Lecture 17 & 18 (Virus Diseases of Swine) Flashcards
Do DNA or RNA viruses have a higher mutation rate?
RNA Viruses
Are enveloped or non-enveloped viruses more durable in the environment?
non-enveloped viruses
What is virulence?
disease severity
t/f: no “long term” decisions are made without lab testing for viral treatment in pigs
true
sampling methods:
Talk about oral fluid collection in pigs
-method used for pathogen detection
-PCR
-more sensitive than nasal/oral swabs on population basis
*an effective tool for swine health monitoring
sampling methods:
talk about processing fluids in pigs
-process tissues → testicles from castration // tails from tail docking
*processing fluids are an effective sample to detect PRRSV in piglets
What is PUCS?
placental umbilical cord serum
*use in utero transmission
When would it be important to collect PUCS to send out?
if we are worried that there is in utero transmission of disease
detect viral nucleic acid (via primer)
a) in situ hybridization
b) immunohistochemistry
a) in situ hybridization
detect viral antigen in lesion (via antibody)
a) in situ hybridization
b) immunohistochemistry
b) immunohistochemistry
Is Swine Influenza Virus a DNA or RNA virus?
RNA virus
What does IAV-S stand for?
Influenza A Virus in Swine
nucleotide changes
a) antigenic drift
b) antigenic shift
a) antigenic drift
gene recombination
a) antigenic drift
b) antigenic shift
b) antigenic shift
Is the influenza virus an antigenic shift or an antigenic drift?
antigenic shift
why are pigs considered the “mixing vessel” for influenza viruses?
because they have receptors for both swine viruses, avian viruses as well as human viruses
*provides an opportunity for recombination
What are the 3 important antigens in the swine influenza virus?
-hemagglutinin (HA) → enables entry into the cell // main antigen for vaccines
-neuraminidase (NA) → allows virus to exit cell/spread within cells
-nucleoproteins → antigen for ELISA antibody test
Traditional strain in the U.S.
a) H1N1
b) H3N2
c) H1N2
a) H1N1
-relatively new strain in US in 1998
-spread throughout country in 2-3 years
-promiscuous gene group – TRIG cassette
a) H1N1
b) H3N2
c) H1N2
b) H3N2
- detected first in Indiana
- combination of other two strains
a) H1N1
b) H3N2
c) H1N2
c) H1N2
How is swine influenza virus transmitted?
direct transmission via aerosols
den onset after incubation
-coughing // fever > 105°F // nasal discharge
-anorexia // lethargy // labored breathing
-abortion
a) Porcine Circovirus 2
b) Swine Influenza
c) Porcine Respiratory and Reproductive Syndrome
d) Porcine Epidemic Diarrhea Virus
b) Swine Influenza
u have a farm with several coughing (“barking”) pigs that have a fever, it’s pretty likely you are seeing…
a) Porcine Circovirus 2
b) Swine Influenza
c) Porcine Respiratory and Reproductive Syndrome
d) Porcine Epidemic Diarrhea Virus
b) Swine Influenza
You see lungs that look like this on necropsy:
-lung is often apical or cardiac lobes
-not pathognomonic
-airways with fluid and mucus
-enlarged bronchial lymph nodes
what virus did this pig most likely have?
Swine Influenza Virus
What causes the cough in a pig that has swine influenza?
Degeneration and necrosis of respiratory epithelium
How do you prevent swine influenza?
-maintain good biosecurity → proper cleaning & disinfecting trucks // quarantine new arrivals
-vaccination → vaccines usually require multiple strains
-maternal derived antibody (MDA) → vaccination of sows to protect pigs
How do you treat a pig with swine influenza?
-no specific therapy
-nursing care // draft-free, warm, dry environment
-antibiotics for secondary bacterial infections
-put anti-inflammatories in the water
How do you diagnose a pig with swine influenza?
-mainly presumptive: acute respiratory outbreak involving the herd
-definitive detection: nasal swab // PCR
-sequencing is common for strain matching
-serology → ELISA
this virus infects dendritic cells (macrophages) especially in the lung → pulmonary alveolar macrophages and pulmonary intravascular macrophages
PRRS virus
What is the most important disease in pigs worldwide?
