Fine structure of cellular inclusions in measles virus infections

Area of Science:

• Cell Biology
• Virology
• Microscopy

Background:

• Measles virus-infected cells exhibit distinct inclusion bodies visible under light microscopy.
• Previous studies identified these inclusions using traditional staining methods.

Purpose of the Study:

• To investigate the fine structure of inclusion material in measles virus-infected HeLa cells using electron microscopy.
• To correlate light microscopy observations with electron microscopy findings.

Main Methods:

• Phase-contrast microscopy was used to identify inclusion bodies in living cells.
• Electron microscopy was employed to examine the ultrastructure of these identified inclusion bodies.
• Osmium-treated cells were analyzed to determine the composition of inclusion material.

Main Results:

• Inclusion material in both nucleus and cytoplasm primarily consists of randomly arranged, low-electron-density filaments.
• Dense, ordered filament arrays, sometimes orthogonally arranged, were observed in the center of nuclear inclusions.
• The observed filaments are too small to be complete measles virus particles (approx. 100 nm diameter).

Conclusions:

• The fine structure of measles virus inclusion bodies is characterized by filamentous material.
• These filaments do not represent fully assembled measles virus, suggesting they may be viral components or aggregates.
• The study provides detailed ultrastructural insights into measles virus-induced cellular changes.