Coronaviridae

Question 1

Severe acute respiratory syndrome

Answer 1

SARS

• new, emerging coronavirus
• economic loss
• affected 29 countries

Question 2

Properties of coronaviruses

Answer 2

Linear, positive sense ssRNA

• 75-160 nm diameter
• envelope with large, widely spaced, club shaped peplomers
• replicates in cytoplasm and virions released by exocytosis

Question 3

What are the 4 structural proteins of coronaviruses?

Answer 3

• peplomer glycoprotein S (E2)
• transmembrane glycoprotein M (E1)
• nucleocapsid phosphorprotein N
• some viruses have peplomers with hemagglutinin plus acetylesterase activities, HE (E3)

Question 4

All coronaviruses contain an ______

Answer 4

Envelope

Question 5

Antigenic group 1

Answer 5

Mammalian

• human coronavirus (229E), common cold
• transmissible gastroenteritis virus of swine: gastroenteritis
• feline infectious peritonitis virus: peritonitis, pneumonia, meningoencephalitis, panophthalmitis, wasting
• canine coronavirus: enteritis

Question 6

Due to coronaviruses share antigenicity?

Answer 6

No, do not cross protect

- due to high chance of mutation and lack of proofreading ability

Question 7

Antigenic group 2

Answer 7

Mammalian

• human coronavirus OC43: common cold
• mouse hepatitis virus: hepatitis, encephalomyelitis, enteritis
• bovine coronavirus: gastroenteritis
• porcine hemagglutinating encephalomyelitis virus: vomiting, wasting, and encephalomyelitis

Question 8

Antigenic group 3

Answer 8

Avian

- infectious bronchitis virus of chickens: tracheobronchitis, nephritis

Question 9

Antigenic group 4

Answer 9

Avian

- bluecomb disease virus of turkeys: enteritis

Question 10

Coronaviruses have been associated with infections of the ______ and _____ tracts

Answer 10

Respiratory and enteric tracts

- CNS disease in monkeys, rats, rabbits, other species

Question 11

Every chicken is vaccinated against _______

Answer 11

Infectious bronchitis virus
- does not completely prevent disease as outbreaks still occur due to viral mutation and selection pressure from constant vaccination (only due to live vaccine)

Question 12

Transmissible gastroenteritis of swine (TGE)

Answer 12

Occurs in winter months

• characterized by vomiting and profuse diarrhea
• causes high mortality in piglets
• efficacy of vaccines is limited

Question 13

Clinical features of TGE

Answer 13

Occurs at farrowing time, incubation time 1-3 days

• infected piglets show vomiting, watery diarrhea and rapid loss of weight
• piglets <7 days old die within 2-7 days –> > 3 weeks old live, but are weak

Question 14

TGE in growing, finishing, and adult swine

Answer 14

Show inappetence, diarrhea, or unnoticed

- sows infected late in pregnancy may develop fever but rarely abort

Question 15

Diagnosis of TGE

Answer 15

• immunofluorescence
• virus isolation
• rising antibody titers in paired sera from sows with affected litters or from pigs that have recovered from the disease
• electron microscopy-negative stain

Question 16

TGE causes ______ in piglets

Answer 16

Sudden death

- vomiting and diarrhea

Question 17

Vaccinate sows with ________

Answer 17

Attenuated vaccine 3 weeks before farrowing in order to provide piglets with high levels of protective Ab in the colostrum
- respiratory variant can interfere with the serodiagnosis

Question 18

Transfer of natural passive immunity

Answer 18

• cow, swine, horse: 3 maternal placental layers, and 3 fetal layers = postnatal transfer
• sheep, goat: 2 or 3 maternal placental layers, 3 fetal layers = postnatal transfer
• dog, cat: 1 maternal layer, 2 or 3 fetal layers = IgG cross of placenta, and postnatal transfer
• mouse, rat: 0 maternal layers, 3 fetal layers = prenatal and postnatal transfer

Question 19

Feline infectious peritonitis

Answer 19

Affects cats of all ages, over 90% have antibody against FIP

• incidence of clinical disease is lower <10%
• subclinical infections are common

