In Brief

Abstract

Infection of mice with Leishmania has previously been shown to be more successful when saliva from the sandfly vector is co-injected. It was subsequently demonstrated that vaccination of mice with saliva could protect against a Leishmania infection (provided saliva is co-injected with either by the vector or by needle). Leishmania major can be transmitted by the sandfly Lutzomyia longipalpis to laboratory mice. Using this model, researchers have discovered a molecule from the saliva of the sandfly that exhibits both activities: exacerbation of L. major infection and induction of protective immunity when used as vaccine [Morris et al. (2001) J. Immunol. 167, 5226–5230]. This molecule, which shows vasodilatory activity, was cloned and coined maxadilan (MAX). MAX has a functional relationship with the mammalian neuropeptide pituitary adenylate-cyclase-activating polypeptide (PACAP), which also has vasodilatory activity, and both molecules can signal the PACAP type 1 receptor. Although MAX could be used as a vaccine, the authors point out that other immunoprotective molecules could be present in sandfly saliva because MAX is not present in salivary glands of Phlebotomus papatasi (saliva of which also has immunoprotective activity). TS