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Malaria Journal Aug 2014A study searching for Plasmodium vivax and Plasmodium falciparum DNA among blood donors from the non-endemic area in Brazil reported a rate of 7.41%. This number is at...
A study searching for Plasmodium vivax and Plasmodium falciparum DNA among blood donors from the non-endemic area in Brazil reported a rate of 7.41%. This number is at least three times higher than what has been observed in blood donors from the Amazon, an endemic area concentrating >99% of all malaria cases in Brazil. Moreover, the majority of the donors were supposedly infected by P. falciparum, a rare finding both in men and anophelines from the Atlantic forest. These findings shall be taken with caution since they disagree with several publications in the literature and possibly overestimate the actual risk of malaria transmission by blood transfusion in São Paulo city.
Topics: Asymptomatic Infections; Humans; Malaria, Falciparum; Malaria, Vivax; Plasmodium falciparum; Plasmodium vivax; Transfusion Reaction
PubMed: 25168246
DOI: 10.1186/1475-2875-13-336 -
Memorias Do Instituto Oswaldo Cruz 2022Plasmodium vivax, the major cause of malaria in Latin America, has a large subtelomeric multigene family called vir. In the P. vivax genome, about 20% of its sequences...
BACKGROUND
Plasmodium vivax, the major cause of malaria in Latin America, has a large subtelomeric multigene family called vir. In the P. vivax genome, about 20% of its sequences are vir genes. Vir antigens are grouped in subfamilies according to their sequence similarities and have been shown to have distinct roles and subcellular locations. However, little is known about vir subfamilies, especially when comes to their functions.
OBJECTIVE
To evaluate the diversity, antigenicity, and adhesiveness of Plasmodium vivax VIR-E.
METHODS
Vir-E genes were amplified from six P. vivax isolates from Manaus, North of Brazil. The presence of naturally acquired antibodies to recombinant PvBrVIR-E and PvAMA-1 was evaluated by ELISA. Binding capacity of recombinant PvBrVIR-E was assessed by adhesion assay to CHO-ICAM1 cells.
FINDINGS
Despite vir-E sequence diversity, among those identified sequences, a representative one was chosen to be expressed as recombinant protein. The presence of IgM or IgG antibodies to PvBrVIR-E was detected in 23.75% of the study population while the presence of IgG antibodies to PvAMA-1 antigen was 66.25% in the same population. PvBrVIR-E was adhesive to CHO-ICAM1.
MAIN CONCLUSIONS
PvBrVIR-E was antigenic and adhesive to CHO-ICAM1.
Topics: Adhesiveness; Antibodies, Protozoan; Antigens, Protozoan; Brazil; Humans; Malaria, Vivax; Plasmodium vivax; Protozoan Proteins
PubMed: 35137905
DOI: 10.1590/0074-02760210227 -
Frontiers in Cellular and Infection... 2021The unique biological features of not only make it difficult to control but also to eliminate. For the transmission of the malaria parasite from infected human to the...
The unique biological features of not only make it difficult to control but also to eliminate. For the transmission of the malaria parasite from infected human to the vector, gametocytes play a major role. The transmission potential of a malarial infection is inferred based on microscopic detection of gametocytes and molecular screening of genes in the female gametocytes. Microscopy-based detection methods could grossly underestimate the reservoirs of infection as gametocytes may occur as submicroscopic or as micro- or macro-gametocytes. The identification of genes that are highly expressed and polymorphic in male and female gametocytes is critical for monitoring changes not only in their relative proportions but also the composition of gametocyte clones contributing to transmission over time. Recent transcriptomic study revealed two distinct clusters of highly correlated genes expressed in the gametocytes, indicating that the male and female terminal gametocytogeneses are independently regulated. However, the detective power of these genes is unclear. In this study, we compared genetic variations of 15 and 11 genes expressed, respectively, in the female and male gametocytes among isolates from Southeast Asia, Africa, and South America. Further, we constructed phylogenetic trees to determine the resolution power and clustering patterns of gametocyte clones. As expected, 25 (PVP01_0616100) and 16 (PVP01_0305600) expressed in the female gametocytes were highly conserved in all geographical isolates. In contrast, genes including 6-cysteine protein (PVP01_0415800) and upregulated in late gametocytes (PVP01_1452800) expressed in the female gametocytes, as well as two CPW-WPC family proteins (PVP01_1215900 and PVP01_1320100) expressed in the male gametocytes indicated considerably high nucleotide and haplotype diversity among isolates. Parasite samples expressed in male and female gametocyte genes were observed in separate phylogenetic clusters and likely represented distinct gametocyte clones. Compared to 25, (PVP01_0415800) and a CPW-WPC family protein (PVP01_0904300) showed higher expression in a subset of Ethiopian samples. Thus, , , and CPW-WPC family proteins including PVP01_0904300, PVP01_1215900, and PVP01_1320100 could potentially be used as novel biomarkers for detecting both sexes of gametocytes in low-density infections and estimating transmission reservoirs.
