English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Background   Plasmodium knowlesi  is now the major cause of human malaria in Malaysia, complicating malaria control efforts that must attend to the elimination of multiple  Plasmodium  species. Recent advances in the cultivation of  P. knowlesi  erythrocytic-stage parasites in vitro, transformation with exogenous DNA, and infection of mosquitoes with gametocytes from culture have opened up studies of this pathogen without the need for resource-intensive and costly non-human primate (NHP) models. For further understanding and development of methods for parasite transformation in malaria research, this study examined the activity of various trans-species transcriptional control sequences and the influence of  Plasmodium vivax  centromeric ( pvcen ) repeats in plasmid-transfected  P. knowlesi  parasites.    Methods  In vitro cultivated  P. knowlesi  parasites were transfected with plasmid constructs that incorporated  Plasmodium vivax  or  Plasmodium falciparum  5′ UTRs driving the expression of bioluminescence markers (firefly luciferase or Nanoluc). Promoter activities were assessed by bioluminescence, and parasites transformed with human resistant allele dihydrofolate reductase-expressing plasmids were selected using antifolates. The stability of transformants carrying  pvcen- stabilized episomes was assessed by bioluminescence over a complete parasite life cycle through a rhesus macaque monkey, mosquitoes, and a second rhesus monkey.    Results  Luciferase expression assessments show that certain  P. vivax  promoter regions, not functional in the more evolutionarily-distant  P. falciparum , can drive transgene expression in  P. knowlesi.  Further,  pvcen  repeats may improve the stability of episomal plasmids in  P. knowlesi  and support detection of NanoLuc-expressing elements over the full parasite life cycle from rhesus macaque monkeys to  Anopheles dirus  mosquitoes and back again to monkeys. In assays of drug responses to chloroquine, G418 and WR9910, anti-malarial half-inhibitory concentration (IC 50 ) values of blood stages measured by NanoLuc activity proved comparable to IC 50  values measured by the standard SYBR Green method.    Conclusion  All three  P. vivax  promoters tested in this study functioned in  P. knowlesi,  whereas two of the three were inactive in  P. falciparum . NanoLuc-expressing, centromere-stabilized plasmids may support high-throughput screenings of  P. knowlesi  for new anti-malarial agents, including compounds that can block the development of mosquito- and/or liver-stage parasites.    Supplementary Information  The online version contains supplementary material available at 10.1186/s12936-021-03773-4.

malaria journal

Activity of Plasmodium vivax promoter elements in Plasmodium knowlesi, and a centromere-containing plasmid that expresses NanoLuc throughout the parasite life cycle