RNA Negative Polarity Genomes: Influenza

Question 1

Orthomyxoviridae include:

Answer 1

Influenza A, B and C.

Question 2

Orthomyxoviridae (4):

Answer 2

• SS negative polarity RNA.
• 8 segments (C - 6).
• Helical neucleocapsid.
• Enveloped (contains 2 glycoproteins).

Question 3

Orthomyxoviridae neucleocapsid composed of (5):

Answer 3

• RNA
• NP
• PB1
• PB2
• PA

Question 4

Two glycoproteins in Orthomyxoviridae envelope:

Answer 4

• H: Hemagglutinin.

- N: Neuraminidase.

Question 5

RNA dependent - RNA polymerase is formed by (3):

Answer 5

• PB1 (PB1-F2)
• PB2
• PA

Question 6

Influenza penetration (4):

Answer 6

• Attachment via hemagglutinin to sialic acid containing receptors.
• Penetrates via viropexis (endocytic).
• Acidification facilitates the initiation of fusion between envelope and vacule.
• Genome released and travels to nucleus.

Question 7

Influenza transcription/translation (4):

Answer 7

• Viral mRNAs are transcribed from -RNA templates.
• Viral mRNAs have 3’ poly A added and a donated capped RNA at the 5’ end.
• mRNA moves to cytoplasm and is translated.
• H and N glycoproteins accumulate in golgi apparatus and are then inserted into the cell surface = budding sites.

Question 8

Influenza genome replication (4):

Answer 8

• Occurs in nucleus.
• -RNA translated into +RNA (replicative intermediate).
• +RNA serves as template for -RNA.
• Move to cytoplasm then budding sites in the golgi apparatus.

Question 9

Neurominidase (2):

Answer 9

• Important in budding of progeny virus particles.

- Lowers viscosity of mucus in vivo during infections.

Question 10

Antigenic sin:

Answer 10

Individual responds to new Influenza A infection with the strongest antibody against the 1st subtype seen.