Genetic diversity of Leishmania major strains isolated from Phlebotomus papatasi and Phlebotomus alexandri in western Iran based on minicircle kDNA

This study aimed to screen the natural infection rate of Leishmania major in Phlebotomus papatasi and Phlebotomus alexandri in two counties (Mehran and Dehloran) of Ilam province as cutaneous leishmaniasis endemic areas in the west of Iran. Furthermore, the genetic diversity of parasite species that are isolated from vectors, was investigated. Sandflies were collected by sticky traps from May 2018 to October 2018. Afterward, specimens were prepared for species identification by morphological features. DNA was extracted from female sandflies, and minicircle kDNA was used to identify Leishmania isolates through nested-PCR, followed by genetic diversity between Leishmania isolates was investigated by sequence analysis of the amplified minicircle kDNA. Natural infection of the L. major was shown in all positive specimens using nested-PCR. Analysis of data from 14 isolates displayed a high level of genetic diversity in L. major. In the phylogenetic trees, all of the L. major isolates occurred in six clusters. Clusters I, II, III, and VI contained isolated strains from P. papatasi. While clusters IV and V contained isolated strains from P. alexandri. Genetic diversity of L. major isolated from vectors was investigated in western Iran for the first time. According to the results of this study, probably "various clones of L. major populations are distributed in the study area.

Molecular characteristic of treatment failure clinical isolates of Leishmania major

Background

Leishmaniasis is a prevalent tropical disease caused by more than 20 Leishmania species (Protozoa, Kinetoplastida and Trypanosomatidae). Among different clinical forms of the disease, cutaneous leishmaniasis is the most common form, with an annual 0.6–1 million new cases reported worldwide. This disease’s standard treatment is pentavalent antimonial (Sb^V) that have been used successfully since the first half of the 20th century as a first-line drug. However, treatment failure is an increasing problem that is persistently reported from endemic areas. It is important to define and standardize tests for drug resistance in cutaneous leishmaniasis. Sb^V must be reduced to its trivalent active form (Sb^III). This reduction occurs within the host macrophage, and the resultant Sb^IIIenters amastigotes via the aquaglyceroporin1 (AQP1) membrane carrier. Overexpression of AQP1 results in hypersensitivity of the parasites to Sb^III, but resistant phenotypes accompany reduced expression, inactivation mutations, or deletion of AQP1. Hence, in this study, a phylogenetic analysis using barcode gene COXII and kDNA minicircle and expression analysis of AQP1 were performed in treatment failure isolates to assess the isolates’ molecular characteristics and to verify possible association with drug response.

Methods

Samples in this study were collected from patients with cutaneous leishmaniasis referred to the Diagnosis Laboratory Center in Isfahan Province, Iran, from October 2017 to December 2019. Among them, five isolates (code numbers 1–5) were categorized as treatment failures. The PCR amplification of barcode gene COXII and kDNA minicircle were done and subsequently analyzed using MEGA (10.0.5) to perform phylogenetics analysis of Treatment failures (TF) and Treatment response (TR) samples. Relative quantification of the AQP1 gene expression of TF and TR samples was assessed by real-time PCR.

Results

All samples were classified as L. major. No amplification failure was observed in the cases of barcode gene COXII and kDNA minicircle amplification. Having excluded the sequences with complete homology using maximum parsimony with the Bootstrap 500 method, four major groups were detected to perform phylogenetic analysis using COXII. The phylogenetic analysis using the barcode target of minicircle showed that all five treatment failure isolates were grouped in a separate sub-clade.

Conclusions

We concluded that the barcode gene COXII and the minicircle kDNA were suitable for identification, differentiation and phylogenetic analysis in treatment failure clinical isolates of Leishmania major. Also, AQP1 gene expression analyses showed that treatment failure isolates had less expression than TR isolates. The isolate with TF and overexpression of the AQP1 gene of other molecular mechanisms such as overexpression of ATP-binding cassette may be involved in the TR, such as overexpression of ATP-binding cassette which requires further research.

