Infection of L cells with reovirus results in a gradual inhibition of host protein synthesis and a concomitant increase in viral specific protein synthesis. Previous in vitro studies using cell-free extracts from uninfected and infected cells suggested that the observed pattern of protein synthesis in infected cells is the consequence of a transition of the host translational apparatus from cap dependence to cap independence. To test this hypothesis, it was necessary to demonstrate that mRNA being translated at late times in infected cells was uncapped. Progeny subviral particles synthesize the bulk of the viral mRNA present in infected cells at late times after infection. Therefore, progeny subviral particles were isolated and the mRNA synthesized by these particles was subjected to 5' terminal analysis. The results of these experiments indicated that progeny subviral particles synthesize uncapped mRNA with the 5' terminal structure pGpC... . Examination of the 5' termini of reovirus mRNA's associated with polyribosomes at different times post infection clearly showed that uncapped viral mRNAs (pG... terminated) were translated with increasing predominance as a function of time after infection. Thus, at late times only uncapped viral mRNAs were translated, while capped host mRNAs, although still present in infected cells, were excluded from polyribosomes. It was concluded from these findings that the mechanism for takeover of protein synthesis by reovirus involves a transition to cap independent translation coupled to the synthesis of large quantities of uncapped viral mRNAs. Further studies indicated that crude initiation factor preparations from uninfected L cells restored the ability of cell-free extracts from infected cells to translate capped mRNAs. Crude initiation factor preparations from late infected cells did not have restoring activity. Numerous studies have shown that cap binding proteins present among eucaryotic initiation factors facilitate transla
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.76737 |
| Date | January 1983 |
| Creators | Zarbl, Helmut. |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Biochemistry.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 000186990, proquestno: AAINK66592, Theses scanned by UMI/ProQuest. |
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