Detection of antimalarial drug resistance polymorphisms in Plasmodium falciparum chloroquine resistance transporter and Plasmodium falciparum multidrug resistance 1 genes of Plasmodium falciparum found in Kano State, Nigeria

Objectives: In 2018, malaria claimed an estimated 380,000 lives in African region, with Nigeria accounting for 24.0% (91,368) of malaria deaths from the region. Mutations in Plasmodium falciparum chloroquine resistance transporter (Pfcrt) and P. falciparum multidrug resistance 1 (Pfmdr-1) genes had reduced the effective use of artemisinin combination therapy through the development of resistance to these antimalarial agents. Our study set out to determine the antimalarial drug resistance polymorphisms in Pfcrt and Pfmdr-1 genes of P. falciparum isolates among patients in Kano State, Nigeria. Material and Methods: Malaria positive samples were collected across the three senatorial districts of Kano State. The samples were amplified using nested polymerase chain reaction to detect the Pfcrt and Pfmdr-1 genes. The amplicons were sequenced and bioinformatic analysis was done using CLC Sequence viewer 8.0 and BioEdit sequence alignment editor to detect the single-nucleotide polymorphisms. Results: In the Pfcrt gene, CVIET haplotype was seen in 26.2% of the samples while only two samples showed the 86Y mutation in the Pfmdr-1 gene. All the 86Y mutations and majority of the CVIET haplotypes were detected in the patients from rural settings where some of them noted that they consumed modern and traditional (herbs) antimalarial agents. One sample was observed to have the CVIET haplotype and N86Y mutation while the other five CVIET haplotypes were seen in five separate samples. A new mutation V62A was found in the Pfmdr-1 gene as observed in one of the sample. Conclusion: It is imperative to ensure the rational use of the right antimalarial agents and employ continuous resistance surveillance/mapping to ensure synergy in malaria containment and elimination strategies.

In vitro and in vivo antimalarial activity of the volatile oil of Cyperus articulatus (Cyperaceae)

Malaria is a disease of global tropical distribution, being endemic in more than 90 countries and responsible for about 212 million cases worldwide in 2016. To date, the strategies used to eradicate this disease have been ineffective, without specific preventive measures such as vaccines. Currently, the existing therapeutic arsenal is limited and has become ineffective against the expansion of artemisinin-resistant Plasmodium, demonstrating the need for studies that would allow the development of new compounds against this disease. In this context, we studied the volatile oil obtained from rhizomes of Cyperus articulatus (VOCA), a plant species commonly found in the Amazon region and popularly used as a therapeutic alternative for the treatment of malaria, in order to confirm its potential as an antimalarial agent by in vitro and in vivo assays. We cultured Plasmodium falciparum W2 (chloroquine-resistant) and 3D7 (chloroquine-sensitive) strains in erythrocytes and exposed them to VOCA at different concentrations in 96-well microplates. In vivo antimalarial activity was tested in BALB/c mice inoculated with approximately 106 erythrocytes infected with Plasmodium berghei. VOCA showed a high antimalarial potential against the two P. falciparum strains, with IC50 = 1.21 µg mL-1 for W2 and 2.30 µg mL-1 for 3D7. VOCA also significantly reduced the parasitemia and anemia induced by P. berghei in mice. Our results confirmed the antimalarial potential of the volatile oil of Cyperus articulatus. (AU)

Potential Factors Responsible for the Development of Plasmodium falciparum and Plasmodium vivax Resistance to Anti-malarial Drugs in Some Parts of India.

Indiscriminate use of chloroquine (CQ) has resulted in chloroquine resistance in Plasmodium falciparum (Pf) in almost all regions of India. Due to the emergence of resistance to CQ in India, the current recommended first line of treatment for Pf has been the combination of artesunate with sulfadoxine-pyrimethamine (SP). Recently, chloroquine resistance to Plasmodium vivax (Pv) has also emerged in some parts of India. Poor drug quality and under dosing of antimalarial treatment are potential factors of drug resistance to malaria parasite. A caution is thus required for quality control of antimalarial drugs now in use and also inadequate treatment. There is an urgent need to strengthen National Drug Control Policy to empower Central Drugs Standard Control Organization to enforce definitive antimalarial drug legislations. Improvement in quality control in production and distribution of antimalarial drugs in India, combined with informed and enforced national guidance on the treatment of malaria, will help to combat the emergence of resistance to antimalarial drugs.

