ABSTRACT
@#Circumsporozoite protein (CSP) central repeat region is one of the main target regions of the RTS,S/AS01 vaccine for falciparum infection as it consists of immunodominant B cell epitopes. However, there is a lack of study for P. knowlesi CSP central repeat region. This study aims to characterise the CSP repeat motifs of P. knowlesi isolates in Peninsular Malaysia. CSP repeat motifs of 64 P. knowlesi isolates were identified using Rapid Automatic Detection and Alignment of Repeats (RADAR). Antigenicity of the repeat motifs and linear B cell epitopes were predicted using VaxiJen 2.0, BepiPred-2.0 and BCPred, respectively. A total of 35 dominant repeat motifs were identified. The repeat motif “AGQPQAQGDGANAGQPQAQGDGAN” has the highest repeat frequency (n=15) and antigenicity index of 1.7986. All the repeat regions were predicted as B cell epitopes. In silico approaches revealed that all repeat motifs were antigenic and consisted of B cell epitopes which could be designed as knowlesi malaria vaccine.
ABSTRACT
@#Recent reports of natural human infection by Plasmodium cynomolgi indicate the increased risk of zoonotic transmission by this simian parasite. The P. cynomolgi Duffy binding protein 2 (PcDBP2) has a potential role in the invasion pathway of host erythrocytes, and it is a possible vaccine candidate against cynomolgi malaria. This study investigates the genetic diversity, haplotypes, and natural selection of PcDBP2 region II from isolates collected from wild macaques in Peninsular Malaysia. Blood samples from 50 P. cynomolgi-infected wild macaques were used in the study. Genomic DNA extracted from the blood samples was used as template for PCR amplification of the PcDBP2 region II. The amplicons were cloned into a plasmid vector and sequenced. MEGA X and DnaSP ver.6.12.03 programmes were used to analyse the DNA sequences. A genealogical relationship of PcDBP2 region II were determined using haplotype network tree on NETWORK ver.10.2. Result showed high genetic diversity (ð = 0.017 ± 0.002; Hd = 1.000 ± 0.001) of the PcDBP2 region II. The Z-test indicates a purifying selection, with population expansion as shown in Tajima’s D analysis. A total of 146 haplotypes of PcDBP2 region II were observed. Phylogenetic tree analysis showed that these haplotypes were grouped into three allelic types (136 for Strain B type, 9 for Berok type, and 1 recombinant type). In the haplotype network, PcDBP2 region II revealed no geographical groupings but was divided into two distinct clusters.
ABSTRACT
@# Normocyte binding protein Xa (NBPXa) has been implied to play a significant role in parasite invasion of human erythrocytes. Previous phylogenetic studies have reported the existence of three types of NBPXa for Plasmodium knowlesi (PkNBPXa). PkNBPXa region II (PkNBPXaII) of type 1, type 2 and type 3 were expressed on mammalian cell surface and interacted with human and macaque (Macaca fascicularis) erythrocytes. The binding activities of PkNBPXaII towards human and macaque erythrocytes were evaluated using erythrocyte-binding assay (EBA). Three parameters were evaluated to achieve the optimal protein expression of PkNBPXaII and erythrocyte binding activity in EBA: types of mammalian cells, post transfection time and erythrocyte incubation time. COS-7, HEK-293, and CHO-K1 cells showed successful expression of PkNBPXaII, despite the protein expression is weak compared to the positive control. COS-7 was used in EBA. All three types of PkNBPXaII showed rosette formation with macaque erythrocytes but not with human erythrocytes. Future studies to enhance the PkNBPXaII expression on surface of mammalian cells is indeed needed in order to elucidate the specific role of PkNBPXaII in erythrocytes invasion.
ABSTRACT
Malaria causes high global mortality and morbidity annually. Plasmodium knowlesi has been recognised as the fifth human Plasmodium sp. and its infection is widely distributed in Southeast Asia. Merozoite surface protein-119 (MSP-119) appears as a potential candidate for malaria blood stage vaccine as it could induce protective immunity. In this study, codon optimized P. knowlesi MSP-119 (pkMSP-119) was expressed and purified in yeast Pichia pastoris expression system. The purified recombinant protein was further evaluated using Western blot assay using knowlesi malaria, non-knowlesi human malaria, non-malarial parasitic infections and healthy serum samples (n = 50). The sensitivity of purified pkMSP-119 towards detection of knowlesi infection was as 28.6% (2/7). pkMSP-119 did not react with all nonmalarial parasitic infections and healthy donor sera, yet reacted with some non-knowlesi human malaria sera, therefore lead to a specificity of 86.0% (37/43).
ABSTRACT
Thirty-nine pediatric patients with ages ranging from 7-14 years admitted to a government hospital because of acute febrile illnesses, were assigned to either mefenamic or acetaminophen in a double-blind studyThe antipyretic action of the mefenamic acid and acetaminophen during these acute febrile periods were comparable. Acetaminophen demonstrated an earlier peak of action whereas mefenamic acid showed longer duration of actionThere were no untoward reactions noted in both mefenamic and acetaminophen during the study. It is however recommended that untoward effects which maybe due to these drugs during a prolonged period of administration should be studied. (Conclusion)
ABSTRACT
Foram realizados testes simultâneos intradérmicos e de ELISA em grupos de leitöes recém desmamados infectados experimentalmente com Mycobacterium bovis, M. avium, M. scrofulaceum, M. intracellulare e Rhodococcus equi. Os testes foram realizados em intervalos de 60 dias, em quatro oportunidades após a infecçäo. Nos grupos de suínos infectados houve maior número de reaçöes positivas ao antígeno aviário aos testes de ELISA. As reaçöes de ELISA surgiram somente a partir do segundo teste, enquanto o teste intradérmico revelou sete suínos positivos, do total de 20, já no primeiro teste. Houve aumento gradual do número de suínos positivos a cada teste de ELISA, em todos os grupos. No grupo infectado com M. scrofulaceum predominaram reaçöes positivas ao teste de ELISA. Os suínos infectados com M. bovis apresentaram reaçöes cruzadas no teste de ELISA com os antígenos bovino e aviário. Estes apresentaram maiores reaçöes intradérmicas para a tuberculina bovina, mas também reaçöes à tuberculina aviária, em todos os testes. Acredita-se que tenha sido usada dose infectante muito elevada como explicaçäo para o ocorrido neste grupo. Suínos infectados com Rhodococcus equi apresentaram reaçöes positivas ao antígeno aviário no ELISA, a partir do segundo teste, com reaçöes cruzadas com antígeno bovino, estas em menor número. Suínos infectados com R. equi säo capazes de produzir anticorpos, detectados pelo teste de ELISA com antígeno aviário