Isolation and Characterization of G9 Human Rotaviruses

Group A rotaviruses are the most common causes of gastroenteritis among infants and young children. The outer capsid layer of the virus is composed of two structural proteins, VP4 and VP7, and they play important roles in protection by eliciting neutralization antibodies. Group A rotaviruses are subdivided into distinct G and P serotypes according to the antigenic differences of the VP7 and VP4, respectively. Rotavirus G9 serotype was thought to be the fifth most common serotype circulating among the population worldwide. In this study, G9 human rotaviruses (HRV) were isolated from fecal samples using MA104 cells and characterized. Characteristic cytopathic effects of rotavirus were observed and rotaviral antigens were confirmed by indirect immunofluorescence antibody test in MA104 cells inoculated with isolated HRV strains. The nucleotide sequences of the VP7 gene of Korean G9 HRV isolated in this study were determined and compared with those of other recent and prototype G9 rotavirus strains from other parts of the world. Also, the nucleotide sequences of VP4 and NSP4 gene of Korean G9 HRV were determined and compared with those of other rotavirus strains from other countries. The results showed that the Korean HRV isolates belong to a G9, P[8] and NSP4 B genotype. The Korean G9 HRV isolates and their nucleotide sequence data would be usefully applied for the vaccine development of HRV in the near future.