Six monoclonal antibodies directed against respiratory syncytial virus proteins were produced. Each was characterized by immunoprecipitation and indirect immunofluorescence. One was directed against the nucleocapsid protein, NP 44, two were directed against a 37,000-dalton protein, two were directed against the major envelope glycoprotein, GP 90, and one was directed against the 70,000dalton envelope protein, VP 70. Indirect immunofluorescence stain patterns of infected HEp-2 cells defined GP 90 and VP 70 as viral proteins expressed on the cell surface, whereas NP 44 and the 37,000-dalton protein were detected as intracytoplasmic inclusions. One of the anti-GP 90 antibodies neutralized virus only in the presence of complement but did not inhibit cell-cell fusion. The anti-VP 70 antibody neutralized virus without complement and inhibited cell-cell fusion of previously infected HEp-2 cells, thus identifying VP 70 as the fusion protein.

Ribavirin was demonstrated to have an antiviral effect on respiratory syncytial virus in vitro. A 50% reduction in plaque number was observed at concentrations of 3 to 10 Ag of ribavirin per ml. This effect was observed when the drug was added as late as 12 h postinfection. At concentrations of greater than 10 ,ug of ribavirin per ml, the size of the syncytial plaque also noticeably decreased. Ribavirin similarly decreased the number of infectious units released into the culture supernatant. The antiviral effect was observed to be inversely related to the size of the viral inoculum, although all concentrations above 3.2 jig of ribavirin per ml visibly lessened the cytopathic effect regardless of the inoculum. Cloning of respiratory synctial virus in inhibitory concentrations of ribavirin failed to show increased resistance to the drug.Ribavirin (1-f8-D-ribofuranosyl-1,2,4-triazole-3-carboxamide) is a synthetic nucleQside that has antiviral properties against a large number of both ribonucleic acid and deoxyribonucleic acid viruses in vitro (5,14,20). In experimental influenza infections in mice, ribavirin has reduced mortality and increased survival time when administered by the oral (4, 6), intraperitoneal (6, 17, 18), and aerosol routes (17). In one study of experimental influenza infections in humans, ribavirin was shown to ameliorate symptoms and fever (8), although other investigators reported that lower doses had only marginal effectiveness against influenza (2, 19).The purpose of this study was to assess the in vitro susceptibility of respiratory syncytial virus (RSV) to ribavirin. Respiratory syncytial virus is a major cause of pneumomia, bronchiolitis, and other respiratory diseases in infants, young children, and even adults (6,16). An inactivated RSV vaccine failed to decrease the incidence of infection and was associated with the paradoxical development of more severe disease when natural infection occurred (7 Eagle minimum essential medium with 10% fetal calf serum (heat inactivated) containing 0.1 mM glutamine, penicillin (100 U/ml), gentamicin (50 j,g/ml), and amphotericin (2.5 ,ug/ml). After 16 to 18 h, the supernatant was aspirated and 0.2 ml of virus was added for 1 h. The wells were overlaid with 5 ml of minimum essential plaque medium containing 5% fetal calf serum, 0.3 mM glutamine, 0.6% agarose, penicillin, gentamicin, and amphotericin. The cultures were fed every 5 days by overlaying them with additional minimum essential plaque medium. Typically, an assay was incubated for 4 to 7 days before the syncytia were judged to be easily countable. The cells were then fixed for 1 h by the addition of 1 ml of 10% Formalin to each well, and the agarose was gently removed. Cells were stained with 0.1% methylene blue to facilitate counting of syncytial plaques.

Although several studies have been done to analyze the peptides of purified 22-nm HbsAg particles, no information has been published about the peptides of the core of the Dane particle which bears the other hepatitis B viral antigen. HbcAg. Dane particles and Dane particle cores (produced by NP-40 treatment of Dane particles) were purified by equilibrium centrifugation in CsCl density gradients. Two populations of Dane particles were observed at densities 1.27 and 1.24 g/ml, respectively. The higher buoyant density Dane particles yielded exclusively cores of buoyant density 1.38 g/ml in CsCl, and the lower buoyant density Dane particles yielded two kinds of cores with buoyant densities of 1.38 and 1.325 g/ml, respectively. Only the higher density Dane particles and cores manifested endogenously primed DNA polymerase activity. The peptides of density 1.38 g/ml Dane particle cores purified by equilibrium CsCl density gradient centrifugation and HBcAg particles from HBV infected chimpanzee liver purified in the same way were analyzed by SDS-polyacrylamide gel electrophoresis. Both kinds of particles were found to consistently contain 3 Coomassie blue staining peptides with approximate molecular weights of 19,000, 70,000 and 80,000 daltons (designated P-19, P-70 and P-80 respectively). In addition, the HBcAg particles from infected liver regularly yielded a protein component with molecular weight greater than 200,000 daltons. This component was occasionally present in electrophoresis runs of core peptides from only one of two patients. Its irregular appearance after gel electrophoresis suggests it may have been an aggregate not completely dissociated under the conditions used. The lower density core component consistently contained P-19, P-70, and P-80, and infrequently additional minor peptides of uncertain origin. The irregular occurrence of the minor peptides in varying amounts suggests they were not intrinsic core proteins.

Ribavirin reduced the amount of respiratory syncytial virus in nasal turbinates and lung tissues of experimentally infected cotton rats by over 90%. An effect was seen when the drug was given either intraperitoneally or by aerosol; however, the antiviral effect was achieved at much lower doses when delivered by the aerosol route. No animal deaths due to the drug were seen.

We developed an indirect fluorescent-antibody test employing a mouse monoclonal antibody directed against the nucleoprotein of RSV for rapid detection of respiratory syncytial virus (RSV). This test demonstrated distinctive fluorescent inclusions in HEp-2 cells infected with 24 RSV isolates collected during 6 previous years but not in cells infected with 13 other respiratory viruses. Examination of nasal cells of 100 infants with acute respiratory illness showed that the indirect fluorescent-antibody test employing the monoclonal antibody was 79o sensitive and 100% specific, as compared with the combination of both culturing and a similar indirect fluorescent-antibody test with commercial anti-RSV serum. This monoclonal antibody is an easily produced, well-characterized, sensitive, and specific reagent for the rapid detection of RSV antigen.