BCH2011 Lecture Notes - Lecture 14: Aspartic Protease, Hiv-1 Protease, Reverse Transcriptase

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20 Jan 2017

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An understanding of protease mechanisms leads to new treatments for. Retroviruses possess an rna genome and an enzyme, reverse transcriptase, capable of using rna to direct the synthesis of a complementary dna. A retrovirus such as hiv has a relatively simple life cycle. Its rna genome is converted to duplex dna in several steps catalyzed by a reverse transcriptase. The duplex dna is then inserted into a chromosome in the nucleus of the host cell by the enzyme integrase. The inserted copy of the viral genome can remain dormant indefinitely. Alternatively, it can be transcribed back into rna, which can then be translated into proteins to construct new virus particles. Most of the viral genes are translated into large polypeptides, which are cut by the hiv protease into the individual proteins needed to make the virus. There are only three key enzymes in this cycle the reverse transcriptase, the integrase, and the protease.

Related Questions

Question 1 10 pts Which class of anti AIDS drugs is used to prevent the virus from integrating into the host genome so that it can live indeï¬nitely in a dormant state inside the host.

Question 2 10 pts Which class of drug interferes with the maturation of the virus by preventing a long nonfunctional polypeptide from being cut into three separate functional proteins?

Nucleoside reverse transcriptase inhibitor
Non-nucleoside reverse transcriptase inhibitor
Protease inhibitor
Integrase inhibitor
Fusion inhibitor
CCR5 inhibitor
Nucleoside reverse transcriptase inhibitor
Non-nucleoside reverse transcriptase inhibitor
Protease inhibitor
Integrase inhibitor
Fusion inhibitor

Question 3 10 pts What is the major limitation in the use of Nucleoside Reverse Transcriptase Inhibitors ( NRTIs) for AIDS treatment?

Question 4 10 pts What is the approximate annual cost of triple combination therapy for HIV infection

Question 5 10 pts Read the article in the Module 8 Learning Materials entitled New hope for babies with HIV:
http://www.cnn.com/2017/07/24/health/hiv-remission-southafrican-boy/index.html
Discuss the the study. Answer the following questions in your discussion:

CCR5 inhibitor
$2,000
$5,000
$15,000
$25,000
1. Describe the study and the results.
2. Give your personal opinion about this strategy for short-term treatment.
3. Do you think this might be a promising treatment for babies in third world countries, since lifelong treatment with triple combination therapies can be too expensive?

1
Which of the following is a component of the HIV virus ?
A
DNA
B
Capsid
C
Nucleus
D
CD4 receptor
Answered
Change your responses to resubmit
2
Assigned as
Homework
2
What is the function of Reverse Transcriptase?
A
To insert the viral RNA into the host DNA.
B
To make an RNA copy of the viral RNA.
C
To make an RNA copy of the viral DNA.
D
To make a DNA copy of the viral RNA.
E
To insert the viral DNA into the host DNA.
Unanswered
Submit
3
Assigned as
Homework
3
Which of the following stages describes a HIV patient in who has a large number of severe opportunistic infections?
A
Primary HIV infection-lasts for a few weeks
B
Clinically asymptomatic stage-lasts for an average of ten years
C
Symptomatic HIV infection
D
Clinical AIDS
Unanswered
Submit
4
Assigned as
Homework
4
Which of the following individuals should be tested for HIV?
A
A newborn child
B
Alex, who studies excessively
C
Sarah, who takes birth control
D
Joe, who uses intravenous steroids
Unanswered
Submit
5
Assigned as
Homework
5
Harry engaged in risky activity that may have lead to exposure to HIV. Two and a half weeks later, he had an HIV test done and it showed a positive result. Which test most likely was done?
A
CD4 test
B
HIV antibody test
C
PCR test
D
Viral load test
Unanswered
Submit
6
Assigned as
Homework
6
How does an Integrase inhibitor work against the HIV virus?
A
It inhibits the generation of viral DNA from viral RNA.
B
It prevents the entry of HIV into the host cell.
C
It inhibits viral proteins from being inserted into new virus particles.
D
It prevents viral DNA from being inserted into host DNA.
E
It prevents the generation of new viral proteins.
Unanswered
Submit
7
Assigned as
Homework
7
How does a Protease inhibitor work to treat HIV infection?
A
It prevents the release of new viral particles.
B
It cleaves viral proteins interfering with their function.
C
It prevents the cleavage of host DNA preventing viral DNA from being inserted into host DNA.
D
It cleaves Reverse transcriptase preventing the generation of viral DNA.
E
It prevents the binding of gp120 to the CD4 protein.
Unanswered
Submit
8
Assigned as
Homework
8
Which of the following describes a combination therapy for HIV infected persons?
A
A preparation used for stimulating a viral response in the body.
B
A single drug given to HIV infected people since interactions with other medications may promote complications in treatment.
C
A drug cocktail-or-combination of antiviral drugs given to HIV infected people since they can be more effective than when given individually
D
A preparation used for stimulating an immune response in the body.
Unanswered
Submit
9
Assigned as
Homework
9
answerable question reference
For HIV to reproduce, which of the following is most critical?
A
Infecting new subjects
B
Producing a Provirus
C
Entering the host cells
D
Taking over the function of DNA in the cell
Unanswered
Submit
10
Assigned as
Homework
10
HIV is a virus which has the following characteristic?
A
It takes of the RNA of the host cell which subsequently by way of transcription and translation makes new virus
B
It attacks the RNA of the host cell causing cellular death
C
It attacks the DNA of the host cell causing cellular death
D
It takes over the DNA of the host cell which subsequently by way of transcription and translation makes new virus

