Ena Camargo

Inhibition of Respiratory syncytial, parainfluenza 3 and measles viruses by 2-deoxy-D-glucose.

Abstract 2-Deoxy- d -glucose was found to inhibit the replication and cytopathic effects of respiratory syncytial, parainfluenza 3 and measles viruses. The effects of the drug were completely reversible and appeared directed against viral functions occurring in the second half of the viral growth cycle. At least some viral functions appeared to be unaffected by the agent. Electron microscopic studies with a temperature-sensitive mutant of respiratory syncytial virus indicated that 2-deoxy- d -glucose produced a morphological change. Surface projections were greatly reduced in virions grown in the presence of the drug.

Genetic Alteration in a Temperature-Sensitive Mutant of Respiratory Syncytial Virus After Replication in Vivo

Summary In the course of a clinical trial of a temperature-sensitive mutant RSV vaccine, a proportion of the virus recovered exhibited genetic alteration. Some of the altered virus showed a temperature-sensitivity pattern intermediate between that of the temperature-sensitive vaccine virus and the temperature-insensitive wild type. Possible genetic mechanisms which might have produced these findings are discussed.

Isolation and characterization of further defective clones of a temperature sensitive mutant (ts-1) of respiratory syncytial virus

SummaryAfter exposure of the temperature sensitivets-1 mutant of respiratory syncytial virus to the chemical mutagen, nitrosoguanidine (NG), 2 clones of virus were recovered which were more temperature sensitive and stable genetically than thets-1 mutant. The initial criterion used for selection of the 2 clones was decreased ability to produce plaques at 36° C. Subsequently it was shown that the 2 clones grew less well at the restrictive temperatures of 37° and 38° C than did thets-1 parent. Peak titers of the NG derived clones were decreased 10–30 told at 37° C and over 100-fold at 38° C compared tots-1. Complementation analysis indicated that the NG mutants retained the same complementation pattern as thets-1 parent.

Effect of 2-deoxy-D-glucose and glucosamine on the growth and functions of respiratory syncytial and parainfluenza 3 viruses.

Abstract 2-Deoxy- d -glucose (2dG) and glucosamine reversibly inhibited the replication and cytopathic effect of two viruses pathogenic for man, respiratory syncytial virus and parainfluenza type 3, by affecting a late step in the growth cycle. Functions attributed to viral glycoproteins, including hemadsorption, hemagglutination, and cell fusion, were significantly depressed whereas complement fixation (CF) antigen(s) was largely unaffected. Viral surface antigens were demonstrable in the cytoplasm but could not be detected on the surface of infected cells treated with these inhibitors. Reversal of the block produced by the inhibitors was rapid and dependent on new protein synthesis. The inhibitory effects of 2dG and glucosamine were distinguishable by the course of their reversal as well as the observation that mannose specifically reversed and prevented only the 2dG inhibition.

Growth and genetic stability of 4 temperature sensitive (ts) mutants of respiratory syncytial (RS) virus in newborn ferrets.

SummaryFour temperature sensitive(ts) mutants of respiratory syncytial (RS) virus were evaluated for growth and genetic stability in newborn ferrets.ts-1, the mutant previously tested in children as a possible live virus vaccine and found to be insufficiently attenuated for the upper respiratory tract, grew in the lungs of newborn ferrets to the same peak titer as wild type RS virus. In addition some genetic alteration of thets-1 mutant occurred. Two more defective subclones ofts-1,ts-1 NG-1 andts-1 NG-16, were greatly restricted in growth in the ferrets lungs.ts-1 NG-16 was also restricted in the nasal turbinates, butts-1 NG-1 grew to high titer in the nasal turbinates. Growth ofts-1 NG-1, however, was delayed 2 weeks compared to the growth of wild type virus. Genetic alteration occurred during growth of either subclone; the virus isolated was intermediate between wild type and input virus in plaque forming ability at restrictive temperatures. In no instance was wild type virus isolated from the ferrets infected with either subclone.ts-2, a plaque morphology mutant that does not fuse cells to form syncytia even at the permissive temperature of 32° C, was restricted in growth in both the lungs and nasal turbinates, and genetically altered virus was not recovered from these animals. Of the mutants tested,ts-2 was the most restricted mutant in the newborn ferret and should be evaluated further as a candidate vaccine virus.