Effect of Phlebotomus papatasi on the fitness,infectivity and antimony-resistance phenotype of antimony-resistant Leishmania major Mon-25.

Leishmania major is responsible for zoonotic cutaneous leishmaniasis. Therapy is mainly based on the use of antimony-based drugs; however, treatment failures and illness relapses were reported. Although studies were developed to understand mechanisms of drug resistance, the interactions of resistant parasites with their reservoir hosts and vectors remain poorly understood. Here we compared the development of two L. major MON-25 trivalent antimony-resistant lines, selected by a stepwise in vitro Sb(III)-drug pressure, to their wild-type parent line in the natural vector Phlebotomus papatasi. The intensity of infection, parasite location and morphological forms were compared by microscopy. Parasite growth curves and IC50 values have been determined before and after the passage in Ph. papatasi. qPCR was used to assess the amplification rates of some antimony-resistance gene markers. In the digestive tract of sand flies, Sb(III)-resistant lines developed similar infection rates as the wild-type lines during the early-stage infections, but significant differences were observed during the late-stage of the infections. Thus, on day 7 p. i., resistant lines showed lower representation of heavy infections with colonization of the stomodeal valve and lower percentage of metacyclic promastigote forms in comparison to wild-type strains. Observed differences between both resistant lines suggest that the level of Sb(III)-resistance negatively correlates with the quality of the development in the vector. Nevertheless, both resistant lines developed mature infections with the presence of infective metacyclic forms in almost half of infected sandflies. The passage of parasites through the sand fly guts does not significantly influence their capacity to multiply in vitro. The IC50 values and molecular analysis of antimony-resistance genes showed that the resistant phenotype of Sb(III)-resistant parasites is maintained after passage through the sand fly. Sb(III)-resistant lines of L. major MON-25 were able to produce mature infections in Ph. papatasi suggesting a possible circulation in the field using this vector.

Infectiousness of Asymptomatic Meriones shawi, Reservoir Host of Leishmania major.

Leishmaniases are neglected diseases caused by protozoans of the genus Leishmania that threaten millions of people worldwide. Cutaneous leishmaniasis (CL) caused by L. major is a typical zoonosis transmitted by phlebotomine sand flies and maintained in rodent reservoirs. The female sand fly was assumed to become infected by feeding on the skin lesion of the host, and the relative contribution of asymptomatic individuals to disease transmission was unknown. In this study, we infected 32 Meriones shawi, North African reservoirs, with a natural dose of L. major obtained from the gut of infected sand flies. Skin manifestations appeared in 90% of the animals, and xenodiagnosis with the proven vector Phlebotomus papatasi showed transmissibility in 67% of the rodents, and 45% were repeatedly infectious to sand flies. Notably, the analysis of 113 xenodiagnostic trials with 2189 sand flies showed no significant difference in the transmissibility of animals in the asymptomatic and symptomatic periods; asymptomatic animals were infectious several weeks before the appearance of skin lesions and several months after their healing. These results clearly confirm that skin lesions are not a prerequisite for vector infection in CL and that asymptomatic animals are an essential source of L. major infection. These data are important for modeling the epidemiology of CL caused by L. major.

On the systematics of Phlebotomus betisi and two new related species from Laos with proposal of the new subgenus Lewisius.

Phlebotomus betisi was described from Malaysia and classified after its description in the subgenus Larroussius. It was the only species to have a pharyngeal armature composed of dot-like teeth and an annealed spermatheca whose head is carried by a neck in females. Males were characterized by having a style bearing five spines and a simple paramere. The study of sandflies originating from a cave in Laos enabled us to discover and describe two sympatric species close to Ph. betisi Lewis & Wharton, 1963 and new for Science: Ph. breyi Vongphayloth & Depaquit n. sp., and Ph. sinxayarami Vongphayloth & Depaquit n. sp. They were characterized morphologically, morphometrically, geomorphometrically, molecularly, and proteomically (MALDI-TOF). All approaches converged to validate the individualization of these species whose morphological differential characters lay in the two genders by the observation of the interocular suture and by the length of the last two segments of the maxillary palps. In males, the length of the genital filaments discriminates these species. Females are distinguished by the length of the ducts of the spermathecae as well as by the narrow or enlarged shape of the neck bearing their head. Lastly, the particular position of the spines of the gonostyle coupled with molecular phylogeny led us to remove these three species from the subgenus Larroussius Nizulescu, 1931 and to classify them in a new subgenus: Lewisius Depaquit & Vongphayloth n. subg.

Title: Sur la systématique de Phlebotomus betisi et de deux nouvelles espèces apparentées du Laos avec proposition du nouveau sous-genre Lewisius. Abstract: Phlebotomus betisi a été décrit de Malaisie et fut classé après sa description dans le sous-genre Larroussius. C'était la seule espèce à posséder chez la femelle une armature pharyngienne composée de dents en forme de points et à avoir une spermathèque annelée dont la tête est portée par un cou. Les mâles se caractérisaient par un style porteur de cinq épines et par un paramère simple. L'étude de Phlébotomes originaires d'une grotte du Laos nous a permis de découvrir et de décrire deux espèces sympatriques proches de Ph. betisi Lewis & Wharton, 1963 et nouvelles pour la Science : Ph. breyi Vongphayloth & Depaquit n. sp., et Ph. sinxayarami Vongphayloth & Depaquit n. sp. Elles ont été caractérisées morphologiquement, morphométriquement, géomorphométriquement, moléculairement et protéomiquement (MALDI-TOF). Toutes ces approches convergent pour valider l'individualisation de chacune de ces espèces dont les caractères morphologiques différentiels reposent dans les deux sexes par l'observation de la suture interoculaire et par la longueur des deux derniers segments des palpes maxillaires. Chez les mâles, la longueur des filaments génitaux discrimine ces espèces. Les femelles sont distinguées par la longueur des conduits des spermathèques ainsi que par la forme étroite ou élargie du cou portant la tête de ces spermathèques. Enfin, la position particulière des épines sur le gonostyle couplée à une phylogénie moléculaire nous amène à extraire ces trois espèces du sous genre Larroussius Nitzulescu, 1931 pour les classer dans un nouveau sous-genre : Lewisius Depaquit & Vongphayloth n. subg.