Читать книгу Principles of Virology - Jane Flint, S. Jane Flint - Страница 76

Before quantitative methods for measuring viruses were developed, evidence of viral propagation was obtained by visual inspection of infected cells. Some viruses kill the cells in which they reproduce, and they may eventually detach from the cell culture plate. As more cells are infected, the changes become visible and are called cytopathic effects.

Many types of cytopathic effect can be seen with a simple light or phase-contrast microscope at low power, without fixing or staining the cells. These changes include the rounding up and detachment of cells from the culture dish, cell lysis, swelling of nuclei, and sometimes the formation of a group of fused cells called a syncytium (Fig. 2.5). High-power microscopy is required for the observation of other cytopathic effects, such as the development of intracellular masses of virus particles or unassembled viral components in the nucleus and/or cytoplasm (inclusion bodies), formation of crystalline arrays of viral proteins, membrane blebbing, duplication of membranes, and fragmentation of organelles.

Figure 2.4 Production of airway-liquid interface cultures of bronchial epithelium. (A) Epithelial cells are seeded onto a permeable membrane and cell culture medium is supplied on both apical (top) and basal (bottom) sides. (B) When the cells are confluent, medium on the apical side is removed. Contact of the cells with air drives differentiation of cells towards types found in the airways, such as goblet cells, ciliated and nonciliated cells, and basal cells. Cultures may be produced that mimic tracheobronchial cells, with different cell types, or human alveolar cells with only two cell types (not shown).