Electron Beam for animal vaccines

Authors: Jesudhasan, Palmy

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/25/2022
Publication Date: 5/30/2025
Citation: Jesudhasan, P. 2025. Electron Beam for animal vaccines. Abstract. eBeam Workshop, College Station, Texas. April 25-29, 2022.

Interpretive Summary:

Technical Abstract: Non-typhoidal Salmonella is commonly transmitted to humans through direct contact with animals and contaminated food such as raw meat, including poultry, raw eggs, raw milk, and other dairy products. According to USDA-ERS (2020), the total estimated cost of human foodborne illness due to non-typhoidal Salmonella in 2018 was 4 billion dollars. The current approaches to reducing the non-typhoidal serotypes in poultry have had limited success. The target of the US Department of Health and Human Services - Healthy People 2020 was to reduce the incidence of Salmonella from 15/100,000 cases to 11/100,000 cases by 2020, but the incidence increased to 17.1 in 2019. The non-typhoidal serotypes remain a major foodborne pathogen globally. Despite strides to prevent Salmonella in poultry production, outbreaks continue to occur, necessitating the need to develop novel intervention tools for controlling them in chickens. Vaccination is considered a compelling alternative to control pathogens without antibiotics. We propose to use a novel method of inactivating Salmonella using electron beam (eBeam) technology (ionizing radiation), which causes irreparable damage to DNA, but the epitopes/antigens necessary for inducing antibodies are mainly intact. Presently, ionizing radiation (eBeam, gamma, x-rays) has been used to develop vaccines against several pathogens, including viral, bacterial, and protozoan parasites (malaria and coccidia). eBeam uses linear accelerators to generate a highly planar stream of energetic electrons from commercial electricity. eBeam causes multiple double-strand breaks in bacterial DNA, resulting in bacterial cells’ inability to multiply. The use of eBeam irradiation for vaccine development is relatively novel, and very few studies have been reported. We developed efficacious eBeam-killed vaccines against S. Typhimurium (ST) and S. Enteritidis (SE). We found that it significantly reduced the colonization and shedding of homologous Salmonella in laying hens and broiler chickens. We have a US patent for an eBeam-killed Salmonella [S. Enteritidis (SE)] vaccine (US8173139B1). We also characterized the eBeam-killed-ST (EB-ST) vaccine on a microbiological and immunological basis to investigate the efficacy using in vitro and in vivo assays. We compared the EB-ST with a live attenuated Salmonella vaccine (del-STM0978::KanR; aroA null), a commercial ST vaccine (Salmune1®, Cevabiomune, Lenexa), and a heat-killed S. Typhimurium (HK-ST). We performed several assays, including, cell membrane integrity, immunoreactive profile, metabolic activity, in vitro stimulatory assays using dendritic cells. We found that the EB-ST (1) retained stable immunogenic properties for several months at room temperature (No need for cold chain vaccine storage); (2) stimulated innate pro-inflammatory response (TNFa) and maturation (MHC-II, CD40, CD80, and CD86) of DC; (3) Immuno-stimulatory potential was on par with both a commercial Salmonella vaccine and live Salmonella cells; (4) did not multiply under permissive in vitro and in vivo conditions; (5) maintains intact cell membrane and surface morphology similar to live ST; (6) triggers Th1-type cellular immune response; (7) elicits a cellular immune response similar to that of live attenuated vaccine, but differ in the magnitude of cytokine secretion; (8) reduced colonization of SE in SE-immunized layer hens.