Assessment of microbiological correlates and immunostimulatory potential of electron beam inactivated metabolically active yet non culturable (MAyNC) Salmonella Typhimurium

PLoS One. 2021 Apr 16;16(4):e0243417. doi: 10.1371/journal.pone.0243417. eCollection 2021.

Abstract

This study investigates the microbiological and immunological basis underlying the efficacy of electron beam-inactivated immune modulators. The underlying hypothesis is that exposure to eBeam-based ionization reactions inactivate microorganisms without modifying their antigenic properties and thereby creating immune modulators. The immunological correlates of protection induced by such eBeam based Salmonella Typhimurium (EBST) immune modulators in dendritic cell (DC) (in vitro) and mice (in vivo) models were assessed. The EBST stimulated innate pro inflammatory response (TNFα) and maturation (MHC-II, CD40, CD80 and CD86) of DC. Immuno-stimulatory potential of EBST was on par with both a commercial Salmonella vaccine, and live Salmonella cells. The EBST cells did not multiply under permissive in vitro and in vivo conditions. However, EBST cells remained metabolically active. EBST immunized mice developed Salmonella-specific CD4+ T-cells that produced the Th1 cytokine IFNγ at a level similar to that induced by the live attenuated vaccine (AroA- ST) formulation. The EBST retained stable immunogenic properties for several months at room temperature, 4°C, and -20°C as well as after lyophilization. Therefore, such eBeam-based immune modulators have potential as vaccine candidates since they offer the safety of a "killed" vaccine, while retaining the immunogenicity of an "attenuated" vaccine. The ability to store eBeam based immune modulators at room temperature without loss of potency is also noteworthy.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • CD4-Positive T-Lymphocytes / immunology
  • Cells, Cultured
  • Cytokines / immunology
  • Dendritic Cells / immunology
  • Electrons
  • Female
  • Mice
  • Mice, Inbred C57BL
  • Salmonella Infections, Animal / immunology
  • Salmonella Infections, Animal / microbiology
  • Salmonella Vaccines / immunology*
  • Salmonella typhimurium / immunology*
  • Vaccines, Attenuated / immunology*
  • Vaccines, Inactivated / immunology

Substances

  • Cytokines
  • Salmonella Vaccines
  • Vaccines, Attenuated
  • Vaccines, Inactivated

Grants and funding

This work was supported by funds from the United States Department of Agriculture, National Institute of Food and Agriculture (USDA-NIFA). The funds were administered through the Texas A&M AgriLife Research project H8708. This research was performed as part of the activities of the IAEA Collaborating Centre at Texas A&M University.