PRRS virus
t/f: PRRS virus is highly infectious and takes only a few viral particles to infect a pig
true
How is PRRS virus transmitted?
- pro-nasal spread
- body secretions including semen
- blood via injections → change needles often
-severe respiratory disease; interstitial pneumonia
-rapid breathing especially after stress
-takes 30-45 days longer to reach market due to virus
-severity of infection diminishes greatly after 8 weeks of age unless co-infected with another agent
in suckling and nursery pigs what virus is this most likely to be?
PRRS virus
t/f: no sow herd is protected from PRRS with vaccination due to new strains always being created
true
severity of PRRS infection greatly diminishes after _____ weeks of age unless co-infected with another agent
8 weeks
you see this on a necropsy
-enlarged lymph nodes
-interstitial pneumonia
-tan discoloration of the lungs // rubbery texture
-when you pull the lungs out they fail to collapse due to being filled with edema
what virus did this pig most likely have?
PRRS virus
What is the treatment and control for PRRS virus?
treatment:
-supportive → aspirin and ibuprofen
-control secondary bacterial infections with antibiotics
biosecurity:
-people shower in and out
-air filtration in facilities
controlled exposure with serum from infected pigs (LVI - live virus inoculation)
cause of infectious congenital tremors; porcine cell line contaminant
a) type 1 PCV
b) type 2 PCV
c) type 3 PCV
a) type 1 PCV
cause of PMWS (post-weaning multi-systemic wasting syndrome)
a) type 1 PCV
b) type 2 PCV
c) type 3 PCV
b) type 2 PCV
recent (2016); 35-40% genetic homology to PCV2
a) type 1 PCV
b) type 2 PCV
c) type 3 PCV
c) type 3 PCV
What is PCV2 now referred to as?
PCVAD (associated disease) or PCVD (disease)
This characteristic of PCV2 makes it very durable
it’s non-enveloped and very stable in the environment
Talk about pathogenesis of PCV2
infects lymphocytes → atrophy of lymph nodes → immune suppression
The PCV2 virus sheds for at least ______ days via nasal secretions and/or feces and is viremic (virus in blood) for ________ months
70 days; 3-5 months
all PMWS cases are __________ positive
PCV2
t/f: not all PCV2 positive pigs have PMWS
true
Why was it difficult to diagnose PCV2 early on?
the virus did not have distinctive case presentation
What are the 3 criteria for diagnosing PCVAD
-wasting
-microscopic lesions: lymphoid depletion → granulomatous infiltration
-detection of PCV2 in lesions → antigen by immunochemistry
these pigs are wasting quickly - cachexia - and water consumption declines so they are becoming dehydrated
what virus do these pigs most likely have?
PCV2
Porcine Dermatitis and Nephropathy Syndrome may be caused by:
a) Porcine Circovirus 2
b) Swine Influenza
c) Porcine Respiratory and Reproductive Syndrome
d) Porcine Epidemic Diarrhea Virus
a) Porcine Circovirus 2
These two types of viruses can cause viral diarrhea in baby pigs
Coronaviruses and Rotavirus (both RNA viruses)
what viral disease is this?
-100% mortality in pigs <2 weeks of age
-severe villous atrophy
-slow regeneration from crypts
-malabsorption → dehydration and hypoglycemia
-all ages develop diarrhea // vomiting commonly observed
PED/TGE
[PED/TGE] emerged in the USA from China in 2014
PED
[PED/TGE] is no longer present
TGE
With PED?TGE there is ___% mortality rate in pigs less than 2 weeks old
100%
How do you manage a PED/TGE outbreak?