Real-time PCR to differentiate among Leishmania (Viannia) subgenus, Leishmania (Leishmania) infantum and Leishmania (Leishmania) amazonensis: Application on Brazilian clinical samples

Leishmaniasis is a complex disease caused by Leishmania species belonging to subgenera Leishmania and Viannia. In South America, L. (L.) infantum is considered the most important causative agent of visceral leishmaniasis, while L. (L.) amazonensis and Viannia subgenus species are responsible for the different cutaneous or mucocutaneous forms. In our previous work, we developed a diagnostic approach for Leishmania species discrimination based on two qPCRs (qPCR-ML and qPCR-ama) targeting the minicircle kDNA followed by melting analysis. This approach allowed to (i) differentiate the subgenera Leishmania and Viannia, and (ii) distinguish between L. (L.) infantum and L. (L.) amazonensis. The aim of this work was to demonstrate the applicability of the approach previously described, using human and canine clinical samples and strains from a Brazilian region, where L. (L.) infantum, L. (L.) amazonensis and Viannia subgenus species coexist. After validation on New World strains, the diagnostic approach was applied blindly to 36 canine clinical samples (peripheral blood and bone marrow) and 11 human clinical samples (peripheral blood and bone marrow). The sensitivity was 95.6% (95% confidence interval 77.3-100%) and 100% (95% confidence interval 76.9-100%) in the canine bone marrow samples and human (peripheral blood and bone marrow) samples, respectively, compared to conventional PCR assays. Concerning the Leishmania species identification, the conventional and qPCR-based methods showed kappa value of 0.876 (95% confidence interval 0.638-1.000), indicating good agreement. Therefore, this approach proved to be useful in both veterinary and human clinical context in regions co-endemic for L. (L.) infantum, L. (L.) amazonensis, and Viannia subgenus, helping to provide rapid diagnosis and to allow studies of species distribution.

Leishmania cytochrome b gene sequence polymorphisms in southern Iran: relationships with different cutaneous clinical manifestations

Background

Cutaneous leishmaniasis (CL) caused by Leishmania species, is a geographically extensive disease that infects humans and animals. CL is endemic in half of the 31 provinces of Iran, with 29,201 incidence cases reported in Fars province from 2010 to 2015. CL is polymorphic and may result in lesions characterized by different clinical features. Parasite genetic diversity is proposed to be one of the factors affecting the clinical outcome and lesion characteristics in CL patients. However, there is still very limited data regarding the genetic variation of Leishmania spp. based on the sequencing of Cytochrome b (Cyt b) gene.

Methods

All patients originated from endemic regions in Fars province. The amplification of the Cyt b gene from isolates of 100 patients with disparate clinical forms of CL was accomplished using Nested-PCR. Sequence analysis of the amplified Cyt b was used to scrutinize the genetic variations among Leishmania isolates and connect the results with clinical pictures. The clinical demonstrations were basically of two types, typical and atypical lesions. Molecular phylogenetic tree was constructed using the Neighbor-Joining method, with species/strains from this study compared to species/strains from other geographical regions.

Results

Leishmania major was identified as the predominant infecting Leishmania spp. (86% of cases), with the remainder of cases being infected by Leishmania tropica. Clinical examination of patients revealed 12 different clinical CL forms. Among Leishmania samples analyzed, five distinct haplotypes were recognized: three in L. major and two in L. tropica. We found a correlation between clinical outcomes and Cyt b sequence variation of Leishmania spp. involved. Moreover, we observed a higher presence of polymorphisms in L. major compared with L. tropica. This difference may be due to the different eco-epidemiologies of both species, with L. tropica being an anthroponosis compared to L. major, which is a zoonosis.

Conclusions

The sequence analysis of Cyt b gene from 25 L. major and L. tropica strains demonstrated genetic variability of L. major and L. tropica causing CL in southern Iran, and a feasible connection amid the genetic heterogeneity of the parasite, geographical source and clinical appearance of the disease in human was detected.