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Positional cloning of the murine flavivirus resistance gene
Andrey A Perelygin1, Svetlana V Scherbik, Igor B Zhulin
1Department of Biology, Georgia State University, Atlanta, GA 30303, USA.
Abstract:
Inbred mouse strains exhibit significant differences in their susceptibility to viruses in the genus Flavivirus, which includes human pathogens such as yellow fever, Dengue, and West Nile virus. A single gene, designated Flv, confers this differential susceptibility and was mapped previously to a region of mouse chromosome 5. A positional cloning strategy was used to identify 22 genes from the Flv gene interval including 10 members of the 2'-5'-oligoadenylate synthetase gene family. One 2'-5'-oligoadenylate synthetase gene, Oas1b, was identified as Flv by correlation between genotype and phenotype in nine mouse strains. Susceptible mouse strains produce a protein lacking 30% of the C-terminal sequence as compared with the resistant counterpart because of the presence of a premature stop codon. The Oas1b gene differs from all the other murine Oas genes by a unique four-amino acid deletion in the P-loop located within the conserved RNA binding domain. Expression of the resistant allele of Oas1b in susceptible embryo fibroblasts resulted in partial inhibition of the replication of a flavivirus but not of an alpha togavirus.
Insights
Mouse strains show varied susceptibility to flaviviruses like Dengue. The Oas1b gene was identified as the key genetic factor, Flv, influencing this difference through a specific protein variation.
Area of Science:
- Virology
- Immunology
- Genetics
Background:
- Inbred mouse strains display differential susceptibility to Flavivirus infections.
- Flaviviruses include significant human pathogens like Dengue and West Nile virus.
- A single gene, Flv, on mouse chromosome 5 controls this varied susceptibility.
Purpose of the Study:
- To identify the specific gene responsible for differential Flavivirus susceptibility in mice.
- To elucidate the molecular mechanism underlying this genetic resistance/susceptibility.
Main Methods:
- Positional cloning was employed to narrow down candidate genes within the Flv interval on mouse chromosome 5.
- Genotyping and phenotypic analysis across nine mouse strains were used to correlate gene variants with virus susceptibility.
- Sequence analysis identified mutations and structural differences in candidate genes.
Main Results:
- The 2'-5'-oligoadenylate synthetase gene, Oas1b, was identified as the Flv gene.
- Susceptible mouse strains possess a truncated Oas1b protein due to a premature stop codon, differing from the resistant strains.
- The Oas1b protein in resistant strains has a unique four-amino acid deletion in the RNA-binding domain.
Conclusions:
- Oas1b is the primary determinant of differential Flavivirus susceptibility in inbred mice.
- The identified Oas1b variants, particularly the truncated protein in susceptible strains, directly impact host defense against flaviviruses.
- Restoring the resistant Oas1b allele in susceptible cells partially inhibited flavivirus replication, confirming its role.