Human rotavirus VP4 and VP7 gene sequences were amplified by reverse transcription-PCR from 53% (322 of 607) of fecal specimens collected from children with severe diarrhea who visited hospitals in six urban areas of South Korea in 2000 and 2001. G2 was the most frequently found G type (constituted 50.6%), followed by G1 (30.1%) and G4 (13.0%). Although the P types of high incidence were P[4] (53.1%) and P[8] (21.4%), a significant incidence of P[6] (20.2%) was also noticeable. The commonest G-and P-type combination found in this study was G2P[4], rather than G1P[8], the most prevalent type known worldwide.Rotaviruses are the major etiological agent of gastroenteritis and cause vomiting, diarrhea, and fever in infants and young children worldwide (8). Rotaviruses are divided into seven groups (groups A to G) on the basis of their antigenic properties. Group A rotaviruses are further divided into the G and the P subtypes according to the antigenic property of the VP7 protein (glycoprotein) and the VP4 protein (protease-susceptible protein), respectively. To date, 10 G types have been identified in humans, but most cases of human infection are associated with four G types (types G1 to G4), of which G1 is the most prevalent worldwide (5, 10). It is well established that the G serotypes coincide with the G genotypes, while P serotypes are classified by a system different from that used to classify P genotypes. Types P[4] and P[8] are most frequently found in humans (according to convention, P genotypes are indicated with brackets). Recent studies, however, indicated the emergence of novel P types in different parts of world (3,11) Rotavirus infection is the most common cause of acute diarrhea in infants and young children in South Korea (14). To monitor the diversity of rotavirus strains circulating in the country, we carried out an analysis of 607 fecal specimens collected from infants and young children with acute diarrhea who visited 18 urban hospitals and four clinical laboratories scattered around the six provinces of the country from January 2000 to April 2001. The fecal suspension (10% in phosphatebuffered saline) was centrifuged at 10,000 ϫ g for 10 min, and the double-stranded viral RNA was extracted by treatment of the supernatant with phenol-chloroform-1% sodium dodecyl sulfate, as described previously (6). Reverse transcription (RT)-PCR was performed with the consensus primers Beg9 and End9 to amplify the VP7 gene sequence in full (1,062 bp) and primers Con2 and Con3 to amplify the VP4 gene sequence (877 bp). A second-round, multiplex PCR was performed with primers specific for G types (G1, G2, G3, G4, G8, and G9) and P types (P[4], P[6], P[8], P[9], and P[10]), as described previously (4, 6). The G and P types were determined from the migration rates of the amplicons in a 1.2% agarose gel. Among the 607 stool samples 322 (53.0%) were positive for rotavirus RNA by RT-PCR. The presence of rotaviral antigens was determined by a latex agglutination assay (Biomerieux, Marcy l'Etoile, France) and an enzyme-li...
Culex pipiens molestus Forskal (Diptera: Culicidae) is the dominant mosquito species in septic tanks in South Korea. An assessment was made of the biological control potential of mud loaches, Misgurnus mizolepis Günther (Cypriniformes: Cobitidae), toward Cx. p. molestus larvae in laboratory and septic tanks. Results were compared with those of temephos 20% emulsifiable concentrate. In laboratory tests, all mud loaches survived on sedimentation chamber- and effluent chamber-collected water of aerobic septic tanks (ASTs), whereas all mud loaches died within 3-12 h after introduction into sedimentation chamber- and effluent chamber-collected water of anaerobic septic tanks, Gill hyperplasia and hemorrhages at the bases of pectoral fins were detected in all dead mud loaches. These appeared to have been caused by bacterial disease, rather than the physical and chemical characteristics of the septic tank water. A mud loach consumed an average range of 1,072-1,058 larvae of Cx. p. molestus in the AST water at 24 h. At the manufacturer's recommended rate (10 ml/ton) in the AST water, the temephos formulation did not cause fish mortality. In the AST experiment, predation of mosquito larvae by mud loaches at a release rate of one fish per 900 mosquito larvae resulted in complete mosquito control from the third day after treatment throughout the 18-wk survey period, compared with temephos 20% emulsifiable concentrate-treated AST water (reduction rate, 40% at 28 days after treatment). Reasonable mosquito control in aerobic septic tanks can be achieved by mosquito breeding season stocking of a rate of one mud loach per 900 mosquito larvae.
The envelope (E) glycoprotein of JEV is the major antigen to elicit neutralizing antibody (NAb) against JEV infection. In order to develop a rapid and safe neutralization assay system for evaluation of the JEV vaccine strains, we constructed JEV-pseudotyped viruses with JEV env genes (Nakayama-NIH, Beijing-1). The titers of JEV-pseudotyped viruses with NK and BJ strains were 4.0×10 4 IFU/ml and 1.3×10 5 IFU/ml in Vero cell cultures, respectively. We have analyzed the neutralization activity of immunized mouse sera with JEV-NK and JEV-BJ pseudotyped viruses. The neutralizing antibody titers of NK and BJ (50% reduction of virus) were about 1:10,000 at each immunized sera. Compared with conventional plaque reduction neutralization test (PRNT), the method using JEV-pseudotyped virus has desirable advantages such as more rapid, easier, and non-biohazardous. This neutralization assay system might be useful to evaluate NAb activity against JEV vaccine strains or vaccine candidates.
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