-feed back intestines from affected pigs to all sows/boars
-euthanize all baby pigs at birth until sows with immunity start to farrow
-clean & disinfect everything (all surfaces)
-vaccinate prior to farrowing for at least 5-6 months
What is the milder form of PED/TGE
Deltacoronavirus
-this virus is very common in herds
-shed in feces for 3 weeks after infection
-durable in the environment
-shed in semen for up to 3 weeks after infection
-causes mummified fetuses
Porcine Parvovirus (PPV)
-Type 1
-this virus causes vesicles like foot and mouth disease
-late summer problem
-main concern is cases at sow slaughter plants
-if diagnosed at farm, sales are stopped until cleared
Senecavirus A (Seneca Valley Virus)
with Porcine Parvovirus:
infection that occurs less than 35 days into gestation results in…
embryos being absorbed
in Porcine Parvovirus:
infection that occurs within 35-70 days gestation results in…
fetal mummification
-this virus is nearly eradicated in USA (feral pigs only)
-DNA virus // herpes virus causes latency
-respiratory disease in any age pigs in addition to CNS signs in neonates and reproductive disease in sows
-will have fever but no other obvious clinical signs initially
Pseudorabies virus
-this is a common disease in early nursery pigs
-causes high pitched sneezing
-a form of porcine cytomegalovirus
-on histopath you will see blue inclusions
inclusion body rhinitis
with this virus you will see nervous clinical signs in nursery/grower pigs (3 to 15 WOA) → listless // ataxia // abnormal postures // recumbency
-reproductive failure
-sporadic outbreaks
Porcine Picornaviruses
-this virus is a form of coronavirus
-cross-reacts with FIP
-causes vomiting and wasting disease
-rare/sporadic cases
Hemagglutinating Encephalomyelitis Virus (HEV)
this is a mild respiratory disease in young pigs // widespread // natural deletion mutant of TGE virus so it cannot attach to intestinal epithelium
-recovered pigs are immune to TGE virus
Porcine Respiratory Coronavirus (PRCV)
-this virus occurs in young pigs
-vesicles to pustules to scabs mainly ventral on sow udders but can spread
-lesions heal in 3-4 weeks
Swine Pox Virus
-eradicated from the USA in 1956
-same virus that causes San Miguel sea lion virus disease
a) vesicular stomatitis
b) vesicular exanthema
b) vesicular exanthema
-endemic in SW USA but not in swine
-periodic outbreaks - every 10 years or so
a) vesicular stomatitis
b) vesicular exanthema
a) vesicular stomatitis
-this is a vesicular disease
-pigs replicate lots of virus
-if suspected, call the state vet
Foot and Mouth Disease
-high mortality rate
-major outbreak in China in the past 2 years
-no effective vaccines
-foreign disease → risk for US introduction
-if suspected, call the state vet
African Swine Fever
-eradicated from US in early 1970’s
-this virus has similar lesions to African Swine Fever but not as severe
-if suspected, call the state vet
classical Swine Fever (Hog Cholera)
-this virus is mosquito born
-common cause of encephalitis in humans in Asia
-pigs are amplifying host but not clinically affected
-pregnant swine: fetal infection → fetal death
Japanese Encephalitis
-this virus was recently implicated as the cause of Shaker Pig disease
-congenital tremor
-pigs shake right after birth → if too severe will be unable to suckle
-outbreak may last 2-3 months
-diagnose via PCR
Atypical Porcine Pestivirus
-this virus is 35-40% nucleotide homologous to PCV2
-originated from bats in China
-fetal death is well documented
-diagnose via PCR
Porcine Circovirus type 3
-this virus was first detected in 1980
-diarrhea in suckling pigs during mid-lactation
-clinically similar to rotavirus and coccidiosis
-reduced weaning weights - 1#/pig
-no or slight increase in mortality
-diagnose via PCR
Porcine sapovirus
This virus clinically causes mild respiratory issues and vaccination is not warranted
Porcine parainfluenza virus type 1
This virus is fairly common but has not been shown to cause disease and is implicated as the contributor in Acute Pulmonary Edema PCV2 cases
Torque Teno Virus (TTV)
This virus is widespread in US swine herds: pigs are the reservoir host
-causes liver inflammation in humans
-present in undercooked pork meat
Hepatitis E Virus
