Population structure analysis of Phlebotomus papatasi populations using transcriptome microsatellites: possible implications for leishmaniasis control and vaccine development.

BACKGROUND: Phlebotomus papatasi is considered the primary vector of Leishmania major parasites that cause zoonotic cutaneous leishmaniasis (ZCL) in the Middle East and North Africa. Phlebotomus papatasi populations have been studied extensively, revealing the existence of different genetic populations and subpopulations over its large distribution range. Genetic diversity and population structure analysis using transcriptome microsatellite markers is important to uncover the vector distribution dynamics, essential for controlling ZCL in endemic areas. METHODS: In this study, we investigated the level of genetic variation using expressed sequence tag-derived simple sequence repeats (EST-SSRs) among field and colony P. papatasi samples collected from 25 different locations in 11 countries. A total of 302 P. papatasi sand fly individuals were analyzed, including at least 10 flies from each region. RESULTS: The analysis revealed a high-level population structure expressed by five distinct populations A through E, with moderate genetic differentiation among all populations. These genetic differences in expressed genes may enable P. papatasi to adapt to different environmental conditions along its distribution range and likely affect dispersal. CONCLUSIONS: Elucidating the population structuring of P. papatasi is essential to L. major containment efforts in endemic countries. Moreover, the level of genetic variation among these populations may improve our understanding of Leishmania-sand fly interactions and contribute to the efforts of vaccine development based on P. papatasi salivary proteins.

Report of a new species of sand fly, Phlebotomus (Anaphlebotomus) ajithii n. sp. (Diptera: Psychodidae), from Western Ghats, India.

BACKGROUND: Western Ghats is a biodiversity treasure trove with reports of indigenous leishmaniasis cases. Hence, systematic sand fly surveillance was carried out among the tribal population. The present study reports a novel sand fly species, Phlebotomus (Anaphlebotomus) ajithii n. sp. (Diptera: Psychodidae), discovered in the Western Ghats of India. METHODS: A comprehensive sand fly survey was conducted across the Kollam, Thrissur, Idukki, Kasaragod and Malappuram districts of Kerala, India. The survey spanned both indoor and outdoor habitats using standard collection methods over a 3-year, 3-month period. DNA barcoding of samples was performed targeting mitochondrial cytochrome c oxidase subunit I (COI) gene, and the sequence generated was subjected to phylogenetic analysis. RESULTS: Phlebotomus (Anaphlebotomus) ajithii, a new sand fly species, is recorded and described in this communication. The morphological relationship of the new species to other members of the subgenus Anaphlebotomus is discussed. Mitochondrial COI barcode followed by phylogenetic analysis confirmed that specimens of Ph. ajithii belong to the same taxonomic group, while a genetic distance of 11.7% from congeners established it as a distinct species. CONCLUSIONS: The Western Ghats, known for its rich biodiversity, has lacked systematic entomological surveys focusing on sand flies. This study aims to fill this gap and reports and describes a new species of sand fly.

Improved high quality sand fly assemblies enabled by ultra low input long read sequencing.

Phlebotomine sand flies are the vectors of leishmaniasis, a neglected tropical disease. High-quality reference genomes are an important tool for understanding the biology and eco-evolutionary dynamics underpinning disease epidemiology. Previous leishmaniasis vector reference sequences were limited by sequencing technologies available at the time and inadequate for high-resolution genomic inquiry. Here, we present updated reference assemblies of two sand flies, Phlebotomus papatasi and Lutzomyia longipalpis. These chromosome-level assemblies were generated using an ultra-low input library protocol, PacBio HiFi long reads, and Hi-C technology. The new P. papatasi reference has a final assembly span of 351.6 Mb and contig and scaffold N50s of 926 kb and 111.8 Mb, respectively. The new Lu. longipalpis reference has a final assembly span of 147.8 Mb and contig and scaffold N50s of 1.09 Mb and 40.6 Mb, respectively. Benchmarking Universal Single-Copy Orthologue (BUSCO) assessments indicated 94.5% and 95.6% complete single copy insecta orthologs for P. papatasi and Lu. longipalpis. These improved assemblies will serve as an invaluable resource for future genomic work on phlebotomine sandflies.