Topics: Biomarkers; Humans; Malaria, Vivax; Phylogeny; Plasmodium vivax; Polymorphism, Genetic
PubMed: 35096643
DOI: 10.3389/fcimb.2021.789417 -
Cell Chemical Biology Jun 2020Plasmodium vivax infects hepatocytes to form schizonts that cause blood infection, or dormant hypnozoites that can persist for months in the liver before leading to...
Plasmodium vivax infects hepatocytes to form schizonts that cause blood infection, or dormant hypnozoites that can persist for months in the liver before leading to relapsing blood infections. The molecular processes that drive P. vivax schizont and hypnozoite survival remain largely unknown, but they likely involve a rich network of host-pathogen interactions, including those occurring at the host-parasite interface, the parasitophorous vacuole membrane (PVM). Using a recently developed P. vivax liver-stage model system we demonstrate that host aquaporin-3 (AQP3) localizes to the PVM of schizonts and hypnozoites within 5 days after invasion. This recruitment is also observed in P. vivax-infected reticulocytes. Chemical treatment with the AQP3 inhibitor auphen reduces P. vivax liver hypnozoite and schizont burden, and inhibits P. vivax asexual blood-stage growth. These findings reveal a role for AQP3 in P. vivax liver and blood stages and suggest that the protein may be targeted for therapeutic treatment.
Topics: Aquaporin 3; Cells, Cultured; Humans; Liver; Malaria, Vivax; Plasmodium vivax
PubMed: 32330444
DOI: 10.1016/j.chembiol.2020.03.009 -
Cell Host & Microbe Jul 2022Malaria-causing Plasmodium vivax parasites can linger in the human liver for weeks to years and reactivate to cause recurrent blood-stage infection. Although they are an...
Malaria-causing Plasmodium vivax parasites can linger in the human liver for weeks to years and reactivate to cause recurrent blood-stage infection. Although they are an important target for malaria eradication, little is known about the molecular features of replicative and non-replicative intracellular liver-stage parasites and their host cell dependence. Here, we leverage a bioengineered human microliver platform to culture patient-derived P. vivax parasites for transcriptional profiling. Coupling enrichment strategies with bulk and single-cell analyses, we capture both parasite and host transcripts in individual hepatocytes throughout the course of infection. We define host- and state-dependent transcriptional signatures and identify unappreciated populations of replicative and non-replicative parasites that share features with sexual transmissive forms. We find that infection suppresses the transcription of key hepatocyte function genes and elicits an anti-parasite innate immune response. Our work provides a foundation for understanding host-parasite interactions and reveals insights into the biology of P. vivax dormancy and transmission.
Topics: Hepatocytes; Humans; Liver; Malaria; Malaria, Vivax; Plasmodium vivax
PubMed: 35443155
DOI: 10.1016/j.chom.2022.03.034 -
PLoS Medicine Apr 2021Cindy S Chu and co-authors review options for diagnosis, safe and radical cure, and relapse prevention of Plasmodium Vivax.
Cindy S Chu and co-authors review options for diagnosis, safe and radical cure, and relapse prevention of Plasmodium Vivax.
Topics: Humans; Malaria, Vivax; Plasmodium vivax
PubMed: 33891587
DOI: 10.1371/journal.pmed.1003561 -
Malaria Journal May 2017Relapse infections resulting from the activation hypnozoites produced by Plasmodium vivax and Plasmodium ovale represent an important obstacle to the successful control...
BACKGROUND
Relapse infections resulting from the activation hypnozoites produced by Plasmodium vivax and Plasmodium ovale represent an important obstacle to the successful control of these species. A single licensed drug, primaquine is available to eliminate these liver dormant forms. To date, investigations of vivax relapse infections have been few in number.
RESULTS
Genotyping, based on polymorphic regions of two genes (Pvmsp1F3 and Pvcsp) and four microsatellite markers (MS3.27, MS3.502, MS6 and MS8), of 12 paired admission and relapse samples from P. vivax-infected patients were treated with primaquine, revealed that in eight of the parasite populations in the admission and relapse samples were homologous, and heterologous in the remaining four patients. The patients' CYP2D6 genotypes did not suggest that any were poor metabolisers of primaquine. Parasitaemia tended to be higher in the heterologous as compared to the homologous relapse episodes as was the IgG3 response. For the twelve pro- and anti-inflammatory cytokine levels measured for all samples, only those of IL-6 and IL-10 tended to be higher in patients with heterologous as compared to homologous relapses in both admission and relapse episodes.
