ABSTRACT
Two variants of the circumsporozoite (CS) protein of Plasmodium vivax (VK210 and VK247) have been identified. Recently, a putative third CS variant of P. vivax, referred to as causing P. vivax-like malaria, has been reported from Papua New Guinea. The objective of this study was to confirm and extend findings on the global distribution of the P. vivax-like parasite. Blood samples were obtained from 126 untreated patients with P. vivax infection acquired in Central America, South America, Africa, Southeast Asia, and the Indian subcontinent. The P. vivax CS gene was amplified by polymerase chain reaction and hybridized with probes specific for the VK210, VK247, and P. vivax-like CS variants. All samples were positive for VK210, VK247, or both. No sample was positive for P. vivax-like DNA. Therefore, the existence of a third variant of P. vivax cannot be confirmed in the geographic areas studied.
Subject(s)
DNA, Protozoan/blood , Malaria, Vivax/parasitology , Plasmodium vivax/isolation & purification , Africa/epidemiology , Animals , Asia/epidemiology , Base Sequence , Blotting, Southern , Central America/epidemiology , DNA Probes , Genes, Protozoan , Humans , Malaria, Vivax/epidemiology , Molecular Sequence Data , Plasmodium vivax/genetics , Protozoan Proteins/genetics , Sensitivity and Specificity , South America/epidemiology , Species SpecificityABSTRACT
Detection and typing of Plasmodium vivax by the polymerase chain reaction (PCR) was evaluated in a prospective blinded comparative field study in Thailand. PCR amplification of the circumsporozoite (CS) gene was compared with microscopy for the detection of P. vivax in blood samples from 174 Thai Rangers and 50 malaria-free Bangkok residents. For PCR analysis, filter paper specimens collected by finger prick were randomly processed and blindly interpreted for the presence of the CS gene of P. vivax. The VK210 and VK247 CS variants of P. vivax were detected by specific fluorescein or radiolabeled oligoprobes. Autoradiography with 32P-labeled probes and enhanced chemoluminescent detection with fluorescein-labeled probes identified 91% and 96%, respectively, of 119 microscopically confirmed infections; both systems detected < 100 parasites/microL. Compared with microscopy, the specificity of PCR and radiometric or enhanced chemoluminescent detection was 96% and 90%, respectively. The ease of collection and transport of filter-paper specimens combined with the sensitive and specific detection of allelic genes of P. vivax by PCR suggests that this method may prove to be a valuable tool for epidemiologic and heterogeneity studies of P. vivax.
Subject(s)
Malaria, Vivax/diagnosis , Polymerase Chain Reaction/methods , Animals , Azure Stains , Base Sequence , Fluorescein , Fluoresceins , Humans , Luminescent Measurements , Malaria, Vivax/epidemiology , Malaria, Vivax/genetics , Molecular Sequence Data , Oligonucleotide Probes , Phosphorus Radioisotopes , Plasmodium vivax/cytology , Prospective Studies , Single-Blind Method , Thailand/epidemiologyABSTRACT
The degradation of a new semisynthetic polyene antibiotic partricin A dimethylamino ethylamide diaspartate (SPA-S-717) at 37 degrees C in water at different pH is studied. It is found to be sensitive to acidic pH and much less sensitive near neutrality. Then a linear relation between pH and logarithm of reaction rate constant is detected. This fact therefore can give some directions as regards the drug somministration in view of pharmacological and clinical trials.