Knockdown resistance mutations in Phlebotomus argentipes sand flies in Bihar, India.

BACKGROUND: Vector control based on indoor residual spraying (IRS) is one of the main components of the visceral leishmaniasis (VL) elimination programme in India. Dichlorodiphenyltrichloroethane (DDT) was used for IRS until 2015 and was later replaced by the synthetic pyrethroid alpha-cypermethrin. Both classes of insecticides share the same target site, the voltage-gated sodium channel (Vgsc). As high levels of resistance to DDT have been documented in the local sand fly vector, Phlebotomus argentipes, it is possible that mutations in the Vgsc gene could provide resistance to alpha-cypermethrin, affecting current IRS pyrethroid-based vector control. METHODS: This study aimed to compare frequencies of knockdown resistance (kdr) mutations in Vgsc between two sprayed and two unsprayed villages in Bihar state, India, which had the highest VL burden of the four endemic states. Across four villages, 350 female P. argentipes were collected as part of a 2019 molecular xenomonitoring study. DNA was extracted and used for sequence analysis of the IIS6 fragment of the Vgsc gene to assess the presence of kdr mutations. RESULTS: Mutations were identified at various positions, most frequently at codon 1014, a common site known to be associated with insecticide resistance in mosquitoes and sand flies. Significant inter-village variation was observed, with sand flies from Dharampur, an unsprayed village, showing a significantly higher proportion of wild-type alleles (55.8%) compared with the three other villages (8.5-14.3%). The allele differences observed across the four villages may result from selection pressure caused by previous exposure to DDT. CONCLUSIONS: While DDT resistance has been reported in Bihar, P. argentipes is still susceptible to pyrethroids. However, the presence of kdr mutations in sand flies could present a threat to IRS used for VL control in endemic villages in India. Continuous surveillance of vector bionomics and insecticide resistance, using bioassays and target genotyping, is required to inform India's vector control strategies and to ensure the VL elimination target is reached and sustained.

Pathogen-associated molecular patterns (PAMPs) derived from Leishmania and bacteria increase gene expression of antimicrobial peptides and gut surface proteins in sand flies.

The interaction between pathogens and vectors' physiology can impact parasite transmission. Studying this interaction at the molecular level can help in developing control strategies. We study leishmaniases, diseases caused by Leishmania parasites transmitted by sand fly vectors, posing a significant global public health concern. Lipophosphoglycan (LPG), the major surface glycoconjugate of Leishmania, has been described to have several roles throughout the parasite's life cycle, both in the insect and vertebrate hosts. In addition, the sand fly midgut possesses a rich microbiota expressing lipopolysaccharides (LPS). However, the effect of LPG and LPS on the gene expression of sand fly midgut proteins or immunity effectors has not yet been documented. We experimentally fed Lutzomyia longipalpis and Phlebotomus papatasi sand flies with blood containing purified LPG from Leishmania infantum, Leishmania major, or LPS from Escherichia coli. The effect on the expression of genes encoding gut proteins galectin and mucin, digestive enzymes trypsin and chymotrypsin, and antimicrobial peptides (AMPs) attacin and defensins was assessed by quantitative PCR (qPCR). The gene expression of a mucin-like protein in L. longipalpis was increased by L. infantum LPG and E. coli LPS. The gene expression of a galectin was increased in L. longipalpis by L. major LPG, and in P. papatasi by E. coli LPS. Nevertheless, the gene expression of trypsins and chymotrypsins did not significantly change. On the other hand, both L. infantum and L. major LPG significantly enhanced expression of the AMP attacin in both sand fly species and defensin in L. longipalpis. In addition, E. coli LPS increased the expression of attacin and defensin in L. longipalpis. Our study showed that Leishmania LPG and E. coli LPS differentially modulate the expression of sand fly genes involved in gut maintenance and defence. This suggests that the glycoconjugates from microbiota or Leishmania may increase the vector's immune response and the gene expression of a gut coating protein in a permissive vector.

