D.7+Antivirals

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**D.7.1**
**State how viruses differ from bacteria**

**Examples of viruses include: common cold, influenza, and diseases such as mumps and measles. Generally, the immune system is strong enough to eradicate the virus, but antiviral drugs do exist for viruses that have such rapid multiplication that they cannot be defeated by the immune system. **

Virus  Bacteria  Describe the different ways in which antiviral drugs work
 * Differences in how bacteria and viruses multiply**
 * insert genetic material (DNA/RNA) into host cell
 * multiply by themselves using cell division / mitosis
 * D.7.2

 ****Antiviral drugs mainly work to prevent virus reproduction/multiplication, in one of these three ways: 1) They block reverse transcriptase enzyme activity with the host cell 2) They alter the host cells genetic material (DNA/RNA) 3) Chemically block the ribosomes preventing the virus from multiplying / replicating 4) They alter the viruses binding site preventing it from binding to the host's cell wall 5) They prevent the virus from enter and/or leaving the host cell **



**D.7.3 **
<span style="color: rgb(0, 0, 255); font-size: 110%;">**Discuss the difficulties associated with solving the AIDS problem**

AIDS (Acquired Immunodeficiency Syndrome) is caused by the HIV virus (human immunodeficiency virus). The HIV virus is a **retrovirus**, meaning that its genetic material comes in the form of RNA, yet it replicates using a DNA intermediate. When one of these viruses attaches to a host cell, a CD4 ⁺ T white blood cell in humans, it binds to specific receptor proteins located on the cell's plasma membrane. The virus then injects its RNA and reverse transcriptase enzymes into the cell's interior. There, the reverse transcriptase serves its purpose, synthesizing DNA from the RNA. The host cell assumes this DNA and thus manufactures more of the virus (called virions), which eventually accumulates, kills the host cell, and is released to infect other cells. The patient does not die from AIDS, but from other diseases which prevail in the patient's weakened immunity state.

Drugs designed to fight HIV center around inhibiting reverse transcriptase, blocking the binding of HIV viruses to cell membranes, and preventing the assembly of the virus in the host cell. These drugs are known as antiretroviral drugs and take effect at various stages in the virus' lifecycle. The most common treatment, highly active antiretroviral therapy (HAART), uses a combination of **reverse transcriptase inhibitors** and **protease inhibitors**, which target and alter the formation of DNA from RNA and the production of virions, respectively.These drugs delay the progress of the virus through the body, yet they are not cures. And, unfortunately, they produce unpleasant side effects. Not to mention that they are costly.

Specific proteins on the HIV virus bind to a receptor protein on certain white blood cells (T cells). Because of the ability of the HIV viruses to mutate, and because their metabolism is linked closely with that of the cell, effective treatment with antiviral drugs is very difficult, as is vaccine development. The control and treatment of HIV is exacerbated by the high price of anti-retroviral agents and sociocultural issues. [|Link to Website]

<span style="color: rgb(0, 0, 0);">**<span style="font-weight: normal; color: rgb(0, 0, 0); font-family: Helvetica;">Antiviral drugs ****<span style="font-weight: normal; color: rgb(0, 0, 0); font-family: Helvetica;">prevent the HIV virus from interacting with human cells by: ** <span style="font-family: Verdana,Geneva,sans-serif;"><span style="color: rgb(0, 0, 0); font-weight: normal; font-family: Helvetica;">
 * <span style="font-family: Verdana,Geneva,sans-serif;">Alters the receptive site so HIV virus can't attach to the human cell
 * <span style="font-family: Verdana,Geneva,sans-serif;">Prevents HIV from losing is protein coat
 * <span style="font-family: Verdana,Geneva,sans-serif;">block reverse transcriptase and production of new viral RNA and proteins
 * <span style="font-family: Verdana,Geneva,sans-serif;">stops viruses from leaving the cell
 * Effective treatment of the HIV virus is difficult because:**
 * <span style="font-family: Verdana,Geneva,sans-serif;">HIV virus mutates rapidly
 * <span style="font-family: Verdana,Geneva,sans-serif;">HIV metabolism depends on the host cell, so treatment to kill HIV can also harm host cell
 * <span style="font-family: Verdana,Geneva,sans-serif;">Drugs therefore harm the host cell as well as HIV
 * <span style="font-family: Verdana,Geneva,sans-serif;">HIV can remain dormant in the host cell