A Case of Imported Plasmodium malariae Malaria

Malaria, the most common vector-borne parasite infection worldwide, results from infection by Plasmodium species. Approximately 80% of malaria cases are caused by P. vivax, which is broadly distributed from tropical to temperate regions; P. falciparum is the second most common infectious species. P. malariae and P. ovale are responsible for a relatively small proportion of malaria cases. Here, we report the case of a 23-yr-old Korean woman who acquired a P. malariae infection while visiting the Republic of Ghana in West Africa for business. She was diagnosed with P. malariae malaria on the basis of peripheral blood smear (PBS) and species-specific conventional and real-time PCR assays for 18S rRNA. She was treated with hydroxychloroquine, and the resulting PBS examination on day 2 suggested that negative conversion occurred. At her 1-month follow-up, however, both the PBS examination and molecular test for malaria demonstrated recurrent parasitemia. We started rescue therapy with mefloquine, and the patient recovered successfully. This is an important finding suggesting possible late recrudescence of a chloroquine-resistant P. malariae strain identified not only by its morphological features, but also by molecular tests.

In vivo sensitivity monitoring of chloroquine for the treatment of uncomplicated vivax malaria in four bordered provinces of Thailand during 2009–2010.

Background & objectives: Chloroquine (CQ), followed by 14-day primaquine, is the recommended regimen for the treatment of Plasmodium vivax infection in Thailand. CQ resistant P. vivax (CRPv) has not yet challenged the efficacy of the drug. The present study was conducted to assess the current response of P. vivax to CQ alone in Thailand. Methods: A 28-day in vivo therapeutic efficacy study was conducted from June 2009 to December 2010 in 4 sentinel sites. Recurrence of parasitaemia and the clinical condition of patients were assessed on each visit during follow-up. The drug levels in recurrent patients’ blood were measured using HPLC. Data were analyzed using the WHO 2008 program for the analysis of in vivo tests. Results: Of the total 212 patients included in the study, 201 completed the 28-days follow-up, while 11 were excluded. In five patients (2.5%), parasitaemia reappeared within the 28-days follow-up. On the day of recurrent parasitaemia, the level of chloroquine/desethylchloroquine (CQ-DCQ) was above the minimum effective concentration (>100 ng/ml) in one patient, but lower in four patients. Conclusion: Reappearance of the parasite within 28 days of follow-up in one of five patients was due to parasite resistance to CQ. The 2.5% prevalence of CQ treatment failure for P. vivax malaria in the study areas signals the need to launch monitoring activities for CQ resistant P. vivax in malaria endemic areas in order to detect further development of parasite resistance and to estimate the level of burden across the country.

Status of Plasmodium vivax Malaria in the Republic of Korea after Reemergence / 한양의대학술지

The annual number of Plasmodium vivax malaria cases had rapidly increased since its reemergence in the Republic of Korea (ROK) in 1993 to reach more than 4,000 cases in 2000. Since 2001, it began to decrease to 864 cases in 2004, and once again increased to reach more than 2,000 cases by 2007. P. vivax malaria mainly has occurred in the areas adjacent to the Demilitarized Zone, which implies that current malaria occurrence in ROK has been strongly influenced by malaria situation of the Democratic People's Republic of Korea (DPRK). Besides the direct influence from DPRK, local transmission within ROK also likely occurred. Chemoprophylaxis performed in the ROK Army since 1997 has contributed to the reduction in cases among military personnel. However, many prophylactic failure cases due to the resistance to the prophylactic regimen have been reported since 2000 and two cases of chloroquine (CQ)-resistant P. vivax were reported, representing the first-known cases of CQ-resistant P. vivax from a temperate region of Asia. Delayed recrudescence, a kind of level I-resistance against CQ, has occurred frequently in DPRK. Continuous surveillance and monitoring are warranted to prevent further expansion of CQ-resistant P. vivax in ROK and DPRK.

