lecture 14

Question 1

Define the characteristics of orthomyxoviruses

Answer 1

characteristics of orthomyxoviruses

• enveloped virus
• negative stranded
• segmented

Question 2

Who are the natural hosts of influenza A virus

Answer 2

wild words are the natural hosts for influenza A virus (ducks, geese and swans)
they are asymptotic or only have very mild conditions
replicate in GIT
birds will shed a large amount of the virus in the environment which mammas come into contact with and become infected
when birds fly to the new country they bring the diseases with them and cause the spread
Wild birds can affect duck and chicken farms causing hug issues

Question 3

What are the two main subtypes for influenza A virus

Answer 3

two main subtypes for influenza A virus
-haemagglutnin
-neuraminidase
they can jump in-between species from birds to pigs to humans

Question 4

What are the mechanisms for avian influenza virus evolution

Answer 4

mechanisms for avian influenza virus evolution
-Reassortment (antigenic shift)
its when 2 viruses infect the same host and this will cause progeny viruses from the 2 original virus.
-Mutation/adaption (antigenic drift); accumulates mutations which allows the virus to be more efficient infection and spread.

Question 5

Explain viral replication for avian influenza virus

Answer 5

Viral replication for avian influenza virus;
virus enter the body
hemagglutinin attaches to silica acid receptors on the cell-> enters the cell-> it will use the cell to read its own RNA, synthesise proteins and assembly for new viruses
RNA synthesis occurs in the nucleus and protein synthesis occurs in the ribosome (cytoplasm)-> new virus frees itself

Question 6

Explain the difference low and high pathogenic avian influenza

Answer 6

low pathogenic avian influenza;
the hemagglutinin precursor molecule can only be cleavaged by proteases found in intestinal and respiratory organs
High pathogenic avian influenza;
cleavage of hemagglutinin can occur in any organ

Question 7

Explain the difference types of Newcastle disease virus

Answer 7

Newcastle disease virus
causes similar symptoms in infected birds
-high virulent strains cause acute infections and high morality
-intermediate virulent strains cause respiratory disease in young chickens and deceased egg production
-avirulent strains cause mild respiratory infections or no symptoms

Question 8

Explain how the use of live birds markets cause the spread of influenza?

Answer 8

birds are put upside down on a bike for many kms on a hot day, and then go int a cage and drink from the same containers and then to trucks and then the ones who are not sold go back to the big cage, this is closed circulation of the virus.

Question 9

Discuss the equine influenza virus

Answer 9

equine influenza  virus 
highly contagious and spreads rapidly 
younger horse are more susceptible 
clinical diseases varies from mild to severe 
  -sudden increase in temp
  -cough

Question 10

How do you detect influenza?

Answer 10

detection for influenza
viral RNA techniques
-RT PCR used to target matrix gene or surface glycoproteins to determine the subtype