Virology Chapter 22: Viral Pathogenesis, Transmission, and Host Interactions + Breaking News

What is viral pathogenesis?

The process by which viruses cause disease in a host.

What are the four types of viral infections?

Productive, abortive, acute, and latent infections.

What characterizes a productive viral infection?

New infectious viral particles are produced.

What happens during an abortive viral infection?

Few, if any, new viral particles are produced.

What is an acute viral infection?

An infection with a short duration where signs/symptoms are observed and the infection is cleared.

What is a latent viral infection?

An infection where the virus is present but replication is shut down, with potential reactivation.

What is a persistent viral infection?

A chronic infection where new viral particles are continuously produced, but the host does not clear the virus.

What is horizontal transmission of viruses?

Transfer of viruses from individual to individual within the same species.

What is vertical transmission of viruses?

Transmission from mother to fetus or newborn, such as through the placenta or during birth.

What is zoonotic transmission?

Transmission of viruses from animals to humans.

What is mechanical transmission?

Facilitated transfer of a virus from host to host via another vector, such as medical supplies or insects.

What is necrosis in the context of viral infections?

Cell death characterized by the bursting of the cell, often due to viral replication.

What is apoptosis?

Programmed cell death that is safer for surrounding cells and typically does not induce inflammation.

What are syncytia?

Multinucleated cells formed by the fusion of host cells, often resulting in cell death.

What are inclusion bodies?

Clumps of virus or viral proteins inside host cells that can lead to cell death.

How can viral infections trigger autoimmune responses?

Molecular mimicry may cause the immune system to attack self structures resembling viral peptides.

What role do inflammatory cytokines play in viral infections?

They can cause signs and symptoms of viral infections as part of the immune response.

What is the impact of hepatitis B virus on liver function?

Immune responses against the virus can lead to liver dysfunction by killing infected hepatocytes.

What is the significance of latency associated transcripts (LATs) in herpesviruses?

LATs help maintain latency of the virus within host cells.

What is a prime example of an acute viral infection?

Rhinovirus infection, commonly known as the common cold.

What is the difference between productive and abortive infections?

Productive infections produce new viral particles, while abortive infections do not.

What is the role of the immune system in viral infections?

It can kill infected cells and produce signs/symptoms of the infection.

What is the mechanism of viral-induced necrosis?

Cell bursting due to viral replication or impairment of normal cell functions.

How can viruses evade host defenses?

By replicating intracellularly and employing various strategies to avoid immune detection.

What is the significance of the herpes virus's ability to enter neurons?

It allows the virus to maintain latency and reactivate later, causing recurrent infections.

What are some examples of viruses that can cause zoonotic transmission?

Rabies, West Nile virus, and Ebola.

What is the impact of antiretroviral therapies on vertical transmission of HIV?

They have significantly reduced rates of vertical transmission in the United States.

What are the two distinct ways cells can die due to viral infections?

Necrosis and apoptosis.

What is the primary replication site for herpesviruses?

Mucosal cells at the site of infection.

Optogenetics

Neuroscience methodology developed by Karl Diesseroth that allows researchers to experimentally control individual neurons using light

From what type of organisms are the light-activated proteins used in optogenetics derived?

Single-cell microbial organisms

What biological function do microbial opsins perform in response to light exposure?

They convert light energy directly into electrical signals across membranes.

How many genes are required to encode a single light-activated microbial opsin protein?

A single gene