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Updated: Aug 26, 2026
Influenza Virus Propagation in Embryonated Chicken Eggs
Published on: March 19, 2015
Observations with the electron microscope on cells of the chick chorio-allantoic membrane infected with influenza
Abstract:
Preparations of influenza-infected chick chorio-allantoic membrane made by two types of tissue culture and by sectioning, have been studied in the electron microscope. Comparisons have been made of influenza A' (FM1), influenza A (PR8), and swine influenza (V15), three strains which produce different relative numbers of filaments. Normal surface projections which may be confused with influenza filaments are described. Extruded products of degenerating cells, usually bleb-shaped, may also be found both in uninfected allantoic fluid and tissue cultures. It appears that the filaments and spheres of influenza virus, concurrently projecting from the free cell surface, represent the only visible change in the cells until late in the infection,-how late the present work does not tell. No definite evidence of a generalized infection throughout the cytoplasm or of inclusions was found. Additional evidence is presented for the assumption that the filaments have a significant role in the final development of the free virus.
Insights
Electron microscopy revealed that influenza virus filaments and spheres projecting from cell surfaces are the primary visible changes in infected chick chorio-allantoic membranes. These structures appear crucial for the final development of free influenza virus particles.
Area of Science:
- Virology
- Cell Biology
- Microscopy
Background:
- Influenza virus infection affects the chorio-allantoic membrane of chick embryos.
- Understanding the morphological changes during influenza virus infection is crucial for comprehending viral replication and pathogenesis.
Purpose of the Study:
- To investigate the ultrastructural changes in influenza-infected chick chorio-allantoic membranes using electron microscopy.
- To compare the morphological characteristics of different influenza virus strains (A', A, and swine influenza) in infected tissues.
- To elucidate the role of viral filaments in the development of infectious influenza virus particles.
Main Methods:
- Preparation of infected chick chorio-allantoic membranes using two tissue culture methods and sectioning.
- Examination of prepared samples using electron microscopy.
- Comparative analysis of three influenza virus strains: influenza A' (FM1), influenza A (PR8), and swine influenza (V15).
Main Results:
- Observed normal surface projections that could be mistaken for viral filaments.
- Identified extruded products from degenerating cells, distinct from viral structures.
- Noted that influenza virus filaments and spheres projecting from the cell surface were the main visible changes until late infection stages.
- Found no evidence of generalized cytoplasmic infection or inclusions.
Conclusions:
- Influenza virus filaments and spheres are the primary observable cellular alterations during infection.
- These viral structures are implicated in the final development and release of free influenza virus.
- Distinguishing viral filaments from normal cellular projections is important for accurate interpretation.
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