Polypeptides and immunoreactivity of empty adenovirus type 1 particles

Area of Science:

• Virology
• Molecular Biology
• Structural Biology

Background:

• Human adenovirus type 1 (HAdV1) assembly involves the formation of complete virions and potentially empty capsids.
• Understanding the nature and origin of empty virus particles is crucial for deciphering viral assembly pathways.

Purpose of the Study:

• To characterize distinct populations of empty particles in HAdV1-infected cells.
• To investigate the relationship between empty capsids, assembly intermediates, and complete virions.
• To determine the effect of antibody binding on virion structure and protein stability.

Main Methods:

• Characterization of empty particle populations using CsCl density gradients.
• Analysis of protease sensitivity and polypeptide composition.
• Immunological assays using antihexon and antifibre antibodies.
• Investigation of antibody-induced structural changes and protein loss.

Main Results:

• Two distinct CsCl-stable empty particle populations (A and B) were identified.
• These empty particles are likely degradation products of different assembly intermediates, exhibiting varied protease sensitivity and polypeptide composition.
• Both empty particle populations showed similar reactivity to antihexon antibodies as complete virions, indicating conserved exposed epitopes.
• Antifibre and antihexon antibodies induced structural changes in complete virions, leading to the specific loss of core protein V.

Conclusions:

• The conserved arrangement of exposed type-specific epitopes on empty capsids suggests a stable structural framework during adenovirus assembly.
• Antibody-mediated aggregation triggers a conformational change in complete virions, resulting in the release of internal protein V.
• These findings provide insights into adenovirus structural stability and the mechanisms of antibody-induced virion disassembly.