title: Protective immunity induced by a LLO-deficient Listeria monocytogenes.
abstract: Listeria monocytogenes is a food-borne pathogen able to cause serious disease in human and animals. Listeriolysin O (LLO), a major virulence factor secreted by this bacterium, is a vacuole-specific lysin that facilitates bacterial entrance into the host cytosol. Thus, LLO plays a key role in the translocation and intracellular spread of L. monocytogenes. To study the effect of LLO on virulence and immunopotency, a LLO-deficient L. monocytogenes mutant was constructed using a shuttle vector followed by homologous recombination. The mutant strain had lost hemolytic activity, which resulted in an extremely reduced virulence, 5 logs lower than that of the parent strain, yzuLM4, in BALB/c mice. The number of bacteria detected in the spleens and livers of mice infected with the mutant was greatly reduced, and the bacteria were rapidly eliminated by the host. Kinetics studies in this murine model of infection showed that the invasion ability of the mutant strain was much lower than that of the parent strain. Moreover, immunization with the mutant strain conferred protective immunity against listerial infection. In particular, stimulation with Ag85B240-259, strong specific Th1 type cellular immunity was elicited by vaccination C57BL/6 mice with hly deficient strain delivering Mycobacterium tuberculosis fusion antigen Ag85B-ESAT-6 via intravenous inoculation. These results clearly show that highly attenuated LLO-deficient L. monocytogenes is an attractive vaccine carrier for delivering heterologous antigens.
authors.affiliation: Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Jiangsu 225009, PR China.
authors.forename: Yuelan
authors.initials: Y
authors.lastname: Yin
authors.forename: Chenju
authors.initials: C
authors.lastname: Zhang
authors.forename: Hui
authors.initials: H
authors.lastname: Dong
authors.forename: Zhongwei
authors.initials: Z
authors.lastname: Niu
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Pan
authors.forename: Jinlin
authors.initials: J
authors.lastname: Huang
authors.forename: Xinan
authors.initials: X
authors.lastname: Jiao
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics / Q000276:immunology*; D001427:Bacterial Toxins / Q000235:genetics; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D004195:Disease Models, Animal; D005260:Female; D005822:Genetic Vectors; D006360:Heat-Shock Proteins / Q000172:deficiency* / Q000235:genetics; D006460:Hemolysin Proteins / Q000172:deficiency* / Q000235:genetics; D006801:Humans; D007114:Immunization; D008089:Listeria monocytogenes / Q000235:genetics / Q000276:immunology*; D008088:Listeriosis / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009154:Mutation; D011995:Recombination, Genetic; D018417:Th1 Cells / Q000276:immunology*; D014774:Virulence
chemical_list: D000942:Antigens, Bacterial; D001427:Bacterial Toxins; D001428:Bacterial Vaccines; D006360:Heat-Shock Proteins; D006460:Hemolysin Proteins; C072681:Mycobacterium tuberculosis antigens; C038705:hlyA protein, Listeria monocytogenes