Note: this site last updated in 2006
HIV to lie low
An article from "The Molecules of HIV" (c) Dan Stowell
Although helper T cells are the main target of HIV, HIV can only use a helper T cell to replicate when that cell is activated. At any one time, the normal proportion of T cells which are active is around 1 in 10000 - the rest are "dormant".
Is this a "mistake" on HIV's part? No, in fact it allows HIV to lie low, producing only small amounts of new virus and therefore not arousing the suspicion of the human immune system. (HIV-infected monocytes/macrophages, as opposed to T cells, continuously produce these low levels of new virus.) HIV suppresses its own production in cells via the regulatory genes it carries with it.
The key event is when HIV-infected T cells become activated - for example, when the immune system is alerted to the HIV particles seeping through the body. Activated T cells start to produce copious amounts of virus, and of course, this increases the amount of HIV particles in the body. The increased amount of HIV particles stimulates even more T cells to become activated - and this will lead to the production of more virus - which stimulates the immune system even more - and so on! This vicious circle, or autocatalysis, cascades to produce a massive amount of virus - the trojan army attacks!