Viruses

Question 1

What is patient zero?

Answer 1

used to refer to the person identified as the first carrier of a communicable disease in an outbreak of related cases

Question 2

Definition of a virus

Answer 2

1. an ultramicroscopic (20 to 300 nm in diameter), metabolically inert, infectious agent that replicates only within the cells of living hosts
2. hosts are mainly bacteria, plants, and animals: composed of an RNA or DNA core, a protein coat, and, in more complex types, a surrounding envelope.

Question 3

How are viruses classifed?

Answer 3

Based on:
–	The genome (RNA or DNA)
–	Number and sense of RNA/DNA strands
–	Morphology (size, symmetry, envelope)
–	Genome sequence similarity
–	Ecology

Question 4

What is the baltimore classification?

Answer 4

a virus classification system that groups viruses into families, depending on their type of genome (DNA, RNA, single-stranded (ss), double-stranded (ds), etc..) and their method of replication

Question 5

How are viruses controlled?

Answer 5

• Antimicrobials / Antivirals
• Vaccination is the main approach: Live or killed vaccines
• Eradication in some cases (from particular region, country or whole planet (small pox 1980)): FMD, rabies, rinderpest
• Biosecurity: important to minimise contact between virus and host

Question 6

What 2 things combine to form viral pathogenesis

Answer 6

1. Viruses: obligate intracellular parasites that exclusively replicate in cells. Replication may lead to altered cell function
2. IMMUNE response: targets viral antigens both within and outside cell, as well as clearing infection responses may damage both infected and uninfected cells

Question 7

Pathogenesis

Answer 7

“The manner of development of a disease”

1. The mechanism by which the combined effects of virus replication and host immunity may lead to clinical disease

Question 8

Features of pathogenesis

Answer 8

1. rarely completely understood
2. • Highly adapted associated with the ecological niche the virus has found for itself.
3. Academically it covers a wide area of disciplines and techniques.
4. Often highly specific for the host – virus combination as a result of co-evolution

Question 9

Why study pathogeneiss as a vet?

Answer 9

1. unless understand how cause disease = never develop new therapeutics
2. Indentification of control points (how a virus gets into host)
3. Methods and interpretation of diagnosis. = understand where virus is in host to know how to test for it

Question 10

How do viruses pass through host?

Answer 10

1. Ingestion/ inhalation/ injection
2. cross mucosal barriers
3. transmitted through blood
4. identify target cells
5. replicate
6. leave target cell

Question 11

How viruses are transmitted

Answer 11

1. trauma, injection, bite, mechanical or biological vector

2. Oral, resp, reproductive tract

Question 12

What is the main infectious causes of viral resp disease

Answer 12

1. influenza

Question 13

Influenza steucture

Answer 13

1. lipid bilayer = wash hands
2. surface = viral proteins
   3.

Question 14

How does the emergence of new types of virus come about

Answer 14

1. point mutation and genetic reassortment
2. mutations
3. reassortment - 2 or more viruses infect the same cell and develop new subtypes