5. Olds (Finals)

Question 1

Live vaccine is better than killed vaccine, but what is its major disadvantage?

Answer 1

Potential to mutate leading to variants

Can infect host upon administration, can’t be used to immunocompromised hosts.

Question 2

Draw circovirus and influenza (orthomyxo?) virus. Write 5 differences between the viruses in terms of structure, morphology, or chemical composition.

Answer 2

1. Nucleic Acid Conformation - Circo (ssDNA), Influenza (ssRNA)
2. Presence of Envelope - Circo (nonenveloped), Influenza (enveloped)
3. Proteins - Circo (2 major ORFs on opposite sides: replicase and capsid proteins), Influenza (proteins making up ribonucleotide: NP, PA, PB1, PB2) and in lipid envelope (HA, NA, M1, M2)
4. Shape of virions - Circo (spherical), Influenza (pleomorphic, filamentous)

Question 3

Families of RNA viruses that have multiple segments

Answer 3

1. Birnaviridae: 2
2. Orthomyxoviridae: 6-8
3. Arenaviridae: 2
4. Reoviridae: 10-12
5. Bunyaviridae: 3

Question 4

Replication cycle ng Pox

Question 5

Why you can find parvovirus microscopically in cytoplasm

Answer 5

1. Attachment to receptor➡️endocytosis of the virion to the host cell.
2. Virion penetrates into cytoplasm (permeabilization) and reaches the nucleus where uncoating occurs (microtubular transport)

Question 6

Give the clinical sign or lesion of the ff:
a. Ectromelia
b. Porcine circovirus
c. Hog cholera
d. Dry form of fowl pox
e. Dry form of feline infectious peritonitis

Answer 6

a. Ectromelia (Poxviridae) - Papules
b. Porcine circovirus (Circoviridae) - diarrhea
c. Hog cholera (Flaviviridae) - diarrhea, vomiting
d. Dry form of fowl pox (Poxviridae)- Papules
e. Dry form of feline infectious peritonitis - seizures

Question 7

Pathogenesis of fatal rabies starting from bite from leg

Answer 7

centripetal spread
* bite (saliva)
* muscles, peripheral/cns
* spinal cord
* brain a) limbic b) neocortex

centrifugal spread
* brain a) limbic b) neocortex
* salivary

Question 8

Stable or unstable virus:
a. Foot and mouth
b. Blue tongue
c. Vesicular exanthema
d. Rinderpest
e. Ebola

Answer 8

a. Foot and mouth (Picorna) - Stable
b. Blue tongue (Reo) - Stable
c. Vesicular exanthema (Calici) - Stable
d. Rinderpest (Paramyxo) - Unstable
e. Ebola (Filo) - Unstable

Question 9

Draw and describe virus:
a. Cowpox
b. Ebola
c. Rabies
d. PED
e. infectious canine hepatitis virus

Answer 9

a. Cowpox - Brick shaped
b. Ebola- filamentous
c. Rabies - Bullet shaped
d. PED - club shaped
e. infectious canine hepatitis virus - icosahedral

Question 10

Pathogenesis of hog cholera (classical swine fever) to target organs

Answer 10

• Entry: Oronasal
• 1: replication - tonsils
• lymph nodes
• viremia
• endothelial cells, lymphoid organs, bone marrow
• hemorrhages
• leukopenia
• thrombocytopenia
• parenchymatous organs, brain
• hemorrhages
• congestion
• infarction
• DIC
• thrombosis
• enteritis

Question 11

Pathogenesis of Infectious bursal disease (Gumboro disease) to secondary bacterial infection

Answer 11

• Oronasal entry
• 4-5 hours: gut-associated macrophages and lymphocytes in ceca & small intestine
• Primary viremia
• 11 hours: cloacal bursal lymphocytes
• Secondary viremia
• Localization in other lymphoid organs

–——————
* Target organ is Bursa of Fabricious
* 3-4 days after infection –> 5X increase size, edema, hyperemia
* Collapse of lymphoid follicles (B cell death hemorrhages in bursal serosa & necrotic foci in parenchyma
* Grossly atrophic bursa
* Enlarged kidneys with ureates due to dehydration

Question 12

Arrange the following virus according to genomic size (biggest to smallest):
a. psittacine beak and feather disease
b. transmissible gastroenteritis virus
c. Avian encephalomyelitis
d. Lumpy skin disease
e. Feline Panleukopenia

Answer 12

a. psittacine beak and feather disease (Circoviridae): 5 (12-27)
b. transmissible gastroenteritis virus (Coronaviridae): 2 (120-160)
c. Avian encephalomyelitis (Picornaviridae): 3 (30)
d. Lumpy skin disease (Poxviridae) 1 (259 x 299 x 299)
e. Feline Panleukopenia (Parvoviridae)- 4 (18-26)

Question 13

Taqman probe in PCR

Answer 13

DRAW

Principle:
* Intact probe gives no fluorescence signal – fluorophore close to quencher
* Polymerization of primer during PCR breaks the intact probe – fluorophore moves away from quencher leading to unblocked fluorescence

Question 14

Give 4 possible horizontal transmission routes for Porcine Reproductive and Respiratory Syndrome
(PRRS)

Answer 14

1. Sexually
2. Close contact with infected pig
3. Nasal discharge/droplet/ aerosol
4. Mechanically by vehicles
5. Indirect contact - via fomites
6. Iatrogenic transmission - direct result of some activity of the attending veterinarian, veterinary technologist, or other person in the course of caring for animals, usually via non sterile equipment, multiple-use syringes, or inadequate hand washing.
7. Nosocomial transmission - occurs while an animal is in a veterinary hospital or clinic

Question 15

Draw and describe the Ag LFD positive and negative results

Answer 15

DRAW

Negative
1. Absorption zone
2. Detection zone (Control line) - fixed Ab detects conjugate
3. Detection zone (Test line) - fixed Ab detects Ag in sample (none)
4. Conjugate pad
5. Sample pad

Positive
1. Absorption zone
2. Detection zone (Control line) - fixed Ab detects conjugate
3. Detection zone (Test line) - fixed Ab detects Ag in sample (+)
4. Conjugate pad
5. Sample pad

Question 16

Bonus: pano maging valid ang virotype RTPCR ng PED