lecture 6 and 7- porcine virology Flashcards
what is TGEV? what kind of virus?
transmissible gastroenteritis virus
it is 1 of the 3 porcine coronaviruses
what is PEDV? what kind of virus is it?
porcine epidemic diarrhea virus
it is 1 of the 3 porcine coronaviruses
what is SDCV? what kind of virus?
swine delta coronavirus
what are the 3 porcine coronaviruses?
TGEV (transmissible gastroenteritis virus)
PDEV (porcine epidemic diarrhea virus)
swine delta coronavirus (SDCV)
true or false: porcine can be infected with coronaviruses during any production phase?
true
true or false: porcine can be infected with rotavirus during any production phase?
false- they can only be infected during the suckling or weaning phase
what are the gross lesions of porcine rotavirus / porcine coronaviruses?
dehydrated carcass, watery intestinal contents, thin walled intestines
what are histological observations of porcine rotavirus / porcine coronaviruses?
stunted intestinal villi and viral antigens in villi
if diarrhea appears in waves in individual litters or groups of litters in the second half of lactation, is it more likely rotavirus or a coronavirus?
rotavirus
if there is a sudden outbreak of scour involving large numbers of litters with acute diarrhea and high mortality, is it more likely rotavirus or a coronavirus
coronavirus
what is the etiology of porcine epidemic diarrhea ?
coronavirus
how does age impact the mortality of pigs infected with porcine epidemic diarrhea?
suckling pigs have up to 100% mortality, while older pigs have much lower mortality
how can you clinically distinguish between which porcine coronavirus is the cause of an infection?
you cant
what is the incubation period of PED?
3-4 days
which gives more info about virus, detecting protein or genome? why?
detecting for the viral protein gives more info because we can tell if it is actively replicating
what samples can be taken to test for PED?
feces, oral fluid, small intestine, serum for antibodies
which of the following tests will NOT detect PED?
RT-PCR
PCR
ELISA
immunohistochemistry
virus isolation
ELISA serological test
PCR- this is an RNA virus so needs to be RT
can piglets be protected from PED by maternal antibodies in colostrum?
yes
true or false: mortality rates in SDCV is higher than in PED
false, mortality is lower in SDCV
how is TGEV related to porcine respiratory coronavirus (PRCoV)
PRCoV is a mutant of TGEV with a deletion of 225 amino acids in spike protein (it replicates in respiratory tract vs GI)
which animals are at the highest risk of mortality with TGE?
young animals, just like all coronaviruses
where does rotavirus replicate? is this different from coronavirus?
mature enterocytes, just like coronavirus
what is the pathology of coronavirus and rotaviruses replicating in mature enterocytes?
infection of respiratory tract –> replication in mature enterocytes –> enterocytes slough off –> decreased enzymes –> water not reabsorbed –> diarrhea
what body system is most affected by porcine parvovirus?
reproductive
what family is PPV a part of?
parvoviridae
what is SMEDI syndrome
stillbirths
mummification
embryonic death
infertility
in what animal does parvovirus cause SMEDI syndrome?
porcine (and feline?)
how is PPV transmitted?
- virus secreted in feces and other fluids
- sow to fetus transmission in seronegative animals
what are the 3 possible outcomes if a pregnant sow is infected with PPV?
1) early embryonic death and resorption
2) fetal death and mummification
3) survival and seropositivity
if a sow is infected with PPV before day 70 of gestation, will the fetus surive?
unlikely
what kind of placenta do sows have? does this make it difficult for vertical transmission?
epitheliochorial placenta
more difficult (lots of barriers)
a female pig returns to estrus with no apparent reason or delay in parturition and has increased numbers of mummified fetuses and smaller litters
what virus should be considered?
PPV
PPV vaccines are all….
killed vaccines
what family is pseudorabies a part of?
herpesviridae
how is pseudorabies spread?
direct, sexual, indirect, aerosol, somites
what is the natural host of pseudorabies?
porcine
where does primary replication of pseudorabies occur?
respiratory tract
how does pseudorabies spread within pigs?
blood, lymph, and nerves
what body systems are affected by pseudorabies in pigs?
respiratory, nervous, lymph, reproductive
what are the clinical signs of pseudorabies in a neonate/suckling pig? what is the % mortality?
inability to stand/move, sit like dogs due to posterior paralysis, fever, inapp, V+, other nervous system signs
100% mortality
what are the clinical signs of pseudorabies in a weaner/grower/finisher pig? what is the % mortality?
respiratory signs
5-10% in weaners
1-2% in growers and finishers
what are the clinical signs of pseudorabies in an adult pig? what is the % mortality?
mild or unapparent, gilts and sows might have repro problems
how does the pathogenesis of pseudorabies differ in animals other than pigs?
no blood or lymph transport –> only neurological signs
what is the etiology of mad itch?
pseudorabies
how is pseudorabies diagnosed
immunohistochemistry to demonstrate viral antigens
how has pseudorabies been eradicated?
serologic surveillance, culling, biosecurity, vaccination
what family is swine influenza a part of?
