D7 - Antivirals

D.7.1

• State how viruses differ from bacteria.

List the differences you know of between bacteria and viruses.

Bacteria Viruses

List the differences you know of between bacteria and viruses.

Bacteria• Microscopic• Has single, circular strand of

DNA—is able to manufacture RNA from the DNA.

• Cell wall• Can reproduce on its own.

Viruses• Submicroscopic• Has either a section of DNA or

RNA surrounded by a coat of packed protein units called capsomeres.

• No cell wall• Can’t reproduce without a

living host. Takes over cell’s machinery to produce more viruses.

D.7.2

• Describe the different ways in which antiviral drugs work.

Describe the different ways in which antiviral drugs work.

Well known viral infections• Common cold• Influenza (Including H1N1)• HIV/AIDS• Chicken Pox• Herpes/wartsWhat is the body’s natural defense to viral

infections?

Describe the different ways in which antiviral drugs work.

• Viruses multiply very quickly, so antiviral drugs will often have little effect by the time symptoms appear.

• Goal of antiviral drugs is to stop replication.

Describe the different ways in which antiviral drugs work.

• Acyclovir is used as a cream or orally to fight herpes viruses.

• Shortens the time of the outbreak, but does not prevent recurrences.

• It stops replication of viral DNA, and prevents virus from multiplying.

Describe the different ways in which antiviral drugs work.

• Other antiviral drugs prevent new viruses from leaving the cell.

• Amantadine (C10H17N) is used to treat influenza. It inhibits the active site of an enzyme which helps the virus to stick to the cell wall.

D.7.3

• Discuss the difficulties associated with solving the AIDS problem.

Discuss the difficulties associated with solving the AIDS problem.

• HIV (Human Immunodeficiency Virus) can lead to AIDS (Acquired Immune Deficiency Syndrome).

• HIV attacks white blood cells called T helper cells (T4-cells).

• HIV therefore destroys the body’s ability to fight infections, leading to common infections (pneumonia, influenza) which can become life threatening (AIDS).

Discuss the difficulties associated with solving the AIDS problem.

• The virus is a retrovirus since is contains RNA instead of DNA.

• It makes viral DNA from RNA using an enzyme called reverse transcriptase.

• One of the problems with antiviral drugs for HIV is the virus is constantly mutating.

• A drug called AZT has been used to inhibit the reverse transcriptase, and this does not affect normal cells.

• AZT has been effective in prolonging the period until AIDS develops.