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Western equine encephalitis virus is a recombinant virus.
C S Hahn1, S Lustig, E G Strauss
1Division of Biology, California Institute of Technology, Pasadena 91125.
Summary
Western equine encephalitis virus (WEEV) is a recombinant alphavirus. It likely arose from recombination between an eastern equine encephalitis virus-like and a Sindbis virus-like ancestor, supporting the role of recombination in RNA virus evolution.
Area of Science:
- Virology
- Molecular Biology
- Evolutionary Biology
Background:
- Alphaviruses are mosquito-borne viruses causing diverse human diseases, including encephalitis (New World) or fever and rash (Old World).
- Alphavirus genomes are single-stranded RNA, approximately 11,700 nucleotides long, and have evolved from a common ancestor.
Purpose of the Study:
- To determine the evolutionary origins of the New World alphavirus, western equine encephalitis virus (WEEV).
- To investigate the role of recombination in the evolution of RNA viruses.
Main Methods:
- Sequencing of the 3'-terminal 4288 nucleotides of WEEV RNA.
- Comparative analysis of nucleotide and amino acid sequences of WEEV with other alphaviruses.
Main Results:
- WEEV shows evidence of genetic recombination, indicating it is not solely derived from a single ancestor through divergent evolution.
- WEEV capsid protein and 3'-terminal sequences are closely related to eastern equine encephalitis virus (EEEV), a New World alphavirus.
- WEEV glycoproteins E2 and E1 are more closely related to Sindbis virus, an Old World alphavirus.
Conclusions:
- WEEV likely originated from a recombination event between an EEEV-like and a Sindbis-like virus.
- This recombination resulted in a virus with EEEV's encephalitogenic properties and Sindbis virus's antigenic specificity.
- The findings support the hypothesis that recombination is a significant mechanism in the evolution of RNA viruses.