Assessment of a protein cocktail-based skin test for bovine tuberculosis in a double-blind field test in cattle.
Bovine tuberculosis (bTB) is a worldwide zoonosis caused mainly by Mycobacterium bovis. The traditional diagnostic method used often is the tuberculin skin test, which uses bovine purified protein derivatives (PPD-B). However, it is difficult to maintain uniformity of PPD-B from batch to batch, and it shares common antigens with nonpathogenic environmental mycobacteria. To overcome these problems, M. bovis-specific antigens that showed good T cell stimulation, such as CFP-10, ESAT-6, Rv3615c, etc., have been used in the skin test, but there have been no large-scale clinical studies on these antigens. In this study, two combinations (CFP-10/ESAT-6/TB10.4 protein cocktail and CFP-10/ESAT-6/Rv3872/MPT63 protein cocktail) were developed and used as stimuli in the skin test. Cattle were double-blind tested to assess the efficiency of the protein cocktail-based skin tests. The results showed that the CFP-10/ESAT-6/TB10.4 protein cocktail-based skin test can differentiate TB-infected cattle from Mycobacterium avium-infected ones and that it shows a high degree of agreement with the traditional tuberculin skin test (κ = 0.8536) and gamma interferon (IFN-γ) release assay (κ = 0.8154). Compared to the tuberculin skin test, the relative sensitivity and relative specificity of the CFP-10/ESAT-6/TB10.4-based skin test were 87% and 97%, respectively., The relative sensitivity and relative specificity of the CFP-10/ESAT-6/TB10.4-based skin test were 93% and 92%, respectively, on comparison with the IFN-γ release assay. The correlation between the increases in skin thickness observed after the inoculation of stimuli was high (PPD-B versus CFP-10/ESAT-6/TB10.4, Spearman r of 0.8435). The correlation between the optical density at 450 nm (OD450) obtained after blood stimulation with PPD-B and the increase in skin thickness observed after inoculation of the CFP-10/ESAT-6/TB10.4 protein cocktail was high (Spearman r = 0.7335). Therefore, the CFP-10/ESAT-6/TB10.4-based skin test responses correlate to traditional measures of bovine TB evaluation, including skin test and gamma interferon release assay.
Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China.
Ting
T
Xin
Hong
H
Jia
Jiabo
J
Ding
Pingjun
P
Li
Hongjun
H
Yang
Shaohua
S
Hou
Weifeng
W
Yuan
Xiaoyu
X
Guo
Haichun
H
Wang
Qianqian
Q
Liang
Ming
M
Li
Bin
B
Wang
Hongfei
H
Zhu
D000818:Animals; D000942:Antigens, Bacterial / Q000302:isolation & purification; D001426:Bacterial Proteins / Q000302:isolation & purification; D002417:Cattle; D004311:Double-Blind Method; D059425:Interferon-gamma Release Tests; D009163:Mycobacterium bovis / Q000276:immunology*; D011994:Recombinant Proteins / Q000302:isolation & purification; D012680:Sensitivity and Specificity; D012882:Skin Tests / Q000379:methods; D014374:Tuberculin Test; D014380:Tuberculosis, Bovine / Q000175:diagnosis*; D014730:Veterinary Medicine / Q000379:methods*
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D011994:Recombinant Proteins