Plasmodium vivax Malaria: Status in the Republic of Korea Following Reemergence

The annual incidence of Plasmodium vivax malaria that reemerged in the Republic of Korea (ROK) in 1993 increased annually, reaching 4,142 cases in 2000, decreased to 864 cases in 2004, and once again increased to reach more than 2,000 cases by 2007. Early after reemergence, more than two-thirds of the total annual cases were reported among military personnel. However, subsequently, the proportion of civilian cases increased consistently, reaching over 60% in 2006. P. vivax malaria has mainly occurred in the areas adjacent to the Demilitarized Zone, which strongly suggests that malaria situation in ROK has been directly influenced by infected mosquitoes originating from the Democratic People's Republic of Korea (DPRK). Besides the direct influence from DPRK, local transmission within ROK was also likely. P. vivax malaria in ROK exhibited a typical unstable pattern with a unimodal peak from June through September. Chemoprophylaxis with hydroxychloroquine (HCQ) and primaquine, which was expanded from approximately 16,000 soldiers in 1997 to 200,000 soldiers in 2005, contributed to the reduction in number of cases among military personnel. However, the efficacy of the mass chemoprophylaxis has been hampered by poor compliance. Since 2000, many prophylactic failure cases due to resistance to the HCQ prophylactic regimen have been reported and 2 cases of chloroquine (CQ)-resistant P. vivax were reported, representing the first-known cases of CQ-resistant P. vivax from a temperate region of Asia. Continuous surveillance and monitoring are warranted to prevent further expansion of CQ-resistant P. vivax in ROK.

Antimaláricos: construcción de híbridos moleculares de la cloroquina: [revisión] / Antimalarials: construction of molecular hybrids based on chloroquine: [review]

La resistencia desarrollada por el Plasmodium falciparum ante los fármacos tradicionales del tipo 4-amino-7-cloroquinolínicos ha llevado al diseño y síntesis de inhibidores duales, como los híbridos de la cloroquina. Además del farmacóforo típico en esta clase de antimaláricos, tales híbridos incorporan un espaciador metilénico como parte de un fragmento diamínico, cuyo propósito es la funcionalización del grupo amino terminal en sistemas heterocíclicos diversos con actividades biológicas reportadas. Esto con el fin de evitar la rápida e liminación de la molécula por parte del parásito, lo que se conoce como resistencia. Se discuten el diseño y síntesis de estos híbridos moleculares.

The resistance developed by Plasmodium falciparum againsttraditional 4-amino-7-chloroquinolinic drugs has lead to the design and synthesis of dual inhibitors such as chloroquine hybrids. Besides the usual pharmacophore in this type of antimalarials, such hybrids incorporate a methylenic spacer as part of a diaminic fragment whose purpose is the functionalization of the terminal amino group in various heterocyclic systems having reported biological activities. The prime goal is to avoid the molecule rapid elimination by the parasite, which is known as resistance. The design and synthesis of these molecular hybrids are discussed.

A resistência desenvolvida pelo Plasmodium falciparum frente aos fármacos tradicionais do tipo 4-amino-7-cloroquinolínicos tem levado ao desenho e síntese de inibidores duais, como os híbridos da cloroquina. Além do farmacóforo típico nesta classe de antimaláricos, tais híbridos incorporam um espaçador metilénico como parte de um fragmento diamínico, que tem por propósito a funcionalização do grupo amino terminal em sistemas heterocíclicos diversos com atividadesbiológicas reportadas. Isto com a finalidade de evitar a rápida eliminação da molécula por parte do parasito, o que se conhece como resistência. É discutido o desenho e sínteses destes híbridos moleculares.

