Background Reversible protein phosphorylation is relatively unexplored in the intracellular protozoa of the Apicomplexa family that includes the genus Plasmodium, to which belong the causative agents of malaria. Members of the PP1 family represent the most highly conserved protein phosphatase sequences in phylogeny and play essential regulatory roles in various cellular pathways. Previous evidence suggested a PP1-like activity in Plasmodium falciparum, not yet identified at the molecular level. Results We have identified a PP1 catalytic subunit from P. falciparum and named it PfPP1. The predicted primary structure of the 304-amino acid long protein was highly similar to PP1 sequences of other species, and showed conservation of all the signature motifs. The purified recombinant protein exhibited potent phosphatase activity in vitro. Its sensitivity to specific phosphatase inhibitors was characteristic of the PP1 class. The authenticity of the PfPP1 cDNA was further confirmed by mutational analysis of strategic amino acid residues important in catalysis. The protein was expressed in all erythrocytic stages of the parasite. Abrogation of PP1 expression by synthetic short interfering RNA (siRNA) led to inhibition of parasite DNA synthesis. Conclusions The high sequence similarity of PfPP1 with other PP1 members suggests conservation of function. Phenotypic gene knockdown studies using siRNA confirmed its essential role in the parasite. Detailed studies of PfPP1 and its regulation may unravel the role of reversible protein phosphorylation in the signalling pathways of the parasite, including glucose metabolism and parasitic cell division. The use of siRNA could be an important tool in the functional analysis of Apicomplexan genes.

Background Mosquitoes that have been genetically modified to better encapsulate the malaria parasite Plasmodium falciparum are being considered as a possible tool in the control of malaria. Hopes for this have been raised with the identification of genes involved in the encapsulation response and with advances in the tools required to transform mosquitoes. However, we have only very little understanding of the conditions that would allow such genes to spread in natural populations. Methods We present here a theoretical model that combines population genetical and epidemiological processes, thereby allowing one to predict not only these conditions (intensity of transmission, evolutionary cost of resistance, tools used to drive the genes) but also the impact of the spread of refractoriness on the prevalence of the disease. Results The main conclusions are 1) that efficient transposons will generally be able to drive genes that confer refractoriness through populations even if there is a substantial (evolutionary) cost of refractoriness, but 2) that this will decrease malaria prevalence in the human population substantially only if refractoriness is close to 100% effective. Conclusions If refractoriness is less than 100% effective (because of, for example, environmentally induced variation in the effectiveness of the mosquito's immune response), control programmes based on genetic manipulation of mosquitoes will have very little impact on the epidemiology of malaria, at least in areas with intense transmission.

Background The malarial parasite, Plasmodium falciparum (Pf), is responsible for nearly 2 million deaths worldwide. However, the mechanisms of cellular signaling in the parasite remain largely unknown. Recent discovery of a few protein kinases and phosphatases point to a thriving reversible phosphorylation system in the parasite, although their function and regulation need to be determined. Results We provide biochemical and sequence evidence for a protein serine/threonine phosphatase type PP5 in Plasmodium falciparum, and named it PfPP5. The 594-amino acid polypeptide was encoded by a 1785 nucleotide long intronless gene in the parasite. The recombinant protein, expressed in bacteria, was indistinguishable from native PfPP5. Sequencing comparison indicated that the extra-long N-terminus of PfPP5 outside the catalytic core contained four tetratricopeptide repeats (TPRs), compared to three such repeats in other PP5 phosphatases. The PfPP5 N-terminus was required for stimulation of the phosphatase activity by polyunsaturated fatty acids. Co-immunoprecipitation demonstrated an interaction between native PfPP5 and Pf heat shock protein 90 (hsp90). PfPP5 was expressed in all the asexual erythrocytic stages of the parasite, and was moderately sensitive to okadaic acid. Conclusions This is the first example of a TPR-domain protein in the Apicomplexa family of parasites. Since TPR domains play important roles in protein-protein interaction, especially relevant to the regulation of PP5 phosphatases, PfPP5 is destined to have a definitive role in parasitic growth and signaling pathways. This is exemplified by the interaction between PfPP5 and the cognate chaperone hsp90.

Background Plasmodium falciparum erythrocyte membrane protein-1, a variant antigen of the malaria parasite, is potentially a target for the immune response. It would be important to determine whether there are CD4 T cells that recognise conserved regions. However, within the relatively conserved region, there is variation. It is not possible to test T cell responses from small field samples with all possible peptides. Methods We have aligned sequences that are relatively conserved between several PfEMP1 molecules, and chosen a representative sequence similar to most of the PfEMP1 variants. Using these peptides as pools representing CIDRα, CIDRβ and DBLβ-δ domains, DBLα domain, and EXON 2 domain of PfEMP1, we measured the CD4 T cell responses of malaria-exposed donors from Benin, West Africa by a FACS based assay. Results All the three peptide pools elicited a CD4 T cell response in a proportion of malaria-exposed and non-exposed donors. CD4 T cell proliferation occurs at a relatively higher magnitude to peptide pools from the DBLα and EXON 2 in the malaria-exposed donors living in Benin than in the UK malaria-unexposed donors. Conclusions These findings suggest that an immunological recall response to conserved peptides of a variant antigen can be measured. Further testing of individual peptides in a positive pool will allow us to determine those conserved sequences recognised by many individuals. These types of assays may provide information on conserved peptides of PfEMP1 which could be useful for stimulating T cells to provide help to P. falciparum specific B cells.

