A. Helps fight the intruders and are custom - made to each virus.
a disease in which there is a severe loss of the body's cellular immunity, greatly lowering the resistance to infection and malignancy. HIV can be spread through any type of unprotected inter course, if one of the partners has the virus. This can happen when body fluids such as semen, vaginal fluids, or blood from an infected person get into the body of someone who is not infected.
Breathing and heartbeat (using either the inside of the wrist or the big vein in your neck that I always forget the name of, haha)
Good luck~~