Molecular evaluation of pvdhfr and pvmdr-1 mutants in Plasmodium vivax isolates after treatment with sulfadoxine/pyrimethamine and chloroquine in Iran during 2001-2016

Molecular surveillance of antifolate drug resistance markers in Plasmodium vivax from Khyber Pakhtunkhwa province, northwest Pakistan

The emergence and spread of antimalarial drug resistance pose significant challenges in the fight against malaria. Mutations in dihydrofolate reductase (DHFR) and dihydropteroate synthetase (DHPS) in Plasmodium vivax are associated with sulfadoxine-pyrimethamine (SP) drug resistance. This study assessed SP resistance status in P. vivax isolates collected in Khyber Pakhtunkhwa province, Pakistan, by analyzing mutations in pvdhfr and pvdhps. Both genes were successfully amplified concurrently from 112 Pakistan P. vivax isolates. Sequence analysis of pvdhfr indicated that mutations F57L, S58R, and S117N were present with frequencies of 0.9 %, 31.3 %, and 46.4 %, respectively. The predominant wild-type haplotype F57S58T61S117 was identified in 51.8 % of samples, whereas mutant haplotypes were also detected: F57R58T61N117 (29.5 %), F57S58T61N117 (16.9 %), F57R58T61S117 (0.9 %), and L57R58T61S117 (0.9 %). In pvdhps, the sole mutation A383 G was found at a low frequency of 1.8 %, leading to a mutant haplotype S382G383K512A553V585. The integrated analysis of pvdhfr and pvdhps haplotypes showed that the wild-type haplotype was the most prevalent (50.9 %), followed by mutant haplotypes F57R58T61N117/ S382A383K512A553V585 (28.6 %) and F57S58T61N117/S382A383K512A553V585 (16.9 %). These findings indicate a relatively low level of antifolate resistance in Pakistan P. vivax isolates, suggesting that Pakistan P. vivax may still be amenable to SP treatment. Nevertheless, the persistence of similar mutation rates and patterns associated with SP resistance in the Pakistan pvdhfr and pvdhps populations, despite the absence of current SP pressure, underscores the importance of ongoing monitoring of SP resistance in the Pakistan P. vivax population.

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 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.

Global assessment of genetic paradigms of Pvmdr1 mutations in chloroquine-resistant Plasmodium vivax isolates

BACKGROUND

Chloroquine (CQ) is generally prescribed as the front-line antimalarial drug of choice to treat Plasmodium vivax infections; however, some clinical CQ-resistant P. vivax isolates have been indigenously reported around the world during the last decade.

METHODS

In this study, P. vivax isolates (n=52) were obtained from autochthonous samples in southeast Iran during 2015-2017. The genomic DNA of samples was extracted, amplified (nested PCR) and sequenced by targeting the multidrug-resistance 1 gene. To verify the global genetic diversity of CQ-resistant P. vivax strains, the sequences of Pvmdr1 originating from Asia and the Americas were retrieved.

RESULTS

A total of 46 haplotypes were grouped into three distinct geographical haplogroups. The haplotype diversity and occurrence rates of Pvmdr1 976F/1076L mutations indicate that the efficacy of CQ is being compromised in Mexico, China, Nicaragua, Thailand, Brazil (2016), Ethiopia, Mauritania (2012) and southwest India in the near future. The cladistic phylogenetic tree showed that Pvmdr1 sequences isolated from the southeast Asian clade has a partial sister relationship with the American clade.

CONCLUSIONS

The current findings will serve as a basis to develop appropriate malaria control strategies and public health policies in symptomatic imported malaria cases or plausible CQ-resistant P. vivax strains.