This dataset includes deidentified data on patients receiving artesunate through the National Artesunate for Severe Malaria Program from April- December 2019. This dataset contains the data from the case report form only. Please see the links below for the other datasets and the attached document 'Guide to NASMP Datasets': Data from Case Report Form- https://data.cdc.gov/Global-Health/National-Artesunate-for-Severe-Malaria-Program-Cas/igaz-icki Data on Artesunate Dosing- https://data.cdc.gov/dataset/National-Artesunate-for-Severe-Malaria-Program-Art/qan4-gt4k Data on Microscopy (Parasitemia values)- https://data.cdc.gov/Global-Health/National-Artesunate-for-Severe-Malaria-Program-Mic/v2k9-ctv4 All data can be easily linked using the ParticipantID field, a unique ID number assigned to each participant.

We report the first in vitro and genetic confirmation of Malarone® (GlaxoSmithKline; atovaquone and proguanil hydrochloride) resistance in Plasmodium falciparum acquired in Africa. On presenting with malaria two weeks after returning from a 4-week visit to Lagos, Nigeria without prophylaxis, a male patient was given a standard 3-day treatment course of Malarone®. Twenty-eight days later the parasitaemia recrudesced. Parasites were cultured from the blood and the isolate (NGATV01) was shown to be resistant to atovaquone and the antifolate pyrimethamine. The cytochrome b gene of isolate NGATV01 showed a single mutation, Tyr268Asn which has not been seen previously.

This dataset includes deidentified data on patients receiving artesunate through the National Artesunate for Severe Malaria Program from April- December 2019. This dataset contains microscopy data only. Please see the links below for the other datasets and the attached document 'Guide to NASMP Datasets: Data from Case Report Form- https://data.cdc.gov/Global-Health/National-Artesunate-for-Severe-Malaria-Program-Cas/igaz-icki Data on Artesunate Dosing- https://data.cdc.gov/dataset/National-Artesunate-for-Severe-Malaria-Program-Art/qan4-gt4k Data on Follow-On Dosing- https://data.cdc.gov/Global-Health/National-Artesunate-for-Severe-Malaria-Program-Fol/g3k9-gyw7 All data can be easily linked using the ParticipantID field, a unique ID number assigned to each participant.

This data release includes metadata and tabular data from a field study of avian diseases (malaria and pox virus) that threatened recovery of the last extant population of ‘Alalā (Corvus hawaiiensis) before it went extinct in the wild in the early part of the 21st century. The study focused on habitat occupied by the last remaining wild ‘Alalā and determined prevalence of avian malaria (Plasmodium relictum) in native and non-native forest bird reservoir hosts (Atkinson et al. 2005), oviposition trap captures of Culex quinquefasciatus (the primary vector of avian malaria and pox virus) and Aedes albopictus across an altitudinal gradient, prevalence of malaria within the vector population, wing lengths of Culex quinquefasciatus and Aedes albopictus at different elevations, primary larval habitats and abundance of those habitats across an altitudinal gradient, environmental factors (temperature, humidity and rainfall) that might affect vector distribution and longevity, details about reduction in larval habitat after management actions to drain feral pig damaged tree ferns (Cibotium spp), and pre- and post-treatment oviposition trap catches before and after habitat management.

This data release includes metadata and tabular data from a field study of avian diseases (malaria and pox virus) that threatened recovery of the last extant population of ‘Alalā (Corvus hawaiiensis) before it went extinct in the wild in the early part of the 21st century. The study focused on habitat occupied by the last remaining wild ‘Alalā and determined prevalence of avian malaria (Plasmodium relictum) in native and non-native forest bird reservoir hosts (Atkinson et al. 2005), oviposition trap captures of Culex quinquefasciatus (the primary vector of avian malaria and pox virus) and Aedes albopictus across an altitudinal gradient, prevalence of malaria within the vector population, wing lengths of Culex quinquefasciatus and Aedes albopictus at different elevations, primary larval habitats and abundance of those habitats across an altitudinal gradient, environmental factors (temperature, humidity and rainfall) that might affect vector distribution and longevity, details about reduction in larval habitat after management actions to drain feral pig damaged tree ferns (Cibotium spp), and pre- and post-treatment oviposition trap catches before and after habitat management.

Background Plasmodium falciparum malaria, is a major health problem in forested tribal belt of central India. Rapid and accurate methods are needed for the diagnosis of P. falciparum. We performed a blinded evaluation of the recently introduced Determine™ malaria pf test (Abbott, Laboratories, Japan) compared with microscopy and splenomegaly in children in epidemic prone areas of district Mandla to assess the impact of intervention measures. Methods Children aged 2–10 yrs with and without fever were examined for spleen enlargement by medical specialist by establishing a mobile field clinic. From these children thick blood smears were prepared from finger prick and read by a technician. Simultaneously, rapid tests were performed by a field lab attendant. The figures for specificity, sensitivity and predictive values were calculated using microscopy as gold standard. Results In all 349 children were examined. The sensitivity and specificity for Determine rapid diagnostic test were 91 and 80% respectively. The positive predictive values (PPV), negative predictive values (NPV) and accuracy of the test were respectively 79, 91 and 85%. On the contrary, the sensitivity and specificity of spleen in detecting malaria infection were 57 and 74 % respectively with PPV of 73%, NPV 59 % and an accuracy of 65%. Conclusions Determine™ malaria rapid diagnostic test is easier and quicker to perform and has other advantages over microscopy in not requiring prior training of personnel or quality control. Thus, highlighting the usefulness of a rapid antigen test in assessing prevailing malaria situation in remote areas.