TGF-β Has a Role in Survival in the Vector.

Despite the increasing number of studies concerning insect immunity, immune responses in the presence of infection has not been widely investigated. The few available studies analyzed the role of the Toll and IMD pathways involved in response against and microbial infections. Nevertheless, effector molecules responsible for controlling sand fly infections have not been identified.

The sandfly Lutzomyia longipalpis LL5 embryonic cell line has active Toll and Imd pathways and shows immune responses to bacteria, yeast and Leishmania.

Background: Lutzomyia longipalpis is the main vector of visceral leishmaniasis in Latin America. Sandfly immune responses are poorly understood. In previous work we showed that these vector insects respond to bacterial infections by modulating a defensin gene expression and activate the Imd pathway in response to Leishmania infection.