AIDS- lqc 9a

Question 1

what determines the speed of development of AIDS?

Answer 1

Many factors are involved – the health of the host before infection, their genetic resistance to infection, the quality of their immune response to infection, their lifestyle, their nutritional status, the availability of drug treatment, other infections.

Question 2

describe the acute phase

Answer 2

HIV antibodies appear in the blood after 3 – 12 weeks (once detected the individual is said to be HIV positive). Person may experience fever, sweats, headache, sore throat and swollen lymph glands. There is a rapid replication of new virus particles and loss of T helper cells. After a few weeks, infected T helper cells are targeted by T killer cells and destroyed. This greatly reduces the rate of viral replication, but does not totally eliminate it.

Question 3

describe the chronic phase

Answer 3

Also known as the latent phase – can last 20 years. The virus replicates rapidly, but the immune system keeps numbers in check. There may be no symptoms apart from more colds and minor infections. TB and shingles can reactivate.

Question 4

describe the disease phase

Answer 4

Eventually an increased viral load and significant reduction in T helper cell count (<200 / mm3 of blood) indicates the onset of AIDS. The immune system is now vulnerable to opportunistic infections such as TB and pneumonia. Karposi’s sarcoma (type of skin cancer) can develop. There is also significant weight loss and sometimes the development of dementia. The development of these symptoms leads to death.

Question 5

What are the drugs used to treat an HIV infection collectively known as?

Answer 5

antiretroviral drugs

Question 6

two main types and new type of antiretroviral drug

Answer 6

Reverse transcriptase inhibitors – these prevent the viral RNA from making DNA for integration into the host’s genome. Protease inhibitors – these inhibit the proteases that catalyse the cutting of larger proteins into small polypeptides for use in the construction of new viruses. An integrase inhibitor and fusion inhibitor drugs have also been approved for use.

Question 7

why are drugs given in combination?

Answer 7

HIV can develop resistance to anti-HIV drugs. If the virus becomes resistant to one drug, it may still be susceptible to the other drugs being taken.