Viral Zooneses I

Question 1

RABIES taxonomy

Answer 1

Family: Rhabdoviridae
Order: Mononegaviraes
Genus: Lyssavirus

Question 2

The genome of rabies virus

Answer 2

Linear (-) non segmented ssRNA, encodes 5 proteins (GLMNP)

Question 3

Viral particle of rabies virus

Answer 3

Bullet-shaped

Helical nucleocapsid

Question 4

Antigenic properties of rabies

Answer 4

Purified spikes (elicits antibodies)
Antiserum against purified nucleocapisd (immunofluirescence)

Question 5

How can you control rabies virus in the lab?

Answer 5

CO2
Trypsin 
Lipid solvents (0.1% sodium deoxycholate and ether)
Heat (50C for 1 hr)
UV rad or sunlight

Question 6

T or F: all warm-blooded animals are susceptible to rabies

Answer 6

True

Question 7

Natural reservoir of rabies

Answer 7

Bats and raccoons

Question 8

T or F: the rabies virus can only be found in the blood

Answer 8

False, it is widely disseminated. Found in Nervous system, saliva, lymph, blood, urine, and milk

Question 9

T or F: the bite of a rabid animal gives you a 20x greater chance of acquiring rabies than scratches

Answer 9

F 50x

Question 10

Human-human transmission of rabies t or f

Answer 10

??? Not yet confirmed

Question 11

How does rabies virus enter the body?

Answer 11

Adsorption

Question 12

This step of the rabiesviral replication comes after uncoating wherein mRNAs are syntheisized and is important in order to replicate inside cell

Answer 12

Transcription

Question 13

This step of the rabies viral replication process involves synth of 5 stuc proteins

Answer 13

Translation

Question 14

G-protein glycosylation in rabies

Answer 14

Processing step (after translation)

Question 15

How does rabies exit?

Answer 15

Budding

Question 16

Preferred site of rabies virus in the CNS

Answer 16

Brain stem and medulla

Question 17

Responsible for rabies viral replication in CNS

Answer 17

Endoneurium of schwann cells and associated spaces in sensory nerves

**reason why infected dog brains are examined

Question 18

When is saliva infectious in rabies

Answer 18

Two weeks before appearance of signs

Question 19

Other sites where rabies can replicate, produce cellular infiltrates and cause necrosis

Answer 19

Salivary glands and cornea

Question 20

Effects of rabies on the body

Answer 20

Hyperemia
Nerve cell destruction in midbrain, basal ganglia, cortex, pons and especially the medulla
Degeneration of axons and myelin sheaths
Demyelinization in white matter
Posterior horns of spinal cord: neuronophagia and Cellular Infiltrates: mononuclear, perineural, perivascular

Question 21

IP in dogs rabies

Answer 21

3-8 weeks, can be 10 days

Question 22

Rabies IP in humans

Answer 22

30-90 days

*shorter in children than adults

Question 23

Clinical stages of rabies virus in dogs

Answer 23

Prodromal

Excitative Paralytic

Question 24

This stage in dogs is characterized by fever and sudden change in behavior

Answer 24

Prodromal

Question 25

This stage in dogs is the most dangerous. Marked by irritability, restlessness, nervousness, exaggeration of response to light and sound, convulsive seizures, difficulty swallowing

Answer 25

Excitative

Question 26

T or F: All rabid dogs undergo excitative phase

Answer 26

False, can be skipped

Question 27

This stage in humans is marked by non-specific symptoms, pain or paresthesia in the inoculation site and involvement of symptoms in respiratory, GI, and CNS

Answer 27

Prodromal phase **other symptoms Agitation  Photophobia  Priapism (persistent & painful penile erection)  Increased libido  Depression  Insomnia  Nightmares  Encephalitis  Brain conditions  Psychiatric disturbances

Question 28

Begins with signs of CNS dysfunction in humans

Answer 28

Acute neurologic period

Question 29

Form of acute neurologic period characterized by hyperactivity, hydrophobia and aerophobia

Answer 29

Furious (classic or encephalitis)

Question 30

This form of acute neuro period in humans is marked by paralysis

Answer 30

Dumb rabies

Question 31

T or F: microscopic examination of rabies is done through light microscopy

Answer 31

False, immunofluorescence of infected using anti-rabies hamster serum

Question 32

Usual specimen if rabies virus

Answer 32

Cornea and brain

Question 33

Definitve diagnosis of rabies in microscopy

Answer 33

Presence of negri bodies in brain or spinal cord **not found in all cases

Question 34

Considered as gold standard in diagnosing rabies virus

Answer 34

Isolation of virus

Question 35

In virus isolation, what is usually observed for?

Answer 35

Rabies antigen and negri bodies

Question 36

It is a serially passaged strain that cannot produce disease in animals so it is used for vaccination (LAV); found in chick embryos

Answer 36

Flury strain

Question 37

T or F: rabies virus can still be extracted in dead humans for PCR

Answer 37

False

Question 38

Why is immunogenic vaccine or antibody applied immediately

Answer 38

To prevent CNS invasion | To provide more time for stimulation of antibodies before CNS invasion

Question 39

Immunization regimen for persons with high risk exposure to rabies

Answer 39

Pre-exposure (involves HDCV and DEV)

Question 40

This immunization regimen involves thorough cleansing of the wound, administration of RIG and ARS and immunization with HDCV or DEV

Answer 40

Post-exposure

Question 41

T or F: All rabies vaccines administered to humans contain inactivated rabies virus

Answer 41

True

Question 42

Where is HDCV grown from?

Answer 42

WI-38 human normal fibroblast cell line (free of nervous system and foreign proteins (concentration of virus: ultracentrifugation then it is inactivated with tri-N-butyl phosphate, or Beta-Propiolactone) Fetal rhesus monkey lung diploid cell line

Question 43

It is sufficiently antigenic and elicits greatest efficacy in antibody response. 4-6 doses are needed.

Answer 43

HDCV * pre-exposure: 3 times 1 ml * post-exposure: 5x 1 ml

Question 44

Developed to minimize post-vaccinal encephalitis, has low antigenicity and can be administered 3-25 times subcutaneously.

Answer 44

DEV **needs multiple doses Pre-exposure: 3-5x of 1 ml Post-exposure: 16-25x of 1 ml

Question 45

Rabies glycoprotein is inserted into vaccinia virus; orally given

Answer 45

Recombinant virus vaccine

Question 46

It is prepared via cold ethanol fractionation of plasma of hyperimmunized individual. Dose: 20 IU/kg (intramuscular and around bite)

Answer 46

Rabies Ig

Question 47

Concentrated horse serum that were hyperimmunized with the rabies virus

Answer 47

ARS, equine | Dose: 40 IU/kg

Question 48

Factors to consider in administering post exposure prophylaxis

Answer 48

``` Nature of animal -HDCV and RIG Existence of Rabies in area Manner of attack and biting severity Advice ```

Question 49

PEP measure if contact with suspected rabid animal: Touching/feeding animals Licks on intact skin

Answer 49

None

Question 50

PEP if contact is nibbling and minor scratches and abrasions

Answer 50

Immediate vaccination | Local wound treatment

Question 51

PEP if contact is: Single/multiple transdermal bites/scratches Licks on broken skin Contamination of mucous membrane with saliva from licks Contact s with bats

Answer 51

Immediate vaccination Administration of Ig Local wound treatment (3rd category)