Respiratory syncytial virus polypeptides. III. The envelope-associated proteins

Area of Science:

• Virology
• Molecular Biology
• Protein Chemistry

Background:

• Respiratory Syncytial Virus (RSV) envelope proteins are crucial for viral structure and function.
• The exact viral or cellular origin of the GP1 protein in RSV infections has been debated.
• Understanding the structural relationships between RSV envelope proteins is key to deciphering viral assembly and infectivity.

Purpose of the Study:

• To definitively establish the viral structural status of the GP1 protein in RSV.
• To investigate the quaternary structure and potential disulfide linkages of other RSV envelope proteins, VGP48, GP26, and VPM27.

Main Methods:

• Polyacrylamide gel electrophoresis (PAGE) under various conditions (Laemmli's discontinuous buffer, neutral SDS-PAGE, non-reducing PAGE).
• Enzymatic treatment with trypsin to differentiate viral from cellular proteins.
• Purification of RSV strains (RSN-2 and Long) from infected cells.
• One-dimensional peptide mapping for protein analysis.

Main Results:

• GP1 was confirmed as a viral structural protein, distinguishable from a cellular glycoprotein by trypsin sensitivity and differential migration on SDS-PAGE.
• GP1 was detected in purified RSN-2 and Long strains of RSV.
• Under non-reducing conditions, VGP48 and GP26 migrated as a single entity, suggesting they form a disulfide-linked complex.
• VPM27 resolved into two distinct bands, likely representing variants with different disulfide bond configurations.

Conclusions:

• GP1 is a bona fide viral structural protein of Respiratory Syncytial Virus.
• VGP48 and GP26 likely exist as a single disulfide-bonded protein in the virion, analogous to paramyxovirus fusion proteins.
• VPM27 may exist in multiple forms due to variations in disulfide bonding, impacting its structure within the virion.