Evaluation of barcoded magnetic bead-based immunoassays for the simultaneous detection of feline leukemia virus antigen and antibody against feline immunodeficiency virus.

Testing platforms that leverage automation, require minimal sample volume, and enable various tests to be performed simultaneously on a single sample have the potential to improve workflow and efficiency in veterinary diagnostic laboratories. We evaluated a barcoded magnetic bead (BMB) technology using established immunoassays for detection of feline leukemia virus (FeLV) p27 antigen and antibody against feline immunodeficiency virus (FIV). Analytical sensitivity, limit of blank, and limit of detection were used to establish a functional sensitivity of 1.00 ng/mL of inactivated FeLV antigen and 35.7 ng/mL of anti-FIV monoclonal antibody. Common interferents, such as hemoglobin, lipid, and bilirubin, were not found to interfere with the performance of the assay. Intra- and inter-assay CVs were <13% for both assays using manufactured samples. Using a set of 116 feline samples, the diagnostic accuracy of our multiplex assay was 100% compared to reference assays. Performance in a convenience set of 1,000 feline samples submitted to a commercial diagnostic laboratory revealed a proportion of positive results of 1.3% for FeLV and 3.7% for FIV. BMB technology should enable rapid screening of samples for various markers in a single immunoassay well.

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

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.