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Nucleotide sequence of the splice junction of feline leukemia virus envelope mRNA
1Department of Microbiology, University of Washington, Seattle 98195.
Abstract:
The splice donor and acceptor sequences for the subgenomic envelope messenger RNA of feline leukemia virus (FeLV) were determined. The splice junction was characterized for viral mRNA from a prototype subgroup A FelV and an immunodeficiency-inducing FeLV variant. Thirty-seven of 38 partial envelope cDNAs, cloned after PCR amplification from T cells infected with either virus, utilized the same splice donor and acceptor sites to generate a mRNA that would be predicted to encode envelope protein. One novel cDNA, which could also code for envelope protein, was generated from a cryptic splice acceptor 109 nucleotides downstream of the normal junction. No additional subgenomic FeLV gene products were detected using reverse transcription and polymerase chain reaction amplification of FeLV sequences from chronically infected cells.
Insights
Researchers identified feline leukemia virus (FeLV) splice sites for envelope mRNA. Most T cell infections used standard sites, but one novel cryptic site was found, producing envelope protein without other FeLV gene products.
Area of Science:
- Virology
- Molecular Biology
- Genetics
Background:
- Feline leukemia virus (FeLV) is an oncogenic retrovirus that infects domestic cats.
- Understanding FeLV gene expression, particularly envelope protein synthesis, is crucial for developing antiviral strategies.
- Subgenomic messenger RNAs (mRNAs) play a key role in retroviral protein production.
Purpose of the Study:
- To determine the precise splice donor and acceptor sequences for the subgenomic envelope mRNA of FeLV.
- To characterize the splice junction in viral mRNA from both a prototype subgroup A FeLV and an immunodeficiency-inducing FeLV variant.
- To investigate the potential for alternative splicing events and the production of other FeLV gene products.
Main Methods:
- Polymerase chain reaction (PCR) amplification of viral sequences from infected T cells.
- Cloning and sequencing of partial envelope cDNAs.
- Reverse transcription and PCR amplification to detect additional subgenomic FeLV gene products.
Main Results:
- Identified conserved splice donor and acceptor sites used by 37 out of 38 partial envelope cDNAs.
- Characterized the splice junction for both prototype FeLV subgroup A and an immunodeficiency-inducing FeLV variant.
- Discovered one novel cDNA generated from a cryptic splice acceptor site, 109 nucleotides downstream of the standard junction, which also encodes envelope protein.
- No additional subgenomic FeLV gene products were detected in chronically infected cells.
Conclusions:
- The primary pathway for FeLV envelope mRNA synthesis involves specific, conserved splice donor and acceptor sites.
- A novel cryptic splice acceptor site can also be utilized, leading to the production of envelope protein.
- The study did not detect evidence of other subgenomic FeLV gene products, suggesting a focused expression strategy for the envelope protein.