RESUMO
Introduction of rapid malaria diagnostic tests (RDT) initiated numerous field evaluations in various epidemiologic settings. But the efficiency of some RTD kits based on aldolase raised reservations for direct implementation of RDT into clinical settings. We performed Binax Now malaria test in 84 Korean Plasmodium vivax isolates and compared it with the traditional Giemsa stain microscopy test as the reference standard. The sensitivity of Binax Now was 62.0% for P. vivax cases (52/84, 95% CI 51.2-71.6%) with 100.0% specificity (50/50, 95% confidence interval 92.9-100%). After the aldolase gene sequence analysis of 84 isolates, two synonymous mutations in aldolase gene were identified in both Binax Now positive and negative samples. No significant association between the mutations and Binax Now malaria tests was found. Thus, the genetic variability would not explain the poor performance of P. vivax RDTs by detecting aldolase in ROK isolates.
Assuntos
Frutose-Bifosfato Aldolase/genética , Malária Vivax/diagnóstico , Plasmodium vivax/enzimologia , Adolescente , Adulto , Animais , Variação Genética , Humanos , Pessoa de Meia-Idade , Plasmodium vivax/genética , Polimorfismo de Nucleotídeo Único , Kit de Reagentes para Diagnóstico , Sensibilidade e Especificidade , Adulto JovemRESUMO
The Ookinete surface proteins of Plasmodium vivax (P. vivax), Pvs25 and Pvs28, were candidates for the transmission blocking vaccine (TBV), which exhibited great antigenic diversities among various isolates. Polymorphisms of these genes in the isolates from Republic of Korea (ROK) were analysed, which provided valuable baseline data for the field trials of TBV-based vaccines. A total of 98 isolates were collected over 11 years from 1996 to 2007. pvs25 and pvs28 genes from the above isolates were amplified, sequenced and compared against Sal-1 strain. Sequencing analysis of PCR products from P. vivax pvs25 revealed two allelic types, Q97T130 and E97/T130 alleles with the frequencies of 54.5% and 45.5%, respectively, in comparison with Sal I type sequence (E97/I130). From pvs28 gene, polymorphisms at M52L and T140S in the first and third EGF-like domains in comparison to Sal-1 strain were detected, respectively. Six GSGGE tandem repeats followed by GSGGDT or SSGGDT were identified at the end of the fourth EGF-like domain in all Korean isolates. Interestingly, different tandem repeats of amino acid substitutions were observed from isolates collected after 2006 in comparison with preceding years. The ROK isolates revealed limited sequence polymorphisms in pvs25 and tandem repeats in pvs28 in comparison with reported isolates from other nations. Current observations suggested the rapid progresses of genetic changes among Korean isolates.
Assuntos
Antígenos de Protozoários/genética , Antígenos de Superfície/genética , DNA de Protozoário/genética , Vacinas Antimaláricas/genética , Proteínas de Membrana/genética , Plasmodium vivax/genética , Polimorfismo Genético , Sequência de Aminoácidos , Antígenos de Superfície/imunologia , Primers do DNA , DNA de Protozoário/imunologia , Humanos , Proteínas de Membrana/imunologia , Dados de Sequência Molecular , Plasmodium vivax/isolamento & purificação , Reação em Cadeia da Polimerase , República da CoreiaRESUMO
Nucleotide sequence analysis of the Plasmodium vivax PvMSP-3alpha gene was conducted on blood from 143 malaria patients admitted to Korea University Medical Center from 1996 to 2007 in the Republic of Korea (ROK). From 1996 to 2002, the PvMSP-3alpha alleles were of two types, SKOR-67 (2.53 kb) and SKOR-69 (1.78 kb), which differed in length and amino acid sequence. Two new variants with similar size to SKOR-67 were first observed in 2002 and in 2006-2007 accounted for nearly 50% (25/51) of the sampled isolates. The new variants had the same amino acid sequence as SKOR-69 in the N-terminal region, but in Blocks I and II and in the C-terminal region, they were similar to previously reported isolates from Thailand, Papua New Guinea, India, Brazil, and Ecuador strains.