title: Proteomic analysis and immunogenicity of secreted proteins from Rhodococcus equi ATCC 33701.
abstract: Rhodococcus equi is one of the most important causes of mortality in foals between 1 and 6 months of age. Although rare, infection also occurs in a variety of other mammals including humans, often following immunosuppression of various causes. Secreted proteins are known to mediate important pathogen-host interactions and consequently are favored candidates for vaccine development as they are the most easily accessible microbial antigens to the immune system. Here, we describe the results of a proteomic analysis based on SDS-PAGE, immunoblot and mass spectrometry, which was carried out aiming the identification of secreted proteins that are differently expressed at 30 degrees C versus 37 degrees C and at mid-exponential versus early-stationary growth phase and antigenic proteins from R. equi ATCC 33701. A total of 48 proteins was identified regardless of growth conditions. The cholesterol oxidase ChoE appears to be the major secretory protein. Moreover, four proteins revealed high homologies with the mycolyl transferases of the Ag85 complex from Mycobacterium tuberculosis. The sequence analysis predicted that 24 proteins are transported by a signal peptide-dependent pathway. Moreover, five antigenic proteins of R. equi were identified by immunoblot, including a novel strongly immunoreactive protein of unknown function. In conclusion, the elucidation of the secretome of R. equi identified several proteins with different biological functions and a new candidate for developing vaccines against R. equi infection in horse.
authors.affiliation: AFSSA, Laboratoire d'Etudes et de Recherches en Pathologie Equine, IPC, Goustranville, 14430 Dozulé, France.
authors.forename: Corinne
authors.initials: C
authors.lastname: Barbey
authors.forename: Aurélie
authors.initials: A
authors.lastname: Budin-Verneuil
authors.forename: Séverine
authors.initials: S
authors.lastname: Cauchard
authors.forename: Axel
authors.initials: A
authors.lastname: Hartke
authors.forename: Claire
authors.initials: C
authors.lastname: Laugier
authors.forename: Vianney
authors.initials: V
authors.lastname: Pichereau
authors.forename: Sandrine
authors.initials: S
authors.lastname: Petry
mesh_terms: D000193:Actinomycetales Infections / Q000662:veterinary*; D000595:Amino Acid Sequence; D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D001426:Bacterial Proteins / Q000235:genetics* / Q000276:immunology / Q000302:isolation & purification; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D004798:Enzymes / Q000737:chemistry; D006734:Horse Diseases / Q000382:microbiology*; D006736:Horses; D015151:Immunoblotting; D013058:Mass Spectrometry; D009169:Mycobacterium tuberculosis / Q000201:enzymology / Q000235:genetics; D020543:Proteome; D016929:Rhodococcus equi / Q000235:genetics* / Q000254:growth & development / Q000276:immunology; D017386:Sequence Homology, Amino Acid; D013696:Temperature; D014357:Trypsin
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D017931:DNA Primers; D004798:Enzymes; D020543:Proteome; D014357:Trypsin