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Mutants of Sindbis virus. III. Host polypeptides present in purified HR and ts103 virus particles
Abstract:
The amounts of host-encoded protein present in purified Sindbis virions of both the HR strain and of a mutant (ts103) which makes multicored particles were examined. Cells were labeled with [35S]methionine before infection and with [3H]methionine postinfection. Virions were purified by velocity sedimentation and isopycnic banding, and their polypeptides were examined by polyacrylamide gels in a sodium dodecyl sulfate-containing discontinuous buffer system. Host prelabeled material was found principally in a small number of discrete polypeptides in HR virions, which contained as little as 0.2% host-encoded protein. Virus-sized particles of mutant ts103 contained significantly more host material, and multiploid particles from ts103 infection contained up to 12% host prelabeled protein.
Insights
Researchers quantified host proteins in Sindbis virus particles. Mutant Sindbis virus (ts103) produced multicored particles containing significantly more host-encoded proteins than the wild-type HR strain.
Area of Science:
- Virology
- Molecular Biology
- Biochemistry
Background:
- Sindbis virus is an enveloped RNA virus.
- Virion composition can be influenced by genetic mutations.
- Understanding viral protein incorporation is crucial for virology.
Purpose of the Study:
- To quantify and characterize host-encoded proteins within purified Sindbis virions.
- To compare host protein content between the wild-type HR strain and a mutant (ts103) that forms multicored particles.
Main Methods:
- Cells were pre-labeled with 35S-methionine and post-infected with 3H-methionine.
- Sindbis virions were purified using velocity sedimentation and isopycnic banding.
- Polypeptides were analyzed using SDS-polyacrylamide gel electrophoresis.
Main Results:
- Wild-type HR Sindbis virions contained minimal host protein (as little as 0.2%).
- Mutant ts103 produced virus-sized particles with increased host protein content.
- Multicored particles from ts103 infection incorporated up to 12% host-encoded protein.
Conclusions:
- The ts103 mutation leads to increased incorporation of host proteins into Sindbis virions.
- Particle morphology (multicored) correlates with higher levels of host protein contamination.
- These findings highlight the impact of viral mutations on virion composition.