LEC 17 - Orthomyxviruses

Question 1

Characteristics: Influenza Type A

Answer 1

Broad host range

Question 2

Characteristics - influenza type B

Answer 2

Humans

Seals

Question 3

Characteristics Influenza Type C

Answer 3

Minor disease in humans and pigs

Question 4

What is the structure of the influenza envelope?

Answer 4

Contains spikes with hemagglutinin + neuraminidase

Question 5

What is the genomic structure of influenza?

Answer 5

Segmented

ssRNA (-)

Question 6

What two proteins are contained in the envelope?

Answer 6

M1 + M2

Question 7

Describe M1

Answer 7

Envelope matrix protein

Question 8

Describe M2

Answer 8

Ion channels

Question 9

What is the flu virus sensitive to?

Answer 9

Heat

Acid

Solvents + Detergents

Question 10

What is bound to the RNA of influenza?

Answer 10

RNA polymerase complex

Question 11

What is the components of the influenza nomenclature?

Answer 11

Virus type + Host + Geographic origin + Strain # + Year

(H + N subtype)

Question 12

What are the pandemic vaccines?

Answer 12

Avian influenza

H 5 + 7 + 9

Question 13

What are the regular vaccines?

Answer 13

B

H1 (Russian)

H3 (Avian)

H2 (Hong kong)

Question 14

What is needed to start the replication process with influenza?

Answer 14

HA spikes bind to sialic acid receptors on cell = viral host range + tissue trophisms

Question 15

How does the influenza virus enter the cell?

Answer 15

Receptor-mediated endocytosis

Vesicle acidified

M2 allows H+ ions to transverse membrane

Leads to conformation change in HA allowing membrane fusion

Nucleocapsid release from M1 to host

Question 16

When is the maturation of the influenza virus complete?

Answer 16

Virions bud through host membrane lipid rafts w/ inserted viral spike + matrix protein

Question 17

What is critical for viron release?

Answer 17

viral NA

Question 18

What is the function of viral NA?

Answer 18

Cleaves sialic acid receptors that would otherwise bind + trap virus

Question 19

What must happen to hemagglutinin inorder to allow for infection?

Answer 19

Viral protein must undergo postranslational cleavage

Question 20

Describe HPAI

Answer 20

Highly pathogenic avian influenza have HA forms that are cleaved by a wider array of proteases

Question 21

What are the common symtpoms seen with HPAI influenzas?

Answer 21

Produce severe uniformly fatal disease affecting most organs

Question 22

What two things occurs within a virus that allow it to be so diverse and change so quickly?

Answer 22

Antigenic drift + shift

Question 23

Describe antigenic drift?

Answer 23

Point mutation

Question 24

Describe antigenic shift

Answer 24

Resssortment of genome segments

Question 25

What happens with antigenic shift that allows for influenza virus to be so dangerous?

Answer 25

Bird virus + human virus mist in swine cell and by a hybrid virus that is more pathogenic

Question 26

Where does the low pathogenicitic virus tend to target?

Answer 26

Intestinal epithelium Few disease symtpoms seen

Question 27

What is the method of transmission of the influenza type A virus?

Answer 27

Fecal-oral

Question 28

What is the common reservior for the influenza type A virus?

Answer 28

Water fowl

Question 29

What does equine influenza cause?

Answer 29

Respiratory disease

Question 30

What is the main equine influenza type?

Answer 30

H3N8

Question 31

What is the improtance of the flu vaccine with the equine influenza?

Answer 31

Counters antigenic drift

Question 32

What symptoms are seen with equine influenza?

Answer 32

Fast onset Reddening nasal mucosa + discharge Fever Paroxysmal cough

Question 33

How long does it take a horse to normally recover from equine influenza?

Answer 33

2 to 3 weeks

Question 34

What are the signs there is a secondary bacterial infection with EIV?

Answer 34

Purulent nasal exudate Bronchiopneumonia

Question 35

Where does EIV replicated?