Question 20

FIP occurs in association with ______

Answer 20

Retroviruses (feline leukemia, feline immunodeficiency, feline syncytial virus, parvovirus (feline panleukopenia))
- feline coronavirus that causes diarrhea may be a variant of FIP

Question 21

Coronavirus is likely to ______

Answer 21

Mutate

- interference between respiratory and intestinal coronavirus

Question 22

Clinical signs of FIP

Answer 22

• depressed, may have a fever
• classic wet form: abdominal distention
• only a proportion of clinically diseased cats develop peritonitis
• pleuritis results in dyspnea
• neurologic and ocular disease may occur

Question 23

Diagnosis

Answer 23

• virus isolation: peritoneal exudates, blood
• detection of antibody: only works if antibody titer is high
• hypergammaglobulinemia

Question 24

Epidemiology and control of FIP

Answer 24

Spread via aerosol

• seropositive cats develop more progressive form of disease than seronegative
• vaccines are available (not effective)
• control depends on segregation of infected cats

Question 25

Canine coronavirus diarrhea

Answer 25

Causes mild gastroenteritis - occurs in association with canine parvovirus infection = more severe diarrhea - commonly infects pups

Question 26

CCV serology

Answer 26

Closely related to transmissible TGEV, but CCV does not infect pigs - TGEV: produces a subclinical infection in dogs

Question 27

CCV diagnosis

Answer 27

Virus isolation, EM | - inactivated vaccine is available

Question 28

What serves as a model system for coronavirus infection?

Answer 28

Mouse Hepatitis Virus

Question 29

Mouse Hepatitis Virus

Answer 29

Causes: hepatitis, encephalomyelitis, enteritis, nephritis - high mortality in neonatal mice - weanlings can sustain subclinical infections

Question 30

Type and severity of MHV is dependent on:

Answer 30

Strain of the virus and the age/strain of the mouse

Question 31

Porcine Hemagglutinating Encephalomyelitis Virus

Answer 31

Occurs in piglets <2 weeks old - anorexia, hyperesthesia, muscle tremors, paddling of legs, vomiting = emaciation and death - diarrhea is not common! - high mortality in young piglets

Question 32

PHEV is similar to _________

Answer 32

Porcine polioencephalomyelitis - caused by picornavirus - requires differentiation based on viral particles

Question 33

PHEV pathogenesis

Answer 33

Infection via URT and pharynx --> spreads to brain via peripheral nerves

Question 34

PHEV diagnosis

Answer 34

Virus isolation in primary cultures of porcine cells and detection of the virus by HA - no vaccines available

Question 35

Bovine coronavirus diarrhea

Answer 35

Affects the vili of the small intestine and the large intestine - diarrhea occurs in 1 week old calves (similar to rotavirus) - affects glucose and lactose metabolism

Question 36

Is villous atrophy more severe with rotavirus or coronavirus?

Answer 36

Coronavirus

Question 37

Infectious bronchitis virus

Answer 37

More than 20 serotypes --> no cross protection

Question 38

IBV - respiratory manifestations

Answer 38

- wet eyes - gasping - coughing and sneezing - tracheal rales - nasal discharge

Question 39

IBV - nonrespiratory manifestations

Answer 39

- decreased egg production - misshapen eggs - nephritis/nephrosis (not common in US)

Question 40

How does IBV affect the poultry industry?

Answer 40

- increased mortality, condemnation at processing, downgrading of carcasses - decreased production - slowing of the line speed during inspection

Question 41

IBV prevention

Answer 41

- biosecurity - management (ex: use more hygenic nipple drinkers) - vaccination - monitoring immunity - equipment

Question 42

Bluecomb disease

Answer 42

Affects turkeys of all ages --> most severe in 1-6 week old poults - loss of appetite, chirping, diarrhea - skin of head and neck become cyanosed - enteritis

Question 43

Bluecomb disease vaccine

Answer 43

Inactivated vaccine is available --> not effective

Question 44

Porcine coronavirus

Answer 44

CV777 - Porcine Epidemic Diarrhea - acute diarrhea in swine of all ages - is not related to 4 groups of coronaviruses antigenically - 50% mortality rate - adults are subclinical - no vaccine!