Novel protein targets of the humoral immune response to Listeria monocytogenes infection in rabbits.
The role of the humoral immune response in protective immunity against listerial infection has been overlooked and is essentially unknown. This study aimed to discover the protein targets of Listeria monocytogenes that elicit an antibody response following infection in a rabbit model. A genomic expression library for L. monocytogenes was constructed and differentially screened to identify genes encoding proteins that reacted with antiserum from rabbits infected with live L. monocytogenes serotype 4b (RalphaL), but not with that from animals immunized with heat-killed bacteria (RalphaK). Thirty-one clones expressing proteins that reacted exclusively with RalphaL were identified and sequenced. Sequence analysis, together with Western blot analysis of the proteins expressed from positive clones, led to the identification of eight L. monocytogenes proteins as targets of humoral immune responses during listerial infection: three internalin members (InlA, InlD and InlC2) and five novel proteins of unknown function (designated IspA, IspB, IspC, IspD and IspE, respectively). Exhibition of humoral immune responses to these proteins in actively infected rabbits but not in animals receiving heat-killed L. monocytogenes suggested that they were induced or significantly upregulated in vivo during infection and thus are important in Listeria pathogenesis. With the exception of antibodies to InlA, this is the first demonstration of antibodies to the other seven proteins in infected hosts. These immunogenic proteins may be useful candidates for elucidation of the role of antibodies in protective immunity in the context of listerial infection, as well as potential targets for serodiagnostic reagents and vaccine and drug development.
Yu
Wei Ling
WL
Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON K1H 8M5, Canada.|Animal Diseases Research Institute, Ottawa, ON K2H 8P9, Canada.
Dan
Hanhong
H
Animal Diseases Research Institute, Ottawa, ON K2H 8P9, Canada.
Lin
Min
M
Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON K1H 8M5, Canada.|Animal Diseases Research Institute, Ottawa, ON K2H 8P9, Canada.
D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood* / Q000276:immunology; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D015698:Genomic Library; D006801:Humans; D008089:Listeria monocytogenes / Q000276:immunology*; D008088:Listeriosis / Q000276:immunology* / Q000382:microbiology; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011817:Rabbits; D017422:Sequence Analysis, DNA
D000907:Antibodies, Bacterial; D001426:Bacterial Proteins