Johne's Disease or
Paratuberculosis is a chronic
granulomatous enteritis disease affecting ruminants. Detection of subclinically infected animals is difficult, hampering the control of this disease. The aim of this work was to evaluate the performance of detection of
IgG isotypes in a PPA-ELISA to improve the recognition of cattle naturally infected with Map in different stages. A total of 108 animals from
Tuberculosis-free herds were grouped as follows: exposed (
n = 30), subclinically infected (n = 26), clinically infected (n = 14), and healthy controls (n = 38). Receiver-operating characteristic (ROC) curves of isotypes/PPA-ELISAs were constructed and areas under the curves were compared to evaluate the performance of each test. Our study demonstrated that the conventional PPA-ELISA (detecting
IgG) is the best to identify clinically infected animals with high sensitivity (92.9%) and specificity (100%). Meanwhile,
IgG2/PPA-ELISA improved the number of subclinically infected cattle detected as compared with conventional
IgG/PPA-ELISA (53.8 versus 23.1%). In addition, it had the maximum sensitivity (65.0%, taking into account all Map-infected cattle). In conclusion, the combination of
IgG and
IgG2/PPA-ELISAs may improve the identification of Map-infected cattle in different stages of disease. The usefulness of
IgG2 detection in serological tests for
Johne's Disease diagnosis should be further evaluated.