Dataset Information

Phlebotomus sergenti in a cutaneous leishmaniasis focus in Azilal province (High Atlas, Morocco): molecular detection and genotyping of Leishmania tropica, and feeding behavior.

ABSTRACT:

Background

Phlebotomus (Paraphlebotomus) sergenti is at least one of the confirmed vectors for the transmission of cutaneous leishmaniasis caused by Leishmania tropica and distributed widely in Morocco. This form of leishmaniasis is considered largely as anthroponotic, although dogs were found infected with Leishmania tropica, suggestive of zoonosis in some rural areas.

Methodology and findings

This survey aimed at (i) studying the presence of Leishmania in field caught Phlebotomus sergenti, (ii) investigating genetic diversity within Leishmania tropica and (iii) identifying the host-blood feeding preferences of Phlebotomus sergenti. A total of 4,407 sand flies were collected in three rural areas of Azilal province, using CDC miniature light traps. Samples collected were found to consist of 13 species: Phlebotomus spp. and 3 Sergentomyia spp. The most abundant species was Phlebotomus sergenti, accounting for 45.75 % of the total. 965 female Phlebotomus sergenti were screened for the presence of Leishmania by ITS1-PCR-RFLP, giving a positive rate of 5.7% (55/965), all being identified as Leishmania tropica. Nucleotide heterogeneity of PCR-amplified ITS1-5.8S rRNA gene-ITS2 was noted. Analyses of 31 sequences obtained segregated them into 16 haplotypes, of which 7 contain superimposed peaks at certain nucleotide positions, suggestive of heterozygosity. Phlebotomus sergenti collected were found to feed on a large variety of vertebrate hosts, as determined by Cytochrome b sequencing of the DNA from the blood meals of 64 engorged females.

Conclusion

Our findings supported the notion that Phlebotomus sergenti is the primary vector of Leishmania tropica in this focus, and that the latter is genetically very heterogeneous. Furthermore, our results might be suggestive of a certain level of heterozygosity in Leishmania tropica population. This finding, as well as the feeding of the vectors on different animals are of interest for further investigation.

SUBMITTER: Ajaoud M

PROVIDER: S-EPMC4380298 | biostudies-literature | 2015 Mar

REPOSITORIES: biostudies-literature

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Publications

Phlebotomus sergenti in a cutaneous leishmaniasis focus in Azilal province (High Atlas, Morocco): molecular detection and genotyping of Leishmania tropica, and feeding behavior.

Ajaoud Malika M Es-Sette Nargys N Charrel Rémi N RN Laamrani-Idrissi Abderahmane A Nhammi Haddou H Riyad Myriam M Lemrani Meryem M

PLoS neglected tropical diseases 20150331 3

<h4>Background</h4>Phlebotomus (Paraphlebotomus) sergenti is at least one of the confirmed vectors for the transmission of cutaneous leishmaniasis caused by Leishmania tropica and distributed widely in Morocco. This form of leishmaniasis is considered largely as anthroponotic, although dogs were found infected with Leishmania tropica, suggestive of zoonosis in some rural areas.<h4>Methodology and findings</h4>This survey aimed at (i) studying the presence of Leishmania in field caught Phlebotomu ...[more]

PMID: 25826399

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Project description:BACKGROUND:Phlebotomus tobbi is a vector of Leishmania infantum, and P. sergenti is a vector of Leishmania tropica. Le. infantum and Le. tropica typically cause visceral or cutaneous leishmaniasis, respectively, but Le. infantum strains transmitted by P. tobbi can cause cutaneous disease. To better understand the components and possible implications of sand fly saliva in leishmaniasis, the transcriptomes of the salivary glands (SGs) of these two sand fly species were sequenced, characterized and compared. METHODOLOGY/PRINCIPAL FINDINGS:cDNA libraries of P. tobbi and P. sergenti female SGs were constructed, sequenced, and analyzed. Clones (1,152) were randomly picked from each library, producing 1,142 high-quality sequences from P. tobbi and 1,090 from P. sergenti. The most abundant, secreted putative proteins were categorized as antigen 5-related proteins, apyrases, hyaluronidases, D7-related and PpSP15-like proteins, ParSP25-like proteins, PpSP32-like proteins, yellow-related proteins, the 33-kDa salivary proteins, and the 41.9-kDa superfamily of proteins. Phylogenetic analyses and multiple sequence alignments of putative proteins were used to elucidate molecular evolution and describe conserved domains, active sites, and catalytic residues. Proteomic analyses of P. tobbi and P. sergenti SGs were used to confirm the identification of 35 full-length sequences (18 in P. tobbi and 17 in P. sergenti). To bridge transcriptomics with biology P. tobbi antigens, glycoproteins, and hyaluronidase activity was characterized. CONCLUSIONS:This analysis of P. sergenti is the first description of the subgenus Paraphlebotomus salivary components. The investigation of the subgenus Larroussius sand fly P. tobbi expands the repertoire of salivary proteins in vectors of Le. infantum. Although P. tobbi transmits a cutaneous form of leishmaniasis, its salivary proteins are most similar to other Larroussius subgenus species transmitting visceral leishmaniasis. These transcriptomic and proteomic analyses provide a better understanding of sand fly salivary proteins across species and subgenera that will be vital in vector-pathogen and vector-host research.