Answer 35

Respiratory tract epithelium

Question 36

Effects of EIV on upper respiratory tract

Answer 36

Destroys ciliated cells = inflammation + discharge

Question 37

Effects of EIV on lower respiratory tract

Answer 37

Traceitis + Bronchitis + Bronchointersitial pneumonia with congestion alveolar edema

Question 38

How is EIV diagnosed?

Answer 38

Clinical symptoms + rtPCR Nasal or Oropharyngeal areas Virus culture in eggs or cells lines w/ trypsin

Question 39

How is EIV controlled?

Answer 39

Biosecurity Antibiotics for secondary infections Watching horses that travel often

Question 40

When is the EIV infections most prevalent?

Answer 40

April to October --- race season

Question 41

What was the first recognized swine flu?

Answer 41

H1N1

Question 42

What is the generic pathogenesis of swine flu?

Answer 42

Progressive necrotic, attack on epithleium in respiratory tract

Question 43

Progression rate of swine flu

Answer 43

Short incubation period Abrupt disease onset

Question 44

Symptoms of swine flu

Answer 44

Fever Huddling Respiratory distress w. paroxysmal cough Nasal discharge

Question 45

What are the two major variants of H1N1?

Answer 45

US strain - similar to original European strain - avian reservior derived strain

Question 46

Where is it thought that mixing of the flu viruses most likely occurs?

Answer 46

Pigs

Question 47

What is the used to diagnose swine flu?

Answer 47

rt-PCR Rapid test kits Virus isolation

Question 48

What is typed via PCR?

Answer 48

Hemagglutinin Neuramindase

Question 49

When are outbreaks of swine flu most common?

Answer 49

Fall and winter

Question 50

What is the general epidemology of swine flu?

Answer 50

Explosive spread No carrier state known Big economic impact

Question 51

What is the key to controlling the swine flue?

Answer 51

Vaccination

Question 52

What is the goal of the swine flu vaccine?

Answer 52

To prevent clinical disease The vaccine does not prevent infection or shedding

Question 53

Why can't we control all infections with a vaccine that contains H1,2,3 + N1,2?

Answer 53

Vaccinate sows - maternal antibodies decline Vaccines do not stop infection Constant shift/drift allow flu virus to stay Virus get to pigs from other sources

Question 54

What is another name for the avian flu?

Answer 54

Fowl plague

Question 55

What is the reservoir for the avian flu?

Answer 55

Waterfowl

Question 56

What are the symtpoms of a HPAI strain of AVI?

Answer 56

Sudden ddeath without any previous signs

Question 57

What are the symptoms of AVI?

Answer 57

Respiratory distress No eggs Lacrimation Diarrhea Edema of head and neck Cyanosis of comb + wattle Tremors Stargazing

Question 58

When does the LPAI strain of AVI cause problems?

Answer 58

In Turkeys

Question 59

What symptoms are seen with LPAI strains of AVI?

Answer 59

Respiratory distress Decrease in egg laying Anorexia

Question 60

Where does AVI replicate?

Answer 60

Intestinal + respiratory tracts

Question 61

What does the most virulent forms of HPAI AVI produce in a chicken?

Answer 61

Virema Multifocal lymphoid/visceral organ necrosis

Question 62

What is the two key roles of HA in the infection process of AVI?

Answer 62

Attachment Fusion of host + viral membranes

Question 63

What is HA a large determinant of?

Answer 63

Pathogenicity

Question 64

What changes the virulence of AVI?

Answer 64

Changes in the AA sequence of the cleavage site

Question 65

What is the change at the AA sequence in AVI that causes it to be a LPAI?

Answer 65

one basic AA at the cleavage site

Question 66

Where does HPAI strains of AVI tend to replicate in the body?

Answer 66

Liver Lungs Kidneys Brains

Question 67

How is AVI detected?

Answer 67

rt-PCR to detect viral M gene +'s = tested for H5/H7 genes +'s = Clocal/tracheal swabs cultured

Question 68

What is a notifiable disease when it comes to AVI?

Answer 68

HPAI or LPAI with H5 or H7

Question 69

Where is waterfowl shedding AVI from?

Answer 69

Feces

Question 70

How is AVI controlled?

Answer 70

HPAI is watched for closing with rapid mass culling when virus is detected