Identification of virus-coded nonstructural polypeptides in bunyavirus-infected cells

Area of Science:

• Virology
• Molecular Biology
• Genetics

Background:

• Bunyaviruses are RNA viruses known to induce nonstructural proteins during infection.
• Understanding the genetic basis and function of these nonstructural proteins is crucial for viral pathogenesis research.
• Previous studies have identified viral RNA segments coding for structural proteins like nucleocapsid (N).

Purpose of the Study:

• To identify and characterize virus-induced nonstructural polypeptides in bunyavirus infections.
• To determine the viral RNA segments responsible for coding specific nonstructural proteins in Snowshoe Hare (SSH) and La Crosse (LAC) viruses.
• To analyze the genetic relatedness of these nonstructural proteins between SSH and LAC bunyaviruses.

Main Methods:

• Analysis of bunyavirus-infected cell extracts using polyacrylamide gel electrophoresis.
• Construction and analysis of SSH-LAC reassortant viruses to map protein coding regions.
• Tryptic peptide analysis of [3H]leucine- or [3H]arginine-labeled nonstructural proteins (NSs).

Main Results:

• Identified two major virus-induced nonstructural polypeptides: NSs (approx. 7.4 kDa) and NSM (approx. 12 kDa).
• The SSH small (S) RNA species codes for the NSs nonstructural polypeptide, which contains unique sequences compared to the SSH nucleocapsid (N) protein.
• The SSH medium (M) RNA species codes for the NSM nonstructural polypeptide; a similar but distinct polypeptide (LAC NSM, approx. 11 kDa) is coded by LAC M RNA.

Conclusions:

• The small RNA of Snowshoe Hare virus encodes a unique nonstructural protein (NSs).
• The medium RNA of SSH and LAC viruses encodes distinct nonstructural proteins (NSM).
• Further research is needed to determine the function and relationships of these nonstructural proteins and other identified viral polypeptides (p10, p18).