Influence of lysates of the salivary glands of Lutzomyia longipalpis on the development of a Leishmania-major -like parasite in the skin of the golden hamster

Abstract

Twelve years ago, some mice inoculated with Leishmania major were found to develop larger lesions, containing more amastigotes, if the inoculum used to infect them contained a lysate of salivary glands from Lutzomyia longipalpis than if no lysate was included. In the present study, outbred golden hamsters (Mesocricetus auratus) were each inoculated in a footpad with 10(4), 10(5), 10(6) or 10(7) stationary-phase promastigotes of a Leishmania-major-like parasite (MHOM/BR/71/BH49). Some of the inocula used each contained a lysate of the salivary glands from a laboratory-reared, female Lu. longipalpis. Only the hamsters inoculated with 10(7) promastigotes each developed macroscopic cutaneous lesions (all 10 co-inoculated with lysate but only two of the 10 co-inoculated with diluent). Each of the lesions developed into cutaneous nodule affecting the dermis and underlying subcutaneous tissue of the inoculated footpad, with, histologically, an intensive, diffuse and productive, inflammatory reaction. There were no apparent differences between the lesions of hamsters infected with inocula containing salivary-gland lysate and those seen in the animals infected with lysate-free inocula. Future studies will follow the histological changes at the sites of Lu. longipalpis bites.