Viral properties

Question 1

What are Koch’s postulates and what are they used for?

Answer 1

Used for proving a virus causes a disease

Microorganism must be found exclusively in diseased animals

Organism must be grown in isolation from diseased animal, and should produce same effect in another healthy animal

Suspected microorganism must be removed from this now diseased animal and upon comparison with the first microorganism, be identical

Question 2

What is a virus? Define it.

Answer 2

OBLIGATE intracellular parasite, with a genome of RNA or DNA

Question 3

How do viruses cause infection?

Answer 3

Using proteins and RNA or DNA to take over host cell machinery to replicate

Question 4

How are viruses classified?

Answer 4

Baltimore Classification system

7 types, depending on type of nucleic acid used

Question 5

What is a capsid and envelope?

Answer 5

Capsid is protein shell

Envelope is capsid with lipid membrane

Question 6

List the generic replication cycle of a virus

Answer 6

ATTACHMENT of virus to membrane

ENTRY of VIRAL GENOME into cell

TRANSLATION of viral mRNA

REPLICATION of viral genome

ASSEMBLY of viral proteins

EXIT

Question 7

What are the phases of viral growth?

Answer 7

Eclipse

Logarithmic

Cell death

Question 8

What is a plaque assay and what is it used for?

Answer 8

A dilution method to see the foci of infection - i.e. lowest concentration needed to cause infection

Question 9

What are the methods of viral diagnosis?

Answer 9

Detecting viral genome by PCR

Detecting viral antigen by IFA or ELISA

Detecting virus particles by EM

Detecting virus’ cytopathic effect - vorus isolation

Question 10

HOw can viruses be manipulated?

Answer 10

De novo synthesis due to small size

THen grow under different conditions etc