Lipoarabinomannan (
LAM) is a major glycolipidic
antigen on the mycobacterial envelope. The aim of this study was to characterize the humoral immune response induced by immunization with a
LAM extract in bovines and to evaluate the role of the generated
antibodies in the in vitro
infection of macrophages with Mycobacterium avium subsp.
paratuberculosis (MAP). Sera from fourteen calves immunized with
LAM extract or PBS emulsified in Freund's Incomplete Adjuvant and from five
paratuberculosis-infected bovines were studied.
LAM-immunized calves developed specific
antibodies with
IgG1 as the predominant isotype. Serum
immunoglobulins were isolated and their effect was examined in MAP ingestion and viability assays using a bovine macrophage cell line. Our results show that the
antibodies generated by
LAM immunization significantly increase MAP ingestion and reduce its intracellular viability, suggesting an active role in this model.