Remember how viruses work: They are merely little bits of genetic material that "hijack" the host cell's mechanisms and cause the host cell to start cranking out many, many new copies of the virus. Eventually, the host cell bursts, releasing all the new virions (virus particles) to go infect new hosts. It's simply this rupturing of the host cell's membrane that kills it, and it's pretty-much the same story with any virus, from good old cold viruses (rhinoviruses) to HIV.

 11:21, 27 Apr 2005 (UTC)