Antiretroviral Agents and HIV Treatment

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary target for the binding of the HIV envelope protein gp160?

CD4 receptor (correct)

CCR5 coreceptor

CXCR4 coreceptor

Macrophage lineage cells

Which of the following agents is NOT classified as an antiretroviral treatment for HIV?

Nonnucleoside Reverse Transcriptase Inhibitors

HIV Protease Inhibitors

Antihypertensive medications (correct)

Integrase inhibitors

What role does CCR5 and CXCR4 play in the HIV life cycle?

They act as viral envelope proteins.

They inhibit HIV infection.

They serve as primary receptors for virus entry. (correct)

They are targets for virus replication.

Why is understanding the HIV life cycle important in therapy?

It assists in rational therapy of the infection. (A) Signup and view all the answers

Which statement about the current status of HIV treatment is accurate?

Daily oral regimens can lead to a normal life expectancy. (A) Signup and view all the answers

What is primarily responsible for the emergence of permanent drug resistance in HIV treatment?

Improper use of antiretroviral agents (C) Signup and view all the answers

What signal indicates a shift from CCR5 to CXCR4 in HIV-infected individuals?

Increased affinity of HIV-1 for CXCR4 (B) Signup and view all the answers

What role does the gp41 domain of env serve in the HIV life cycle?

Controlling the fusion of the virus with the host cell (A) Signup and view all the answers

Which of the following statements about HIV pathogenesis is correct?

Replication of HIV can be constant due to persistent infection. (B) Signup and view all the answers

What is the significance of the coreceptor switch from CCR5 to CXCR4 in HIV infections?

It may cause accelerated loss of CD4+ T cells. (B) Signup and view all the answers

What is the role of the env gene in the HIV virus?

It encodes the envelope protein responsible for cell binding and entry. (A) Signup and view all the answers

Which viral protein is responsible for combating host defenses?

Tat (A) Signup and view all the answers

What happens to the CD4+ T-lymphocyte count after an initial HIV infection?

It steadily declines after an initial rise. (D) Signup and view all the answers

How long is the median time from CCR5-tropic HIV-1 infection to clinical AIDS if untreated?

8 to 10 years (D) Signup and view all the answers

What crisis point occurs when the peripheral CD4 count falls below 200 cells/mm3?

Risk of opportunistic diseases increases. (B) Signup and view all the answers

What is the relationship between HIV RNA concentration and CD4+ T-lymphocyte count during HIV infection?

HIV RNA concentration rises as CD4 count declines. (B) Signup and view all the answers

Which small genes in HIV are responsible for enhancing virion production?

tat, rev, nef, vpr (A) Signup and view all the answers

What is a characteristic of HIV's reverse transcriptase?

It is prone to errors and lacks a proofreading function. (B) Signup and view all the answers

Which subtype of HIV is primarily associated with the global epidemic?

HIV-1 (A) Signup and view all the answers

How frequently does mutation occur during full-length replication of HIV?

At about three bases for every full-length replication. (D) Signup and view all the answers

What role does viral integrase play in the HIV life cycle?

It integrates virus-derived DNA into the host chromosome. (D) Signup and view all the answers

What is a unique feature of the HIV genome's structure?

It contains two copies of the genome in the nucleocapsid core. (C) Signup and view all the answers

Which type of drugs are HIV-2 specifically resistant to?

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) (B) Signup and view all the answers

Where is the structural protein assembly concentrated in the HIV life cycle?

At the cell membrane in cholesterol-rich lipid rafts. (B) Signup and view all the answers

Following integration into the host chromosome, what can occur with the HIV virus?

The virus becomes dormant and may remain quiescent. (B) Signup and view all the answers

Study Notes

Antiretroviral Agents and Treatment of HIV Infection

Pathogenesis of HIV-Related Disease: HIV is a lentivirus, a retrovirus that establishes a chronic persistent infection, with gradual symptom onset. Virus replication is constant after infection. There's no true latency period. Humans and non-human primates are the only natural hosts.
Two major families of HIV exist: HIV-1 and HIV-2. HIV-1 is mostly responsible for the global epidemic. HIV-2 is more closely related to SIV and common in western Africa. HIV-1 has genetic diversity, with five subfamilies or clades. NNRTIs are specific to HIV-1.
Virus Structure: HIV is a retrovirus with a small RNA genome of 9300 base pairs. It has two copies of the genome within a nucleocapsid core, surrounded by a lipid bilayer (envelope) derived from the host cell. The genome encodes gag (structural proteins), pol (reverse transcriptase, protease, and integrase), and env (envelope protein for cell attachment and entry). These regulatory proteins include tat, rev, nef, and vp.
Virus Life Cycle: The envelope protein gp160 controls HIV tropism(target cell binding). The main target is the CD4 receptor on lymphocytes and macrophages, but co-receptors CCR5 and CXCR4 are also required for entry. CCR5-tropic infections are the most common. A shift to CXCR4 tropism is associated with disease progression. gp41 domain of env controls the viral lipid bilayer's fusion with the host cell. Viral RNA enters the cytoplasm, replicated into DNA, and integrated into a host chromosome by the viral integrase. Reverse transcriptase is error-prone, leading to frequent mutations, occurring at about three times per replication.
How the Virus Causes Disease: HIV infection is likely initiated by one or a few infectious particles. After infection, there's a rapid burst of replication (peak at 2 - 4 weeks), reaching 10⁶ CD4+ cells. Subsequent host immune responses decrease infectious virions in plasma, reaching a set point. The average infected individual produces billions of infectious particles daily. A steady decline in CD4+ T lymphocyte count and an increase in plasma HIV RNA concentration happen over time, leading to a higher risk of opportunistic diseases, and ultimately, death.
Principles of HIV Chemotherapy: Current treatment focuses on suppressing viral replication to prevent drug resistance. A standard care regimen involves three antiretroviral drugs simultaneously during initiation of treatment, and two to three drugs afterward. Initiating therapy regardless of baseline CD4 count is the current global standard (based on randomised clinical trials). Treatment is for life to control virus replication.

Principles of HIV Chemotherapy

Drug resistance is a significant challenge. Untreated patients frequently harbor viruses with resistance mutations.
Drug regimens usually need to contain a combination of multiple drugs to prevent resistance.
A successful therapy goal is an undetectable viral load (≤50 copies/mL).
Breaks in treatment increase resistance risk and disease progression. Long-term toxicity of drugs is important to consider.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Dive into the complexities of HIV infection and its treatment with antiretroviral agents. This quiz explores the pathogenesis of HIV-related diseases, the structural aspects of the virus, and the various treatment options available. It covers the significance of HIV-1 and HIV-2, their genetic diversity, and the role of NNRTIs.