title: Borrelia burgdorferi elongation factor EF-Tu is an immunogenic protein during Lyme borreliosis.
abstract: Borrelia burgdorferi, the etiological agent of Lyme disease, does not produce lipopolysaccharide but expresses a large number of lipoproteins on its cell surface. These outer membrane lipoproteins are highly immunogenic and have been used for serodiagnosis of Lyme disease. Recent studies have shown that highly conserved cytosolic proteins such as enolase and elongation factor Tu (EF-Tu) unexpectedly localized on the surface of bacteria including B. burgdorferi, and surface-localized enolase has shown to contribute to the enzootic cycle of B. burgdorferi. In this study, we studied the immunogenicity, surface localization, and function of B. burgdorferi EF-Tu. We found that EF-Tu is highly immunogenic in mice, and EF-Tu antibodies were readily detected in Lyme disease patients. On the other hand, active immunization studies showed that EF-Tu antibodies did not protect mice from infection when challenged with B. burgdorferi via either needle inoculation or tick bites. Borrelial mouse-tick cycle studies showed that EF-Tu antibodies also did not block B. burgdorferi migration and survival in ticks. Consistent with these findings, we found that EF-Tu primarily localizes in the protoplasmic cylinder of spirochetes and is not on the surface of B. burgdorferi. Taken together, our studies suggest that B. burgdorferi EF-Tu is not surfaced exposed, but it is highly immunogenic and is a potential serodiagnostic marker for Lyme borreliosis.
authors.affiliation: Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
authors.forename: Sebastian E
authors.initials: SE
authors.lastname: Carrasco
authors.affiliation: Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
authors.forename: Youyun
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
authors.forename: Bryan
authors.initials: B
authors.lastname: Troxell
authors.affiliation: Department of Veterinary Medicine, University of Maryland, College Park, MD 20742, USA.
authors.forename: Xiuli
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Veterinary Medicine, University of Maryland, College Park, MD 20742, USA.
authors.forename: Utpal
authors.initials: U
authors.lastname: Pal
authors.affiliation: Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
authors.forename: X Frank
authors.initials: XF
authors.lastname: Yang
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000378:metabolism; D000942:Antigens, Bacterial / Q000276:immunology*; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology; D025065:Borrelia burgdorferi / Q000235:genetics / Q000276:immunology*; D006801:Humans; D018884:Ixodes / Q000382:microbiology; D007814:Larva; D008074:Lipoproteins / Q000235:genetics / Q000276:immunology; D008193:Lyme Disease / Q000276:immunology* / Q000382:microbiology; D051379:Mice; D008809:Mice, Inbred C3H; D010444:Peptide Elongation Factor Tu / Q000235:genetics / Q000276:immunology*; D011994:Recombinant Proteins
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D008074:Lipoproteins; D011994:Recombinant Proteins; D010444:Peptide Elongation Factor Tu