Characterization of drug resistance genes in Indian Plasmodium falciparum and Plasmodium vivax field isolates.

One of the major challenges for malaria control and elimination is the spread and emergence of antimalarial drug resistance. Mutations in Plasmodium falciparum (Pf) and Plasmodium vivax (Pv) field isolates for five drug resistance genes viz. crt, mdr1, dhps, dhfr and kelch known to confer resistance to choloroquine (CQ), sulfadoxine-pyrimethamine (SP) and artemisinin (ART) and its derivatives were analyzed. A total of 342 symptomatic isolates of P. falciparum (Pf) and P. vivax (Pv) from 1993 to 2014 were retrieved from malaria parasite repository at National Institute of Malaria Research (NIMR). Sample DNA was extracted from dried blood spots and various targeted single nucleotide polymorphisms (SNPs) associated with antimalarial drug resistance were analysed for these isolates. 72S (67.7%) and 76T (83.8%) mutations along with SVMNT haplotype (67.7%) predominated the study population for Pfcrt. The most prevalent SNPs were 108N (73.2%) and 437G (24.8%) and the most prevalent haplotypes were ACNRNI (51.9%) and SAKAA (74.5%) in Pfdhfr and Pfdhps respectively. Only two mutations in Pfmdr1, 86Y (26.31%) and 184F (56.26%), were seen frequently in our study population. No mutations associated with Pfk13 were observed. For Pv, all the studied isolates showed two Pvdhps mutations, 383G and 553G, and two Pfdhfr mutations, 58R and 117N. Similarly, three mutations, viz. 958M, 908L and 1076L were found in Pvmdr1. No variations were observed in Pvcrt-o and Pvk12 genes. Overall, our study demonstrates an increase in mutations associated with SP resistance in both Pf and Pv, however, no single nucleotide polymorphisms (SNPs) associated with ART resistance have been observed for either species. Various SNPs associated with CQ resistance were seen in Pf; whereas only Pvmdr1 associated resistant SNPs were observed in Pv. Therefore, molecular characterization of drug resistance genes is essential for timely monitoring and prevention of malaria by identifying the circulating drug resistant parasites in the country.

Genetic diversity and natural selection of apical membrane antigen-1 (ama-1) in Cameroonian Plasmodium falciparum isolates.

Antigenic variation associated with genetic diversity in global Plasmodium falciparum apical membrane antigen-1 (PfAMA-1) is a major impediment to designing an effective malaria vaccine. Here, we report the first study on genetic diversity and natural selection of the Pfama-1 gene in P. falciparum isolates from Cameroon. A total of 328 P. falciparum positive samples collected during 2016 and 2019 from five localities of Cameroon were analysed. The ectodomain coding fragment of Pfama-1 gene was amplified for polymorphism profiling and natural selection analysis. A total of 108 distinct haplotypes were found in 203 P. falciparum isolates with considerable nucleotide diversity (π = 0.016) and haplotype diversity (Hd = 0.976). Most amino acid substitutions detected were scattered in ectodomain-I and few specific mutations viz P145L, K148Q, K462I, L463F, N471K, S482L, E537G, K546R and I547F were seen only in Cameroonian isolates. A tendency of natural selection towards positive diversifying selection was observed (Taj-D = 2.058). Five positively selected codon sites (P145L, S283L, Q308E/K, P330S and I547F) were identified, which overlapped with predicted B-cell epitopes and red blood cell (RBC) binding sites, suggesting their potential implication in host immune pressure and parasite-RBC binding complex modulation. The Cameroonian P. falciparum populations indicated a moderate level of genetic differentiation when compared with global sequences, with few exceptions from Vietnam and Venezuela. Our findings provide baseline data on existing Pfama-1 gene polymorphisms in Cameroonian field isolates, which will be useful information for malaria vaccine design.

MSN, MWCNT and ZnO nanoparticle-induced CHO-K1 cell polarisation is linked to cytoskeleton ablation.

BACKGROUND: The cellular response to nanoparticles (NPs) for the mechanical clue and biochemical changes are unexplored. Here, we provide the comprehensive analysis of the Chinese Hamster Ovary (CHO-K1) cell line to study cell behaviour following the exposure of mesoporous silica nanoparticle (MSN), multiwall carbon nanotubes (MWCNTs), and zinc oxide (ZnO) NPs. RESULTS: Through the high-throughput proteomic study, we observed that the effect of NPs is alone not restricted to cell viability but also on cell polarisation. In the case of MSN, no drastic changes were observed in cellular morphology, but it upregulated chaperons that might prevent protein aggregation. However, MWCNT showed elongated cell appearance with numerous cytoplasmic vacuoles, and induce lamellipodia formation through actin polymerisation. The cytoskeleton remodelling was accompanied by the increased expression of Dlc-1, cofilin and Rac1 proteins. While ZnO NPs resulted in the rounded cell morphology along with nuclear abnormalities. The proteome analysis revealed that UBXN11 control cell roundness and DOCK3 leads to actin stress fibre formation and finally, loss of cell adhesion. It enhances the expression of catastrophic DNA damage and apoptotic proteins, which was unrecoverable even after 72 h, as confirmed by the colony formation assay. All three NPs trigger over-expression of the endocytic pathway, ubiquitination, and proteasomal complex proteins. The data indicate that ZnO and MSN entered into the cells through clathrin-mediated pathways; whereas, MWCNT invades through ER-mediated phagocytosis. CONCLUSIONS: Based on the incubation and concentration of NPs, our work provides evidence for the activation of Rac-Rho signalling pathway to alter cytoskeleton dynamics. Our results assist as a sensitive early molecular readout for nanosafety assessment.