Читать книгу Principles of Virology, Volume 2 - Jane Flint, S. Jane Flint - Страница 82

Following reproduction at the site of entry, virus particles can remain localized or can spread to other tissues. Spread beyond the initial site of infection depends on multiple parameters, including the initial viral dose, the presence of viral receptors on other cells, and the relative rates of immune induction and release of infectious virus particles. Localized infections in the epithelium are usually limited by the physical constraints of the tissue and are brought under control by the intrinsic and innate immune defenses discussed in Chapter 3. An infection that spreads beyond the primary site (usually near the point of viral entry) is said to be disseminated. If many organs are viral targets, the infection is described as systemic. Spread beyond the primary site requires continued breaching of the host’s physical barriers. For example, virus particles may be able to cross a basement membrane when the integrity of that structure is compromised by inflammation and epithelial cell destruction. Below the basement membrane are subepithelial tissues, where virus particles encounter tissue fluids, the lymphatic system, and phagocytes. These host components make substantial contributions to clearing foreign particles, but may also allow infectious virus particles to be carried beyond the primary site of infection.