Swine Coronavirus Flashcards
1
Q
What is the virus family Coronaviridae?
A
- Corona = halo / crown
- Single-stranded
- Positive sense
- RNA virus
- enveloped
- Four Genera:
- Alphacoronavirus, Betacoronavirus, Deltacoronavirus, Gammacoronavirus
2
Q
What does a corona virus look like?
A
- ssRNA: 28 kb
- Spike proteins:
- projects from envelope
- binds to host cell receptor
- mediates viral entry
- induces neutralizing antibodies
3
Q
What are the Porcine Coronaviruses?
A
- Genus Alphacoronavirus:
- Porcine epidemic diarrhea virus (PEDV)
-
Transmissible gastronteritis virus (TGEV)
- pathogenesis and clinical disease identical to PEDV
- Porcine respiratory coronavirus (PRCV)
- derived from TGEV
- Genus Deltacoronavirus
- Porcine deltacoronavirus (PDCoV)
4
Q
what is the epidemiologic information of PEDV?
A
- Introduced into US in April 2013
- Within 1 year, 7 million pigs died
- Spread rapidly, now reported in >39 states
-
Seasonal:
- higher incidence during winter
- Pig only known hosts
- Clinical presentation depends on viral isolate, pigs age, concurrent infections, rate of group exposure
-
Infectious dose is extremely small
- level in piglet feces 10,000 x higher than sow feces
5
Q
What are the Key concepts of PEDV?
A
- Characterized by severe enteritis, vomiting, watery diarrhea and weight loss
- Severity of infection is age-dependent
- Recently introduced to US swine, spread rapidly and now widely distributed
6
Q
How is PEDV transmitted?
A
- Primarily Fecal/Oral transmission
- Additionally:
- Contaminated fomites, trucks/trailers, people
- Contaminated feed
- Environmental exposure
- +/- aerosol
7
Q
What is the pathogenesis of PEDV?
A
- Oral exposure leads to virus replication in mature intestinal enterocytes
- neonatal pigs have long villi with more mature enterocytes permissive to replication and a slower turnover of enterocytes
- Virus replication in SI enterocytes causes cell lysis
- cell and virus expelled in feces
- Viral shedding typically occurs for 3-4 wpi
8
Q
What are Villi?
A
- Projections into the intestinal lumen
- Involved in digestive & absorptive function (some secretory activities
- Mature enterocytes
- Cells survive only a few days
- Nonproliferative
9
Q
What are intestinal crypts?
A
- Invaginations of the intestinal epithelium around the villi
- Primarily involved in secretory functions
- Stem cell progenitors of the villus enterocytes
- Continually dividing
10
Q
What is the clinical disease of PEDV?
A
- All ages susceptible to infection
- disease inversely related to age - suckling pigs most severe
- Incubation short: 2-4 days
- High morbidity (up to 100%)
- Mortality varies based on age
- suckling pigs: typically 50-80%
- Growing/adult pigs: typically 1-3%
11
Q
What are the clinical signs of PEDV?
A
- Vomiting
- Watery diarrhea
- decreased appetite
- weight loss
- lethargy/depression
- dehydration
12
Q
What is Chronic/Endemic TGEV?
A
- Sows immune and antibodies in colostrum/milk protect pigs while nursing
- Pigs become susceptible after weaning when lactogenic immunity wanes
- Signs usually mild - diarrhea, dehydration, unthriftiness and runting
- Low mortality
13
Q
What are the Gross Lesions associated with PEDV/TGEV?
A
- Thin, transparent intestinal walls with accumulation of large amounts of yellow fluid in the intestinal lumen
- Congestion of mesenteric vessels
- Edematous mesenteric lymph nodes
14
Q
What are the Microscopic Lesions are associated with PEDV/TGEV?
A
- Acute, diffuse, severe atrophic enteritis
- Atrophy and fusion of villi in jejunum and ileum
- Results in malabsorptive diarrhea and dehydration
15
Q
When should PEDV be suspected in a herd?
A
- Clinical history of diarrhea in more than 50% of pigs on a site over a short period of time
16
Q
How is PEDV diagnosed?
A
- Viral Ag or nucleic acid
- feces or intestine - best to collect from actually-affected live pigs
- PCR, IHC, VI, sequencing
- Serology
- IFA, SN, ELISA
17
Q
How is PEDV treated?
A
- Supportive care:
- maintain hydration
- Provide clean, dry, draft-free environment