CONCLUSIONS
The data from this limited number of patients with confirmed relapse episodes mirror previous observations of a significant proportion of heterologous parasites in relapses of P. vivax infections in Thailand. Failure of the primaquine treatment that the patients received is unlikely to be due to poor drug metabolism, and could indicate the presence of P. vivax populations in Thailand with poor susceptibility to 8-aminoquinolines.
Topics: Adolescent; Adult; Antimalarials; Cohort Studies; Drug Resistance; Follow-Up Studies; Genotype; Humans; Malaria, Vivax; Middle Aged; Plasmodium vivax; Primaquine; Recurrence; Thailand; Young Adult
PubMed: 28558712
DOI: 10.1186/s12936-017-1877-x -
Neurological and psychiatric safety of tafenoquine in Plasmodium vivax relapse prevention: a review.Malaria Journal Mar 2020Tafenoquine is an 8-aminoquinoline anti-malarial drug recently approved as a single-dose (300 mg) therapy for Plasmodium vivax relapse prevention, when co-administered... (Review)
Review
BACKGROUND
Tafenoquine is an 8-aminoquinoline anti-malarial drug recently approved as a single-dose (300 mg) therapy for Plasmodium vivax relapse prevention, when co-administered with 3-days of chloroquine or other blood schizonticide. Tafenoquine 200 mg weekly after a loading dose is also approved as travellers' prophylaxis. The development of tafenoquine has been conducted over many years, using various dosing regimens in diverse populations.
METHODS
This review brings together all the preclinical and clinical data concerning tafenoquine central nervous system safety. Data were assembled from published sources. The risk of neuropsychiatric adverse events (NPAEs) with single-dose tafenoquine (300 mg) in combination with chloroquine to achieve P. vivax relapse prevention is particularly examined.
RESULTS
There was no evidence of neurotoxicity with tafenoquine in preclinical animal models. In clinical studies in P. vivax relapse prevention, nervous system adverse events, mainly headache and dizziness, occurred in 11.4% (36/317) of patients with tafenoquine (300 mg)/chloroquine versus 10.2% (19/187) with placebo/chloroquine; and in 15.5% (75/483) of patients with tafenoquine/chloroquine versus 13.3% (35/264) with primaquine (15 mg/day for 14 days)/chloroquine. Psychiatric adverse events, mainly insomnia, occurred in 3.8% (12/317) of patients with tafenoquine/chloroquine versus 2.7% (5/187) with placebo/chloroquine; and in 2.9% (14/483) of patients with tafenoquine/chloroquine versus 3.4% (9/264) for primaquine/chloroquine. There were no serious or severe NPAEs observed with tafenoquine (300 mg)/chloroquine in these studies.
CONCLUSIONS
The risk:benefit of single-dose tafenoquine/chloroquine in P. vivax relapse prevention is favourable in the presence of malaria, with a low risk of NPAEs, similar to that seen with chloroquine alone or primaquine/chloroquine.
Topics: Aminoquinolines; Antimalarials; Humans; Malaria, Vivax; Nervous System Diseases; Plasmodium vivax; Secondary Prevention
PubMed: 32169086
DOI: 10.1186/s12936-020-03184-x -
PLoS Medicine Apr 2021Lorenz von Seidlein and Nicholas White introduce a Collection on Plasmodium vivax malaria.
Lorenz von Seidlein and Nicholas White introduce a Collection on Plasmodium vivax malaria.
Topics: Humans; Malaria, Vivax; Plasmodium vivax
PubMed: 33891584
DOI: 10.1371/journal.pmed.1003593 -
Transactions of the Royal Society of... Apr 2019Until World War II the only clinical phenotype of Plasmodium vivax generally recognised in medicine was one associated with either a long (8-9 months) incubation period...
Until World War II the only clinical phenotype of Plasmodium vivax generally recognised in medicine was one associated with either a long (8-9 months) incubation period or a similarly long interval between initial illness and the first relapse. Long-latency P. vivax 'strains' were the first in which relapse, drug resistance and pre-erythrocytic development were described. They were the infections in which primaquine radical cure dosing was developed. A long-latency 'strain' was the first to be fully sequenced. Although long-latency P. vivax is still present in some parts of Asia, North Africa and the Americas, in recent years it has been largely forgotten.
Topics: Antimalarials; Asia; Disease Eradication; Humans; Infectious Disease Incubation Period; Malaria, Vivax; Plasmodium vivax
PubMed: 30809676
DOI: 10.1093/trstmh/trz002