Question 1 10 pts

What three kinds of cells are infected by HIV?

macrophages, T-Helper cells and dendritic cells

B-cells, skin cells and T-helper cells

B-cells, T-Helper cells and T-killer cells

macrophages, dendritic cells and cytotoxic T-cells

Question 2 10 pts

Sometimes an HIV infected cell is not killed immediately after infection, but lives on, and continues to be a source of the infection for the lifetime of the patient. What is the mechanism that allows the HIV virus to remain in the cell, to get passed down to all descendants of that cell, and to retain the ability to be reactivated for the lifetime of the patient?

Question 3 10 pts

List the three processes that viruses are dependent on their host cells for.

Question 4 10 pts

What does the ELISA test for HIV infection measure?

HIV-specific antibodies

Hepatitis B-specific antibodies

circulating HIV particles

HIV-specific DNA

Question 5 10 pts

What is the cell surface receptor for HIV?

CD4

CD8

MHCII

HIV

Question 6 10 pts

What is the likely origin of HIV-1?

infection of humans by a simian virus native to the chimpanzee

germ warfare research by the CIA

sexually transmitted to humans through relations with sheep

a new human-chimpanzee hybrid virus accidentally made in a laboratory with recombinant DNA

Question 7 10 pts

How does AZT block the production of infectious virus?

It acts as a substitute for a DNA nucleotide that can only be inserted by the viral reverse transcriptase. The presence of the AZT in the DNA aborts the production of new viral DNA.

It directly blocks the reverse transcriptase.

It blocks the protease that cuts apart the three viral proteins, which is a necessary step during viral synthesis.

It blocks the adsorption of the virus to the CXCR4 and CCR5 receptors on the T-cell surface.

Question 8 10 pts

How do protease inhibitors work?

It blocks the protease that cuts apart the three viral proteins, which is a necessary step during viral synthesis.

It directly blocks the reverse transcriptase.

It acts as a substitute for a DNA nucleotide that can only be inserted by the viral reverse transcriptase. The presence of the AZT in the DNA aborts the production of new viral DNA.

It blocks the adsorption of the virus to the CXCR4 and CCR5 receptors on the T-cell surface.

Question 9 10 pts

What are the 2 most common causes of a false negative result in the HIV test?

Questions 10-13

The next set of 4 questions deal with the possible ways that a virus, not necessarily the HIV, can enter the body. Answer TRUE or FALSE to each question.

Question 10 2.5 pts

Some viruses can enter the body through breaks in the skin.

True

False

Question 11 2.5 pts

Some viruses can enter the body through the anal/genital tract.

True

False

Question 12 2.5 pts

Some viruses can enter the body through the oral cavity and the digestive tract.

True

False

Question 13 2.5 pts

Some viruses can enter the body through inhalation via the respiratory tract.

True

False

BCH2011 Lecture Notes - Lecture 14: Aspartic Protease, Hiv-1 Protease, Reverse Transcriptase

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