Repeat tuberculin skin testing leads to desensitisation in naturally infected tuberculous cattle which is associated with elevated interleukin-10 and decreased interleukin-1 beta responses

TB Research Group, Veterinary Laboratories Agency, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, United Kingdom.
Veterinary Research (Impact Factor: 2.82). 10/2009; 41(2):14. DOI: 10.1051/vetres/2009062
Source: PubMed


The principal surveillance tool used to control bovine tuberculosis in cattle is the removal of animals that provide a positive response to the tuberculin skin-test. In this study we performed a longitudinal investigation of the immunological and diagnostic consequences of repeated short-interval skin-tests in cattle naturally infected with Mycobacterium bovis. Tuberculin skin-test positive cattle were subjected to up to four further intradermal comparative cervical skin-tests at approximately 60-day intervals. A significant progressive reduction in the strength of the skin-test was observed after successive tests. In contrast, the magnitude of interferon-gamma (IFN-gamma) responses was not influenced by repeat skin-testing either transiently around the time of each skin-test or longitudinally following repeated tests. A significant boost in blood interleukin-10 (IL-10) production was observed within 3 days following each skin-test although the magnitude of this boosted response returned to lower levels by day 10 post-test. The application of a novel multiplex assay to simultaneously measure seven cytokines and chemokines also identified that skin-testing resulted in a significant and progressive reduction in antigen specific interleukin-1beta (IL-1beta) whilst confirming stable IFN-gamma and elevated IL-10 responses in the blood. Therefore, we have demonstrated that in cattle naturally infected with M. bovis, repeat short-interval skin-testing can lead to a progressive reduction in skin-test responsiveness which has potential negative consequences for the detection of infected animals with marginal or inconclusive skin-test responses. The desensitising effect is associated with decreased IL-1beta and elevated IL-10 responses, but importantly, does not influence antigen specific IFN-gamma responses.

Download full-text


Available from: Derek Clifford
  • Source
    • "Furthermore, there is evidence that PPD inoculation may sensitise the animals, thereby affecting the result of a subsequent skin test in the same animal (Thom et al 2004). It is possible that repeated tuberculin testing may affect the results of other blood-based immune assays used to diagnose tuberculosis (Thom et al 2004, Coad et al 2010). The complexity of tuberculin, the presence of cross-reactive components, and the low specificity have fueled the search for new antigens and diagnostic assays specific to M. bovis (Pollock et al 2005, Aagaard et al 2010). "
    [Show abstract] [Hide abstract]
    ABSTRACT: The skin test with purified protein derivatives (PPD) from Mycobacterium bovis has been used for the diagnosis of bovine tuberculosis. However, due to the suboptimal specificity of this protein mixture, improved tests based on defined specific antigens are needed. In the present study, recombinant proteins from M. Bovis were evaluated as antigens in the skin test. Among these proteins, EsxI, Mb0143, PE5, and PE13 are antigens tested for the first time in skin test on cattle. Sensitised and non-sensitised cattle to the inactivated AN5 strain of M. Bovis were simultaneously injected with each recombinant protein, a cocktail with all recombinant proteins, M. Bovis PPD, M. Avium PPD and saline. Only the proteins EsxI, Mb0143 and PE5 were able to differentiate sensitised and non-sensitised cattle when 320 μg of protein was used and the reading done 24 hours post-injection. EsxI and PE5 exhibited a sensitivity level of 83.33% and specificity of 100% and 80%, respectively. The results of the present study suggest that the recombinant proteins have potential to be assessed as antigens in skin tests in cattle.
    Preview · Article · Jan 2015 · Archivos de Medicina Veterinaria
  • Source
    • "We assessed the effect of pathogen genotype on skin test response (PPD-B – PPD-A) by comparing the influence of genotype with other potential sources of variation, extracting skin test results for animals that tested positive under the standard interpretation . We excluded animals that had an inconclusive result at the previous skin test because they might have become desensitised to tuberculin, characterised by a progressive decrease in response to each subsequent test by cattle undergoing repeated short interval testing (Coad et al., 2009) or those with advanced disease (de la Rua-Domenech et al., 2006). Following these exclusions , 11,799 animals remained, 78% of which were female. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Strains of many infectious diseases differ in parameters that influence epidemic spread, for example virulence, transmissibility, detectability and host specificity. Knowledge of inter-strain variation can be exploited to improve management and decrease disease incidence. Bovine tuberculosis (bTB) is increasingly prevalent among farmed cattle in the UK, exerting a heavy economic burden on the farming industry and government. We aimed to determine whether strains of Mycobacterium bovis (the causative agent of bTB) identified and classified using genetic markers (spoligotyping and multi-locus VNTR analysis) varied in response to the tuberculin skin test; this being the primary method of bTB detection used in the UK. Inter-strain variation in detectability of M. bovis could have important implications for disease control. The skin test is based on a differential delayed type hypersensitivity (DTH) response to intradermal injections of purified protein derivative (PPD) from M. bovis (PPD-B) and Mycobacterium avium (PPD-A). We searched for an association between skin test response (PPD-B skin rise minus PPD-A skin rise) and M. bovis genotype at the disclosing test in culture-confirmed cases using a field dataset consisting of 21,000 isolates belonging to 63 genotypes of M. bovis from cattle in Northern Ireland. We found no substantial variation among genotypes (estimated responses clustered tightly around the mean) controlling for animal sex, breed and test effects. We also estimated the ratio of skin test detected to undetected cases (i.e. cases only detected at abattoir). The skin test detection ratio varied among abattoirs with some detecting a greater proportion of cases than others but this variation was unrelated to the community composition of genotypes within each abattoir catchment. These two lines of evidence indicate that M. bovis genotypes in Northern Ireland have similar detectability using the skin test.
    Full-text · Article · May 2013 · Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases
  • Source
    • "VeBus holds the individual measurements (a1, a2, b1 and b2) from all tests (failed or not) for a subset of animals, while VetNet holds data for the last test only of all cattle classified as reactors. Two important biases affect these measurements: (1) all reactors have, by definition, exceeded the prescribed threshold, so the expectation of any relationship with ‘22’ is unclear; (2) repeat testing can potentially lead to smaller swellings [22]. Consequently, for both consistency and to control for desensitisation we used the first non-reacting test results for each animal recorded in VeBus, regardless of whether that animal went on to become a reactor later in its life. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Bovine tuberculosis (bTB) imposes an important financial burden on the British cattle industry, yet despite intense efforts to control its spread, incidence is currently rising. Surveillance for bTB is based on a skin test that measures an immunological response to tuberculin. Cattle that fail the test are classified as "reactors" and slaughtered. Recent studies have identified genetic markers associated with the reaction of cattle to the tuberculin test. At marker INRA111 a relatively common '22' genotype occurs significantly more frequently in non-reactor cattle. Here we test the possibility that the putative protective '22' genotype does not confer resistance but instead causes cattle that carry it to react less strongly to the prescribed test, and hence avoid slaughter, potentially even though they are infected. We show that, after controlling for age and breed, '22' cattle react less strongly to the immunological challenge and may therefore be less likely to be classified as a reactor. These results highlight the potential discrepancy between infection and test status and imply that the effectiveness of the test-and-slaughter policy may be being compromised by selection for cattle that are genetically predisposed to react less strongly to tuberculin.
    Full-text · Article · Mar 2013 · PLoS ONE
Show more