Mutations at Alternative 5' Splice Sites of M1 mRNA Negatively Affect Influenza A Viral Viability and Growth Rate
| Autor: | Chiayn Chiang, 蔣佳穎 |
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| Rok vydání: | 2008 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 97 Different amino acid sequences of influenza viral proteins contribute to different viral phenotypes. However, the diversity of the sequences and its impact on non-coding regions or splice sites has not been intensively studied. This study focuses on the sequences at alternative 5’ splice sites on M1 mRNA. Six different mutations at the splice sites were introduced and viral growth characteristics for those mutants generated by 12 plasmids-based reverse genetics were examined, among which G12C (the G to C mutation at the first nucleotide of the intron for mRNA3 5’ splice site), C51G (3’ end of the exon of M2 mRNA 5’ splice site), and G146C (the first nucleotide of the intron for mRNA4) are lethal mutations. On the other hand, G11C (the 3’ end of exon of mRNA3 5’ splice site), G52C (the first nucleotide of the intron for M2 mRNA), and G145A (the 3’ end of the exon of mRNA4) were rescued, however, with significantly attenuated growth rates. Notably, these mutations did not change any amino acids in M1 or M2 proteins. The levels of precursor (M1 mRNA) and spliced products (M2 mRNA, mRNA3, and mRNA4) from the recombinant mutant virus-infected cells were further analyzed. The production of mRNA3 was reduced in G11C, G52C and G145A mutant virus-infected cells, in comparison with that in wild-type recombinant virus-infected ones. More M2 mRNA was produced in G11C-infected cells than in wild-type virus-infected cells, and little and none in G145A and G52C mutants-infected ones. Results obtained here suggest that introducing these mutations into the alternative 5’ splice sites disturbed M1 mRNA splicing, which may attenuate viral growth rates. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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