Neutrophil extracellular traps formation: effect of Leishmania major promastigotes and salivary gland homogenates of Phlebotomus papatasi in human neutrophil culture.

BACKGROUND: Leishmaniasis as a neglected tropical disease (NTD) is caused by the inoculation of Leishmania parasites via the bite of phlebotomine sand flies. After an infected bite, a series of innate and adaptive immune responses occurs, among which neutrophils can be mentioned as the initiators. Among the multiple functions of these fighting cells, neutrophil extracellular traps (NETs) were studied in the presence of Leishmania major promastigotes and salivary gland homogenates (SGH) of Phlebotomus papatasi alone, and in combination to mimic natural conditions of transmission. MATERIAL & METHODS: The effect of L. major and SGH on NETs formation was studied in three different groups: neutrophils + SGH (NS), neutrophils + L. major (NL), neutrophils + L. major + SGH (NLS) along with negative and positive controls in 2, 4 and 6 h post-incubation. Different microscopic methods were used to visualize NETs comprising: fluorescence microscopy by Acridine Orange/ Ethidium Bromide staining, optical microscopy by Giemsa staining and scanning electron microscopy. In addition, the expression level of three different genes NE, MPO and MMP9 was evaluated by Real-Time PCR. RESULTS: All three microscopical methods revealed similar results, as in NS group, chromatin extrusion as a sign of NETosis, was not very evident in each three time points; but, in NL and especially NLS group, more NETosis was observed and the interaction between neutrophils and promastigotes in NL and also with saliva in NLS group, gradually increased over times. Real-time reveals that, the expression of MPO, NE and MMP9 genes increased during 2 and 4 h after exposure, and then decreased at 6 h in most groups. CONCLUSION: Hence, it was determined that the simultaneous presence of parasite and saliva in NLS group has a greater impact on the formation of NETs compared to NL and NS groups.

Molecular monitoring of insecticide resistance in major disease vectors in Armenia.

BACKGROUND: Armenia is considered particularly vulnerable to life-threatening vector-borne diseases (VBDs) including malaria, West Nile virus disease and leishmaniasis. However, information relevant for the control of the vectors of these diseases, such as their insecticide resistance profile, is scarce. The present study was conducted to provide the first evidence on insecticide resistance mechanisms circulating in major mosquito and sand fly populations in Armenia. METHODS: Sampling sites were targeted based mainly on previous historical records of VBD occurrences in humans and vertebrate hosts. Initially, molecular species identification on the collected vector samples was performed. Subsequently, molecular diagnostic assays [polymerase chain reaction (PCR), Sanger sequencing, PCR-restriction fragment length polymorphism (RFLP), quantitative PCR (qPCR)] were performed to profile for major insecticide resistance mechanisms, i.e. target site insensitivity in voltage-gated sodium channel (vgsc) associated with pyrethroid resistance, acetylcholinesterase (ace-1) target site mutations linked to organophosphate (OP) and carbamate (CRB) resistance, chitin synthase (chs-1) target site mutations associated with diflubenzuron (DFB) resistance and gene amplification of carboxylesterases (CCEs) associated with resistance to the OP temephos. RESULTS: Anopheles mosquitoes were principally represented by Anopheles sacharovi, a well-known malaria vector in Armenia, which showed no signs of resistance mechanisms. Contrarily, the knockdown resistance (kdr) mutations V1016G and L1014F/C in the vgsc gene were detected in the arboviral mosquito vectors Aedes albopictus and Culex pipiens, respectively. The kdr mutation L1014S was also detected in the sand fly, vectors of leishmaniasis, Phlebotomus papatasi and P. tobbi, whereas no mutations were found in the remaining collected sand fly species, P. sergenti, P. perfiliewi and P. caucasicus. CONCLUSIONS: This is the first study to report on molecular mechanisms of insecticide resistance circulating in major mosquito and sand fly disease vectors in Armenia and highlights the need for the establishment of systematic resistance monitoring practices for the implementation of evidence-based control applications.

