Immune Response to Salmonella Enteritidis Infection in Broilers Immunized Orally With Chitosan-Based Salmonella Subunit Nanoparticle Vaccine.

Veerupaxagouda Patil,Jennifer Schrock,Gourapura J Renukaradhya,Ramesh Selvaraj,Sankar Renu,Yi Han,Ninoshkaly Feliciano-Ruiz

doi:10.3389/fimmu.2020.00935

Veerupaxagouda Patil, Jennifer Schrock + Show 5 more

Open Access

https://doi.org/10.3389/fimmu.2020.00935

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Abstract

Salmonella enterica serovar Enteritidis (S. Enteritidis, SE) infection in broilers causes a huge economic loss and public health risk. We previously demonstrated that orally delivered chitosan based (CS) Salmonella subunit nanoparticle (NP) vaccine containing immunogenic outer membrane proteins (OMP) and flagellin (FLA) of SE [CS-NP(OMP+FLA)] induces immune response in broilers. The objective of this study was to evaluate the dose- and age-dependent response and efficacy of CS-NP(OMP+FLA) vaccine in broilers. Three-day old birds were vaccinated and boosted once or twice. Additional groups were vaccinated at three weeks with no booster or boosted once a week later. Each dose of CS-NP vaccine had either 10 or 50 μg of OMP+FLA antigens. Our data revealed that two doses of vaccine were required to induce substantial immune response. Birds received 2 doses of CS-NP(OMP+FLA) vaccine at 3 days and 3 weeks of age with 10 μg antigens, and birds inoculated twice at 3 and 4 weeks of age with 50 μg antigens had lowest challenged bacterial load in the cecal contents with over 0.5 log10 reduction. In CS-NP(OMP+FLA) vaccinated birds, antigen-specific splenocyte proliferation, mucosal and systemic antibody response and the frequency of IFNγ-producing T cells were increased compared to control groups. At the molecular level, in the cecal tonsils of CS-NP(OMP+FLA) immunized birds, mRNA levels of toll-like receptor (TLR) 2 and TLR 4, and cytokines IL-4 and IL-10 were upregulated. The CS-NP(OMP+FLA) vaccine given orally has the potential to induce a protective immune response against SE infection in broilers.

Highlights

Salmonellosis is responsible for ∼1 million foodborne illnesses, 20,000 hospitalizations and 4,380 deaths annually in the United States [1]
When antibody responses in relation to the age of birds were compared, birds received the first dose at 3-day of age had higher levels of both specific IgA and IgG responses (Figures 1B,C)
3-day vaccinates with lower dose, when sampled at 5 weeks of age, induction of higher IgG response compared to Sol.Ag(OMP+FLA) and mock groups was observed (Figure 1C III)

Summary

Introduction

Salmonellosis is responsible for ∼1 million foodborne illnesses, 20,000 hospitalizations and 4,380 deaths annually in the United States [1]. Vaccination against Salmonella is considered a viable control strategy. During our market validation of Salmonella vaccination in poultry under a ICorps@Ohio activity [4], we interviewed 67 people throughout US comprising of poultry veterinarians, research scientists, consultants, laboratory diagnosticians, farm managers, vaccine manufacturers and USDA regulators of poultry products. The survey revealed that ∼1% of broilers receive live Salmonella vaccine within first week of hatching, and not anytime later due to risk of vaccine bacteria getting into human food chain. Most of the broiler breeders are vaccinated with live and killed Salmonella vaccines. This approach is expected to confer maternal immunity in chicks. None of the current vaccination methods provide satisfactory control of Salmonella in broilers

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