Orthomyxoviridae and Paramyxovirdae

Question 1

Orthomixoviridae

Answer 1

• ssRNA
• replicates in nucleus; released from cells by budding
• enveloped by 2 major glycoproteins: Haemagglutin and Neuraminidase

Question 2

Purposed of Haemagglutinin (H or HA)

Answer 2

• Allows virus to attach to respiratory epithelium
• bind RBC useful in diagnostic assays
• Greatest antigenic consequence; shft and drifft

Question 3

Purpose of Neuraminidase

Answer 3

• allows virus to detach from the respiratory epithelium when existing in the cell

Question 4

Paramyxoviridae

Answer 4

-ssRNA
- replicate in cytoplasml, released from cell by budding
- enveloped
- 2 Attachment proteins (HN) and G which allows virus to bind to host cell.
Fusion protein F- causes virus envelop to fuse w host cell
- very fragile in environment
- cell mediated immunity important

Question 5

Significant paramyxoviruses

Answer 5

• Morbillivirus
• Avulavirus; Newcastle disease (affect bird)
• Henipavirus: Hendra, menangle virus (stillbirth in pigs), Nipah

Question 6

Pathogenesis of paramyxoviruses

Answer 6

• respiratory route
• droplets coughed or sneezed
  1. virus enters respiratory tract or conjunctival:
• HN or G initiate attachment–> triggers humoral immunity
• F proteins mediate fusion and entry and also mediate cell to cell dusion and direct cell to cell spread

Question 7

Hendra virus

Answer 7

source: bats as reservoir host

Question 8

Hendra virus transmission

Answer 8

• bats excrete virus and contaminate feed

- amplifier is horse ingests contaminated material

Question 9

Hendra prevention

Answer 9

• eliminate source, vaccination, remove fruit trees, protect from bats

Question 10

Nipah virus

Answer 10

Bats—> pigs–> humans

bats are reservoirs, pigs are amplifier- ingest bat excretions

Question 11

Diagnosis Hendra

Answer 11

RT-PCR of fluids
ELISA
virus excreted in body fluifd