supported by external and internal funds. Elanco Animal Health (Greenfield, IN, USA) provided test materials and external research funds; G.F. Erf, PI. Internal funding was provided by the Endowed Tyson Professorship in Avian Immunology (G. F. Erf), and a Graduate Research Assistantship (J.M. Santamaria) from the Department of Poultry Science, University of Arkansas System, Division of Agriculture.