In Saudi Arabia, malaria is one of the major health concerns. P. falciparum and P. vivax is prevalent species in Jazan. Appropriate diagnosis and species identification is a very significant factor for convenient treatment of malaria. In general, microscopy is the standard method for diagnosis of malaria. However, polymerase chain reaction (PCR) assays display many possible benefits over microscopy as species identification of malaria especially in an era with few skilled microscopists. This study was conducted to compare microscopy and the multiplex PCR targeting the 18S rRNA gene for detection Plasmodium vivax and Plasmodium falciparum. A total 102 clinical blood specimens from suspicious malaria cases were gathered. Specimens were examined for the presence of Plasmodium falciparum and Plasmodium vivax by microscopy and multiplex PCR as well. The performance of multiplex PCR, OptiMAL test and microscopy was compared. The results revealed that 31.4%, 36.3% and 34.3% were positive by Microscopy, OptiMAL test and Multiplex PCR respectively. Multiplex PCR assay discovered two cases of P. falciparum / P. vivax mixed infections that cannot be detected by microscopic examination and OptiMAL test as mixed infections. Compared with microscopy, the sensitivity, specificity and test accuracy of OptiMAL test for detection of P. falciparum was 100%, 90.5% and 93.14% and multiplex PCR assay was 100%, 97.3% and 98.04% respectively. The sensitivity of OptiMAL test and multiplex PCR assay for detection of P. vivax was 50% and 75% respectively, while specificity of each method was 100%. Test accuracy of OptiMAL test and multiplex PCR assay was 98% and 99% respectively. In conclusions: our data showed that multiplex PCR is a sensitive, specific, and fast instrument so it can provide a beneficial differential diagnostic instrument for detecting P. vivax and P. falciparum.

Background: Radopholus similis (Cobb) Thorne is a migratory endoparasitic nematode infesting several tropical and sub-tropical plant species. Computational screening and conserved domain annotation of assembled EST sequences from the burrowing nematode (R. similis) revealed seven contigs similar to glutathione S-transferases (GSTs) and four contigs for carboxylesterases / cholinesterases (CESs). One of the contigs corresponding to each gene were cloned from R. similis cDNA (KM670018, KP027005) and characterized by phylogeny and structural motif comparison. Glutathione S-transferase is a critical antioxidant and detoxification enzyme and carboxylesterase is responsible for controlling the nerve impulse, detoxification and various developmental functions. Detoxifying ability of these proteins makes them as major targets of pesticides used for plant parasitic nematode (PPN) management. Methodology: In the present work, both molecular biology and bioinformatics approaches have been used to study two potential target genes of R. similis. The study presents 3D-structural models for Rs-GST and Rs-CES proteins using conventional molecular modeling techniques and structural motifs have been characterized with motif elucidation and sequence analysis methods. Subsequently, consense based phylogenetic analysis approach was followed to define the evolutionary relationships for each target proteins. Results: We report for the first time the presence and amplification of two novel target genes (GSTs and CESs) from R. similis. The structural motif characterization of the two genes with corresponding nematode genes indicated the functional diversity of the conserved motifs present in Rs-GST and Rs-CES. The search for protein signature motifs through InterProScan analysis confirmed the presence of thioredoxin-like fold (IPR012336), glutathione S-transferase, N-terminal (IPR004045), glutathione S-transferase, C-terminal (IPR010987) and glutathione S-transferase domain (PF00043) for Rs-GST and carboxylesterase, type B (IPR002018), alpha/beta hydrolase fold (IPR029058) and carboxylesterase domain (PF00135) for Rs-CES. The 3D protein models of each protein were developed through homology modeling and the active-site residues were predicted. Phylogenetic analysis revealed the evolutionary relationships of each target proteins. Conclusions: Identifying and cloning of genes involved in nematode survival and determining their functions are vital to elucidate the parasitism and host invasion processes of PPNs. The comparative structural analysis and motif characterization of studied targets will probably offer a novel approach for controlling plant nematodes.