Molecular detection of antimalarial resistance in Plasmodium vivax isolates from a tertiary care setting in Puducherry.

PURPOSE: The study was aimed at detecting the mutation patterns in the drug targets in Plasmodium vivax that confer resistance to the common antimalarial agents used in India. METHODS: A total of 27 Plasmodium vivax isolates collected from whole blood samples over a three year period were subjected to PCR amplification followed by sequencing of the genes pvmdr1, pvdhfr, pvdhps and pvk12, which serve as the molecular targets to detect resistance to chloroquine, pyrimethamine, sulfadoxine and artemisinin respectively. RESULTS: The study found T958 M F1076L double mutants of pvmdr1 in 52 %(14/27) isolates, S58R S117 N double mutants of pvdhfr in 67 % (18/27) isolates, A383G A553G double mutant pvdhps in 59 % (16/27) isolates and wild type of pvk12 gene in all the isolates. CONCLUSIONS: There was a rise in the proportion of double mutants of pvmdr1 and pvdhfr over time. Those cases with double mutant pvmdr1 gene in their isolates were found to have a prolonged hospital stay compared to those without, indicating reduced clinical response to chloroquine.

Prevalence of Plasmodium falciparum haplotypes associated with resistance to sulfadoxine-pyrimethamine and amodiaquine before and after upscaling of seasonal malaria chemoprevention in seven African countries: a genomic surveillance study.

BACKGROUND: Seasonal malaria chemoprevention is used in 13 countries in the Sahel region of Africa to prevent malaria in children younger than 5 years. Resistance of Plasmodium falciparum to seasonal malaria chemoprevention drugs across the region is a potential threat to this intervention. METHODS: Between December, 2015, and March, 2016, and between December, 2017, and March, 2018, immediately following the 2015 and 2017 malaria transmission seasons, community surveys were done among children younger than 5 years and individuals aged 10-30 years in districts implementing seasonal malaria chemoprevention with sulfadoxine-pyrimethamine and amodiaquine in Burkina Faso, Chad, Guinea, Mali, Nigeria, Niger and The Gambia. Dried blood samples were collected and tested for P falciparum DNA by PCR. Resistance-associated haplotypes of the P falciparum genes crt, mdr1, dhfr, and dhps were identified by quantitative PCR and sequencing of isolates from the collected samples, and survey-weighted prevalence and prevalence ratio between the first and second surveys were estimated for each variant. FINDINGS: 5130 (17·5%) of 29 274 samples from 2016 and 2176 (7·6%) of 28 546 samples from 2018 were positive for P falciparum on quantitative PCR. Among children younger than 5 years, parasite carriage decreased from 2844 of 14 345 samples (19·8% [95% CI 19·2-20·5]) in 2016 to 801 of 14 019 samples (5·7% [5·3-6·1]) in 2018 (prevalence ratio 0·27 [95% CI 0·24-0·31], p<0·0001). Genotyping found no consistent evidence of increasing prevalence of amodiaquine resistance-associated variants of crt and mdr1 between 2016 and 2018. The dhfr haplotype IRN (consisting of 51Ile-59Arg-108Asn) was common at both survey timepoints, but the dhps haplotype ISGEAA (431Ile-436Ser-437Gly-540Glu-581Ala-613Ala), crucial for resistance to sulfadoxine-pyrimethamine, was always rare. Parasites carrying amodiaquine resistance-associated variants of both crt and mdr1 together with dhfr IRN and dhps ISGEAA occurred in 0·05% of isolates. The emerging dhps haplotype VAGKGS (431Val-436Ala-437Gly-540Lys-581Gly-613Ser) was present in four countries. INTERPRETATION: In seven African countries, evidence of a significant reduction in parasite carriage among children receiving seasonal malaria chemoprevention was found 2 years after intervention scale-up. Combined resistance-associated haplotypes remained rare, and seasonal malaria chemoprevention with sulfadoxine-pyrimethamine and amodiaquine is expected to retain effectiveness. The threat of future erosion of effectiveness due to dhps variant haplotypes requires further monitoring. FUNDING: Unitaid.

Functional inclusion bodies produced in bacteria as naturally occurring nanopills for advanced cell therapies.

Inclusion bodies (50-500 nm in diameter) produced in recombinant bacteria can be engineered to contain functional proteins with therapeutic potential. Upon exposure, these protein particles are efficiently internalized by mammalian cells and promote recovery from diverse stresses. Being fully biocompatible, inclusion bodies are a novel platform, as tailored nanopills, for sustained drug release in advanced cell therapies.

