Anti-phenolic glycolipid antibodies in infected cattle.

, the causative agent of bovine tuberculosis (bTB), causes significant financial losses in the agricultural industry. Additionally, transmission from animals to humans can result in zoonotic TB, especially in low- and middle-income countries (LMICs), highlighting the need to enhance One Health surveillance to mitigate this threat. Antibodies directed against a major mycobacterial cell wall component of , phenolic glycolipid-I (PGL-I), have shown excellent performance in identifying infection in humans and animals. In this study, we therefore investigated whether antibodies against PGL similarly represent a useful biomarker for infection in cattle. Comparing sera from naturally -infected and the single intradermal comparative cervical tuberculin test (SICCT)-negative cattle, we assessed the potential of PGL antibodies to identify this mycobacterial infection. Our results show that serum levels of anti- PGL IgG and -IgM in -infected cattle were significantly higher than in the SICCT-negative cattle. The sensitivity for anti- PGL IgM in infected animals was, however, moderate (44.9 %) and the false-positive rate was 6.3 % in SICCT-negative cattle. Notably, vaccination with BCG- or heat-killed did not affect serum levels of anti- PGL IgM in cattle. Moreover, none of the 57 anti- PGL-seropositive cattle tested positive in the anti- PGL-I assay. This study shows for the first time that anti PGL antibodies can be detected in infected cattle: anti- PGL IgM is a highly specific, but moderately sensitive biomarker for infection in cattle, showing potential for differentiate infected from vaccinated animals (DIVA). It could be a valuable component in a multi-biomarker approach for diagnosing bTB.