rhabdoviridae Flashcards Preview

VIRO final > rhabdoviridae > Flashcards

Flashcards in rhabdoviridae Deck (41):
1

rhabdoviridae morphology

visions enveloped with large spikes bullet shaped, helically coiled cylindrical nucleocapsid

2

rhabdoviridae general proteins

L protein, G protein, N protein, P protein, M protein, single molecule linear - sense ssRNA, cytoplasmic replication, mature through budding of plasma membrane, can be cytopathoic or noncytopathic forms

3

L protein Large protein

RNA dependent RNA polymerase (transcriptase)

4

G protein Glycoprotein

envelope spikes

5

N protein Nucleoprotein

associates with RNA to form the viral nucleocapsid

6

P protein Phosphoprotein

mediates binding of L to nucleocapsid

7

M protein Matrix protein

associates with the viral nucleocapsid and lipid envelope

8

rhabdo classification

genus: ephemerovirus-bovine ephemeral fever
genus: vesiculovirus-vesicular stomatitis
genus: lyssavirus-rabies

9

lyssavirus- rabies

caused by genotype 1, carribean islands, japan, singapore, new zealand, low risk, but worldwide distribution

10

host species for rabies

high risk-cats, cattle
moderate risk-dogs, sheep, goats, horses, monkeys, humans
all warm blooded susceptible

11

rabies transmission

bite or scratch, virus in saliva less often, sometime aerosol, some even from transplants of organs

12

epidemiology of rabies

sylvatic cycle with vampire bats in central and south america
foxes in europe, coyotes in NA, jackals africa

this cycle most common in NA

13

urban cycle of rabies

dogs main reservoir africa asia south and central america; many herbivores are dead end hosts -cattle sheep goats and horses

14

rabies transmission involving bats

many specie harbor it, asymptomatic usually, can develop paresis or paralysis, may sometimes show aggression, insectivore bats common in NA,
vampire bats in mexico and central america, fruit bats in australia

15

rabies transmission involving skunks

most important in USA, most cases of cattle rabies, along with raccoons on the east coast

16

rabies path

1. intramuscular inoculation, can enter peripheral nerves or in non-nervous tissue until reach high concentration
2. the G protein binds to axons terminals of peripheral nerve fibers through lipoprotein receptors like Ach and enter nerves
3. shorter incubation for more highly innervated regions
4 bites to face have greatest risk

17

uncommon routes rabies

intranasal-trigeminal nerves

18

spread of rabies

furious form replicates in limbic system, dumb or paralytic form is CNS spread, can move to salivary glands (hypersalivation)

19

pathology and immunology

inflamed brain, functional lesions over structural.
both hum moral and cell mediated immunity undetected during spread of virus, no MHC proteins, noncytopathic infection, little antigen released but CSF has small amount of antibodies

20

incubation of rabies

depends on strain, site of bite, and degree of innervation, (closer to the brain is shorter), phases include prodromal, acute excitative (furious), and paralytic/endstage ( dumb)
**survival is rare

21

prodromal period

shedding of virus and change in temperature

22

furious form

mad dog syndrome, animal nervous, irritable, aggressive movements, posture change, dilated pupils, lose fear of everything, develop hydrophobia
more common in dogs and cats

23

paralytic form

encephalitis progresses, fury leads to paralysis and ataxia, seizures, death within 2-14 days

24

characteristic of bovine rabies

bellowing tail (elevated), salivation

25

characteristic of equine rabies

dysphagia and salivation, posterior paralysis

26

canine rabies furious form

growling

27

canine paralytic phase

ptyalism, depression, paralysis, sternal recumbency with torticollis

28

diagnosis of rabies

direct FAT to look for rabies antigen, recommended by WHO, look for negri bodies in cytology (only 75% show inclusions), RT-PCR, virus isolation in mice intracerebral inncoluation

29

Direct fluorescent antibody test

negative-shows no fluorescence
positive-shows fluorescence

30

rabies control

quarantine in rabies free countries for 6 months, in endemic countries-vaccinate dogs and cats.
preexposure- vaccinate at 3mo and once a year after
postexposure-revaccinate immediately and keep under owner's control for 45 days
wildlife use bait vaccine*

31

vesicular stomatitis (VS)

caused by group of anti genetically related but distinct viruses
host-cattle pigs and horses, sometimes humans and sheep and goats
serotypes-indiana and new jersey (most virulent)

32

VS distribution

occurs primarily in the Americas and certain areas of the Carribbean

33

VS transmission

enters through breaks in the skin, contaminated milking machine, ingestion of fomites, arthropods (black flies, sand flies, leaf hoppers)

34

VS Path

enters through broken mucosa/ski, common in mucous membrane of the oral cavity and the skin, fluid filled vesicles form, extensive ulceration, entire epithelium of the tongue or teat sloughed, does not usually become systemic and viremic

35

VS clinical signs

excessive salivation, fever, lameness, vesicles on tongue, ulcers, anorexia, more vesicular lesions in swine, humans have self limiting influenza like symptoms 3-5 days

36

VS in cows

ruptured tongue vesicles, almost complete detachment of epithelial surface

37

VS Dx

indistinguishable clinically from other vesicular diseases like foot and mouth, yet horses have only one vesicular Dx (VS)
VS is reportable**

38

Bovine Ephemeral fever

genus: Ephemerovirus
host-water buffalo, cattle
never reported in NA
arthropod borne Cullicoides and mosquitos

39

Bovine Ephemeral virus path

3 day sickness, poorly understood, virus in buffy coat of blood, early neutrophilia with high level of immature neutrophils (left shift), there is an increase in plasma fibrinogen and a significant decrease in plasma calcium

40

Bovine Ephemeral Virus clinical features

polyerositis affecting joints, pleural and peritoneal surfaces, influx of neutrophils
fever, salivation, nasal discharge, lameness, may lay recumbent

41

bovine ephemeral virus Dx

isolation of virus is difficult, can be attempted by inoculation of infected buffy coat cells into culture from A. albopictus