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Recombinant Sendai viruses with L1618V mutation in their L polymerase protein establish persistent infection, but not
Machiko Nishio1, Ai Nagata, Masato Tsurudome
1Department of Microbiology, Mie University School of Medicine, Mie-Prefecture 514-8507, Japan.
Abstract:
The Sendai virus pi strain (SeVpi) isolated from cells persistently infected with SeV shows mainly two phenotypes: (1) temperature sensitivity and (2) an ability of establishing persistent infection (steady state). Three amino acid substitutions are found in the Lpi protein and are located at aa 1088, 1618, and 1664. Recombinant SeV(Lpi) (rSeV(Lpi)) having all these substitutions is temperature sensitive and is capable of establishing persistent infection (steady state). rSeVs carrying the fragment containing L1618V show both phenotypes. rSeV(L1618V), in which leucine at aa 1618 is replaced with valine, has the ability of establishing persistent infection, but is not a temperature-sensitive mutant, indicating that the ability of a virus to establish persistent infection can be separated from temperature sensitivity. The amino acid change at 1618(L-->V) coexisting with aa 1169 threonine is required for acquirement of a temperature-sensitive phenotype. Three amino acid substitutions are also found in the Ppi protein, but rSeV(Ppi) does not show these phenotypes.
Insights
Sendai virus pi strain (SeVpi) exhibits temperature sensitivity and persistent infection. A specific L1618V mutation in the Lpi protein enables persistent infection independently of temperature sensitivity.
Area of Science:
- Virology
- Molecular Biology
- Genetics
Background:
- Sendai virus pi strain (SeVpi) exhibits unique phenotypes: temperature sensitivity and persistent infection.
- Understanding the genetic basis of these phenotypes is crucial for viral research.
Purpose of the Study:
- To investigate the molecular mechanisms underlying SeVpi's temperature sensitivity and persistent infection.
- To identify specific mutations in the Lpi and Ppi proteins responsible for these phenotypes.
Main Methods:
- Isolation and characterization of SeVpi.
- Generation of recombinant Sendai viruses (rSeVs) with specific mutations in Lpi and Ppi proteins.
- Assessment of viral phenotypes, including temperature sensitivity and persistent infection capability.
Main Results:
- Three amino acid substitutions in the Lpi protein (aa 1088, 1618, 1664) were identified in SeVpi.
- Recombinant rSeV(Lpi) with all three substitutions displayed both temperature sensitivity and persistent infection.
- A specific mutation, L1618V in the Lpi protein, was found to confer persistent infection independently of temperature sensitivity.
- The L1618V mutation, when combined with threonine at aa 1169, was necessary for temperature sensitivity.
- Mutations in the Ppi protein did not result in these observed phenotypes.
Conclusions:
- The L1618V substitution in the Lpi protein is a key determinant for establishing persistent Sendai virus infection.
- Temperature sensitivity and persistent infection phenotypes can be genetically separated.
- Specific amino acid changes in viral proteins play critical roles in viral adaptation and pathogenesis.
