picornaviridae

Question 1

picornaviridae general

Answer 1

spherical, non enveloped, visions appear smooth and round

single molecule linear + sense RNA, VPg protein links to 5’ end and genomic RNA is infectious

Question 2

picornaviridae genome

Answer 2

cytoplasmic replication, virion RNA acts as mRNA and is translated to polyprotein to yield 11-12 proteins, most cause cytopathic effects and rapid cel death, very stable at low pH, 29 genera

Question 3

foot and mouth disease FMD

Answer 3

seven serotypes, 80 subtypes, OAC in SA, OAC sAT 123 in Africa western europe and north and central america virus free

Question 4

FMD hosts

Answer 4

all cloven footed domestic and wild animals, horses are genetical resistant

Question 5

FMD distribution

Answer 5

africa, asia, middle east, none in North and Central America

Question 6

FMD stability

Answer 6

stable pH6-9, broken down by citric or acetic acid

Question 7

FMD transmission

Answer 7

mostly through inhalation, can move in wind or inside animal carriers

Question 8

FMD path

Answer 8

inhalation/ingestion->oropharyngeal infection->viremia->spread to different organs and tissues->replication in epidermal cells->characteristic vesicular lesions
**vesicles filled with clear fluid

Question 9

FMD path myocardial lesion

Answer 9

tiger heart, focal necrosis of cardiac muscle
-seen in fatal FMD cases in young animals, streaks of irregular size and shape are visible in myocardium, sudden death from heart failure

Question 10

FMD Path

Answer 10

usually founding the pharynx, needs prolonged period of recovery, virus detectable in cattle up to two years and sheep after six months, virus persistence doesn’t occur in swine

Question 11

FMD clinical signs

Answer 11

most severe in cattle and intensively reared pigs, sheep and goat develop subclinical infections, morbidity high and mortality low

Question 12

FMD cattle clinical signs

Answer 12

fever anorexia depression
decreased milk production, drooling, vesicles around coronary band, crater ulcers from ruptured vesicles
secondary bacterial infections, myocarditis in calves up to 6 months of age, abortion, chronic Diabetes mellitus from endocrine damage

Question 13

FMD clinical sign in swine

Answer 13

lameness is often the first sign of foot and mouth disease, vesicles in mouth less prominent, more on snout

Question 14

FMD in sheep and goats

Answer 14

mostly subclinical infections, if disease occurs its mostly mild

Question 15

FMD Dx

Answer 15

sampling fluid, ELISA, test for antibodies

Question 16

FMD control

Answer 16

notifiable disease, quarantines in disease free countries, infected carcasses must be disposed of properly, vaccination around affected areas, rodent control, ban on swill feeding

Question 17

FMD zoonosis

Answer 17

most human infections are subclinical, clinical signs show fever anorexia, vesiculation

Question 18

tremovirus

avian encephalomyelitis

Answer 18

most seen in chickens 1-3 weeks old, fecal oral transmission or by egg

Question 19

avian encephalomyelitis path

Answer 19

incubation period depends on the route of infection, vertical transmission 1-7 days, horizontal 11 days or more. no gross lesions
histology of central chromatolysis of neurons in the medulla oblongata

Question 20

avian encephalomyelitis clinical signs

Answer 20

young chickens exhibit nervous disease -ataxia leg weakness , paralysis and recumbency, prostration blindness coma and death, may develop cataracts
laying chickens-no neuro signs, no deterioration in egg shell, hatch ability may drop, late embryonic mortality

Question 21

avian encephalomyelitis Dx and control

Answer 21

Dx-virus isolation from brain and duodenum with pancreas, yolk sac of embryonated eggs, demonstration of AE virus antigen brain, spinal cord and other tissues, immunoflourescent staining. for control immunize with breeder pellets, commercial live vaccine AE vaccine combined with fowlpox, AE doesn’t infect humans or other mammals

Question 22

encephalomyocarditis

genus: cardiovirus

Answer 22

tropic to heart and brain, hosts are rodents, epizootics to swine and other wildlife, pigs infected from water contamination and transplacental infection

Question 23

encephalomyocarditis clinical features

Answer 23

myocardial effects contribute to acute and subacute deaths, nonsuppurative meningoencephalitis in young pigs, reproductive issues/late term abortions