Effects of ribavirin on BHK-21 cells acutely or persistently infected with mumps virus.

The effects of ribavirin on BHK-21 cells acutely infected with mumps virus were compared to the effects of the drug on the same cell line persistently infected with mumps virus. Visible cytotoxicity was minimal for both cell types; however, there was an inhibition of cell replication with increasing drug concentrations. Ribavirin had marked antiviral activity against both the acute and persistent infections as determined by an inhibition of hemadsorption plaque formation, decreased immunofluorescence, and a reduction in the release of infectious virus. Even after the drug had been on the persistently infected cells for 72 h, there was still antigen production detectable by immunofluorescence, although the cells no longer hemadsorbed chicken erythrocytes. Ribavirin removal from both types of infection resulted in the renewed synthesis of virus.

Detection of arbovirus antibodies in avian sera by the complement fixation-inhibition test.

The complement fixation-inhibition (CFI) test was described for the detection of antibodies to arboviruses in bird sera. The CFI antibody present in bird sera inhibited the standard complement-fixation reaction of a reference complement-fixing antigen-antibody pair. Using reference antigens (St. Louis encephalitis, eastern equine encephalomyelitis, western equine encephalomyelitis, and yellow fever) prepared from infected mouse brains and reference antisera prepared in rabbits or horses, reproducible CFI antibody titers were obtained in artificially immunized chickens. Time-course studies on the CFI immune response in birds inoculated with live St. Louis encephalitis virus indicated that the CFI antibody was distinct from the antibody detected by the hemagglutination-inhibition test.

Release of membrane constituents following polyethylene glycol treatment of HEp-2 cells.

HEp-2 cell monolayers were treated with 40% polyethylene glycol for 5 min which resulted in fusion during the subsequent incubation period. A loss of cell membrane components was detected in the polyethylene glycol-treated as well as phosphate buffer/saline-treated control cells, however the polyethylene glycol-treated cells released nearly twice the amount of [14C]acetate-labeled material and [3H]glycerol-labeled lipids into culture fluids than the control cells. It was further detected that the polyethylene glycol-treated cells released only approximately half the amount of protein, glycoprotein, and glycolipid as the control cells. These results suggest that polyethylene glycol exerts a differential mode of action against cell surface components and causes the treated cells to release membrane components rich in lipids but relatively low in protein and carbohydrate-containing components.

Radioimmunofluorescent antibody technique for detection of reovirus antigen in cell culture.

Antibody against reovirus type I must partially purified and conjugated with fluorescein isothiocyanate (FITC). The FITC-labeled antibody was then conjugated with 125I. A gamma globulin fraction of normal sera was similarly labeled with FITC followed by a 131I label. The FITC + 125I-labeled immune reagent was then mixed on an equal protein basis with the FITC + 131I control reagent. This mixture was used to stain acetone-fixed reovirus-infected cover slips. After staining, the cover slips were examined by fluorescence microscopy. Infected cover slips demonstrated characteristic reovirus immunofluorescence, whereas uninfected cover slips were negative. After visual examination, the cover slips were placed in tubes and counted in a two-channel gamma analyzer. By comparing the quantitative isotope data with the qualtitative information from immunofluorescence on a single preparation, it was possible to correlate antigen production sites with quantitative production values.

Simplified procedure for preparation of specific antibodies to gamma globulins.

Antibodies were prepared to rhesus monkey, rabbit, dog, and hamster gamma globulins which had been purified by agar-block electrophoresis. Immunoelectrophoretic analysis demonstrated that these antisera were specific for gamma globulin components in whole serum. The use of these antisera as secondary serological reagents was examined.