Geographical and Molecular Analysis of Haplotype Variations in Leishmania major Among Infected Iranian Phlebotomus papatasi.

PURPOSE: Leishmania major is main causative agent and Phlebotomus papatasi is only proven vector of Zoonotic Cutaneous Leishmaniasis (ZCL) in Iran. Human leishmaniasis is mostly susceptible to climatic conditions and molecular variations of Leishmania parasites within sandflies. METHODS: L. major was analyzed based on geographical, environmental, climatic changes and haplotype variations within P. papatasi. Molecular tools and different geographical aspects were employed using Arc-GIS software for mapping the geographic distribution of samples and other statistics tests. Fragments of ITS-rDNA, k-DNA, and microsatellite genes of Leishmania were used for PCR, RFLP, sequencing, and phylogenetic analyses. RESULTS: Totally 81 out of 1083 female P. papatasi were detected with Leishmania parasites: 70 and five were L. major and L. turanica, respectively. Golestan and Fars provinces had the highest (13.64%) and lowest (4.55%) infection rates, respectively. The infection rate among female P. papatasi collected from gerbil burrows was significantly higher (15.15%) than animal shelters, yards, and inside houses (4.48%) (P < 0.0%). Microsatellite was more sensitive (22.72%) than k-DNA (18.8%) and ITS-rDNA (7.48%). More molecular variations of L. major were found in Isfahan province. CONCLUSIONS: Arc-GIS software and other statistics tests were employed to find Leishmania positive and haplotype variations among sand flies. Geographical situations, altitude, climate, precipitation, humidity, temperature, urbanization, migrations, regional divergences, deforestation, global warming, genome instability, ecology, and biology of the sand flies intrinsically, and the reservoir hosts and neighboring infected locations could be reasons for increasing or decreasing the rate of Leishmania infection and haplotype variations.

Comparative genomics of Leishmania donovani progeny from genetic crosses in two sand fly species and impact on the diversity of diagnostic and vaccine candidates.

Sand fly transmitted Leishmania species are responsible for severe, wide ranging, visceral and cutaneous leishmaniases. Genetic exchange can occur among natural Leishmania populations and hybrids can now be produced experimentally, with limitations. Feeding Phlebotomus orientalis or Phlebotomus argentipes on two strains of Leishmania donovani yielded hybrid progeny, selected using double drug resistance and fluorescence markers. Fluorescence activated cell sorting of cultured clones derived from these hybrids indicated diploid progeny. Multilocus sequence typing of the clones showed hybridisation and nuclear heterozygosity, although with inheritance of single haplotypes in a kinetoplastid target. Comparative genomics showed diversity of clonal progeny between single chromosomes, and extraordinary heterozygosity across all 36 chromosomes. Diversity between progeny was seen for the HASPB antigen, which has been noted previously as having implications for design of a therapeutic vaccine. Genomic diversity seen among Leishmania strains and hybrid progeny is of great importance in understanding the epidemiology and control of leishmaniasis. As an outcome of this study we strongly recommend that wider biological archives of different Leishmania species from endemic regions should be established and made available for comparative genomics. However, in parallel, performance of genetic crosses and genomic comparisons should give fundamental insight into the specificity, diversity and limitations of candidate diagnostics, vaccines and drugs, for targeted control of leishmaniasis.

Reconstructing the post-glacial spread of the sand fly Phlebotomus mascittii Grassi, 1908 (Diptera: Psychodidae) in Europe.

