Hm. Vordermeier et al., Use of synthetic peptides derived from the antigens ESAT-6 and CFP-10 for differential diagnosis of bovine tuberculosis in cattle, CL DIAG LAB, 8(3), 2001, pp. 571-578
In Great Britain an independent scientific review for the government has co
ncluded that the development of a cattle vaccine against Mycobacterium bovi
s infection holds the best long-term prospect for tuberculosis control in B
ritish herds, A precondition for vaccination is the development of a comple
mentary diagnostic test to differentiate between vaccinated animals and tho
se infected with M, bovis so that testing and slaughter-based control strat
egies can continue alongside vaccination. To date bacillus Calmette-Guerin
(BCG), an attenuated strain of M, bovis, is the only available vaccine for
the prevention of tuberculosis. However, tests based on tuberculin purified
protein derivative cannot distinguish between M. bovis infection and BCC v
accination, Therefore, specific antigens expressed by M, bovis but absent f
rom BCG constitute prime candidates for differential diagnostic reagents. R
ecently, two such antigens, ESAT-6 and CFP-10, have been reported to be pro
mising candidates as diagnostic reagents for the detection of M, bovis infe
ction in cattle, Here we report the identification of promiscuous peptides
of CFP-10 that were recognized by M, bovis-infected cattle. Five of these p
eptides were formulated into a peptide cocktail together with five peptides
derived from ESAT-6, Using this peptide cocktail in T-cell assays, M. bovi
s-infected animals were detected, while BCG-vaccinated or Mycobacterium avi
um-sensitized animals did not respond. The sensitivity of the peptide cockt
ail as an antigen in a whole-blood gamma interferon assay was determined us
ing naturally infected field reactor cattle, and the specificity was determ
ined using blood from BCG-vaccinated and noninfected, nonvaccinated animals
. The sensitivity of the assay in cattle with confirmed tuberculosis was fo
und to be 77.9%, with a specificity of 100% in BCG-vaccinated or nonvaccina
ted animals, This compares favorably with the specificity of tuberculin whe
n tested in noninfected or vaccinated animals. In summary, our results demo
nstrate that this peptide cocktail can discriminate between M, bovis infect
ion and BCG vaccination with a high degree of sensitivity and specificity.