To study the antigenic characteristics of respiratory syncytial virus (RSV), we developed and evaluated monoclonal antibodies (MAbs) to three strains of RSV: 11 to Long, 4 to 18537, and 9 to A2. Six of these MAbs immunoprecipitated the nucleoprotein, six the large glycoprotein, and 11 the fusion protein. By the pattern of the reactions of these MAbs to 16 strains of RSV in an indirect immunofluorescence assay or enzyme-linked immunosorbent assay, we were able to distinguish three subgroups. With a panel of 10 of these 24 MAbs, we tested 26 strains isolated between 1979 and 1982 in Boston and found that 22 belonged to group 1, 4 to group 2, and none to group 3. The pattern of the reactions of the MAbs against representative strains from the three groups identified nine epitopes by indirect immunofluorescence assay: three of each on the nucleoprotein, the large glycoprotein, and the fusion protein. These results, along with those of previous studies, suggest that groups 1 and 3 are antigenically similar and group 2 is antigenically more distinct.

Summary.Reference equine antisera to all 47 serotypes of human adenoviruses presently described have been prepared and evaluated by reciprocal neutralization and hemagglutination-inhibition tests. All tests were carried to endpoint dilutions a minimum of five times in each direction to give accurate values for homologous and heterologous antibody titers. Significant cross-reactions in the horse antisera were compared to similar data obtained from rabbit antisera. Using this analysis, major antigenic relationships exist among types 12-18-31 of subgenus A, types 7-11-14 and 34-35 of subgenus B, types

Virus infectivity and antibody neutralization titers for respiratory syncytial virus were determined in cell cultures in microtiter plates. After an appropriate incubation period, the cells were fixed, and an enzymelinked immunosorbent assay was performed directly in the microtiter plates for detection of virus. Results could be read and recorded automatically, which is especially helpful when running large numbers of tests.

To characterize the interrelationship of monoclonal antibodies (MAbs) against respiratory syncytial virus (RSV) and their respective epitopes, we developed a competitive binding assay based on the biotin-avidin system and a tissue culture enzyme-linked immunosorbent assay. The competitive binding assay clearly distinguished between competing and noncompeting MAbs. Eight MAbs against the fusion protein (F protein) demonstrated two blocking patterns consistent with two antigenic sites. MAbs reacting at one site neutralized the virus, while those reacting at the other site did not. Eight MAbs against the large glycoprotein (G protein) demonstrated five blocking patterns consistent with three antigenic sites, one with three epitopes and the other two with one each. None of the MAbs against G protein neutralized the virus. The reaction pattern of the MAbs against three strains of RSV identified three additional epitopes on the F protein and no additional epitopes on the G protein. The epitopes on G protein showed the greatest antigenic diversity among the three strains. These results help us better understand the functional and antigenic structure of the two surface glycoproteins of RSV.

This rapid and sensitive test appears to be much more sensitive than traditional antigen detection assays but will require more extensive field testing on clinical specimens.