Orthomyxoviridae

replication

nucleus

enveloped or non enveloped

enveloped

strand

single-stranded RNA viruses, spherical or pleomorphic morphology

Labile in environment, sensitive to heat, dessication, lipid solvents, detergents, irradiation, oxidizing agents

Orthomyxoviridae

Orthomyxoviridae: Cause influenza in

humans and animals

Orthos=

correct/right/proper

Myxa=

mucus

Release of virions by

budding from plasma membranes

peplomers; surface projections of glycoproteins

“Spikes”

2 types of spikes / orthomyxoviridae

• Haemagglutinin (H)

• Neuraminidase (N)

virus attachment (promoting entry of virus)

Haemagglutinin (H)

cleaving viral receptors (release of virions from infected cells)

Neuraminidase (N)

responsible for virus neutralization

Antibodies against H glycoprotein

Target receptors

sialic acid receptors (surface of epithelial cells in respiratory tract

Genome

6-8 segments of linear, negative-sense- single stranded RNA

4 genera

•Influenzavirus A

•Influenzavirus B

•Influenzavirus C

•Thogotovirus

most important; significant pathogen of animals and humans

Influenzavirus A

most important; significant pathogen of humans

•Influenzavirus B

•Influenzavirus C

tick-borne arboviruses

•Thogotovirus

usually replicate poorly in humans

Influenza A viruses •Avian influenza virus (AIV)

Both human and avian influenza subtypes replicate in ___(where genetic reassortment occurs)

pig

often implicate major pandemics

Novel subtypes

Avian influenza

fowl plague

Outbreaks of several clinical disease (Avian influenza (Fowl plague))

subtypes H5 and H7

acute infection, highly pathogenic avian influenza (HPAI)

Occur periodically in chickens and turkeys

Live vaccines not used (risk of reversion to virulence

Avian influenza (Fowl plague)

(takes place in epithelial cells of respiratory and digestive tracts

cleavage of viral hemagglutinin

Common cause of acute respiratory disease in horses

Equine influenza

Equine influenza: CS

Fever, cough, nasal discharge

First identified: 1918, USA

Swine Influenza

as mixing vessels

PIGS: SWINE INFLUENZA

2009 Pandemic H1N1

originated from swine influenza viruses