Effect of Lutzomyia whitmani (Diptera: Psychodidae) salivary gland lysates on Leishmania (Viannia) braziliensis infection in BALB/c mice

Abstract

Previous reports showed thatKey words: Leishmania braziliensis -saliva -Lutzomyia whitmani -BALB/c mice Leishmaniases are parasitic diseases caused by protozoan parasites of the genus Leishmania that produce either tegumentary (cutaneous, mucocutaneous, diffuse) or visceral clinical presentations in man and are responsible for significant morbidity and mortality in many areas throughout the world (Pearson et al. 1999). The mammalian host becomes infected with Leishmania when the sand fly vector, Phlebotomus species in the Old World and Lutzomyia species in the New World, probes the skin of parasitized host for a blood meal and injects the parasite admixed with its saliva (Titus et al. 1994).Previous studies have shown that salivary gland lysates of Lu. longipalpis and P. papatasi markedly enhance the infectivity of L. major in mice (Titus & Ribeiro 1988, Theodos et al. 1991 World, such as L. mexicana (Theodos et al. 1991) and L. braziliensis (Samuelson et al. 1991, Lima & Titus 1996. Additionally, it has been shown that the enhancement of infectivity is not due to a direct effect of the saliva on the parasite but rather to an effect on the host. Sand fly saliva has several pharmacological activities, including vasodilation, inhibition of platelet aggregation, and inhibition of coagulation (Ribeiro 1987). Besides, sand fly saliva may also have immunomodulatory effects related to the pathogenesis of leishmanial infections (Hall & Titus 1995, Qureshi et al. 1996, Mbow et al. 1998.We report here the effect of salivary gland lysate of Lu. whitmani on the course of L. (V.) braziliensis infection in BALB/c mice. The rationale for extending these observations to a model using L. (V.) braziliensis plus salivary gland lysate from Lu. whitmani is that this sand fly is the most important natural vector for L. (V.) braziliensis in Ceará, Brazil (Queiroz et al. 1994). Moreover, L. (V.) braziliensis is transmitted in nature neither by Lu. longipalpis nor P. papatasi, the sand fly species targeted on saliva studies up to now.The L. (V.) braziliensis strain (MCAN-BR-92-19914) used in this study was maintained in Schneider's insect medium (Sigma, St. Louis, MO) supplemented with 10% heat-inactivated fetal calf serum (Sigma), 2% sterile normal human urine, 100 U/ml penicillin (Sigma), 100 µg/ml streptomycin (Sigma) and 2 mM L-glutamine (Gibco BRL, Grand Island, NY) at 26 o C. Parasites were used at no later than the fourth passage. Salivary gland lysates were obtained from sugar-fed 3-5-day-old adult laboratory-reared, female Lu. whitmani from a closed laboratory colony maintained at Núcleo de Medicina Tropical/UFC and used as described previously (Titus & Ribeiro 1988).When L. (V.) braziliensis promastigotes were inoculated with salivary gland lysate, the lesion appeared around seven days post-infection. They peaked in size at 28 days of evolution and persisted for up to 42 days, then regressed in a slower way than the lesions of the controls without saliva (Figure). Also, in the animals coinjected with L. (V.) braziliensis plus...

Feeding Preferences ofLutzomyia longipalpis(Diptera: Psychodidae), the Sand Fly Vector, forLeishmania infantum(Kinetoplastida: Trypanosomatidae)

“…Although L. longipalpis and L. evandroi show great similarity in behavior, life cycle, and geographic distribution (Ximenes et al 1999, 2007), the former transmits L. infantum , whereas there is no evidence that L. evandroi can serve as a vector for Leishmania species either in natural or experimental conditions. In contrast, L. whitmani , which was captured in both rural and periurban regions, has been associated with transmission of cutaneous leishmaniasis due to Leishmania braziliensis (Bezerra and Teixeira 2001). Sand fly abundance is closely correlated with poor sanitary conditions and with the presence of animals in the peridomestic areas.…”

Neither Mosquito Saliva nor Immunity to Saliva Has a Detectable Effect on the Infectivity ofPlasmodiumSporozoites Injected into Mice

“…Indeed, a recent review (36) contended that "in virtually every system analyzed, arthropod saliva has in fact enhanced infection with pathogens." Nevertheless, the review also noted that this was not universal and cited several studies in which saliva was found to have little or no effect on transmission of Leishmania (7,8,25). Because Plasmodium sporozoites are the most important pathogens transmitted by arthropods, there is considerable interest in the role that mosquito saliva may play in sporozoite infectivity.…”

Sand fly saliva: effects on host immune response and Leishmania transmission

“…When injected with L. whitmani saliva, Le. braziliensis lesions increase only in size but heal similarly to controls (Bezerra and Teixeira 2001).…”