An inhibitor of leukotriene-A 4 hydrolase from bat salivary glands facilitates virus infection

Significance An immunosuppressant protein (MTX), which facilitates virus infection by inhibiting leukotriene A4 hydrolase (LTA4 H) to produce the lipid chemoattractant leukotriene B4 (LTB4 ), was identified and characterized from the submandibular salivary glands of the batMyotis pilosus . To the best of our knowledge, this is a report of an endogenous LTA4 H inhibitor in animals. MTX was highly concentrated in the bat salivary glands, suggesting a mechanism for the generation of immunological privilege and immune tolerance and providing evidence of viral shedding through oral secretions. Moreover, given that the immunosuppressant MTX selectively inhibited the proinflammatory activity of LTA4 H, without affecting its antiinflammatory activity, MTX might be a potential candidate for the development of antiinflammatory drugs by targeting the LTA4 -LTA4 H-LTB4 inflammatory axis.