medicine of course well i guess doctors also help too.
You are thinking of an antibody.
they defend against infection and viruses
Blood cells defend the body basically by destroying virus cells. They do this basically by inhaling them.
what two organ stysems that defend the body against infection are
A vaccin is a weakend version of the virus, so the human body can make itself resistant against it, without getting the symptoms of the illness/disease. So your body will be resistant against virusses, as it "recognizes"(Because it made anti-virus against this typical kind of virus the first time) the virus, when it enters the body, it uses the anti-virus cells made earlier and then duplicates/copys them to kill the virus.
4. the presence in the body of the virus that cuases AIDS
The bodies first defence against a virus is your skin. The body first defense against a virus is Mucus. Mucus
interferon
They don't make you sick because the doctors, or whoever, take a DEAD flu virus, or whatever it is, and they put it in the syringe used to inject you with, so your body knows how to defend itself against that particular virus.
they help to defend the body against diseases
The stomach contains acids that defend your body against microbes. Most of these microbes are destroyed once they are digested and enter into the acidic stomach.
Essentially, the HIV virus disables the body's ability to defend itself. It targets white blood cells, specifically T-helper cells or CD4+ cells, and kills them. By doing this, the body slowly loses the ability to defend itself against infections.