Viruses r host specific ie they cannot jump from one species to another then how come aids virus shi

Viruses are host specific, but for example when it comes to the polio virus, biologists actually infect monkey cells with the virus, and it adapts itself. This creates a new virus that is slow growing in humans because it has been adapted to monkey cells. (this was done to create a live vaccine that the body can naturally defeat) In other words, although AIDS didn't start out as a human virus, they have adapted themselves to infect humans. hope this helps

Viruses r host specific ie they cannot jump from one species to another then how come aids virus shifted from?windows live messenger

Viruses mutate. Life always finds a way to survive.