Phlebotomine sand flies (Diptera: Phlebotominae) are the principal vectors of Leishmania spp. (Kinetoplastida: Trypanosomatidae). In Central Europe, Phlebotomus mascittii is the predominant species, but largely understudied. To better understand factors driving its current distribution, we infer patterns of genetic diversity by testing for signals of population expansion based on two mitochondrial genes and model current and past climate and habitat suitability for seven post-glacial maximum periods, taking 19 climatic variables into account. Consequently, we elucidate their connections by environmental-geographical network analysis. Most analyzed populations share a main haplotype tracing back to a single glacial maximum refuge area on the Mediterranean coasts of South France, which is supported by network analysis. The rapid range expansion of Ph. mascittii likely started in the early mid-Holocene epoch until today and its spread possibly followed two routes. The first one was through northern France to Germany and then Belgium, and the second across the Ligurian coast through present-day Slovenia to Austria, toward the northern Balkans. Here we present a combined approach to reveal glacial refugia and post-glacial spread of Ph. mascittii and observed discrepancies between the modelled and the current known distribution might reveal yet overlooked populations and potential further spread.

Genetic diversity and phylogeography of Phlebotomus argentipes (Diptera: Psychodidae, Phlebotominae), using COI and ND4 mitochondrial gene sequences.

BACKGROUND: Phlebotomus argentipes complex is the primary vector for cutaneous leishmaniasis, a burgeoning health concern in contemporary Sri Lanka, where effective vector control is important for proper disease management. Understanding the genetic diversity of the P. argentipes population in Sri Lanka is vital before implementing a successful vector control program. Various studies have indicated that genetic divergence, caused by genetic drift or selection, can significantly influence the vector capacity of arthropod species. To devise innovative control strategies for P. argentipes, exploring genetic diversity and phylogeography can offer valuable insights into vector competence, key genetic trait transfer, and impact on disease epidemiology. The primary objective is to analyze the genetic diversity and phylogeography of the P. argentipes complex in Sri Lanka, based on two mitochondrial genomic regions in modern representatives of P. argentipes populations. METHODOLOGY: A total of 159 P. argentipes specimens were collected from five endemic areas of cutaneous leishmaniasis and identified morphologically. Two mitochondrial regions (Cytochrome c oxidase subunit I (COI) and NADH dehydrogenase subunit 4 (ND4) were amplified using the total DNA and subsequently sequenced. Partial sequences of those mitochondrial genes were utilized to analyze genetic diversity indices and to explore phylogenetic and phylogeographic relationships. PRINCIPAL FINDINGS: Among five sampling locations, the highest genetic diversity for COI and ND4 was observed in Hambantota (Hd-0.749, π-0.00417) and Medirigiriya (Hd-0.977, π-0.01055), respectively. Phylogeographic analyses conducted using COI sequences and GenBank retrieved sequences demonstrated a significant divergence of P. argentipes haplotypes found in Sri Lanka. Results revealed that they have evolved from the Indian ancestral haplotype due to historical- geographical connections of the Indian subcontinent with Sri Lanka. CONCLUSIONS: Utilizing high-mutation-rate mitochondrial genes, such as ND4, can enhance the accuracy of genetic variability analysis in P. argentipes populations in Sri Lanka. The phylogeographical analysis of COI gene markers in this study provides insights into the historical geographical relationship between India and P. argentipes in Sri Lanka. Both COI and ND4 genes exhibited consistent genetic homogeneity in P. argentipes in Sri Lanka, suggesting minimal impact on gene flow. This homogeneity also implies the potential for horizontal gene transfer across populations, facilitating the transmission of genes associated with traits like insecticide resistance. This dynamic undermines disease control efforts reliant on vector control strategies.

Molecular surveillance of insecticide resistance in Phlebotomus argentipes targeted by indoor residual spraying for visceral leishmaniasis elimination in India.

