Finals: Picornaviridae

Question 1

Picornaviruses were the first demonstrated as a ______ _____ that caused disease in animals by Loeffler and Frosch in 1898

Answer 1

Filterable agent

Question 2

The filterable agent of Picornaviruses caused what?

Answer 2

Foot-and-mouth disease (FMD)

Question 3

Picornaviruses have played a big role in what?

Answer 3

Development of virology

Question 4

What are the 8 Picornaviridae genera?

Answer 4

Aphtovirus
Teschovirus
Erbovirus
Hepatovirus
Enterovirus
Cardiovirus
Kobuvirus
Parechovirus
There are two more proposed

Question 5

What virus was removed from the Picornaviridae in 2006 to be reclassified to Enterovirus?

Answer 5

Rhinovirus

Question 6

What are the virion properties of Picornaviruses?

Answer 6

Non-enveloped, ss, positive sense RNA viruses
Icosahedral symmetry
Genomic RNA is infectious

Question 7

Picornaviruses are stable in what?

Answer 7

Mucous and feces
Can withstand strong sunlight
Unstable in aerosols
High humidity favors survival for several hours
Sodium carbonate is an effective disinfectant

Question 8

Where does the replication of Picornavirus occur?

Answer 8

In the cytoplasm
Most Picornaviruses enter cells through endocytosis or fuse with the cell membrane
Poliovirus does not enter cells through endocytosis: VP4 and the amino terminal of VP1 relocate to the virion surface. VP1 makes a pore in the cell membrane allowing injection of viral capsid into the cell

Question 9

Tell me about foot-and-mouth disease virus (FMDV)

Answer 9

Picornaviridae, Aphthovirus
There are 7 distinct serotypes, and not cross protective
Inactivated at pH below 6.5 and above 11
Survives in milk, milk products, bone marrow

Question 10

When was the last reported case of Foot-and-mouth disease in the US?

Answer 10

1929

Question 11

When were the last reported cases of foot-and-mouth disease in Canada and Mexico?

Answer 11

1953

Question 12

FMDV is a disease of who?

Answer 12

A disease of cloven hoofed animals

It should not be confused with hand, foot and mouth disease in humans caused by coxsackie virus A6, A10, A16 or enterovirus 71

Question 13

What are the clinical signs of FMDV infection?

Answer 13

Incubation of 2-12 days
Early clinical signs include fever excessive salivation and nasal discharge (cattle).
Lesions (initially vesicles) on the buccal area and in the buccal cavity (snout in pigs).
Vesicles on the coronary bands and interdigital space
Recover in two weeks unless secondary infections arise
Abortion
Death in young animals
Lesions on teats

Question 14

What are the clinical signs of FMDV in goats and sheep

Answer 14

Mild, if any, signs
Fever, oral lesions, lameness

Make recognition of infection and prevention of spread difficult

Maintenance hosts

Question 15

What is the relevance of FMDV?

Answer 15

Highly contagious trans-boundary animal disease.
Cause major socio-economic losses due to:
-loss of livestock production
-limitation of international trade in livestock and animal products

Question 16

What are the morbidity and mortality of FMDV?

Answer 16

Morbidity 100% in susceptible animal population.
Mortality less than 1%: higher in young animals infected with highly virulent virus strains, animals generally destroyed to prevent spread.

Question 17

What is the transmission of FMDV?

Answer 17

Respiratory aerosols: proper temperature and humidity, survives 1-2 days in human respiratory tract

Direct contact: ingestion of infected animal parts, artificial insemination, biologicals, hormones

Indirect contact via fomites

Question 18

How do we clinically diagnose FMDV?

Answer 18

Clinically, vesicular diseases are indistinguishable!!!
Salivation, lameness with vesicles - requires further testing.
Tranquilization may be necessary to complete examination.

Question 19

What is the proper way for sample collection for testing for FMDV?