Comparación de técnicas in vitro para detectar resistencia de Plasmodium falciparum a medicamentos / Comparison of in vitro techniques for the detection of Plasmodium falciparum resistance to drugs

Debido a que la resistencia de Plasmodium falciparum a medicamentos se percibe como uno de los problemasque más agrava la situación de la malaria en Colombia, existe la necesidad de implementar procedimientos que permitan hacer una búsqueda amplia y confiable de resistencia para establecer la prevalencia y la variación del fenómeno al nivel epidemiológico. En este trabajo se estableció la resistencia de varias cepas de referencia y algunos aislamientos de campo de P. falciparum a medicamentos como cloriquina, amodiaquina, mefloquina, quinina, halofantrina, pirimetamina y sulfadoxina. La búsqueda de resistencia se hizo a través de cuatro estrategias experimentales: una prueba modificada en nuestro laboratorio, eficaz para detectar resistencia a varios medicamentos de manera simultánea (prueba radiométrica); ensayos de PCR para detectar el polimorfismo de la región 3' del gen pfmdr1 (gen de resistencia múltiple a medicamentos de P. falciparum) asociado con resistencia a cloroquina; ensayos de PCR para detectar mutaciones en la dihidrofolato reductasa (DHFR) y en la dihidropteroato sintetasa (DHPS), relacionadas con resistencia a pirimetamina y sulfadoxina respectivamente, y una técnica modificada por nosotros para establecer resistencia a cloroquina (Rapid-test). Se estableció que el ensayo más adecuado para hacer una búsqueda de resistencia in vitro a medicamentos es el PCR. infortunadamente, aun se desconocen las bases moleculares de la resistencia a varios de los antimaláricos empleados y esto hace que la prueba radiométrica sea la mejor alternativa para detectar, a escala espidemiológica, la resistencia in vitro a cloroquina, amodiaquina, mefloquina, quinina y halofantrina

Brodimoprim, a new bacterial dihydrofolate reductase inhibitor: a minireview.

This brief review article synthesizes the principal literature regarding the clinical status of co-trimoxazole compared to monotherapy with one of the two diaminopyrimidines available commercially: trimethoprim or brodimoprim. Both these inhibitors of bacterial dihydrofolate reductase compare favorably to co-trimoxazole as antimicrobial chemotherapy. Brodimoprim is characterized by its advantageous pharmacokinetics in comparison to both co-trimoxazole and trimethoprim.

Aspects of the reversal of methotrexate toxicity in rodents.

An ip injection of a Lactobacillus casei dihydrofolate reductase preparation into rats and mice given a single lethal dose of methotrexate (MTX) caused a marked lowering of free MTX in the blood. Alternatives to citrovorum factor as agents for reversing MTX toxicity were explored in mice. dl, L-5-Methyltetrahydrofolate, dl,L-5,10-methylenetetrahydrofolate, l,L-5,10-methylenetetrahydrofolate, and dihydrofolate were also effective MTX antagonists; d,L-5,10-methylenetetrahydrofolate was inert.

The chemotherapy of rodent malaria, XXIII Causal prophylaxis, part II: Practical experience with Plasmodium yoelii nigeriensis in drug screening.

Data are presented on the causal prophylactic action of about 100 compounds of various types against Plasmodium yoelii nigeriensis N67 in mice. Examples are given to show how action against pre-erythrocytic schizonts may be differentiated from action on emerging erythrocytic stages. In a series of 35 8-aminoquinolines, all but 10 showed definite causal prophylactic activity at tolerated doses. The data permit the compounds to be ranked in order of activity, and many are shown to be more active in this test system than primaquine. Marked causal prophylactic activity is displayed by a variety of quinone structures, several of which show a significant residual action on blood stages. A high level of activity is found in dihydrofolate reductase inhibitors within several chemical classes. Rorguanil is more effective as a causal prophylactic than a blood schizontocide in the mouse as in man. Sulphonamides and sulphones are also effective in this system. The active levels are influenced by the content of PABA in the diet of the hosts. Causal prophylactic action has been detected in a number of experimental compounds including some antibiotics (such as tetracycline and clindamycin). The pyrocatechol RC 12 shows only slight activity at the maximum tolerated dose. Chloroquine, mepacrine, quinine, quinolinemethanols and phenanthrenemethanols are inactive as causal prophylactics. It is concluded that a rodent malaria-mouse model does provide a relatively simple model for the screening of drugs for causal prophylaxis, and the data so obtained are of relevance to the detection of causal prophylactics against human malaria.