Orthomyxoviruses (influenzaviruses)

Question 1

What is the Structure of Orthomyxoviruses (influenzaviruses) ?

Answer 1

1- Single-stranded – sense RNA viruses
2- segmented genome
3- the only RNA virus replicates in nucleus. 
4- helical symmetry 
5- virus envelope (glycoprotein)

Question 2

What is the types of virus envelope (glycoprotein) ?

Answer 2

1- hemagglutinin (HA) : bind to sialic acid to enter the cell, Ab against it = no infectivity

2- neuraminidase (NA) : penetrate the mucus &make the envelope, Ab against it=↓spread

Question 3

What is the types of influenza in Orthomyxoviruses (influenzaviruses) ?

Answer 3

1- influenza A: has wide host range & antigenically highly variable
2- influenza B: human only pathogen , has minor antigenic changes→ antigenic drift
3- influenza C: antigenically stable

Question 4

What is the different between Antigenic in Orthomyxoviruses (influenzaviruses) ?

Answer 4

1- Antigenic shift: a major antigenic change due to Genetic reassortment
2- Antigenic drift: Minor antigenic variation due to point mutation affects HA & NA

Question 5

a major antigenic change due to Genetic reassortment (NOT mutation) is ?

Answer 5

Antigenic shift

Question 6

Minor antigenic variation due to point mutation affects HA & NA is ?

Answer 6

Antigenic drift

Question 7

What is the influenza that cause pandemics ?

Answer 7

influenza A