An unlabelled probe-based real time PCR and modified semi-nested PCR as molecular tools for analysis of chloroquine resistant Plasmodium vivax isolates from Afghanistan

Molecular epidemiology of potential candidate markers for chloroquine resistance in imported Plasmodium vivax malaria cases in Iran

BACKGROUND

The spread of Plasmodium vivax strains resistant to chloroquine (CQ) has posed a challenge to control strategies aimed at eliminating malaria. Molecular analysis of candidate resistance markers is very important for monitoring the P. vivax resistance to CQ in different endemic regions. In the present study, the multidrug resistance 1 (pvmdr1) gene, a possible marker for CQ resistance in P. vivax, was evaluated by molecular methods.

METHODS

A simple PCR-RFLP method was developed for mutation analysis in pvmdr1 gene. A number of 120 blood spots were obtained from patients with P. vivax mono-infection in 2021. All of the samples were collected from Pakistani patients who travelled to Iran.

RESULTS

None of the samples had any mutation at codon 976 of pvmdr1, while the 1076 mutation was detected in 96.2% of the examined isolates. Only two pvmdr1 haplotypes were identified, including the single mutant (Y976/1076L) as the most prevalent haplotype (with 96.2% frequency) and the wild type (Y976/F1076; with 3.8% frequency).

CONCLUSIONS

In this study, the major CQ resistance-mediating mutation and multiple mutant haplotypes of the pvmdr1 gene was not detected. However, continuous monitoring of drug resistance markers and close supervision of the efficacy of CQ is essential to detect the potential emergence of CQ-resistant P. vivax isolates in Iran. This data is important for performing future epidemiological surveillance to monitor CQ resistance in this endemic area and the bordering regions.

Simultaneous Detection of Three Genotypes of Gene Methylene Tetrahydrofolate Reductase and Methionine Synthase Reductase Based on Multiplex Asymmetric Real-Time PCR-HRM Biosensing

Genotyping of folate metabolism genes is of great importance in disease diagnosis and prevention. However, most current detection methods used for folate metabolism gene genotyping are based on sequencing and chips, which suffer from a high cost and laborious and time-consuming procedures. Herein, we reported a multiplex asymmetric PCR-HRM strategy for identifying genotypes of folate metabolism genes in a single tube. The proposed multiplex PCR-HRM assay has been successfully applied to identify the genotypes of folate metabolism genes, methylene tetrahydrofolate reductase (C677T, A1298C) and methionine synthase reductase A66G, on 1 μL of genomic DNA (gDNA) samples directly released from blood specimens, and the genotyping results were 100% consistent with the results of sequencing. The assay allows us to accurately detect the genotypes of gDNA with the detection limit down to 1 ng, which meets the clinical requirement. What is more, the capacity of resistance to aerosol pollution of the multiplex asymmetric PCR-HRM biosensing was first addressed and has been evaluated as it can withstand contamination of roughly 12.5-25% interfering nucleic acids. Because of the advantages of multiplex detection, high accuracy, and resistance to aerosol pollution and having no open tube procedure, this approach would pave the way for establishing a fast and cost-effective platform for folate metabolism gene genotyping and other SNP genotyping in clinical diagnostics.

The Drug Resistance of Plasmodium falciparum and P. vivax in Iran: A Review Article

Background

One of the main obstacles to malaria control in the world has been the emergence of resistance in Plasmodium falciparum to chloroquine and other anti-malarial drugs. This study aimed to review studies in Iran on resistance in P. falciparum and P. vivax to drugs, and to reveal the mechanisms and molecular markers of resistance of these two species.

Methods

The databases of PubMed, Scopus, Google Scholar, Magiran, and reputable Iranian journals were searched to find published studies on the resistance in P. falciparum and P. vivax to antimalarial drugs in Iran.

Results

There is a significant relationship between resistance to chloroquine in P. falciparum and the emergence of K76T mutation in the P. falciparum chloroquine-resistance transporter gene in Iran. Resistance to sulfadoxine-pyrimethamine (SP) in P. falciparum is also significantly associated with the development of mutations in the dihydrofolate reductase and dihydropteroate synthase genes. Resistance to chloroquine in P. vivax has not been reported in Iran and it is used as a first-line treatment for P. vivax malaria.

Conclusion

P. falciparum has become resistant to chloroquine in different regions of Iran and is not currently used to treat malaria. Besides, cases have emerged of P. falciparum resistance to SP in different parts of southern Iran, and SP is not administered alone for treating P. falciparum.