Lecture 4: Swine Viruses 1

Question 1

What are the general clinical signs of porcine viral enteritis

Answer 1

• General clinical signs: acute watery diarrhea, loss of appetite

Question 2

What is the prognosis of porcine viral enteritis?

Answer 2

• Prognosis: 60% mortality in suckling pigs, 2% mortality in feeder/grower

Question 3

What should you expect on necropsy when looking at porcine viral enteritis

Answer 3

• Necropsy; grossly: watery intestines, no significant lesions
  o Histo: observe the tropism (preference for different cells)

Question 4

What are the possible agents causing porcine viral enteritis and what ages of pig does it affect?

Answer 4

o Rotavirus: suckling pigs and weaners

o Transmissible gastroenteritis virus (corona): All ages

o Porcine epidemic diarrhea virus (corona): All ages

o Delta coronavirus: All ages

Question 5

What are the clinical signs of rotavirus induced porcine viral enteritis?

Answer 5

 Clinically: waves of diarrhea in 2nd half of lactation

Question 6

What cells are affected by porcine rotavirus

Answer 6

 Histo: tropism for mature enterocytes

Question 7

Clinical consequences of Transmissible gastroenteritis virus

Answer 7

 Clinically: vomit/acute watery diarrhea/weight loss/dehydration/agalactia
 More severe if young

Question 8

What is a unique feature of Transmissible gastroenteritis virus

Answer 8

 Forms the respiratory porcine corona virus by a deletion of a 225 aa in spike protein

Question 9

What is the morbidity and mortality of Porcine epidemic diarrhea virus

Answer 9

 Morbidity: can be 100%
 Mortality; 80-100% suckling piglets, if >10day = <10%, adult <5%

Question 10

What are the clinical signs of Porcine epidemic diarrhea virus

Answer 10

diarrhea/vomiting/metabolic acidosis

Question 11

What is the incubation period of Porcine epidemic diarrhea virus

Answer 11

 Incubation: 3-4 days

Question 12

What are the features you would see on necropsy of Porcine epidemic diarrhea virus

Answer 12

 Histo: shortened villi (tropism for mature enterocytes)
 Gross: thin walled/watery intestines

Question 13

How to diagnose Porcine epidemic diarrhea virus

Answer 13

 Dx: RT-PCR/ELISA/IHC to identify, and ELISA/immunofluorescence/serum neutralization for serology (ig response)
* Use feces/oral fluid/small intestine/serum

Question 14

How to prevent Porcine epidemic diarrhea virus

Answer 14

 Prevent; natural maternal immunity (colostrum) until 4-13 days if mom immune/biosecurity/no vaccination in NA

Question 15

What are the clinical signs of delta coronavirus

Answer 15

 Clinically: diarrhea/vomiting/metabolic acidosis

Question 16

What are the features of porcine coronavirus causing viral enteritis?

Answer 16

o Corona virus: many litters with acute diarrhea and high mortality
 Highly infectious in piglets
 Similar lesions

Question 17

What are the viral features of Porcine Parvovirus

Answer 17

• Viral features: ssDNA, non-enveloped
  o Requires rapidly replicating cells (fetal cells have high mitotic index)

Question 18

How does porcine parvovirus appear clinically

Answer 18

• Clinically: SMEDI (stillbirth, mummification, embryonic death, infertility)
  o Sows with no clinical signs

Question 19

How is porcine parvovirus transmitted

Answer 19

• Transmission: body fluids/feces
  o Only transmitted to fetus in seronegative/naive animals
  o Epithelia-chorial placenta = many barriers
  o Probably transport via immune cells

Question 20

What is the pathogenesis of porcine parvovirus

Answer 20

• Pathogenesis: transmission 12-18 day after initial infection of dams
  o Before day 35 = embryonic death
  o Day 35-70 = fetal death and mummification
  o >day 70 = survival/seropositive

Question 21

How does parvovirus affect other species (not pigs)

Answer 21

o Canine/Feline: affect crypt enterocytes
o Porcine: no enteritis/neuropathy – mainly a reproductive disease
o Bovine

