Human Caliciviruses in Korea: A New Prevalent Group Defined by RNA-Dependent RNA Polymerase Diversity

Human caliciviruses (HuCVs) cause sporadic cases and outbreaks of acute gastroenteritis (AGE). Three maior genogrovps of HuCVs have been described including the Norwalk virus (NV)-, the Snow Mountain virus (SMA)-, and the Sapporo-genogroups. This study describes the detection and genetic variation of HuCVs from hospitalized infants with AGE in Korea by RT-PCR and sequencing. The cDNA fragments of 206 to 470bp corresponding to the region of 3 primer pairs (36/35, 35/51 or 3/51) in the polymerase region of NV were generated. Of 185 stools screened, 8% were positive by RT-PCR and their sequences showed that all strains contained the GLPSG and YGDD motifs which are conserved for HuCVs. Amino acid (aa) sequence analysis showed that these strains can be divided into 3 maior genogroups. High conservation was observed in that one strain shares 100% of as sequence with Southampton virus, another shares 99% with the Sapporo virus, and six strains share 90 to 95% with Snow Mountain virus. However, significant sequence variation was also found in other strains. This study indicates that all maior genogroups of HuCVs are circulating in Korea.

Antisense GLUT1 RNA suppresses the transforming phenotypes of NIH 3T3 cells transformed by N-Ras

An antisense approach was attempted to investigate the role of antisense GLUT1 RNA in suppressing tumor cell phenotypes using N-ras-transformed NIH 3T3 cells. The established cell line transformed by ras showed typical biological characteristics of cancer cells, such as increased glucose transport, GLUT1 mRNA contents, and the ability to form colonies on the soft agar. In this system, the plasmids (pMAM-GLUT1(rev)) which can transcribe the antisense GLUT1 RNA were transfected and the accompanying changes in the phenotypes of the ras-transformed cells were observed. The expression of antisense GLUT1 RNA by induction with dexamethasone reduced the glucose transport by 30% (1.97 +/- 0.13 nmoles) after 4 min incubation when compared to the non-induction group of transformed cell (2.85 +/- 0.19 nmoles). Also, the number of colonies sized over 50 microns on the soft agar was reduced significantly in the antisense RNA expressing group compared to non-induction group. These results suggest that the expression of antisense GLUT1 RNA reduced the glucose transport and transforming potential in soft agar possibly by hybridization with GLUT1 mRNA in N-ras-transformed NIH 3T3 cells.