Читать книгу Principles of Virology, Volume 2 - Jane Flint, S. Jane Flint - Страница 78

As sentient humans (and animals), we are constantly surveying our environment for dangers and opportunities. Such senses help all organisms to evade predation and to locate food sources but may also be useful in avoiding infections. For example, a rather typical human behavior upon locating some food toward the back of the refrigerator is to sniff it to see if it is still “good,” and people are usually quite adept at knowing when food is no longer acceptable to eat based on smell and appearance. In principle, food surveillance is a kind of quality control to ensure that the items we eat do not carry dangerous microbes. Similarly, avoiding a murky hot tub or declining the advances of a dubious sexual partner could also be considered finely honed skills that may help to avoid contact with pathogens.

The cells in which a virus reproduces obviously influence the kind of disease that can occur, and thus tropism is a crucial parameter of pathogenesis. Human herpes simplex virus is considered neurotropic because of its ability to infect, and be reactivated from, the nervous system, but in fact, this virus can reproduce in many cells and tissues in the host. In most hosts, a localized infection occurs at the site of infection, followed by latent infection of neurons that innervate that tissue. In some individuals with weakened immune systems, such as neonates and the elderly, the virus may cause viremia, enabling access to distal organs, or may cross from the peripheral nervous system to the central nervous system. While rare, both of these outcomes pose serious risk for long-term disease.