For the determination/confirmation of the vector species of Japanese encephalitis in Korea and for the study of their bionomics, a preliminary assessment of different collecting methods of sampling mosquito population was undertaken. Man-biting catches, cow-biting catches, pig-baited window-trap hut, light trap, dry ice trap and man-baited double net were employed. The advnntages and disadvantages of these methods are discussed. A pig-baited window-trap hut and cow-biting catches outdoors are considered the best ways of collecting large numbers of Culex tritaeniorhynchus summorosus, the most important vector of Japanese encephalitis, for virus isolation and insecticide susceptility testing. The latter method requires, however, more man-power. Light traps set in a pigsty or cowshed are the simplest and most convenient tools for studying tne mosquito population density and seasonal prevalence.
parasitology-arthropoda ; Japanese encephalitis ; vector ; mosquito ; Culex tritaeniorhynchus summorosus

A coiled nematode, which was removed surgically from a Thai woman, was consulted to the authors in July 1987. She was known to suffer from meningoencephalitis since she was in Thailand. Numerous eosinophils were detected from her CSF. The worm was 12.3 mm long and 0.9 mm wide. It had a head bulb beset with eight rows of spines, a cervical constriction, esophagus, cervical sacs, dark intestine and testis. Cuticle of anterior half of the worm was covered with numerous spines. The spines at anterior part was stout and had 3-4 tips, but they became slender, shorter, single tipped and sparser and finally they disappeared posteriorly. Cuticular spines reappeared at tail which had 4 pairs of pedunculated papillae. By above morphological characteristics, the worm was identified as an adult male of Gnathostoma spinigerum. The present case is the first authentic case of imported intracranial gnathostomiasis in Korea, although clinical informations of the case were obtained limitedly.
parasitology-helminth-nematoda ; encephalitis ; gnathostomiasis ; Gnathostoma spinigerum ; case report ; Thailand

Acanthamoeba cysts are resistant to unfavorable physiological conditions and various disinfectants. Acanthamoeba cysts have 2 walls containing various sugar moieties, and in particular, one third of the inner wall is composed of cellulose. In this study, it has been shown that down-regulation of cellulose synthase by small interfering RNA (siRNA) significantly inhibits the formation of mature Acanthamoeba castellanii cysts. Calcofluor white staining and transmission electron microscopy revealed that siRNA transfected amoeba failed to form an inner wall during encystation and thus are likely to be more vulnerable. In addition, the expression of xylose isomerase, which is involved in cyst wall formation, was not altered in cellulose synthase down-regulated amoeba, indicating that cellulose synthase is a crucial factor for inner wall formation by Acanthamoeba during encystation.
Acanthamoeba castellanii/*enzymology/genetics/metabolism ; Aldose-Ketose Isomerases/*biosynthesis ; Amebiasis/*pathology ; Benzenesulfonates ; Cell Wall/chemistry/genetics/*metabolism ; Cellulose/biosynthesis ; Down-Regulation ; Encephalitis/parasitology ; Glucosyltransferases/*biosynthesis/genetics ; Keratitis/parasitology ; Microscopy, Electron, Transmission ; RNA Interference ; RNA, Small Interfering

The pathogenic mechanism of granulomatous amebic encephalitis (GAE) and amebic keratitis (AK) by Acanthamoeba has yet to be clarified. Protease has been recognized to play an important role in the pathogenesis of GAE and AK. In the present study, we have compared specific activity and cytopathic effects (CPE) of purified 33 kDa serine proteinases from Acanthamoeba strains with different degree of virulence (A. healyi OC-3A, A. lugdunensis KA/E2, and A. castellanii Neff). Trophozoites of the 3 strains revealed different degrees of CPE on human corneal epithelial (HCE) cells. The effect was remarkably reduced by adding phenylmethylsulfonylfluoride (PMSF), a serine proteinase inhibitor. This result indicated that PMSF-susceptible proteinase is the main component causing cytopathy to HCE cells by Acanthamoeba. The purified 33 kDa serine proteinase showed strong activity toward HCE cells and extracellular matrix proteins. The purified proteinase from OC-3A, the most virulent strain, demonstrated the highest enzyme activity compared to KA/E2, an ocular isolate, and Neff, a soil isolate. Polyclonal antibodies against the purified 33 kDa serine proteinase inhibit almost completely the proteolytic activity of culture supernatant of Acanthamoeba. In line with these results, the 33 kDa serine proteinase is suggested to play an important role in pathogenesis and to be the main component of virulence factor of Acanthamoeba.
Virulence Factors/isolation & purification/*metabolism ; Virulence ; Trophozoites/physiology ; Substrate Specificity ; Soil/parasitology ; Serine Endopeptidases/isolation & purification/*metabolism ; Humans ; Epithelial Cells/parasitology/*pathology ; Encephalitis ; Cornea/cytology/parasitology/*pathology ; Cells, Cultured ; Animals ; Acanthamoeba castellanii/enzymology/growth & development/pathogenicity ; Acanthamoeba Keratitis/parasitology ; Acanthamoeba/classification/*enzymology/growth & development/*pathogenicity

No abstract available.
Adult ; Anemia, Aplastic/*surgery ; Antiprotozoal Agents/therapeutic use ; Drug Therapy, Combination ; Encephalitis/diagnosis/drug therapy/*parasitology ; Female ; Hematopoietic Stem Cell Transplantation/*adverse effects ; Humans ; Immunosuppressive Agents/adverse effects ; Magnetic Resonance Imaging ; Parasitology/methods ; Polymerase Chain Reaction ; Republic of Korea ; Toxoplasma/genetics/*isolation & purification ; Toxoplasmosis, Cerebral/diagnosis/drug therapy/*parasitology ; Transplantation, Homologous ; Treatment Outcome

We have cloned a cDNA encoding a cysteine proteinase of the Acanthamoeba healyi OC-3A strain isolated from the brain of a granulomatous amoebic encephalitis patient. A DNA probe for an A. healyi cDNA library screening was amplified by PCR using degenerate oligonucleotide primers designed on the basis of conserved amino acids franking the active sites of cysteine and asparagine residues that are conserved in the eukaryotic cysteine proteinases. Cysteine proteinase gene of A. healyi (AhCP1) was composed of 330 amino acids with signal sequence, a proposed pro-domain and a predicted active site made up of the catalytic residues, Cys(25), His(159), and Asn(175). Deduced amino acid sequence analysis indicated that AhCP1 belongs to ERFNIN subfamily of C1 peptidases. By Northern blot analysis, no direct correlation was observed between AhCP1 mRNA expression and virulence of Acanthamoeba, but the gene was expressed at higher level in amoebae isolated from soil than those from clinical samples. These findings raise the possibility that Ahcp1 protein may play a role in protein metabolism and digestion of phagocytosed bacteria or host tissue debris rather than in invasion of amoebae into host tissue.
Acanthamoeba/*enzymology/genetics/pathogenicity ; Amebiasis/parasitology ; Amino Acid Sequence ; Animals ; Base Sequence ; Cathepsins/*genetics ; DNA, Protozoan/chemistry/genetics/*isolation & purification ; Encephalitis/parasitology ; Gene Expression ; Genes, Protozoan ; Humans ; Molecular Sequence Data ; Polymerase Chain Reaction ; Protozoan Proteins/chemistry/genetics/physiology ; Sequence Alignment ; Virulence