Molecular surveillance of resistance is an increasingly important part of vector borne disease control programmes that utilise insecticides. The visceral leishmaniasis (VL) elimination programme in India uses indoor residual spraying (IRS) with the pyrethroid, alpha-cypermethrin to control Phlebotomus argentipes the vector of Leishmania donovani, the causative agent of VL. Prior long-term use of DDT may have selected for knockdown resistance (kdr) mutants (1014F and S) at the shared DDT and pyrethroid target site, which are common in India and can also cause pyrethroid cross-resistance. We monitored the frequency of these marker mutations over five years from 2017-2021 in sentinel sites in eight districts of north-eastern India covered by IRS. Frequencies varied markedly among the districts, though finer scale variation, among villages within districts, was limited. A pronounced and highly significant increase in resistance-associated genotypes occurred between 2017 and 2018, but with relative stability thereafter, and some reversion toward more susceptible genotypes in 2021. Analyses linked IRS with mutant frequencies suggesting an advantage to more resistant genotypes, especially when pyrethroid was under-sprayed in IRS. However, this advantage did not translate into sustained allele frequency changes over the study period, potentially because of a relatively greater net advantage under field conditions for a wild-type/mutant genotype than projected from laboratory studies and/or high costs of the most resistant genotype. Further work is required to improve calibration of each 1014 genotype with resistance, preferably using operationally relevant measures. The lack of change in resistance mechanism over the span of the study period, coupled with available bioassay data suggesting susceptibility, suggests that resistance has yet to emerge despite intensive IRS. Nevertheless, the advantage of resistance-associated genotypes with IRS and under spraying, suggest that measures to continue monitoring and improvement of spray quality are vital, and consideration of future alternatives to pyrethroids for IRS would be advisable.

Morphological and molecular evidence of sandfly (Diptera: Psychodidae: Phlebotomine) and its relevance to recent cases of leishmaniasis from Jammu region of North India.

Present study was conducted to carry out morphological and molecular confirmation of sandflies collected at the Department of Parasitology, Faculty of Veterinary and Animal Sciences, R.S. Pura, Jammu, India. Larva was maggot like with large head, thorax and abdomen with typical black head, 12 abdominal segments and last abdominal segment carried two pairs of caudal bristles with matchstick hairs on each segment. The adult fly possessed head, abdomen and thorax. Head consisted of pair of long, hairy and beaded antenna, proboscis and one pair of prominent black eyes. Thorax possessed a pair of wings and three pairs of legs, wings were hairy and pointed with 2nd longitudinal vein branched twice. The abdominal segments were covered with small hairs and last abdominal segment was having a pair of anal recti. These identification characteristics confirmed the fly under study as Phlebotomus argentipes that confirms its occurance in this region. Molecular characterization of identified flies was carried out on positive morophological flies. Confirmation of Phlebotomus species was ascertained by amplifying the 18S ribosomal RNA gene sequence using PCR. Clear amplification was observed for Phlebotomus argentipes (538 bp). After sequencing/genotyping, Phlebotomus argentipes (OP646634) isolate of present study was clustering in same clade with Phlebotomus argentipes sequences obtained from GeneBank from other locations across globe, irrespective of their geographical location, thus providing the molecular evidence of this species present in Jammu region of North India.

Trichophoromyia auraensis: evidence for cryptic species and first record in the state of Maranhão, Brazil.

Trichophoromyia auraensis (Mangabeira, 1942) (Diptera, Psychodidae, Phlebotominae) has a wide geographic distribution in the western region of the Amazon biome, where it is a putative Leishmania vector. Here, we reported for the first time a population of this species in the Brazilian state of Maranhão, in the eastern Amazon, from which we DNA-barcoded and compared with previously processed specimens from Acre State, in the western Amazon. For this, we analyzed the DNA barcoding fragment (658 bp) of the mitochondrial cytochrome c oxidase subunit I (COI) gene and the nuclear internal transcribed spacer 2 (ITS2) of Trichophoromyia species using phylogenetic gene trees, and species delimitation algorithms. The analyses of COI barcodes showed high values of genetic distance (mean K2P = 5.17) and well-supported clades/MOTUs for the eastern and western populations of T. auraensis, which may indicate a possible complex of cryptic species. The western population of this taxon merged with the close-related sand fly Trichophoromyia velezbernali Posada-López, Galvis and Galati, 2018 from Colombia, which may be associated with the recent speciation history and introgression between these populations. These evidences should be evaluated with a more comprehensive sampling in terms of analyzed populations and molecular markers.