Answer 19

Before collecting or sending any samples, the proper authorities should be contacted.
Notify authorities and wait for instructions before collecting samples.
Samples should only be sent under secure conditions and to authorized laboratories to prevent the spread of the disease.

Question 20

What are the laboratory diagnosis for FMDV?

Answer 20

Lab tests:
Virus isolation and ID
Antigen or nucleic acid detection*
Complement fixation
ELISA and virus neutralization

Question 21

What are the clinical signs on FMDV in cattle?

Answer 21

Oral and hoof lesions, salivation, drooling, lameness, abortions, death in young animals, “panters”

Disease indicators

Question 22

What are the clinical signs of pigs with FMDV?

Answer 22

Severe hoof lesions, hoof sloughing, snout vesicles, less severe oral lesions.

Amplifying Hosts

Question 23

How do we treat FMDV?

Answer 23

There is no treatment available - DO NOT ATTEMPT ANY TREATMENT
For FMD-free countries an outbreak could result in quarantine, euthanization and disposal
Vaccines are available: ramifications are many.

Question 24

How do we prevent FMDV?

Answer 24

USDA APHIS: Strict import restrictions. Prohibit live ruminants, swine, and their products from FMD-affected countries.
>450 FADD to investigate suspicious lesions
State planning/training exercises
Biosecurity protocols for livestock facilities

Question 25

What is the disinfection of FMDV?

Answer 25

Effective solutions include:
2% sodium hydroxide (lye)
4% sodium carbonate (soda ash)
5.25% sodium hypochlorite (household bleach)
0.2% citric acid

Areas must be free of organic matter

Question 26

What are the vaccines for FMDV?

Answer 26

Killed vaccine, serotype specific

Huge implications if vaccination is done

Question 27

Tell me about Enterovirus

Answer 27

Are ubiquitous and occur in all vertebrates
Same cause disease of economic importance in swine and poultry
Cause of swine vesicular disease
Cause of polioencephalomyelitis

Question 28

Tell me about Swine vesicular disease virus (SVDV)?

Answer 28

The virus is enzootic in Italy
Resistant to ambient temperature and to sodium carbonate
Can be transmitted in pork productions
Virus can survive neutral pH at 4C for 160 days

Question 29

Is swine vesicular disease virus found in North America?

Answer 29

Not at all.
So the USA and Canada it is referred to as a foreign animal disease.
Pigs are the only natural host for the swine vesicular disease virus.

Question 30

What is the transmission swine vesicular disease virus?

Answer 30

Virus infects swine via skin abrasions and mucosa by ingestion and inhalation.
Direct contact among infected swine or with their excretions.

Question 31

What are the clinical signs of SVDV?

Answer 31

Sudden appearance of lameness
Fever - transient
Vesicles appear at the junction between heel and coronary bands.
Lesions on the snout, lips and tongue
Occasionally, some pigs may develop encephalomyelitis - ataxia, circling and convulsions

Question 32

What is the pathogenesis of SVDV?

Answer 32

Infection is through fecal-oral route
Replication is in the gastrointestinal tract - predominantly
But skin abrasions may also act as portals of entry, particularly feet.
Pigs can become viremic within 24 h and vesicles appear by 48 h
Virus is excreted in large amounts in feces

Question 33

How do we diagnose SVDV?

Answer 33

The case should be treated as if it was FMD
Rapid tests should be performed to rule out FMD
RT-PCR, particularly multiplexed assays which can detect multiple agents at once.
ELISA can be performed IF enough vesicular fluid is collected.
Virus isolation in swine kidney cells - can produce CPE after 6 h

Question 34

What are the DDx for SVDV?

Answer 34

Foot-and-mouth disease
Vesicular stomatitis
Vesicular exanthema of swine
Chemical or thermal burns

NO VACCINE!!

Question 35

Tell me about sanitary prophylaxis

Answer 35

On-going vesicular disease surveillance program with tracing and humane slaughter of all test positives and contacts
Control of vehicles used for transporting pigs
Thorough disinfection of premises, transport vehicles, and equipment