Genomic Diversity of Human Rotaviruses, a Cause of Diarrhea in Korean Children: 1989-1994

Kim, H; Kim, K; Kim, J; Cho, Y; Kim, D; Choi, T

Abstract

Rotaviruses (Rv) have been recognized as one of the most important agents causing severe viral gastroenteritis in young children and newborn animals throughout the world. The fact that Rv possess a high antigenic diversity and an unpredictable distribution in a wide host range has caused a great difficulty for the development of Rv vaccine. Rv, belong to the family Reoviridae, are non-enveloped and containing double - stranded, segmented RNA viruses with a unique double capsid structure. As found in other viruses having segmented RNA, however, reassortment of Rv gene segments (between human Rv belonging to different genogroups, or between human Rv and animal Rv) occurs at a relatively high frequency in vitro and in vivo, leading to the emergence of genetically or antigenically novel Rv strains, different both in virulence and host range restrictions from the parent strains. Thus it is important that genomic spectrum of Rv, representative of different geographic areas and various clinical profiles, be studied. Therefore, 773 fecal specimens collected during a 5 year period (1989-1994) from diarrheal children in Korea were examined for VP6 by an ELISA with VP6-specific monoclonal antibody and segmented Rv genomic profile by polyacrylamide gel electrophoresis. A total of 432 (56%) were positive for group A Rv antigen and 341 (%) revealed a typical group A rotaviral RNA profile. There was no group B or C Rv detected. RNA electropherotyping of the 341 group A Rvs showed that they were classified into 18 patterns, 4 with short (S) and 11 with long (L) RNA profiles. Of the analyzed specimens, 81% were L forms and 18% were S. Extensive genome variability and cocirculation of different electropherotypes were observed. Furthermore, bovine Rv-like RNA profile was detected in a three year old child with moderate dehydration suggesting interspecies transmission of Rv between humans and cows. Further genetic study of genes coding VP7 or VP4 of these strains may elucidate the molecular basis of preferential selection of this gene and help the future development of Rv vaccines.