Isolation and Characterization of Temperature‐Sensitive Mutants of Sendai Virus

Four virion activities of Newcastle disease virus (hemagglutinating, neuraminidase, hemolytic, and infectious activities) were examined before and after heat stress in low-salt buffer and physiological salt buffer (phosphate-buffered saline). The hemagglutinating and neuraminidase activities of the Australia-Victoria wildtype (AV-WT) strain were thermostable at both salt concentrations tested, whereas the thermostabilities of the hemolytic and infectious activities were salt dependent (thermostable in phosphate-buffered saline but not in low-salt buffer). Virions of RNA' temperature-sensitive (ts) mutants of AV-WT were tested for

Section: Discussionsupporting

confidence: 68%

Thermostabilities of Virion Activities of Newcastle Disease Virus: Evidence that the Temperature-Sensitive Mutants in Complementation Groups B, BC, and C Have Altered HN Proteins

Peeples

Glickman

Bratt

1983

“…When these mutants are tested for RNA-synthesizing ability, a relatively large fraction of them are RNA negative (RNA-; i.e., they show reduced synthesis of virus-specific RNA at nonpermissive temperatures) (2,16,30,32,42). For NDV, one group of Sendai virus, and measles virus, these RNAmutants fall into two, two, and three complementation groups, respectively (1,5,42), which is consistent with the involvement of two or three proteins in RNA synthesis. In contrast, seven complementation groups have been identified for another group of Sendai virus mutants (30).…”

supporting

confidence: 55%

“…Temperature-sensitive (ts) mutants have been isolated from several paramyxoviruses, including measles virus (2,16), respiratory syncytial virus (14,15), Sendai virus (1,30), and Newcastle disease virus (NDV) (31,36,42). When these mutants are tested for RNA-synthesizing ability, a relatively large fraction of them are RNA negative (RNA-; i.e., they show reduced synthesis of virus-specific RNA at nonpermissive temperatures) (2,16,30,32,42).…”

mentioning

confidence: 99%

RNA synthesis by Newcastle disease virus temperature-sensitive mutants in two RNA-negative complementation groups

Peeples¹,

Rasenas²,

Bratt³

1982

The temperature-sensitive RNA-negative mutants of Newcastle disease virus comprise two complementation groups, group A (seven members) and group E (one member). The RNA-synthesizing activities of four representative members of group A and the single member of group E were compared with the activity of the wild type. These mutants were defective to varying extents in primary transcription at the nonpermissive temperature, ranging from mutant Al, which had no activity, to mutant El, which lost only 50% of its activity. All of the mutants were also defective in a postprimary transcriptive process since after preincubation at the permissive temperature in the presence of cycloheximide, there was no subsequent RNA synthesis at the nonpermissive temperature upon removal of the cycloheximide. Similarly, in experiments in which cycloheximide was not used, shifts from the permissive temperature to the nonpermissive temperature before 3 h postinfection did not result in RNA synthesis. However, later shifts to the nonpermissive temperature did allow RNA synthesis. With the exception of mutant Al, all of the mutants maintained this RNA-synthetic ability for at least 3 h, suggesting that RNA synthesis from progeny genomes was not the major postprimary transcriptive defect in these mutants. In contrast, the RNAsynthetic ability of mutant Al rapidly decayed at the nonpermissive temperature, suggesting that the A gene product is involved in RNA synthesis from progeny genomes. The postprimary transcriptive defect(s) of the other mutants may be in the processing or stability of a protein, in the processing of mRNA, or in replication. Plaque-forming revertants (ts+) of all of the mutants coreverted for RNA synthesis. This finding strengthens the relationship between temperature sensitivity for plaquing and both the primary and postprimary RNA-negative phenotypes.

“…Both HN and F are transmembrane proteins, at least in Sendai virus (5), and thus have the potential to interact with internal components of virions. RNA' ts mutants of Sendai virus which direct the assembly of virions containing F but few HN molecules have been described (1,34). Taken together, these results suggest that F, but not HN, may be required for virion assembly.…”

Section: Discussionmentioning

confidence: 86%

Revertant analysis of a temperature-sensitive mutant of Newcastle disease virus with defective glycoproteins: implication of the fusion glycoprotein in cell killing and isolation of a neuraminidase-deficient hemagglutinating virus

Smith¹,

Hightower²

1982

Biological and molecular properties of a temperature-sensitive mutant (Cl) of Newcastle disease virus and its revertants were analyzed. Cl exhibited three temperature-sensitive alterations (plaque formation, virion assembly, and cytopathogenicity) and several defects which were also present at the permissive temperature. Ci virions contained low amounts of hemagglutinin-neuraminidase glycopolypeptides and consequently were deficient in hemagglutinating and neuraminidase activities. These virions also contained defective fusion glycoproteins which rendered them poorly hemolytic and slow to penetrate cultured chicken embryo cells. The biological activities of the membrane glycoproteins were recovered sequentially in a series of plaque-forming revertants. The coreversion of hemolysis, membrane-penetrating activities, and cytopathogenicity in the first-step revertant (Si) suggested that fusion glycoproteins were major contributors to cellular destruction. This revertant also provided evidence of a role for fusion glycoproteins in virion assembly. From Si we isolated a large-plaqueforming revertant (Li) that assembled wild-type amounts of biologically active hemagglutinin-neuraminidase glycoproteins into virions. Although it was normal for hemagglutination, Li had less than 3% of the neuraminidase activity of the wild type, demonstrating that these two activities can be uncoupled genetically. The neuraminidase deficiency of Li did not impair its virulence in ovo or its reproduction in cultured cells. The envelope of the avian paramyxovirus Newcastle disease virus (NDV) contains two types of biologically active glycoproteins which form physically (36) and antigenically (4, 39) distinct spikes on the surfaces of virions (reviewed in references 11 and 14). One population