Immunization of mice with live or heat-killed Listeria monocytogenes (HKLM) efficiently primes pathogen-specific CD8(+) T cells. T lymphocytes primed by HKLM, however, undergo attenuated proliferation and do not fully differentiate. Thus, only infection with live bacteria induces long-term, CD8(+) T cell-mediated protective immunity. In this study we demonstrate that live and heat-killed bacteria, while both associating with Mac-3(+)CD11b(hi) cells, localize to distinct splenic areas following intravenous inoculation. While HKLM localize to the marginal zone and the splenic red pulp, live L. monocytogenes are carried to the T cell zone of splenic white pulp. Despite these differences, in vivo depletion of CD11c-expressing cells prevents priming of naive T cells by either HKLM or live L. monocytogenes. Analysis of CD11c(hi) dendritic cells (DC) reveals that infection with live L. monocytogenes induces higher levels of CD40, CD80 and CD86 expression than immunization with HKLM. Our results suggest that CD8(+) T cell priming following HKLM immunization or live infection is mediated by DC and that the disparate outcomes of priming can be attributed to suboptimal conditioning of DC in the absence of live, cytosol-invasive bacteria.
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http://dx.doi.org/10.1002/eji.200526024 | DOI Listing |
Sci Rep
January 2025
Microbial Safety Division, National Institute of Agricultural Sciences, Rural Development Administration, Wanju, 55365, Republic of Korea.
The close genetic resemblance between Listeria monocytogenes and Listeria innocua, combined with their presence in similar environments, poses challenges for species-specific detection in food products. Ensuring food safety through microbiological standards necessitates reliable detection of pathogens like L. monocytogenes and L.
View Article and Find Full Text PDFBMC Biol
December 2024
Key Laboratory of Applied Biotechnology on Animal Science & Veterinary Medicine of Zhejiang Province, Zhejiang Engineering Research Center for Veterinary Diagnostics & Advanced Technology, Zhejiang International Science and Technology Cooperation Base for Veterinary Medicine and Health Management, Belt and Road International Joint Laboratory for One Health and Food Safety, China-Australia Joint Laboratory for Animal Health Big Data Analytics, College of Veterinary Medicine, Zhejiang A&F University, 666 Wusu Street, Lin'an District, Hangzhou, Zhejiang Province, 311300, China.
Background: The intracellular bacterium Listeria monocytogenes is an attractive vector for cancer immunotherapy as it can effectively deliver tumor antigens to antigen-presenting cells, leading to a robust antitumor response.
Results: In this study, we developed a novel vaccine platform called Listeria-based Live Attenuated Double Substitution (LADS), which involves introducing two amino acid substitutions (N478AV479A) into the virulence factor listeriolysin O (LLO). LADS is a safe vaccine platform, with an attenuation of nearly 7000-fold, while retaining complete immunogenicity due to the absence of deletion of any virulence factors.
Langmuir
December 2024
Department of Chemistry, Visva-Bharati University, Santiniketan 731235, India.
Microbiol Res
January 2025
College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang 524088, China. Electronic address:
Listeria monocytogenes, a pathogenic bacterium causing zoonotic diseases, necessitates the urgent search for novel anti-Listeria monocytogenes drugs due to the continuous emergence of drug-resistant bacteria. In this study, we isolated and identified a bacteriocin-producing strain CM7-4 from seawater as Bacillus velezensis through 16S rRNA sequence analysis. Moreover, we successfully purified a novel bacteriocin named PCM7-4 from Bacillus velezensis CM7-4.
View Article and Find Full Text PDFJ Food Prot
December 2024
Department of Food Sciences and Technology, Faculty of Pharmacy Tehran Medical Sciences, Islamic Azad University, Tehran, Iran; Nutrition and Food Sciences Research Center, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran.
Postbiotics have gained attention in the food industry due to their functional properties and ease of use compared to their live parent cells. Postbiotics are the metabolic byproducts of probiotic microorganisms, offering advantages such as antimicrobial and anti-diabetic effects. The study aimed to explore the potential antibacterial, antioxidant, and cholesterol-lowering effects of postbiotics from Lactobacillus acidophilus (LA) and Lactiplantibacillus plantarum (LbP) through in vitro and in vivo studies.
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