Detection of Leishmania DNA in Phlebotomine Sand Flies in Tsatee, a Community in the Volta Region, Ghana.

Leishmania parasites, which are spread by infected female sand flies, are the cause of the disease leishmaniasis. Although cutaneous leishmaniasis has been found to occur in the Volta Region, there is limited data on vector species and reservoirs. This study focused on the Tsatee community, in the South Dayi District of the Volta Region, and is aimed at identifying the sand fly fauna and detecting the presence of Leishmania DNA by the use of primers that target the conserved region of Leishmania spp. minicircle DNA of the parasite kinetoplast. The miniature light traps and hand aspirators provided by the Centers for Disease Control and Prevention (CDC) were used to collect outdoor and indoor sand flies for five months in a guinea woodland and semideciduous forest area. From the collections, 4,580 phlebotomine sand flies were obtained and identified, and females were examined for Leishmania DNA using PCR. The male flies were 1,202 (26.24%), non-blood-fed females were 3,321 (72.51%), and 57 (1.25%) were blood-fed females. It was observed that Sergentomyia species constituted 99.91% of the total collected sand flies with S. africana (76.77%) as the predominant species. Phlebotomus rodhaini (0.09%) was the only Phlebotomus species identified from the study area. From 283 non-blood-fed sand fly pools and 57 individual blood-fed species screened, Leishmania DNA was detected in 12 (4.24%) pools and 8 (14.04%) individuals, respectively. It was observed that Leishmania DNA was detected in all the sand fly species identified except S. collarti. This study reports the first detection of Leishmania DNA in P. rodhaini in Ghana, with an infection rate of 33.33% (95% CI, 1.23-88.32). The findings suggest that the role of Phlebotomus in disease transmission in the study area cannot be discounted. Future studies should include continuous surveillance, blood meal preferences, and vector competence of the various infected phlebotomine sand flies to create effective control measures.

On abnormal Phlebotomus perniciosus (Diptera: Psychodidae: Phlebotominae) from the center of Tunisia.

Phlebotomus perniciosus is the most important vector of Leishmania infantum in the Western part of the Mediterranean basin. Atypical specimens of Ph. perniciosus called (pna) with a parameral sheath simply curved, not bifurcated, have been reported in many locations. In this study, we describe abnormal Ph. perniciosus male specimens. Sand flies were collected in center Tunisia and identified morphologically. Cytochrome b PCR-sequencing was carried out for abnormal Ph. perniciosus male specimens in order to confirm the morphological identification and assess the intraspecific genetic polymorphism. Abnormal Ph. perniciosus specimens were characterized by a multifurcated parameral sheath. A parsimonious haplotype network based on cyt b locus analysis showed that typical and abnormal Ph. perniciosus described in our investigation were grouped together in the same branch. Thus, genetic outcomes confirmed that the new phenotype is only an original morphotype of Ph. perniciosus.

Molecular identification of Phlebotomus kandelakii apyrase and assessment of the immunogenicity of its recombinant protein in BALB/c mice.

