Rapid Detection of Serum Antibody by Dual-Path Platform VetTB Assay in White-Tailed Deer Infected with Mycobacterium bovis

Abstract

Bovine tuberculosis (TB) in cervids remains a significant problem affecting farmed herds and wild populations. Traditional skin testing has serious limitations in certain species, whereas emerging serological assays showed promising diagnostic performance. The recently developed immunochromatographic dual-path platform (DPP) VetTB assay has two antigen bands, T1 (MPB83 protein) and T2 (CFP10/ESAT-6 fusion protein), for antibody detection. We evaluated the diagnostic accuracy of this test by using serum samples collected from groups of white-tailed deer experimentally inoculated with Mycobacterium bovis, M. avium subsp. paratuberculosis, or M. bovis BCG Pasteur. In addition, we used serum samples from farmed white-tailed deer in herds with no history of TB, as well as from free-ranging white-tailed deer culled during field surveillance studies performed in Michigan known to have bovine TB in the wild deer population. The DPP VetTB assay detected antibody responses in 58.1% of experimentally infected animals within 8 to 16 weeks postinoculation and in 71.9% of naturally infected deer, resulting in an estimated test sensitivity of 65.1% and a specificity of 97.8%. The higher seroreactivity found in deer with naturally acquired M. bovis infection was associated with an increased frequency of antibody responses to the ESAT-6 and CFP10 proteins, resulting in a greater contribution of these antigens, in addition to MPB83, to the detection of seropositive animals, compared with experimental M. bovis infection. Deer experimentally inoculated with either M. avium subsp. paratuberculosis or M. bovis BCG Pasteur did not produce cross-reactive antibodies that could be detected by the DPP VetTB assay. The present findings demonstrate the relatively high diagnostic accuracy of the DPP VetTB test for white-tailed deer, especially in the detection of naturally infected animals. Mycobacterium bovis, the cause of tuberculosis (TB) in cattle, can also infect a broad range of other mammalian host species, including cervids. Free-ranging deer are known to play a role as wildlife reservoirs of M. bovis infection (1, 2), whereas farmed deer are reportedly involved in disease transmission to cattle (3, 4) and to humans (5, 6). In the last decade, M. bovis outbreaks in captive cervids have been increasingly found in the United States, including multiple herds of white-tailed deer (Odocoileus virginianus) in Michigan, elk (Cervus canadensis) in Indiana, a mixed herd of red deer (Cervus elaphus) and fallow deer (Dama dama) in New York, and a farm of elk and fallow deer in Nebraska (7-9).In captive cervids, bovine TB control relies primarily on intradermal tuberculin testing and more rarely on slaughter surveillance. Skin test procedures, however, have not been fully validated for use in various cervid species. These limitations were clearly demonstrated in the recent M. bovis outbreak in farmed elk and fallow deer in Nebraska, where only 3/28 animals that had gross lesions and produced positive culture results were reactors in the single c...

Control of bovine tuberculosis in a farmed red deer herd in England

“…The uncertainty over the effectiveness of the SICCT in cervids has led to studies of supplementary blood tests that, when used together with a tuberculin skin test, can increase the sensitivity and/or specificity of BTB infection detection: The Dual Path Platform (DPP) VetTB rapid immunochromatographic antibody test (Chembio Diagnostic Systems, Medford, New York, USA) has a published sensitivity and specificity in US white-tailed deer of 65 per cent and 98 per cent, respectively ( Lyashchenko and others 2013 ), and in Spain the DPP VetTB test used in parallel with the comparative skin test (interpretation as in Jaroso and others 2010 ) was found to increase the sensitivity of detection of confirmed infected individuals from 76 per cent (skin test alone) to 97 per cent (skin test-positive plus DPP VetTB-positive combined) ( Boadella and others 2012 ). A more dramatic example of an ineffective skin test being compensated by serology was described in a herd of farmed elk and fallow deer in Nebraska ( Waters and others 2011 ).…”

Effects of Serial Skin Testing with Purified Protein Derivative on the Level and Quality of Antibodies to Complex and Defined Antigens in Mycobacterium bovis-Infected Cattle

“…Chembio DPP technology was used to detect bovine IgG and IgM responses to the polyepitope fusion protein MPB83-MPB70 (14,19). As a detection system, goat anti-bovine IgG and anti-bovine IgM antibodies (Kirkegaard & Perry Laboratories) were conjugated to colloidal gold nanoparticles using Chembio standard procedures.…”

“…As a detection system, goat anti-bovine IgG and anti-bovine IgM antibodies (Kirkegaard & Perry Laboratories) were conjugated to colloidal gold nanoparticles using Chembio standard procedures. Serum samples were tested at a dilution of 1:40 in assay running buffer, and results were recorded at 20 min using an optical reader to measure test band reflectance in relative light units (RLU), as described previously (14).…”

Fecal Volatile Organic Ccompound Profiles from White-Tailed Deer (Odocoileus virginianus) as Indicators of Mycobacterium bovis Exposure or Mycobacterium bovis Bacille Calmette-Guerin (BCG) Vaccination

“…Palmer et al [ 24 ] demonstrated the sensitivity and specificity of the CCT alone to be 97% and 81% respectively in 169 known infected and non-infected WTD. The estimated sensitivity and specificity of DPP in WTD was 65% and 98%, respectively [ 25 ].…”