APPLICATION OF SIMPLIFIED DIFFERENTIAL DISPLAY POLYMERASE CHAIN REACTIONTO ISOLATE CHLOROQUINE-RESISTANT RELATED GENES OFPLASMODIUM BERGHEI / 中国人兽共患病学报

To insight into genetic differences between chloroquine-resistant line (RC) and chloroquine-sensitive strain (N) of Plasmodium berghei. MethodsAfter continous cbloroquine-pressure upon RC line at higher dosage (50mg/kg. d) ,total RNAs from the RC line and the N strain of P. berghei were isolated for simplified differential display reverse transcript polymerase chain reaction (sDDRT-PCR ). The generated differential fragments had been repetitively rescued and identified by PCRs before one pair of suspected differential fragments (N25 and R25 )were cloned and sequenced. Then, their sequences were analyzed through PC-gene program and BLAST search. ResultsThough the identity of two nucleotide sequences of N252 and R251 ,cloned separately from the N25 and R25 fragments, were up to 99.8％ ,their predicted amino acid secondary structures were quite different due to multiple mutations. Compared with the published sequences in GeneBank,EMBL,DDBJ and PDB database ,no similar gene was found ,using BLAST search. However their partial nucleotide sequences (62nt from query 128nt to189nt bore highly homology to part sequence(from 1053nt to1114nt)of rattus norvegicus mRNA for phospholipase B,up to 93.5％ in N251 and 91.9％ in N252 respectively. ConclusionIt is feasible to isolate chloroquine-resistant related genes by using simplified DDRT-PCR combined repetitively rescuing and PCR identifying the interest differential DNAs together with sequence analyses.

A study of chloroquine resistance of plasmodium falciparum using the in-vitro sensitivity test and polymerase chain reaction (PCR)

The widespread and increasing resistance of Plasmodium falciparum to antimalarial drugs is one of several factors that contributed to the persistence and even worsening of the malaria problem. Resistance to Chloroquine is of utmost concern, considering that it had been the most reliable antimalarial until the emergence and spread of Chloroquineresistant P. falciparum. Until recently, Chloroquine and Sulfadoxine-Pyrimethamine were the first and second line antimalarials in use in the Philippines. However, this has been changed to a combination of Chloroquine and Sulfadoxine-Pyrimethamine, because of the high percentage of treatment failures in therapeutic efficacy studies done in northern and southern Philippines. The objective of this study is to apply PCR in determining the occurence of Chloroquine resistance in southeastern Mindanao using in-vitro test and polymerase chain reaction (PCR)In the first study, the in-vitro susceptibility of P. falciparum to Chloroquine was tested in 33 isolates using the World Health Organization (WHO) Semi-Microtest Method. These isolates were collected from patients who consulted or were admitted at the regional hospital of Davao del Norte. The results showed that 10 (30.3 percent) were susceptible with IC50 80 nM, 12 (36.4 percent) isolates had decreased sensitivity with 80 nM /- IC50 114 nM, and 11 (33.3 percent) were resistant with IC 114 nM. Ten of these 11 (91 percent) were from Davao del Norte. A closer look at the municipalities of this province showed that the geometric mean (SD) of IC50 of Asuncion was 133 (41) nM and was significantly higher (p=0.025) than nearby Kapalong at 82 (25) nMThe PCR, Apo1 restriction revealed that 30 (90.9 percent) of the isolates manifested the PfCRT (K76T) mutation. These findings are indicative of the presence of Chloroquine resistance among the isolates. Comparison with the results of the invitro test (33.3 percent resistance) showed that the frequency of the PfCRT gene (90.9 percent) was very high. This finding suggests that the mere presence of the PfCRT gene does not mean the expression of Chloroquine resistance. It is possible that other genes such as the Pfmdr and cg2 are also involved in the expression of Chloroquine resistance. The study also shows that PCR and Apo1 restriction may be limited in generating results that can be used to correlate with those of the in-vitro or even in-vivo tests

Research Progress on Chloroquine Resistance in Plasmodium falciparum and Resistance Reversal Agent / 中国寄生虫学与寄生虫病杂志

Emergence and broad spread of chloroquine resistance urge human beings to change drug policy in malaria control and to find more effective new drugs. Nevertheless, chloroquine is still used in the treatment of falciparum malaria in some poor endemic regions due to economic and development reasons. It should be of great significance to un-derstand the mechanism of chloroquine resistance and find the way to reverse it in order to bring chloroquine with high efficacy and low cost back to the first line of the combat to malaria. Advent and development of resistance reversal agents provide a new clue for this purpose. When used together with chloroquine, it can partly restore the efficacy of chloroquine in resistant Plasmodium falciparum. The article summarizes the research progress on chloroquine resistance in P. falciparum and resistance reversers.