Viruses A virus is a NON-Living particle made of DNA or RNA and a protein coat. Look at table 25-1 on p. 487 in text book. VERY small. ~ 0.001micron

Viral Replication Because they are not cells they can’t replicate on their own. Intracellular parasites. They invade a host cell and use that cell to reproduce.

Lytic Cycle

Viruses and Human Disease H1N1 HIV Common Cold Chicken Pox Measles Mumps Polio Rabies Hepatitis Small Pox West Nile Mono

Prevention and Treatment Antiviral drugs drugs that interfere with virus replication. There are very few antiviral drugs so they are not commonly used. Vaccines are used to prevent viral infections.

Immunity When you are in contact with a virus your white blood cells create what are called antibodies.  Antibodies are disease-fighting proteins located on the cell membrane. If you come in contact with this exact same virus again your body will recognize it and destroy it.

Vaccines Helps the body's own defense system prevent a disease by producing antibodies against it. Vaccines use a weakened or killed version of the virus. Researchers may spend years working on a vaccine. They have still not succeeded against HIV or against malaria, but they are trying. Not all vaccines offer long-term protection. The tetanus vaccine, for example, offers protection for only about ten years. Then a person must be immunized again. Some vaccines are made with animal material. For example, influenza vaccine is grown in chicken eggs. This can be a problem for people who are allergic to eggs.