Comparison of Bloodmeal Digestion and the Peritrophic Matrix in Four Sand Fly Species Differing in Susceptibility to Leishmania donovani

Abstract

The early stage of Leishmania development in sand flies is closely connected with bloodmeal digestion. Here we compared various parameters of bloodmeal digestion in sand flies that are either susceptible (Phlebotomus argentipes and P. orientalis) or refractory (P. papatasi and Sergentomyia schwetzi) to Leishmania donovani, to study the effects on vector competence. The volume of the bloodmeal ingested, time of defecation of bloodmeal remnants, timing of formation and degradation of the peritrophic matrix (PM) and dynamics of proteolytic activities were compared in four sand fly species. Both proven vectors of L. donovani showed lower trypsin activity and slower PM formation than refractory species. Interestingly, the two natural L. donovani vectors strikingly differed from each other in secretion of the PM and midgut proteases, with P. argentipes possessing fast bloodmeal digestion with a very high peak of chymotrypsin activity and rapid degradation of the PM. Experimental infections of P. argentipes did not reveal any differences in vector competence in comparison with previously studied P. orientalis; even the very low initial dose (2×103 promastigotes/ml) led to fully developed late-stage infections with colonization of the stomodeal valve in about 40% of females. We hypothesise that the period between the breakdown of the PM and defecation of the bloodmeal remnants, i.e. the time frame when Leishmania attach to the midgut in order to prevent defecation, could be one of crucial parameters responsible for the establishment of Leishmania in the sand fly midgut. In both natural L. donovani vectors this period was significantly longer than in S. schwetzi. Both vectors are equally susceptible to L. donovani; as average bloodmeal volumes taken by females of P. argentipes and P. orientalis were 0.63 μl and 0.59 μl, respectively, an infective dose corresponding to 1–2 parasites was enough to initiate mature infections.

Leishmania donovani development in Phlebotomus argentipes: comparison of promastigote- and amastigote-initiated infections

“…Here we compared Leishmania donovani infection in its natural vector Phlebotomus argentipes using culture form promastigotes and amastigotes grown ex vivo in bone marrow-derived macrophages (BMM). We published previously (Pruzinova et al 2015) that the Ethiopian L. donovani strain (GR374) used in the present study develops similarly in both African and Indian vector species – Phlebotomus orientalis and Phlebotomus argentipes , respectively. Additionally, for the first time, the transmission potential of parasites to the vertebrate host was assessed which is the most significant marker of successful Leishmania development in the vector.…”

“…In both the compared groups, the development of L. donovani was rapid; parasites escaped from the endoperitrophic space before 24 h PBM and reached the cardia by day 2 PBM with colonization of the stomodeal valve by day 4 PBM. This rapid progress is typical for P. argentipes and is caused by very fast bloodmeal digestion followed by degradation of the peritrophic matrix and defecation of blood remnants by day 3 PBM (Pruzinova et al 2015). In contrast there was a pronounced difference between promastigote- and amastigote-initiated infections observed during the first days PBM in both morphology of parasites and kinetics of population growth.…”

Effects of Trichoderma viride chitinases on the peritrophic matrix of Lepidoptera

“…Owing to its function as a selective barrier, the PM plays several roles in insect digestion, such as the compartimentalisation of digestive enzymes in the endo‐ and ectoperitrophic spaces and the selective passage of nutrients from the lumen to the epithelial cells . Moreover, it prevents mechanical lesions of the apical cell membrane of midgut cells as a result of food abrasion and non‐specific binding to the cell surface, acts as a protective physical barrier against ingested pathogens and toxins and protects the midgut from allelochemicals and reactive oxygen species by sequestering and detoxifying ingested toxic materials . For all these reasons, the PM represents an excellent target for pest biocontrol agents that impact on PM components, i.e.…”

Leishmania infection and blood sources analysis in Phlebotomus chinensis (Diptera: Psychodidae) along extension region of the Loess Plateau, China

“…Many sand y species are known to rely on a broad range of species for blood meals (19,20,(27)(28)(29) , typically mammals (20,(30)(31)(32)(33) but also various cold-blooded animals (21). In this study, we investigated the blood sources of sand ies by ampli ed speci c animal's mtDNA cyt b fragments using PCR.…”