Preparation of a neutralizing monoclonal antibody specific to serotype 8 rotavirus strains with a super-short RNA pattern.

Extensive cross-neutralization tests have identified seven serotypes of rotavirus. Recently, it has been reported that several human strains (69M, B37 and B38) with a super-short RNA pattern carry new serotype specificity (serotype 8). By using the strain 69M as an immunizing antigen, we prepared a neutralizing monoclonal antibody (designated 69M-2D). In neutralization tests using 18 human and two animal rotavirus strains with different serotype specificities, the 69M-2D antibody was found to neutralize only serotype 8 strains. Also, in an enzyme-linked immunosorbent assay (ELISA), the antibody reacted exclusively with the serotype 8 strains. Thus, the reactivity pattern of the 69M-2D antibody was serotype 8-specific. This antibody should be useful as another reagent for serotyping rotaviruses by ELISA.

Serological and genetic characterization of bovine rotaviruses in Thailand by ELISA and RNA-RNA hybridization: detection of numerous non-serotype 6 strains.

A total of 62 fecal specimens positive for rotavirus were collected from diarrheic cows in Thailand in 1988 and 1989. The antigenic properties of rotaviruses in stool were examined by enzyme-liked immunosorbent assays using specific monoclonal antibodies directed at VP4, VP6 or VP7: all the bovine rotavirus strains were determined as subgroup I; none of the strains were reactive with serotype 6-specific monoclonal antibody; and different reactivities of the bovine strains with two anti-VP4 monoclonal antibodies were observed. Polyacrylamide gel electrophoresis of viral RNA exhibited three different RNA electropherotypes. In RNA-RNA hybridization experiments using cell culture-adapted three strains as well as a reference bovine strain (NCDV), RNA from the Thai bovine strains showed very low homology to that from NCDV; only three or four RNA segments were hybridized between the RNAs from Thai samples and NCDV. These results suggested that bovine rotaviruses isolated in Thailand are serologically and genetically distinct from a reference serotype 6 bovine strain, NCDV.

Determination of subgroup, serotype and electropherotype of human rotaviruses obtained from diarrheic patients in the Philippines.

A total of 40 rotavirus specimens obtained from infants with acute gastroenteritis in Metro Manila, Philippines, were analyzed for their subgroup and serotype specificities and RNA electropherotype. A half (50%) of the specimens contained subgroup I human rotaviruses (HRVs), while 45% of them contained subgroup II HRVs. All subgroup II HRVs were determined to be serotype 1, except one specimen belonging to serotype 3, by an enzyme-linked immunosorbent assay with serotype specific monoclonal antibodies. However, serotype specificity of all subgroup I specimens failed to be determined. In polyacrylamide gel electrophoresis, RNAs extracted from HRVs of either subgroup showed long electropherotype. At least two electropherotypes were distinguished in subgroup I viruses, while five different patterns of viral RNA were found in subgroup II viruses.