C-Terminal Invariable Domain of VlsE Is Immunodominant but Its Antigenicity Is Scarcely Conserved among Strains of Lyme Disease Spirochetes

Abstract

VlsE, the variable surface antigen of Borrelia burgdorferi, contains two invariable domains located at the amino and carboxyl terminal ends, respectively, and a central variable domain. In this study, both immunogenicity and antigenic conservation of the C-terminal invariable domain were assessed. Mouse antiserum to a 51-mer synthetic peptide (Ct) which reproduced the entire sequence of the C-terminal invariable domain of VlsE from B. burgdorferi strain B31 was reacted on immunoblots with whole-cell lysates extracted from spirochetes of 12 strains from the B. burgdorferi sensu lato species complex. The antiserum recognized only VlsE from strain B31, indicating that epitopes of this domain differed among these strains. When Ct was used as enzyme-linked immunosorbent assay (ELISA) antigen, all of the seven monkeys and six mice that were infected with B31 spirochetes produced a strong antibody response to this peptide, indicating that the C-terminal invariable domain is immunodominant. None of 12 monkeys and only 11 of 26 mice that were infected with strains other than B31 produced a detectable anti-Ct response, indicating a limited antigenic conservation of this domain among these strains. Twenty-six of 33 dogs that were experimentally infected by tick inoculation were positive by the Ct ELISA, while only 5 of 18 serum samples from dogs clinically diagnosed with Lyme disease contained detectable anti-Ct antibody. Fifty-seven of 64 serum specimens that were collected from American patients with Lyme disease were positive by the Ct ELISA, while only 12 of 21 European samples contained detectable anti-Ct antibody. In contrast, antibody to the more conserved invariable region IR 6 of VlsE was present in all of these dog and human serum samples.

Crystal Structure of Lyme Disease Variable Surface Antigen VlsE of Borrelia burgdorferi

“…Mice immunized with a 50-aa peptide called Ct corresponding to the Cterminal region of VlsE of B. burgdorferi B31 induced a strong antibody response, indicating that this region is highly immunogenic. Similarly, sera from mice and monkeys infected with B. burgdorferi B31 exhibited a high reactivity with Ct by enzyme immunoassay (22). Mouse antibodies against this peptide could immunoprecipitate extracted VlsE but did not bind at detectable levels to the surface of intact B. burgdorferi (23).…”

“…2), they are the most obvious targets for use in diagnostic tests and vaccination experiments. Although no experiments examining the antigenicity of the invariant Nterminal region have been reported, data about the unique C-terminal region became available recently (22). Mice immunized with a 50-aa peptide called Ct corresponding to the Cterminal region of VlsE of B. burgdorferi B31 induced a strong antibody response, indicating that this region is highly immunogenic.…”

“…However, the close packing of VlsE or binding of VlsE to other protein(s) on the membrane surface may block antibody binding to the lateral surfaces of the protein. In addition, Liang et al (22) reported that antisera against the C-terminal peptide exhibited poor reactivity with VlsE of other Lyme disease borrelia isolates, although antibodies against IR 6 reacted consistently with VlsE in these strains. The interpretation of these results was that the primary structure of the C-terminal region of VlsE was poorly conserved among Lyme disease borrelia.…”

Comparative reactivity of human sera to recombinant VlsE and other Borrelia burgdorferi antigens in class-specific enzyme-linked immunosorbent assays for Lyme borreliosis

“…In efforts to improve the utility of immunodiagnostic tests for Lyme borreliosis, numerous recombinant antigens of B. burgdorferi have been produced and evaluated [8][9][10][11][12][13]. ELISAs with outer-surface protein (Osp) C, OspF, protein (p) 35 and p37 yield highly specific results but may exhibit low sensitivity [9,12].…”

Dogs Vaccinated with Common Lyme Disease Vaccines Do Not Respond to IR6, the Conserved Immunodominant Region of the VlsE Surface Protein ofBorrelia burgdorferi

“…Recently, a short segment of a B. burgdorferi surface protein named VlsE (Vmp-like sequence, expressed) has been used (9)(10)(11)(12)(13)(14)(15)(16), in addition to the full-length protein (7), to construct antibody detection assays that have excellent sensitivity and virtually eliminate false-positive results. This peptide, named C 6 , is 25 amino acids in length and reproduces the sequence of an immunodominant and conserved region (IR 6 ) of VlsE (12).…”