VM 709- Virology Introduction (DNA and RNA Families)

What is the classification of viruses (how do they live)?

Obligate intracellular parasites

What does a virus require to replicate?

A host cell

What is one of the major cellular parts of viral DNA replication?

DNA polymerase

Is DNA or RNA more durable in living tissue?

DNA

What are the 4 criterion used to categorize viruses?

1. Structure

2. Type of genome

3. Nucleotide sequence

4. Pathophysiology

What are the 4 main DNA viruses (in the context of this class)?

1. Herpesvirus

2. Papillomavirus

3. Parvovirus

4. Poxvirus

What are the main structural parts of herpesvirus?

1. Capsule

2. Envelope

How is herpesvirus mainly transmitted?

Respiratory secretions/nose-to-nose contact

What are the main diagnostic clues used to diagnose herpesvirus?

1. Intranuclear inclusions

2. PCR from nasal swabs

3. PCR from whole blood

What does the structure of parvovirus look like?

1. Non-enveloped

2. Icosahedral capsid

Which kinds of viruses are harder to eliminate— enveloped or non-enveloped viruses?

Non-enveloped viruses

How does parvovirus enter the body?

Via mucosal cells (M cells)

Which intestinal structures are destroyed by parvovirus?

Crypts and Peyer’s patches

What are the main diagnostics used to diagnose parvovirus?

1. Snap ELISA

2. PCR

3. Virus isolation

4. Hemagglutination inhibition test

Which 2 clinical signs are often normal in cattle with papillomavirus?

1. No fever

2. Normal appetite

What part of papillomavirus results in the warts?

Destruction of function of p53 (stimulating cellular proliferation)

Which cells are targeted by papillomavirus?

Basal epithelial cells

Where does papillomavirus replicate?

In the nucleus

What are the main diagnostic clues used to diagnose papillomavirus?

1. Epithelial hyperplasia

2. Viral DNA in nucleus

3. Histopathology

What is the main distinguishing feature that differentiates poxvirus from most other DNA viruses?

Zoonotic

Which is the largest DNA virus encountered in veterinary medicine?

Poxvirus

Where does poxvirus replicate?

Cytoplasm

What are the main diagnostic clues used to diagnose poxvirus?

1. Cytoplasmic inclusions

2. Characteristic skin lesions

3. PCR

What are the 4 main RNA viruses (in the context of this class)?

1. Retrovirus

2. Coronavirus

3. Orthomyxovirus

4. Rhabdovirus

What are the main general features of RNA viruses?

1. Single or double-stranded

2. Segmented or non-segmented

3. Enveloped or non-enveloped

4. Cytoplasmic replication

5. Rapid mutation

What RNA exclusive enzyme is required for replication of RNA viruses?

RNA-dependent RNA polymerase (RdRp)

Why is retrovirus named retrovirus?

It uses reverse transcriptase, which inserts complementary DNA strand backwards into the host genome

Which form of a virus is integrated into the host cell genome?

Provirus

Which strain of Feline Leukemia Virus (FeLV) is spread from one cat to another?

Strain A

What are the 3 main pathways of infection of FeLV?

1. Abortive

2. Regressive

3. Progressive

What is the main example of a coronavirus in felines?

Feline Infectious Peritonitis (FIP)

What can mutated FIP (a coronavirus) do that other viruses can’t?

It can spread systemically from enterocytes to other body systems

How is HPAI in cats contracted?

Ingestion of raw/unpasteurized milk; exposure to livestock/poultry

What are the main clinical signs of HPAI in cats?

1. Ataxia

2. Seizures

3. Tremors

4. Circling

What is the structure of Influenza A virus (an orthomyxovirus)?

1. Enveloped

2. Helical

3. Segmented

What are the 6 requirements of reassortment of viruses?

1. Sympatry

2. Ecology

3. Coinfection

4. Packaging

5. Replicative compatibility

6. Fitness

What is the main type of rhabdovirus in animals?

Rabies

What is the structure of rhabdoviruses?

1. Enveloped

2. Helical

3. Single-stranded

4. Bullet-shaped

How is rabies transmitted?

By saliva that enters neural tissue through the neuromuscular junction

What are the 2 main forms of rabies?

1. Furious/encephalitic

2. Dumb/paralytic