Viral Pathogenesis: Overview

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the term for the circulation of viruses through the whole body, usually in the blood or lymph?

Primary viraemia

Viraemia (correct)

Local replication

Secondary viraemia

Which of the following organs is typically affected during the secondary viraemia of a blood-borne virus?

Lungs

Brain

Liver (correct)

Skin

What is the route of transmission of Canine Parvovirus?

Airborne transmission

Direct contact transmission

Vector-borne transmission

Faecal-oral transmission (correct)

What is the term for the initial replication of a virus in cells at the site of entry?

Local replication Signup and view all the answers

What is the site of major pathology during a viral infection?

Target organ Signup and view all the answers

What is the difference between acute and persistent viral infection?

Acute infection is short-term, while persistent infection is long-term Signup and view all the answers

What is a necessary condition for a cell to be infected by a virus?

The cell must have appropriate host factors for viral replication Signup and view all the answers

Which type of cells does Canine parvovirus need to infect?

Rapidly dividing cells Signup and view all the answers

What can affect the disease severity of a viral infection?

Changes in tropism Signup and view all the answers

How does Rabies virus reach the central nervous system (CNS) after infection?

Through motor nerves Signup and view all the answers

What is the role of the salivary gland in the transmission of Rabies virus?

It provides a site for onwards transmission Signup and view all the answers

Why does the immune system of the host have a reduced ability to detect and respond to Rabies virus infection in the brain?

The virus has a mechanism to evade the immune system Signup and view all the answers

What is the primary function of the keratinized layer of skin in relation to viral infections?

To act as an effective barrier against virus infection Signup and view all the answers

Which of the following immune cells is NOT typically recruited to sites of inflammation in the skin?

Cytotoxic T cells Signup and view all the answers

What is the term for the spread of viruses from the initial site of infection to other parts of the body through the bloodstream?

Secondary viraemia Signup and view all the answers

Which of the following is NOT a route of transmission for viruses?

Muscular system Signup and view all the answers

What is the term for the process by which viruses change to infect other hosts?

Viral adaptation Signup and view all the answers

Which of the following immune responses is NOT specific to a particular tissue or site?

Systemic immune responses Signup and view all the answers

What is the primary reason why viruses cause pathology in hosts?

As a necessary step for transmission to new hosts Signup and view all the answers

What determines the viral fitness of a virus?

The survival and transmission of the virus Signup and view all the answers

What is the term for the damage to host cells caused by a virus?

Cytopathic effects Signup and view all the answers

Why do emerging viruses not have to evolve to become less pathogenic?

Because they do not have to coexist with the host Signup and view all the answers

What is the term for the process by which a virus is released from an infected host?

Shedding Signup and view all the answers

What is the site of entry and exit for FMDV?

Vesicular fluid and salivary gland Signup and view all the answers

What is the primary factor that influences the ease of transmission and dose of insect-borne viruses in a livestock population?

Stocking density Signup and view all the answers

Which of the following factors is NOT a viral factor that influences whether infection results in disease?

Host nutrition practices Signup and view all the answers

What is the characteristic of latent infections that allows the virus to reactivate in certain circumstances?

Limited recognition of molecules on infected cells Signup and view all the answers

Which of the following climatic conditions is likely to facilitate the flying of midges, increasing the transmission of insect-borne viruses?

High rainfall Signup and view all the answers

What is the outcome of an acute viral infection in a host?

Infection is cleared by the immune system Signup and view all the answers

Which of the following Practices is likely to increase the risk of transmission of insect-borne viruses in a livestock population?

Importation of new feedstuff Signup and view all the answers

Study Notes

Viral Infection and Pathogenesis

Viruses cause disease and pathology, which may be necessary for transmission
Viral fitness is determined by survival and transmission

Stages of Viral Infection

Entry into host through various routes (e.g., skin, respiratory tract, gastrointestinal tract)
Local replication at site of entry
Primary viraemia
Replication at secondary site(s)
Secondary viraemia
Target organ replication

Mechanisms of Viral Pathology

Direct effects: cytopathic effects (CPE) damage to host cells, resulting in cell death
Indirect effects: virus-induced immune response, inflammation, and tissue damage

Viral and Host Factors Influencing Disease

Viral factors: tropism, virulence, and level of replication
Host factors: susceptibility, immune response, and genetics

Types of Viral Infection

Acute infection: rapid, self-limiting infection cleared by the immune system
Persistent infection: virus persists at low levels following recovery, with potential to reactivate

Latent Infection

Virus persists in immune-privileged sites (e.g., neurons)
Limited viral protein synthesis and infectious virus production
Latency-associated transcripts reduce MHC expression and block apoptosis

Transmission of Viruses

Faecal-oral transmission (e.g., FMDV)
Salivary transmission (e.g., rabies)
Blood-borne transmission (e.g., H5 avian influenza)
Vector-borne transmission (e.g., insect-borne viruses)

Defences Against Viral Infection

Physical barriers (e.g., skin, mucosal surfaces)
Innate immune system (e.g., macrophages, neutrophils, natural killer cells)
Adaptive immune system (e.g., antibodies, cytotoxic T cells)

Environmental Factors Influencing Viral Transmission

Climatic conditions (e.g., high rainfall, temperature)
Nutrition and feed (e.g., pasture, animal feed)
Stocking density and animal husbandry practices
Veterinary policy (e.g., vaccination programs)

Studying That Suits You

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

Description

This quiz assesses your understanding of the stages of viral infection, mechanisms of disease causation, and factors influencing disease outcomes. Test your knowledge of viral pathogenesis and how it affects the whole organism.