Due to the possible emergence of resistance and safety concerns on certain treatments, development of new drugs against parasites is essential for the effective control and subsequent eradication of parasitic infections. Several drug targets have been identified which are either genes or proteins essential for the parasite survival and distinct from the hosts. These include the phosphagen kinases (PKs) which are enzymes that play a key role in maintenance of homeostasis in cells exhibiting high or variable rates of energy turnover by catalizing the reversible transfer of a phosphate between ATP and naturally occurring guanidine compounds. PKs have been identified in a number of important human and animal parasites and were also shown to be significant in survival and adaptation to stress conditions. The potential of parasite PKs as novel chemotherapeutic targets remains to be explored.
Animals ; Antiparasitic Agents/*pharmacology ; Humans ; Parasites/*enzymology ; Phosphotransferases/*antagonists & inhibitors

The beta-glucans derived from yeast cell walls have been reported for having many immunomodulatory activities in vivo and in vitro. In this study, Aureobasidium-derived soluble branched (1,3-1,6) beta-glucan (Sophy beta-glucan) was checked for natural killer (NK) activity and for the production of IFN-gamma and IL-4 in Leishmania amazonensis infection. The main experiment was performed with a group of female C57BL/6 and BALB/c mice, orally supplemented with 5% of Sophy beta-glucan and infected with promastogotes of L. amazonensis (1 x 10(7)) into the footpad. Increase in the footpad thickness with time was observed in BALB/c mice in spite of the oral Sophy beta-glucan supplement, but it was less in C57BL/6 mice. The difference in overall mean footpad thickness between 'infection only' versus 'infection + glucan' groups was statistically significant (P < 0.001). High NK activity in C57BL/6 than BALB/c mice was observed in 'glucan only' group compared to the control group and also in 'infection + glucan' group compared to 'infection only' group. The difference in the NK activity among these groups was significant (P < 0.05). The IFN-gamma level increased at weeks 7 and 8 post-infection in C57BL/6 mice and was significantly high in 'infection + glucan' group compared to the 'infection only' group (P < 0.05). IL-4 levels did not increase up to detectable levels throughout the study. The results led a conclusion that Sophy beta-glucan enhances NK activity and cellular immunity in L. amazonensis-infected mice.
Administration, Oral ; Animals ; Ascomycota/*chemistry ; Cytotoxicity Tests, Immunologic ; Female ; Foot/pathology ; Glucans/administration & dosage/*isolation & purification/pharmacology/*therapeutic use ; Immunologic Factors/administration & dosage/*isolation & purification/pharmacology/*therapeutic use ; Interferon-gamma/biosynthesis ; Interleukin-4/biosynthesis ; Killer Cells, Natural/drug effects/*immunology ; Leishmania mexicana/*immunology ; Leishmaniasis, Cutaneous/*drug therapy/immunology/pathology ; Mice ; Mice, Inbred BALB C ; Mice, Inbred C57BL ; Severity of Illness Index ; Time Factors

Cutaneous leishmaniasis (CL) is an emerging disease in Sri Lanka, more than 400 cases having been reported since 2001. However, the morphology and taxonomic status of the Sri Lankan strain of Leishmania is not known yet. Therefore, it is important to study the morphology and to analyze the phylogenetic position to predict the risk and expansion of the disease and thereby to develop an effective control programme. Morphology of the amastigote of the Sri Lankan isolate was checked by light microscopy and electron microscopic observation. Presence of amastigotes within macrophages was confirmed in skin biopsy samples. The promastigote had the characteristic appearance of a kinetoplastid cell in cultures. The kinetoplast minicircle DNA has been used for diagnosis of Leishmania for a long time and also for phylogenetic studies on trypanosomatid flagellates. The kinetoplast minicircle was amplified using PCR and subsequently sequenced from samples obtained from Sri Lankan patients with cutaneous lesions. Mitochondrial cytochrome b gene has been recently shown to be useful for identification and phylogenetic analysis of the genus Leishmania. The nucleotide sequence of the cytochrome b gene of Sri Lankan Leishmania was determined using the semi-nested PCR and 620 bp of this gene obtained. Phylogenetic analysis using these sequences unambiguously indicated that Sri Lankan isolate of Leishmania belongs to L. donovani complex. However, the Sri Lankan isolate forms a distinct lineage within the complex and probably represents a new branch.

Objectives To determine exon/intron organization of the Toxocara canis (T. canis) AK (TCAK) and to test green and black tea and several other chemicals against the activity of recombinant TCAK in the guanidino-specific region by site-directed mutants. Methods Amplification of genomic DNA fragments containing introns was carried out by PCRs. The open-reading frame (1 200 bp) of TCAK (wild type) was cloned into the BamH1/SalI site of pMAL-c2X. The maltose-binding protein-TCAK fusion protein was expressed in Escherichia coli TB1 cells. The purity of the expressed enzyme was verified by SDS-PAGE. Mutations were introduced into the guanidino-specific region and other areas of pMAL/TCAK by PCR. Enzyme activity was measured with an NADH-linked assay at 25 °C for the forward reaction (phosphagen synthesis). Results Arginine kinase in T. canis has a seven-exon/six-intron gene structure. The lengths of the introns ranged from 542 bp to 2 500 bp. All introns begin with gt and end with ag. Furthermore, we measured the enzyme activity of site-directed mutants of the recombinant TCAK. The K

The aim of this study is to delineate ‘admixed hybrid’ and ‘introgressive’ Fasciola genotypes present in the Fasciola population in Vietnam. Adult liver flukes collected from ruminants in 18 Provinces were morphologically sorted out by naked eyes for small (S), medium (M) and large (L) body shapes; and human samples (n=14) from patients. Nuclear ribosomal (rDNA) ITS1 and ITS2, and mitochondrial (mtDNA) nad1 markers were used for determination of their genetic status. Total 4,725 worm samples of ruminants were tentatively classified by their size: 6% (n=284) small (S)-, 13% (n=614) medium (M)-, and 81% (n=3,827) large (L)-forms. All the representative (n=120, as 40 each group) and 14 human specimens, possessed maternal mtDNA of only F. gigantica and none of F. hepatica. Paternally, all (100%) of the L-(n=40) and 77.5% (n=31) of the M-flukes had single F. gigantica rDNA indicating ‘pure’ F. gigantica. A majority (90%, n=36) of the S- and 15% (n=6) of the M-worms had single F. hepatica rDNA, indicating their introgressive; the rest (10%, n=4) of the S- and 7.5% (n=3) of the M-flukes had mixture of both F. gigantica and F. hepatica rDNAs, confirming their admixed hybrid genetic status. Fourteen human samples revealed 9 (64%) of pure F. gigantica, 3 (22%) of introgressive and 2 (14%) of admixed hybrid Fasciola spp. By the present study, it was confirmed that the small worms, which are morphologically identical with F. hepatica, are admixed and/or introgressive hybrids of Fasciola spp., and able to be the pathogens of human fascioliasis.
Adult ; DNA, Mitochondrial ; DNA, Ribosomal ; Fasciola hepatica ; Fasciola ; Fascioliasis ; Genotype ; Humans ; Liver ; Ranunculaceae ; Ruminants ; Vietnam