Project description:BACKGROUND:The vector-borne disease leishmaniasis is transmitted to humans by infected female sand flies, which transmits Leishmania parasites together with saliva during blood feeding. In Iran, cutaneous leishmaniasis (CL) is caused by Leishmania (L.) major and L. tropica, and their main vectors are Phlebotomus (Ph.) papatasi and Ph. sergenti, respectively. Previous studies have demonstrated that mice immunized with the salivary gland homogenate (SGH) of Ph. papatasi or subjected to bites from uninfected sand flies are protected against L. major infection. METHODS AND RESULTS:In this work we tested the immune response in BALB/c mice to 14 different plasmids coding for the most abundant salivary proteins of Ph. sergenti. The plasmid coding for the salivary protein PsSP9 induced a DTH response in the presence of a significant increase of IFN-? expression in draining lymph nodes (dLN) as compared to control plasmid and no detectable PsSP9 antibody response. Animals immunized with whole Ph. sergenti SGH developed only a saliva-specific antibody response and no DTH response. Mice immunized with whole Ph. sergenti saliva and challenged intradermally with L. tropica plus Ph. sergenti SGH in their ears, exhibited no protective effect. In contrast, PsSP9-immunized mice showed protection against L. tropica infection resulting in a reduction in nodule size, disease burden and parasite burden compared to controls. Two months post infection, protection was associated with a significant increase in the ratio of IFN-? to IL-5 expression in the dLN compared to controls. CONCLUSION:This study demonstrates that while immunity to the whole Ph. sergenti saliva does not induce a protective response against cutaneous leishmaniasis in BALB/c mice, PsSP9, a member of the PpSP15 family of Ph. sergenti salivary proteins, provides protection against L. tropica infection. These results suggest that this family of proteins in Ph. sergenti, Ph. duboscqi and Ph. papatasi may have similar immunogenic and protective properties against different Leishmania species. Indeed, this anti-saliva immunity may act as an adjuvant to accelerate the cell-mediated immune response to co-administered Leishmania antigens, or even cause the activation of infected macrophages to remove parasites more efficiently. These findings highlight the idea of applying arthropod saliva components in vaccination approaches for diseases caused by vector-borne pathogens.

Project description:BackgroundPhlebotomus (Larroussius) guggisbergi is among the confirmed vectors for cutaneous leishmaniasis (CL) transmission in Kenya. This scarring and stigmatizing form of leishmaniasis accounts for over one million annual cases worldwide. Most recent CL epidemics in Kenya have been reported in Gilgil, Nakuru County, where the disease has become a public health issue. However, little is known about the factors that drive its transmission. Here, we sought to determine the occurrence, distribution and host blood feeding preference of the vectors, and to identify Leishmania species and infection rates in sandflies using molecular techniques. This information could lead to a better understanding of the disease transmission and improvement of control strategies in the area.Methodology/ principal findingsAn entomological survey of sandflies using CDC light traps was conducted for one week per month in April 2016, and in June and July 2017 from five villages of Gilgil, Nakuru county; Jaica, Sogonoi, Utut, Gitare and Njeru. Sandflies were identified to species level using morphological keys and further verified by PCR analysis of cytochrome c oxidase subunit I (COI) gene. Midguts of female sandflies found to harbour Leishmania were ruptured and the isolated parasites cultured in Novy-MacNeal-Nicolle (NNN) media overlaid with Schneider's insect media to identify the species. Leishmania parasite screening and identification in 198 randomly selected Phlebotomus females and parasite cultures was done by PCR-RFLP analysis of ITS1 gene, nested kDNA-PCR and real-time PCR-HRM followed by sequencing. Bloodmeal source identification was done by real-time PCR-HRM of the vertebrate cytochrome-b gene. A total of 729 sandflies (males: n = 310; females: n = 419) were collected from Utut (36.6%), Jaica (24.3%), Sogonoi (34.4%), Njeru (4.5%), and Gitare (0.1%). These were found to consist of nine species: three Phlebotomus spp. and six Sergentomyia spp. Ph. guggisbergi was the most abundant species (75.4%, n = 550) followed by Ph. saevus sensu lato (11.3%, n = 82). Sandfly species distribution across the villages was found to be significantly different (p<0.001) with Jaica recording the highest diversity. The overall Leishmania infection rate in sandflies was estimated at 7.07% (14/198). Infection rates in Ph. guggisbergi and Ph. saevus s.l. were 9.09% (12/132) and 3.57% (2/56) respectively. L. tropica was found to be the predominant parasite in Gilgil with an overall infection rate of 6.91% (13/188) in Ph. guggisbergi (n = 11) and Ph. saevus s.l. (n = 2) sandflies. However, PCR analysis also revealed L. major infection in one Ph. guggisbergi specimen. Bloodmeal analysis in the 74 blood-fed sandflies disclosed a diverse range of vertebrate hosts in Ph. guggisbergi bloodmeals, while Ph. saevus s.l. fed mainly on humans.Conclusions/ significanceThe high infection rates of L. tropica and abundance of Ph. guggisbergi in this study confirms this sandfly as a vector of L. tropica in Kenya. Furthermore, isolation of live L. tropica parasites from Ph. saevus s.l. suggest that there are at least three potential vectors of this parasite species in Gilgil; Ph. guggisbergi, Ph. aculeatus and Ph. saevus s.l. Molecular identification of L. major infections in Ph. guggisbergi suggested this sandfly species as a potential permissive vector of L. major, which needs to be investigated further. Sandfly host preference analysis revealed the possibility of zoonotic transmissions of L. tropica in Gilgil since the main vector (Ph. guggisbergi) does not feed exclusively on humans but also other vertebrate species. Further investigations are needed to determine the potential role of these vertebrate species in L. tropica and L. major transmission in the area.

Dataset Information

Phlebotomus sergenti in a cutaneous leishmaniasis focus in Azilal province (High Atlas, Morocco): molecular detection and genotyping of Leishmania tropica, and feeding behavior.

Background

Methodology and findings

Conclusion

Publications

Phlebotomus sergenti in a cutaneous leishmaniasis focus in Azilal province (High Atlas, Morocco): molecular detection and genotyping of Leishmania tropica, and feeding behavior.

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