Picornaviridae

Question 1

Picornaviridae virion properties

Answer 1

• non enveloped virions
• virion is rounded and smooth
• 27 nm diameter
• icosahedral symmetry
• differences in stability to low pH

Question 2

Picornaviridae genome

Answer 2

Single molecule of linear positive RNA

Question 3

Significance of icosahedral symmetry

Answer 3

Allows for efficient assembly that does not require energy

• most efficient shape that can hold the most volume with the least amount of effort
• more geometric, rigid due to capsule

Question 4

Non-enveloped properties of picornaviridae

Answer 4

Allows virus to infect via oral route and survive conditions of the GIT

Question 5

Picornaviridae genera

Answer 5

• aphthovirus
• avihepatovirus
• cardiovirus
• enterovirus
• teschovirus
• tremovirus

Question 6

Foot and Mouth Disease is a member of the ______ family

Answer 6

Aphthovirus

- is a vesicular disease!!

Question 7

FMD symptoms

Answer 7

Fever, loss of appetite, depression, and marked drop in milk production
- drooling of saliva due to vesicular stomatitis

Question 8

Vesicles of FMD

Answer 8

Tongue, gums, interdigital skin, coronary band of feet, teats
- vesicle rupture: denuded ulcerative lesions

Question 9

FMD aftosa

Answer 9

7 serotypes, 60 subtypes

• no cross protection!!
• cloven hoofed animals
• inactivated at pH 6.5 and above 11
• survives in milk, milk products, bone marrow, lymph glands

Question 10

Cross protection

Answer 10

Immunity against one serotype is not or incompletely effective against other serotypes

Question 11

FMD is not seen in _______

Answer 11

Horses!

- common in cattle and swine

Question 12

FMD serotypes

Answer 12

• A
• O
• C
• SAT-1
• SAT-2
• SAT-3
• Asia 1

Question 13

What are the 3 forms of animal transmission for FMD?

Answer 13

• respiratory aerosols: requires proper temp and humidity
• -> survives 1-2 days in human respiratory tract
• direct contact: ingestion of infected food or animal parts, artificial insemination of biologicals, hormones
• indirect contact via fomites

Question 14

Humans become ________ for 1-2 days when working with infected animals

Answer 14

Asymptomatic carriers

Question 15

FMD morbidity and mortality

Answer 15

Morbidity: 100% in animal population (US, Canada, Mexico)
Mortality: less than 1%
- higher in young animals and highly virulent virus strains
- animals generally destroyed to prevent spread

Question 16

FMD in the US

Answer 16

Disease is not present in the US, but the population is highly susceptible

Question 17

FMD clinical signs in cattle

Answer 17

Oral lesions

• vesicles on tongue, dental pad, gums, soft palate, nostrils, muzzle
• excess salivation, drooling, serous nasal discharge

Question 18

FMD leison progressivity

Answer 18

Oral lesions heal within days

• may become infected with bacteria leading to prolonged lameness and mucopurulent nasal discharge
• mortality in adult cattle is low
• calves younger than 6 months: possible mortality due to myocarditis

Question 19

FMD clinical signs in pigs

Answer 19

• hoof lesions: lameness, lesions on coronary band, heel, interdigital space (more severe than in cattle)
• snout vesicles
• oral vesicles are less common, drooling is rare

Question 20

FMD clinical signs in sheep and goats

Answer 20

Mild, if any signs

• fever
• oral lesions
• lameness
• makes diagnosis difficult

Question 21

Clinical susceptibility and epizootiology

Answer 21

• cattle: best indicator due to prominent clinical signs
• pigs: best amplifier
• sheep: silent shedders

Question 22

High mortality in calves with FMD due to ________

Answer 22

Myocarditis and myocardial necrosis

- causes acute death

Question 23

FMD virus and hosts

Answer 23

Aphthovirus

• cattle, sheep, swine are susceptible
• horses are resistant

Question 24

Swine vesicular disease virus and hosts

Answer 24

Enterovirus

• swine are susceptible
• cattle, sheep, horse are resistant

Question 25

Vesicular stomatitis virus and hosts

Answer 25

Rhabdovirus | - cattle, sheep, swine, and horses are susceptible

Question 26

Vesicular exanthema of swine virus and hosts

Answer 26

Coronavirus - swine and horses are susceptible - cattle, sheep are resistant

Question 27

FMD in wildlife

Answer 27

May act as reservoirs | - may or may not show clinical signs

Question 28

FMD diagnostic samples

Answer 28

- vesicular epithelium - vesicular fluid (best sample!) - oesophageal-pharyngeal fluids - serum (acute and convalescent)

Question 29

Collection of OP fluids

Answer 29

Use a probe inserted into the esophagus - collect all fluid in the area - mix with transport media for viruses - pink color is normal (pH is normal) - yellow color: pH is acidic and virus is dead

Question 30

FMD antigen detection

Answer 30

- virus isolation (in vitro or in vivo) - complement fixation - ELISA

Question 31

FMD antibody detection

Answer 31

- virus infection associated antigen! - virus neutralizaiton - ELISA

Question 32

FMD nucleic acid detection

Answer 32

RT-PCR | - common and efficient way to diagnose

Question 33

National Animal Health Laboratory Network

Answer 33

Cooperative effort between - Animal and Plant Health Inspection Service - National Institute of Food - Agriculture American Association of Veterinary Laboratory Diagnosticians

Question 34

Vesicular diseases

Answer 34

Economical and trade problems - all vesicular diseases are clinically similar - diagnostics are necessary - notifiable disease

Question 35

Recommended actions if FMD is suspected

Answer 35

Should be reported immediately upon diagnosis or suspicion of disease

Question 36

Swine vesicular disease

Answer 36

Enterovirus - sporadically in Europe and Asia - vesicles between heel and coronary band - lameness - 10% of cases vesicles are seen on snout, lips, and tongue - looks similar to FMD without diagnostics!!

Question 37

Equine Rhinovirus 1

Answer 37

Aphthovirus (Rhinitis A virus) - severe systemic and respiratory signs in horses - nasal discharge, pharyngitis, lymphadenitis, cough - viral shedding in feces

Question 38

Avian encephalomyelitis

Answer 38

Tremovirus - neurological disease - young chickens (1-21 days old) - dullness, progressive ataxia, tremors, weight loss, blindness, paralysis - no gross lesions!!

Question 39

Histopath of avian encephalomyelitis

Answer 39

Mononuclear encephalomyelitis

Question 40

Avian encpehalomyelitis has _______ transmission

Answer 40

Vertical - get disease from hens through the egg, chick will hatch infected - could also be infected through feces (horizontal transmission) --> 3-4 weeks clinical signs

Question 41

Encephalomyocarditis

Answer 41

Cardiovirus - natural host are rodents - transmitted from rodents to humans, monkeys, horses, cattle, and swine - myocarditis with fatalities

Question 42

Porcine polioencephalomyelitis

Answer 42

Aka: Teschen/Talfan disease - Teschovirus - neurological diseases in swine with paralysis - may be related to stillbirth, fetal mummification, embryonic death infertility

Question 43

Duck viral hepatitis

Answer 43

Avihepatovirus - severe disease of ducks - ducks younger of 3 weeks - mortality can approach 100% - extensive hepatic necrosis - located primarily in Asia