THE EFFECT OF ANTI-SANDFLY SALIVA ANTIBODIES ON PHLEBOTOMUS-ARGENTIPES AND LEISHMANIA-DONOVANI

A study was undertaken to find the effect of repeated bites of the san dfly, Phlebotomus argentipes, on its host as well as on the vector its elf. The study also aimed to find the effect of the immune serum on th e parasite, Leishmania donovani, naturally transmitted by the vector. The hamster which was exposed to sandfly feeding showed good antibody titre against the sandfly salivary-gland secretion, which indicates th at the salivary-gland secretion is immunogenic in nature. The result a lso revealed that the feeding attraction of the females, which has bee n expressed as the percentage of engorgement, gradually decreased as t he mortality rate increased during the subsequent bites. Similar morta lity rate was observed when the flies were fed with the immune sera th rough an artificial membrane feeding method. When the sandflies were f ed both with the immune sera and the blood-parasite (L. donovani) susp ension, in addition to the major loss of the number of vectors, there was an inhibition of development in the gut and a concomitant reductio n in the migration of the parasite in the surviving females. These res ults indicate that the anti-sandfly saliva immune sera probably bind w ith the respective antigen-presenting sites of the sandfly salivary gl and and, thus, cause the sandfly death. The possible explanation of th e inhibition of the forward movement of the parasites is that the attr action of the parasites to the oesophagus, mediated by the sandfly sal iva, is inhibited by the anti-saliva antibodies. The importance of ant i-sandfly saliva antibodies as a tool of vector control and also to bl ock the transmission of leishmaniasis has been indicated. (C) 1998 Aus tralian Society for Parasitology. Published by Elsevier Science Ltd.