Orthomyxoviridae
how many types of swine influenza are there? what do we care about
4 (A-D)
type A* infects animals and humans, (type D infects cattle)
how many subtypes of HA and NA are there? (regarding type A influenza viruses)
HA (18)
NA (11)
what does HA bind to on host cell
sialic acid residues
what is significant about the receptor types of HA in pigs and quail?
pigs can bind to both the avian 2-3 sialic acid receptor (gut and lung) and human 2-6 linked sialic receptor (non-ciliated epithelium of human airway)
this makes pigs a mixing pot for human and avian influenza strains, leading to reassortment and antigenic shift
what are 2 requirements of reassortment/antigenic shift
1) virus must be segmented
2) multiple virus strains must enter one cell
which strain of influenza persists the longest?
H1N1
what family is PED, SDCV, and TGE a part of?
Coronaviridae
what is the structure of PED, SDCV, and TGE (given they are a part of Coronaviridae)?
enveloped, positive sense
what is the replication strat of PED, SDCV, and TGE (given they are a part of Coronaviridae)?
ssRNA + (viral genome acts as mRNA)
if you delete 225 amino acids from the spike protein of _______, you get PRCoV
TGEV
what is the structure of PPV?
naked, positive sense
what is the replication strat of PPV?
ssDNA (cellular DNA pol –> dsDNA –> cellular RNA pol2 –> mRNA)
what kind of cells are required for parvoviral replication in sows?
mitotically active stem cells
what is the structure of pseudorabies?
enveloped
what is the replication strat of pseudorabies?
dsDNA (cellular RNA pol2 –> mRNA)
what is the structure of swine influenza?
enveloped, negative sense
what is the replication strat of swine influenza, given it is orthomyxo?
ssRNA- (virion RdRp –> mRNA)
what is PCV
Porcine Circovirus
what family is PCV a part of
Circoviridae
how many PCV strains are there? which is most significant for us to pay attention to?
4 (PCV1-4)
PCV2 - most prevalent across the world and has both field observation and experimental reproduction
which PCV strain is spread worldwide in both domestic and wild boar populations
PCV3
what influences the clinical significance of PCV2? 4 things
1) difference between PCV2 isolates
2) co infection
3) immune modulation
4) host susceptibility
what are the 4 possible outcomes of PCV-2 infection? explain the clinical signs of each
1) subclinical infection (no signs, some decreased gain)
2) systemic disease (sig weight loss, ill-thrift, sometimes resp/GI disorders, lymphoid depletion)
3) reproductive disease (abortions/mummifications)
4) dermatitis and nephropathy syndrome (dark red papules and macules on skin- usually on hind and perineal area)
on histo, which virus shows depleted lymphoid with multinucleated giant cells and lots of viral proteins (when clinical)
PCV2
what cells do PCVD (derm) target during fetal life and postnatally?
fetus- cardiomyocytes, hepatocytes, macrophages
postnatally- macrophages
how to diagnose PCV2?
- clinical hx
- post mortem findings
- immunohistochemistry on lymph tissue
- PCR
- qPCR
what is the structure of PCV (naked or enveloped)
naked
what is the replication strat of PCV?
ssDNA (cell DNA pol –> dsDNA –> cell RNA pol2)
what are 3 things that make the PCV vaccine worth administering
1) can be given during gestation
2) cross-protection between PCV2 strains
3) decreases clinical disease (not infection)
what is PRRSV?
porcine respiratory and reproductive syndrome virus
what family is PRRSV in?
Arteriviridae
what is the structure and repro of PRRSV
enveloped positive sense RNA virus
how many strains of PRRSV is there? which broad ones are the American and which are the European strains
lots of strains! but…
PRRSV-1: European
PRRSV-2: American
PRRSV replication lends itself to genetic variability through_____ and ____ , causing numerous straight
point mutations and recombination
RNA virus so more mutations!!
what type of cells does PRRSV target?
macrophages (alveolar, tissue, and lots more)
where is PRRSV found during chronic phase?
peripheral lymph nodes and tonsils
what are the clinical signs of PRRSV
-repro problems
- respiratory disease
- cutaneous
- rarely neuro
- blue ears
is persistent infection common in PRRSV?
yes - chronic for as long as 5 months
does PRRSV target the innate or adaptive immune response? what does this result in?
innate- results in delayed immune response
would RT-PCR be useful in diagnosing PCV (porcine circo) and PRRSV?
PCV- NO its a DNA virus so PCR must be done
PRRSV- yes!! :) RNA so RT-PCR
is the vaccine for PRRSV helpful in preventing disease
yes
virus transmission involving inanimate objects such as needles is
iatrogenic
during herpes virus infection you may observe
intermittent virus shedding
common viruses that cause porcine respiratory disease
pseudorabies (Herpes)
swine influenza (Orthomyxo)
PCV2 (Circo)
PRRSV (Arteri)
common viruses that cause porcine reproductive disease
PPV (Parvo)
Pseudorabies (Herpes)
PCV2 (Circo)
PRRSV (Arteri)
swine influenza –> fever causes aboriton NOT disease
common viruses that cause porcine GI disease?
Corona! (PED, TGEV, SDCV)
sometimes PCV2-SD (Circo)