Sand fly salivary proteins have immunomodulatory and anti-inflammatory features; hence, they are proven to perform important roles in the early establishment of Leishmania parasite in the vertebrate host. Among them, salivary apyrase with anti-hemostatic properties has a crucial role during the blood meal process. In the present study, a Genome-Walking method was used to characterize a full-length nucleotide sequence of Phlebotomus (P.) kandelakii apyrase (Pkapy). Bioinformatics analyses revealed that Pkapy is a ~ 36 kDa stable and hydrophilic protein that belongs to the Cimex family of apyrases. Moreover, recombinant proteins of Pkapy and P. papatasi apyrase (Ppapy) were over-expressed in Escherichia coli BL2 (DE3) and their antigenicity in BALB/c mice was evaluated. Dot-blot and ELISA results indicated that both recombinant apyrases could induce antibodies in BALB/c. Moreover, a partial cross-reactivity between Pkapy and Ppapy was found. In vitro stimulation of splenocytes from immunized mice with the recombinant proteins indicated cross-reactive T cell proliferative responses. Cytokine analysis revealed significant production of IFN-γ (p < 0.001) and IL-10 (p < 0.01) in response to Pkapy. In conclusion, the full-length nucleotide sequence and molecular characteristics of Pkapy were identified for the first time. Immunologic analyses indicated that Pkapy and Ppapy are immunogenic in BALB/c mice and show partial cross-reactive responses. The immunity to Pkapy was found to be a Th1-dominant response that highlights its potential as a component for an anti-Leishmania vaccine.

Low genetic heterogeneity of Leishmania major in different geographical regions of Iran.

To examine the genetic diversity of Leishmania major, 100 Giemsa-stained positive slides were collected from endemic foci of Iran (Northeast, Central, and Southwest provinces) over two consecutive years during 2019-2021. The Leishmania ITS-rDNA gene was amplified and Leishmania sp. was recognized by PCR-RFLP and sequencing. In addition, 178 registered ITS-rDNA sequences from other geographical regions of Iran were retrieved from GenBank, including different host species (human, sandfly and rodent). A total of 40 new haplotypes were discovered using the ITS-rDNA sequence analysis. IR29 (20.6%) and IR34 (61%) were the two most common haplotypes, represented by a star-like feature in the overall population. Analysis of the molecular variance test revealed low genetic diversity of L. major in human cases (Haplotype diversity; 0.341), rodent (Hd; 0.387) and sandfly (Hd; 0.390) sequences. The lowest genetic diversity of L. major was observed in Southwest/Southeast Iran (Hd: 0.104-0.286). The statistically Fst value indicated that L. major is not genetically differentiated between geographic regions of Iran, except for the Northeast-Southwest (Fst: 0.29055) and Central-Southwest (Fst: 0.30294) population pairs. The current study as the first investigation discloses new perspectives for further evaluation in the identification local transmission paradigms and initiating effective prevention strategies.

The Role of the Leishmania infantum Infected Dogs as a Potential Reservoir Host for Toscana Virus in a Zoonotic Visceral Leishmaniasis Focus of Northern Tunisia.

The role of dogs as reservoir hosts for Toscana virus (TOSV) remains undetermined. This study investigated TOSV and Leishmania infantum infections in one healthy and three infected dogs with Leishmania (A, B, C) following natural exposition to sandfly bites in a focus of zoonotic visceral leishmaniasis (ZVL) located in Northern Tunisia from June to October 2020. At the end of the exposition period, infected and healthy dogs were examined for TOSV and L. infantum infections by xenodiagnosis using a colony of Phlebotomus perniciosus. Pools of freshly engorged P. perniciosus at days 0 and those at days 7 post-feeding were screened for TOSV and L. infantum by nested PCR in the polymerase gene and kinetoplast minicircle DNA, respectively. In the exposure site, P. pernicious is the most abundant sandfly species. The infection rates of sandflies with TOSV and L. infantum were 0.10 and 0.05%, respectively. Leishmania infantum DNA and TOSV RNA were detected in P. perniciosus females fed on dog B and C, respectively. The isolation of TOSV in Vero cells was achieved from two pools containing P. perniciosus fed on dog C. No pathogens were detected in P. perniciosus females fed on dog A and on control dog. We report for the first time the reservoir competence of dog with ZVL in the transmission of TOSV to sandfly vectors in natural settings, in addition to its role as a main reservoir host of L. infantum.