Evaluation of P22 ELISA for the Detection of Mycobacterium bovis-Specific Antibody in the Oral Fluid of Goats

Abstract

The ante-mortem diagnosis of tuberculosis (TB) in ruminants is based mainly on the intradermal tuberculin test and the IFN-γ assay. Antibody (Ab)-based tests have emerged as potential tools for the detection of TB infected animals using serum, plasma, or even milk samples. Oral fluids have also been evaluated as alternative samples with which to detect specific Abs against Mycobacterium bovis in pigs or wild boars, but not in ruminants. The objective of this study was, therefore, to evaluate the performance of an in house-ELISA for TB diagnosis (P22 ELISA) in goats as an experimental model for the diagnosis of TB using oral fluid samples. Oral fluid samples from 64 goats from a TB-infected herd (n = 197) and all the animals from a TB-free herd (n = 113) were analyzed using the P22 ELISA. The estimated sensitivity (Se) and specificity (Sp) were 34.4% (95% CI: 22.4–45.6) and 100% (95% CI: 97.4–100), respectively. The optimal cut-off point was set at 100% according to the ROC analysis. Those animals with a higher level of Abs in their oral fluid attained a higher lesion score (p = 0.018). In fact, when taking into account only the setting of the animals with severe lesions (n = 16), the ELISA showed a Se of 75% (95% CI: 53.7–96.2). Results of the present study suggest that the P22 ELISA is highly specific but has a limited value detecting infected animals in oral fluid samples. Nevertheless, its performance is significantly higher in the presence of severe lesions.

Comparative diagnosis of bovine tuberculosis using single intradermal cervical tuberculin technique, conventional methods, enzyme-linked immunosorbent assay, and the gamma-interferon assay

“…Otherwise, the cell-mediated immune response to TB pathogenesis involves IFN-γ and other cytokines [ 30 ]. Antibodies are only produced during the advanced phases of TB and usually cannot be detected in the early stages of the disease [ 31 ]. Single antigen testing also provides low detection sensitivity [ 6 ].…”

Zoonotic Tuberculosis: A Neglected Disease in the Middle East and North Africa (MENA) Region

“…Typically, TST’s discriminatory power could be improved by combining it with the interferon-gamma release assay (IGRA) which improves both sensitivity and specificity [ 29 ]. M. bovis ELISA tests are also available, allowing the detection of antibodies against zoonotic tuberculosis in cattle serum and plasma samples [ 30 ]. Although the ELISA assay is not yet recognized as a standard test for tuberculosis in cattle, it has been approved by the WOAH as being complementary to the TST in cattle.…”

Effect of a recent intradermal test on the specificity of P22 ELISA for the diagnosis of caprine tuberculosis

“…For this reason, in recent years techniques based on antibody (Ab) detection have emerged as ancillary diagnostic tools to detect TB-infected animals, especially those that do not react to cellular tests ( 10 ). Moreover, humoral assays have certain advantages such as their high Sp and the variety of sample types supported, including serum ( 10 , 11 ), milk ( 12 ) and even oral fluid ( 13 ) and urine samples ( 14 ). Furthermore, since they do not have high logistical demands and do not require immunological stimulation with antigens prior conducting the assay, there is interest in its assessment and development ( 11 ).…”