Infectious Diseases: Viruses Overview

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Questions and Answers

What characterizes gp120 that allows it to escape immune response?

It reduces the viral load significantly.

It binds to CD4 cells more effectively. (correct)

It is highly glycosylated, creating a glycan shield.

It has a stable structure that does not change.

What is the consequence of CD4 cell destruction during HIV infection?

Development of AIDS. (correct)

Decreased viral load.

Increase in T cell count.

Improved immune response.

Which type of therapy involves a combination of three different antiretroviral drugs?

cART (correct)

Prophylactic therapy

Initial treatment

Monotherapy

What occurs during the budding stage of HIV replication?

gag proteins bind RNA. Signup and view all the answers

What is a common opportunistic infection associated with AIDS?

Tuberculosis Signup and view all the answers

How does MHC class I downregulation contribute to HIV's immune evasion?

It decreases the recognition of infected cells. Signup and view all the answers

What is the geographical origin of HIV?

Central Africa Signup and view all the answers

How many pills are typically needed daily to control HIV using cART?

1 pill Signup and view all the answers

What is a key characteristic of viruses regarding their replication?

They only replicate within a host cell. Signup and view all the answers

What structures encapsulate the viral nucleic acids?

Capsids Signup and view all the answers

How does a virus enter a host cell?

Through an receptor-mediated attachment. Signup and view all the answers

What is the viral replication cycle's first step?

Entry of the nucleocapsid into the cell. Signup and view all the answers

What is a virion?

The complete virus particle including nucleic acids and protein coat. Signup and view all the answers

What process can lead to the release of new virus particles from a host cell?

Budding or lysis. Signup and view all the answers

What is an essential component that viruses lack for independent replication?

A complete translation system. Signup and view all the answers

Which of the following statements about viral envelopes is true?

Envelopes are acquired from the host cell membrane. Signup and view all the answers

What is the initial step of dengue virus entry into a host cell?

Endocytosis of the virus Signup and view all the answers

What type of antibodies can cause antibody-dependent enhancement (ADE) during a heterologous infection?

Non-neutralizing antibodies Signup and view all the answers

Which protein is involved in the replication process of the dengue virus?

NS5 Signup and view all the answers

What is the role of the 3' UTR in the dengue virus genome?

It generates subgenomic flavivirus RNA (sfRNA) Signup and view all the answers

What happens to the dengue virus after receptor-mediated endocytosis?

Acidification leads to a conformational change Signup and view all the answers

Dengue virus exists as how many serotypes?

4 Signup and view all the answers

What is a major drawback of the treatment approach used for the London patient?

It only works for CCR5 strains. Signup and view all the answers

What is one of the characteristics of the innate immune response?

It occurs within hours of infection. Signup and view all the answers

What is the primary interaction when the dengue virus first attaches to a host cell?

All of the above Signup and view all the answers

What is the role of PKR in the antiviral response?

It phosphorylates eIF2-alpha to an inactive form. Signup and view all the answers

Which of the following statements is true about the translation of the viral polyprotein?

It occurs at the membrane of the rough endoplasmic reticulum Signup and view all the answers

How does the OAS/RNaseL system contribute to the antiviral state?

By degrading viral RNA. Signup and view all the answers

What type of receptor recognizes non-self nucleic acids during viral infections?

RIG-I-like receptors. Signup and view all the answers

What is true about the adaptive immune response?

It produces antibodies that can prevent new infections. Signup and view all the answers

What is a consequence of the high treatment costs in certain therapies?

Limited patient access due to affordability. Signup and view all the answers

What is NOT a function of interferon-stimulated genes (ISGs)?

Promote cell division. Signup and view all the answers

What is a primary function of biofilm formation?

Facilitates nutrient trap for microbial growth Signup and view all the answers

How does biofilm formation contribute to self-defense against the immune system?

By preventing phagocytosis by immune cells Signup and view all the answers

What is a characteristic of the tuberculosis bacterium regarding its growth?

Divides every 24 hours Signup and view all the answers

What is a significant property of the cell wall of tuberculosis bacteria?

Lipid-rich and impermeable Signup and view all the answers

Which of the following is true about antibiotic effects on biofilm formation?

Suboptimal concentrations of antibiotics can promote biofilm formation Signup and view all the answers

What role does interferon gamma play in the immune response against tuberculosis?

Activates macrophages Signup and view all the answers

What is a challenge in developing vaccines for non-typable Haemophilus influenzae?

No effective vaccine has been developed yet Signup and view all the answers

Which of the following statements is true regarding the transmission of tuberculosis?

It is transmitted through aerosols Signup and view all the answers

What is the primary target cell for Mycobacterium tuberculosis infection?

Alveolar macrophages Signup and view all the answers

Why are alveolar macrophages considered the first line of defense against M.tuberculosis?

They reside in alveolar spaces and are readily accessible. Signup and view all the answers

What unique ability does M.tuberculosis have regarding alveolar macrophages?

It prevents phagosome-lysosome fusion. Signup and view all the answers

How does M.tuberculosis evade immune detection within alveolar macrophages?

By exploiting the anti-inflammatory environment of AM. Signup and view all the answers

What role do alveolar macrophages serve concerning nutrients for M.tuberculosis?

They provide access to essential nutrients like iron and fatty acids. Signup and view all the answers

Which of the following is a characteristic behavior of alveolar macrophages in regard to inflammation?

They suppress inflammatory responses under normal conditions. Signup and view all the answers

What factor does M.tuberculosis utilize to detoxify reactive oxygen and nitrogen species produced by alveolar macrophages?

Inhibition of the reactive species production Signup and view all the answers

Why might M.tuberculosis be able to survive and replicate inside alveolar macrophages?

Due to the permissive environment provided by alveolar macrophages. Signup and view all the answers

Study Notes

Infectious Diseases - Background

Viruses are "a piece of bad news wrapped in a protein" or "a package of misinformation"
They are small, obligatory intracellular infectious agents.
Viruses replicate only in a host cell and rely on the host for energy, metabolism, lipids, and protein synthesis.
They do not grow or divide.
Viruses are obligate intracellular parasites, having genomes for reproduction but not complete translation systems.

Infectious Diseases - Terms

Virion: physical virus particle
Capsid: protein shell surrounding viral nucleic acids
Nucleocapsid: capsid + nucleic acid
Envelope: lipid membrane surrounding the capsid (not all viruses have an envelope).

Replication Cycle

Viruses enter cells by binding to receptors on the cell surface.
The nucleocapsid releases viral nucleic acids that are then replicated.
New RNA and capsid proteins are created
The new viruses are then released via budding through the membrane or via cell lysis.

Virus Classification

Viruses are extremely diverse but classify into 7 genome types (Baltimore classification)
The classification criteria include:
- Nucleic acid type (DNA or RNA)
- Strandedness (single or double)
- Transcription strategy (how the RNA is used to make proteins).
- Symmetry of capsid (icosahedral, helical, or complex)
- Presence of envelope (enveloped or naked)

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Description

This quiz covers the fundamental concepts of viruses, including their structure, replication cycle, and basic terminology associated with viral infections. Understand the unique characteristics that differentiate viruses from other pathogens and how they interact with host cells. Test your knowledge on this critical aspect of infectious diseases.