Question 22

How to diagnose porcine parvovirus

Answer 22

• Dx: females return to estrus, increased number of mummified/small litters
  o Submit to lab – use immunofluorescence to detect virus

Question 23

How to prevent porcine parvovirus

Answer 23

• Prevent: killed vaccine

1. Sow born (passive immunity provides protection for 3 weeks post birth)
2. day 22 = inital vx
3. day 28 = booster vx (1 wk later)
4. day 32 = sow is bred/conception
   vaccine provides immunity for firrst 70 days of preganacy

Question 24

What causes Porcine Respiratory Disease Complex

Answer 24

• Multifactorial
  o Viruses; pseudorabies/porcine respiratory and reproductive/swine influenza/porcine respiratory corona/porcine circo viruss
  o Bacteria
  o Other factors: stress/poor ventilation/over crowding

Question 25

What type of virus is pseudorabies

Answer 25

o Suid herpesvirus/aukeszky disease virus  Lifelong carrier once infected

Question 26

Psuedorabies - who does it affect - where is it found - how is it transmitted

Answer 26

o Can affect cattle/sheep/goats/dogs/cat/mink/fox/raccoon/rat o Most countries except Canada o Transmission: direct (nose-nose)/sexual/aerosol/fomites

Question 27

What is the pathologic mechanism of pseudo rabies

Answer 27

o Path: enter respiratory trance – spread via blood/lymph/nerves via retrograde transport from axon to cell body

Question 28

What are the clinical signs of pseudorabies at different age stages

Answer 28

o Clinically: age dependent  Neonate/suckling pig: 100% mortality – paralysis, loss of appetite/vomiting/neurologic signs (convulsion/incoordination)  Weaner: 5-10% mortality – respiratory (cough/sneeze)  Grower/finisher: 1-2% mortality – respiratory disease  Adult: mild/possible repro problems (SMEDI)

Question 29

What is the incubation period of pseudorabies

Answer 29

o Incubation: 2-5 day

Question 30

What are the gross lesions of pseudorabies

Answer 30

o Gross lesions: pulmonary edema/hemorrhage/gastric hemorrhage/hyperemia/necrosis/leptomeningeal hyperemia

Question 31

How does pseudorabies manifest in non-pigs?

Answer 31

o Non-swine clinical path: infect respiratory tract = spread via retrograde transport in nerves (no blood or lymph spread)  Clinically: neuropathy itch: overwhelming puritis/self mutilation

Question 32

How to diagnose pseudorabies

Answer 32

o Dx: can isolate virus in 8 – 25 day via IHC  Detectable antibody response for life

Question 33

How to control pseudorabies

Answer 33

 Eradicated in domestic populations (not wild) – lifelong infection  Vaccination: deleted glycoprotein E in vaccine – serological assay for gE = can differentiate infected and vaccinated animals

Question 34

What is the family of influenza virus

Answer 34

orthhomyxoviridae

Question 34

What is the difference between influnza virus type and subtype

Answer 34

* Many types A (animal/human), B (human/serologically in pigs), C (humans/ some seal/pig), D (cattle/seropositive humans), A (HA and NA subtypes) o Types based on internal proteins (nuclear protein and matrix protein)

Question 35

What are the clinical signs of swine influenza

Answer 35

* Clinically: cough/nasal discharge/hyperthermia/reduce appetite/fever induced abortion o Receptors for human and avian influenza o 5-7 days for recovery (H1N1 = longer recovery time) o 100% morbidity, low mortality

Question 36

How is swine influenza transmitted

Answer 36

* Transmission: nasal discharge/aerosol

Question 37

Where are swine influenza lesions found

Answer 37

* Lesions: lung

Question 38

How to diagnose swine influenza

Answer 38

* Dx: vial detection (nasal/tonsil swab, RT-PCR/sequencing, culture, IHC) serology (haemagglutination inhibition test/ELISA)

Question 39

How to control swine influenza

Answer 39

* Control: vaccine

Question 40

How does HPAI impact pigs

Answer 40

minimally out of a bunch infected only a few seropositive