Effects on Viruses on Host cells

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What are the three effects of viruses on host cells (per the lecture)

Cytocidal, non-cytocidal and cell transformation

Match the different effects of viruses on host cells to their examples/characteristic

Cytocidal = Lysis, apoptosis Non-Cytocidal = Persistent infection Cell transformation = Tumor cells free bee = Free bee

What is the main difference between apoptosis and lysis in viral infections?

Apoptosis allows full viral replication, whereas lysis does not

Apoptosis prevents virions from being released, whereas lysis results in virion release (correct)

Lysis is a controlled process, whereas apoptosis is uncontrolled

Apoptosis occurs only in immune cells, whereas lysis occurs in all cell types

Which of the following pathways is associated with mitochondrial permeability in apoptosis?

Intrinsic pathway (C) Signup and view all the answers

The extrinsic pathway of apoptosis is triggered by:

Death receptor activation (B) Signup and view all the answers

What role do perforin and granzymes play in immune responses?

They induce apoptosis in virus-infected cells (C) Signup and view all the answers

What is required for Antibody-Dependent Cellular Cytotoxicity (ADCC) to occur?

Surface membrane fusion (D) Signup and view all the answers

What does the term "cytopathic effect" (CPE) refer to in virology?

The morphological changes and damage caused to host cells by viral infection (B) Signup and view all the answers

When viruses are inoculated into a monolayer cell culture, what happens as a result of viral replication?

The cells develop abnormal morphology and eventually die (D) Signup and view all the answers

What is the term used to describe the fusion of multiple host cells into a single large multinucleated cell?

Syncytium formation (B) Signup and view all the answers

Inclusion bodies in host cells during viral infection can be:

All of the above (D) Signup and view all the answers

How can inclusion bodies be useful in diagnosing viral infections?

Their staining properties and location in the cell help identify certain viral infections (B) Signup and view all the answers

List the morphological characteristics of inclusion bodies (ie histological appearances)

Intracytoplasmic or intranuclear, or even both; single or multiple; large or small; round or irregular in shape; eosinophilic/acidophilic or basophilic Signup and view all the answers

What type of staining would cause viral inclusion bodies to appear pinkish?

Acidophilic staining Signup and view all the answers

Which of the following is true about basophilic staining?

It stains structures purplish-blue with hematoxylin (C) Signup and view all the answers

How do large DNA viruses like poxviruses inhibit host cell function?

By producing enzymes that degrade cellular DNA (B) Signup and view all the answers

Which of the following viral mechanisms leads to inhibition of mRNA production?

Inhibition of host cell RNA transcription (C) Signup and view all the answers

What is a potential consequence of a virus causing lysosomes to release hydrolytic enzymes?

Destruction of the host cell (B) Signup and view all the answers

The intrinsic pathway of apoptosis is also called ___

Mitochondrial pathway Signup and view all the answers

The extrinsic pathway for apoptosis is also called ___

Death receptor pathway Signup and view all the answers

Cytotoxic T lymphocytes and NK cells can also initiate apoptosis of virus infected target cell, utilizing perforin and granzyme that directly activate caspases in the target cell

True (A) Signup and view all the answers

Receptor membrane fusion/surface fusion occurs in enveloped and naked viruses

False (B) Signup and view all the answers

What is the primary mechanism of Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC)?

Viral glycoproteins remain on the cell surface, marking the cell for immune attack (A) Signup and view all the answers

What is the definition of cell transformation in virology?

The process of a normal cell becoming a cancer cell (A) Signup and view all the answers

What is neoplasia?

The process that leads to abnormal tissue overgrowth (B) Signup and view all the answers

What is the primary difference between benign and malignant neoplasms?

Benign neoplasms remain localized, while malignant neoplasms invade and metastasize (A) Signup and view all the answers

What term is used to describe the study of neoplasia and tumors?

Oncology Signup and view all the answers

What is an oncogenic virus?

A virus that gives rise to tumors Signup and view all the answers

What is metastasis?

The spread of cancer cells from the primary site to other parts of the body Signup and view all the answers

What is the role of proto-oncogenes in normal cellular function?

To encode proteins that facilitate cell division and growth (B) Signup and view all the answers

What is the function of tumor suppressor genes?

They regulate and inhibit uncontrolled cell division (A) Signup and view all the answers

What are two examples of a tumor suppressor gene?

Rob (retinoblastoma protein) and P53 Signup and view all the answers

What is the function of the Rb (retinoblastoma) protein?

It blocks E2F, which normally facilitates cell division (A) Signup and view all the answers

What is the role of the P53 tumor suppressor gene?

It prevents cells with damaged DNA from dividing (B) Signup and view all the answers

How does P53 respond to DNA damage that cannot be repaired?

It promotes apoptosis of the damaged cell (A) Signup and view all the answers

What are oncogenes?

Mutated or abnormally expressed proto-oncogenes (D) Signup and view all the answers

What type of viruses are generally considered oncogenic?

Viruses with a DNA genome or that generate a DNA provirus (C) Signup and view all the answers

How do DNA tumor viruses interact with host cells?

They either complete their replication cycle or transform the host cell (B) Signup and view all the answers

What happens in a productive infection of a DNA tumor virus in a permissive cell?

The virus completes its replication cycle, leading to cell lysis or no cancer (D) Signup and view all the answers

What happens in a non-productive infection of a DNA tumor virus in a non-permissive cell?

The virus transforms the cell, potentially leading to cancer (C) Signup and view all the answers

How can oncogenic DNA viruses lead to cancer in non-permissive cells?

By remaining episomal or integrating into the host genome (B) Signup and view all the answers

How do acutely transforming retroviruses contribute to cancer development?

They steal proto-oncogenes from host DNA and mutate them into oncogenes (B) Signup and view all the answers

What is the mechanism of slow/chronic transforming retroviruses?

They cause cancer by inserting their genome into host regulatory genes, leading to uncontrolled cell division (A) Signup and view all the answers

What is a key difference between acutely transforming and slow/chronic transforming retroviruses?

Acutely transforming retroviruses mutate proto-oncogenes, while slow retroviruses alter their regulatory regions (B) Signup and view all the answers

What are tumor antigens?

New antigens that appear on the surface of tumor cells and may provoke an immune response (C) Signup and view all the answers

What is an example of a tumor antigen (as mentioned in class)?

FOCMA (feline oncoronavirus membrane associated antigen) Signup and view all the answers