Electron microscopic studies of respiratory syneytial temperature-sensitive mutants

Abstract

SummaryThe A2 strain of respiratory syncytial (RS) virus and several temperature sensitive mutants derived from it were grown at the permissive (32 ~ C) and restrictive temperature (39~ in HeLa cells and thin sections of these cells were examined by electron microscopy. The mutants selected for this study were representative of 3 different complementation groups. The parent strain underwent the same sequence of morphogenesis at the permissive and restrictive temperatures. Morphogenesis of each of the mutants at the permissive temperature was similar to that of the parent strain. At the restrictive temperature cells infected with mutants belonging to two of the complementation groups developed a significantly reduced amount of one or more of the recognizable viral structures. In one instance (ts-4, complementation group A) budding and release of virus did not occur, while in another (ts-7, complementation group C) no virus specific structures were seen. Cells infected with the ts-2 mutant of complementation group B exhibited normal viral morphogenesis at restrictive temperature.

RhoA Signaling Is Required for Respiratory Syncytial Virus-Induced Syncytium Formation and Filamentous Virion Morphology

“…In addition, the non-syncytium-inducing phenotype correlates with the lack of viral filaments seen by SEM (25). Thus, RSV infection in the presence of C3 and Y-27632 treatment may be analogous to ts RSV strains, which replicate with equal efficiencies in vitro as their counterpart syncytium-inducing strains, but without significant syncytium formation (25). However, the ts strains are attenuated in vivo, suggesting that viral filament formation and cell-to-cell fusion may represent virulence determinants.…”

“…In addition, we report an association between RhoA-induced viral filaments and RSV-induced syncytium formation. A temperature-sensitive (ts) strain of RSV with a nonsyncytium-inducing phenotype in cell culture has been reported (25). This virus produces equivalent numbers of progeny viruses as normal syncytium-inducing strains of RSV, but the virus is severely attenuated in vivo (25).…”

“…A temperature-sensitive (ts) strain of RSV with a nonsyncytium-inducing phenotype in cell culture has been reported (25). This virus produces equivalent numbers of progeny viruses as normal syncytium-inducing strains of RSV, but the virus is severely attenuated in vivo (25). In addition, the non-syncytium-inducing phenotype correlates with the lack of viral filaments seen by SEM (25).…”

“…This virus produces equivalent numbers of progeny viruses as normal syncytium-inducing strains of RSV, but the virus is severely attenuated in vivo (25). In addition, the non-syncytium-inducing phenotype correlates with the lack of viral filaments seen by SEM (25). Thus, RSV infection in the presence of C3 and Y-27632 treatment may be analogous to ts RSV strains, which replicate with equal efficiencies in vitro as their counterpart syncytium-inducing strains, but without significant syncytium formation (25).…”

Pneumoviruses: the Cell Surface of Lytically and Persistently Infected Cells

“…Transmission electron microscopy of various types of cells infected with human RS virus (Bloth et aL I963;Norrby et aL 197o;B/ichi & Howe, 1973;Kalica et al 1973;Berthiaume et aL 1974;J. E. Parry, unpublished data), bovine RS virus (Ito et al r973); and PVM (Compans et al I967;Berthiaume et al I974) has demonstrated also that surface filaments are abundant at late stages of infection.…”