Complementation of defective reovirus by ts mutants.

Area of Science:

• Virology
• Molecular Biology
• Genetics

Background:

• Defective reovirions, missing the L-1 genomic segment, require helper virus for replication.
• Physical separation of defective and infectious reovirions is challenging due to similar properties.

Purpose of the Study:

• To develop a method for isolating pure populations of defective reovirions.
• To investigate the genetic functions of the L-1 genomic segment in reovirus replication.

Main Methods:

• Controlled digestion of reovirus outer capsomeres to create core particles.
• Separation of defective and infectious core particles based on buoyant density differences.
• Co-infection of L cells with defective cores and a temperature-sensitive mutant (class E).
• Serial passage at permissive (31°C) and non-permissive (39°C) temperatures.

Main Results:

• A buoyant density difference (1.43g/ml vs. 1.415g/ml) allowed separation of defective and infectious reovirus cores.
• Serial passage at non-permissive temperature yielded predominantly defective virions, free of helper virus.
• Complementation analysis revealed the L-1 function is trans-acting, while the class E mutation is cis-acting.

Conclusions:

• A novel method effectively isolates defective reovirions by exploiting buoyant density differences.
• The L-1 genomic segment's function is essential and acts in trans for reovirus replication.
• Defective reovirions can be complemented by specific temperature-sensitive mutants affecting late functions.