Dogs vaccinated with common Lyme disease vaccines do not respond to IR6, the conserved immunodominant region of the VlsE surface protein of Borrelia burgdorferi

Abstract

A 25-amino-acid synthetic peptide (C(6) peptide) derived from an immunodominant conserved region (designated IR(6)) of the VlsE protein of Borrelia burgdorferi has been identified and used to construct immunoenzyme-based diagnostic procedures. These procedures have excellent sensitivity and specificity. Previous reports have demonstrated the usefulness of the C(6) peptide as an antigen for the serodiagnosis of human and canine Lyme disease. Results indicated that assays based on the C(6) peptide were nonreactive to sera from vaccinated nonexposed animals. The purpose of the present study was to confirm these results in a controlled trial by testing sera from experimentally vaccinated dogs known to be uninfected. Nine specific-pathogen-free beagles were assigned to one of three vaccine groups, each containing three dogs. Each group received one of three commercial Lyme vaccines: RECOMBITEK Lyme (Merial), LymeVax (Fort Dodge Animal Health), and Galaxy Lyme (Schering-Plough Animal Health). Each animal was administered a total of five doses of vaccine over a period of 39 weeks. Serum samples were collected prior to vaccination and then on a weekly basis from weeks 3 to 18 and from weeks 33 to 43. Selected samples were tested by the immunofluorescence assay (IFA) and the Western blot (WB) assay using whole-cell B. burgdorferi antigen extracts, and the results were compared to those obtained with two immunoenzyme-based procedures formatted by using the C(6) peptide. Serum specimens from all animals were reactive to the IFA and WB assay at week 5 and became highly reactive following the administration of multiple doses of vaccine. All serum specimens were uniformly nonreactive in the C(6) peptide immunoenzyme procedures at all time points throughout the study.

FIG. 1.

Mean reciprocal IFA titer results for serum samples from experimentally vaccinated animals. IFA results are shown for serum specimens collected throughout the study. Reciprocal IFA titers are given for the mean obtained from three dogs in each vaccine group. The IFA titer was <100 for serum samples from the single unvaccinated control dog at all time points. Dogs were vaccinated at weeks 0, 2, 33, 36, and 39 as described in Materials and Methods. Serum samples were obtained prior to vaccination at weeks 0 and 33. Vaccine manufacturers were Fort Dodge, Schering-Plough, and Merial.

FIG. 2.

Western blot results for serum samples obtained from experimentally vaccinated dogs prior to and at various times (weeks) following initial vaccination. Vaccine was administered to dogs at weeks 0, 2, 33, 36, and 39; WB results are shown for sera collected at weeks 0, 5, 33, 34, and 40. Serum samples were obtained prior to vaccination at weeks 0 and 33. (A) Fort Dodge LymeVax vaccine, administered to dogs FD1, FD2, and FD3; (B) Schering-Plough Galaxy Lyme vaccine, administered to dogs SP1, SP2, and SP3; (C) Merial RECOMBITEK Lyme vaccine, administered to dogs M1, M2, and M3; (D) positive control. Sera from the unvaccinated control dog failed to produce clearly visible bands in the WB assay at any time. WBs were run with the QualiCode canine Lyme disease kit (Immunetics, Inc.) as described in Materials and Methods.