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Identification of Poliovirus Temperature-sensitive Mutants having Defects in Virus Structural Protein
Abstract
SUMMARY
Ten out of 29 temperature-sensitive (ts) mutants of poliovirus lost infecti-vity in vitro at 45° more rapidly than did ts +, and therefore had structural protein defects. This division into structural protein and non-structural protein defectives accorded very closely with their position in the genetic map and with previous tests for maturation defects, enabling the region of the genetic map specifying virus structural protein to be defined. Not all mutants mapping in this region were thermolabile, however. Three out of five ts + revertants from the thermolabile mutants were thermostable and so their thermolability and ts characters almost certainly resulted from mutations in the same gene, i.e. the ts defects of these thermolabile mutants were confirmed as residing in structural protein. Four of the thermolabile mutants were sufficiently unstable at the restrictive temperature to explain their ts character. Three mutants mapping in the structural protein region produced only small amounts of RNA-containing particles and so their defect may act before maturation. Of five structural protein mutants examined, none showed any antigenic difference from ts +. Marked covariation was found between cystine requirement for growth and structural protein defects suggesting that cystine requirement is a property of the structural protein of the virus.
- Received:
- Accepted:
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© Society for General Microbiology 1970