Lecture 4: Swine Viruses 1 Flashcards
What are the general clinical signs of porcine viral enteritis
- General clinical signs: acute watery diarrhea, loss of appetite
What is the prognosis of porcine viral enteritis?
- Prognosis: 60% mortality in suckling pigs, 2% mortality in feeder/grower
What should you expect on necropsy when looking at porcine viral enteritis
- Necropsy; grossly: watery intestines, no significant lesions
o Histo: observe the tropism (preference for different cells)
What are the possible agents causing porcine viral enteritis and what ages of pig does it affect?
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
What are the clinical signs of rotavirus induced porcine viral enteritis?
Clinically: waves of diarrhea in 2nd half of lactation
What cells are affected by porcine rotavirus
Histo: tropism for mature enterocytes
Clinical consequences of Transmissible gastroenteritis virus
Clinically: vomit/acute watery diarrhea/weight loss/dehydration/agalactia
More severe if young
What is a unique feature of Transmissible gastroenteritis virus
Forms the respiratory porcine corona virus by a deletion of a 225 aa in spike protein
What is the morbidity and mortality of Porcine epidemic diarrhea virus
Morbidity: can be 100%
Mortality; 80-100% suckling piglets, if >10day = <10%, adult <5%
What are the clinical signs of Porcine epidemic diarrhea virus
diarrhea/vomiting/metabolic acidosis
What is the incubation period of Porcine epidemic diarrhea virus
Incubation: 3-4 days
What are the features you would see on necropsy of Porcine epidemic diarrhea virus
Histo: shortened villi (tropism for mature enterocytes)
Gross: thin walled/watery intestines
How to diagnose Porcine epidemic diarrhea virus
Dx: RT-PCR/ELISA/IHC to identify, and ELISA/immunofluorescence/serum neutralization for serology (ig response)
* Use feces/oral fluid/small intestine/serum
How to prevent Porcine epidemic diarrhea virus
Prevent; natural maternal immunity (colostrum) until 4-13 days if mom immune/biosecurity/no vaccination in NA
What are the clinical signs of delta coronavirus
Clinically: diarrhea/vomiting/metabolic acidosis
What are the features of porcine coronavirus causing viral enteritis?
o Corona virus: many litters with acute diarrhea and high mortality
Highly infectious in piglets
Similar lesions
What are the viral features of Porcine Parvovirus
- Viral features: ssDNA, non-enveloped
o Requires rapidly replicating cells (fetal cells have high mitotic index)
How does porcine parvovirus appear clinically
- Clinically: SMEDI (stillbirth, mummification, embryonic death, infertility)
o Sows with no clinical signs
How is porcine parvovirus transmitted
- 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
What is the pathogenesis of porcine parvovirus
- 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
How does parvovirus affect other species (not pigs)
o Canine/Feline: affect crypt enterocytes
o Porcine: no enteritis/neuropathy – mainly a reproductive disease
o Bovine
How to diagnose porcine parvovirus
- Dx: females return to estrus, increased number of mummified/small litters
o Submit to lab – use immunofluorescence to detect virus
How to prevent porcine parvovirus
- Prevent: killed vaccine
- Sow born (passive immunity provides protection for 3 weeks post birth)
- day 22 = inital vx
- day 28 = booster vx (1 wk later)
- day 32 = sow is bred/conception
vaccine provides immunity for firrst 70 days of preganacy
What causes Porcine Respiratory Disease Complex
- 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
What type of virus is pseudorabies
o Suid herpesvirus/aukeszky disease virus
Lifelong carrier once infected
Psuedorabies
- who does it affect
- where is it found
- how is it transmitted
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
What is the pathologic mechanism of pseudo rabies
o Path: enter respiratory trance – spread via blood/lymph/nerves via retrograde transport from axon to cell body
What are the clinical signs of pseudorabies at different age stages
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)
What is the incubation period of pseudorabies
o Incubation: 2-5 day
What are the gross lesions of pseudorabies
o Gross lesions: pulmonary edema/hemorrhage/gastric hemorrhage/hyperemia/necrosis/leptomeningeal hyperemia
How does pseudorabies manifest in non-pigs?
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
How to diagnose pseudorabies
o Dx: can isolate virus in 8 – 25 day via IHC
Detectable antibody response for life
How to control pseudorabies
Eradicated in domestic populations (not wild) – lifelong infection
Vaccination: deleted glycoprotein E in vaccine – serological assay for gE = can differentiate infected and vaccinated animals
What is the family of influenza virus
orthhomyxoviridae
What is the difference between influnza virus type and subtype
- 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)
What are the clinical signs of swine influenza
- 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
How is swine influenza transmitted
- Transmission: nasal discharge/aerosol
Where are swine influenza lesions found
- Lesions: lung
How to diagnose swine influenza
- Dx: vial detection (nasal/tonsil swab, RT-PCR/sequencing, culture, IHC) serology (haemagglutination inhibition test/ELISA)
How to control swine influenza
- Control: vaccine
How does HPAI impact pigs
minimally
out of a bunch infected only a few seropositive
