Rabies by Dr. Rakesh Prasad Sah

1. RHABDOVIRUESES
Dr. Rakesh Prasad Sah
Assist Professor, Microbiology

2. Introduction
• Greek word
– Rhabdos  rod shape
• Enveloped virus
• ssRNA genome
• Family  Rhabdoviridae

3. Classification
• Rhabdoviridae
– Vesiculovirus : Vesicular stomatitis virus and
chandipura (arbovirus)
– Lyssavirus: Rabies virus
• Lyssa  madness, synonym for rabies

4. Rabies
• An acute contagious and fatal viral disease of the nervous system that
is caused by a rhabdovirus (species Rabies virus of the genus
Lyssavirus) usually transmitted through the saliva to human beings by
the bite of a rabid animal which causes inflammation of brain which
leads to following typical features
– increased salivation,
– abnormal behavior (Hydrophobia)
– Madness
– convulsions
– eventual paralysis and
– death.

5. Rabies Virus
• Morphology :
– Bullet shaped virus
– Size is 180 x 75 nm
– Has Lipoprotein envelop
– Knob like spikes /Glycoprotein
– Beneath lipoprotien envelop
Matrix (M) protein
– Nucleocapsid  helical
symmetry negative sense RNA
and a RNA-dependent RNA
Polymerase

7. Resistance
• Highly resistant against dryness, cold, decay
etc. and remain infective for many weeks in
the cadaver.
• Eveloped virus  highly sensitive to lipid
solvent e.g.
– Ether
– Chloroform
– Acetone
• Sensitive to quarternary ammonium
compounds, ethanol and iodine
preparations , soaps and detergents.

8. • Is inactivated by
– Phenol
– Formalin
– BPL (Betapropiolactone)
– Sulight
– UV
– Heat
• at 500C for 1hr and
• 600C for 5 mins

9. Antigenic structure
• Rabies virus of man and animals are of
single antigenic type
• Suface spikes composed of glycoproteins G
 strongly Agenic and Ab against it is
protective
• Nucleoprotein induces Ab but not
protective.
• Other Ags includes membrane proteins,
glycolipid and RNA dependent RNA
polymerase

10. Animals Susceptibility

11. Animals Susceptibility and Culture
• Street virus
– isolated from natural human or animal infection called street
virus.
– Negri bodies can be demonstrated in brains of these animals
• Fixed virus
– Several serial intracerebral passages in rabbits
– Undergo certain changes & is termed as fixed virus
2. Chick embryos
– Grows in chick embryo & moi  yolk sac
– Live attenuated vaccine strains
3. Tissue culture
– Grow in chick embryo fibroblasts, hamster kidney cells,
human diploid cells and vero cell cultures.

12. Sources of Infection
• Saliva of Rabid animal
• Dogs and cats-virus in saliva 3-
4 days before clinical
symptoms

13. Transmission
• Abrasions or scratches on skin.
• Mucous membrane exposed to saliva.
• Most frequently via deep penetrating
bite wounds.
• Other routes.
– Inhalation in bat infected caves.
– Ingestion of dead
/infected animal meat
– Corneal transplantation

14. Incubation Period
• Normally 1-3 months.
• May be short that is 7 days or may be prolonged for 3
years.
• Depends on-site of bite
– Severity of bite
– Number of wounds
– Amount of virus injected
– Site of bite
– Treatment taken

17. Saliva infective for several days upto weeks before signs appear  Death
Salivary glands, skin, mucosal surfaces, gut, most other organs
Virus moves out through peripheral and cranial nerves
Multiplies in CNS  Encephalitis
Virus travels up peripheral nerve to CNS
Virus multiplies locally in myocytes for weeks to months
Infection by the bite of rabid animal

19. Symptoms
• Headache, fever, sore throat
• Nervousness, confusion
• Pain or tingling at the site of the bite
• Hallucinations
• Hydrophobia
• Paralysis
• Coma and death

20. Clinical Findings
• Bizarre behavior.
• Agitation
• Seizures.
• Difficulty in drinking.
• Patients will be able to eat solids
• Afraid of water - Hydrophobia.
• Spasms of Pharynx produces choking
• Death in 1 -6 days.
• Respiratory arrest / Death / Some may survive.

21. Stages of Rabies Infection
1. Non specific prodrome
2. Acute neurologic encephalitis
3. Coma
4. Death

23. Non specific prodrome
• 1-2 days  1week
• Fever, headache, sore throat
• Anorexia, nausea, vomiting
• Agitation, depression
• Pain/tingling sensation at
bitten site
• Due to infection of dorsal
root or cranial sensory
ganglia

24. Neurologic phase
Encephalitic
Rabies
80%
Paralytic Rabies
20%

25. Encephalitic Rabies
• Fever, confusion, hallucinations, combativeness,
• Muscle spasms, hyperactivity, seizures.
• Autonomic dysfunction hypersalivation,
Excessive perspiration, gooseflesh, pupillary dilation,
Priapism.
• Hyperexcitability followed by periods of complete lucidity
• Hydrophobia and aerophobia
• “Foaming at the mouth”
• Due to dysfunction of infected brainstem neurons
• Severe brainstem damage coma Death
c

27. Paralytic rabies

28. Rabies can present as Grave
condition

29. Majority will succumb to Disease

32. Diagnosis
1. History
2. Signs and symptoms
3. Clinical examination
4. Detection of antigen by taking skin biopsy using
immunofluorescence
5. virus isolation from saliva & other secretions.
6. CSF analysis and CT scan
7. ELISA
8. RT-PCR
9. DFA testing
10. Negri bodies

33. NEGRI BODIES
appear as intracytoplasmic, oval or round, purplish pink
3-27mm bodies with characteristic basophilic inner granules

34. Prophylaxis
• Pre-Exposure prophylaxis
• Post-Exposure prophylaxis
– Local treatment
– Hyperimmune serum
– Vaccination

35. Local Treatment
• Wound should be thoroughly
washed with soap & water.
• Soap  inactivates virus by
destroying its envelope
• Treat with quarternary
ammonium compound
(cetavlon) or tincture iodine or
alcohol (40-70%).

36. Post-Exposure prophylaxis
Antitetanus vaccine and
antibiotics used.
Antirabic hyperimmune serum
may be infiltrated around the
wound.
Biting animal should be watched,
if possible, for 10 days.

37. Hyperimmune serum
• HRIG :- 20IU/Kg body weight
• Half dose locally to wound and
other half intramuscularly
• Precautions
– Should not be given to
individuals who have had prior
active immunization.
• May depress active immune
response to some extent.

38. Vaccination
1. Neural Vaccines
– Semple vaccine
– Betapropiolactone (BPL) vaccine
– Infant brain vaccine
2. Non-neural vaccines
– Egg vaccines
– Cell culture vaccines
– Subunit vaccine

39. S.N Vaccine Preparation Type Use
Neural
1 Semple vaccine Discontinued - Discontinued
2 BPL vaccine Discontinued - Discontinued
3 Infant brain vaccine Brain of suckling mice UV, BPL
phenol
South America
Non-neural
1 Duck egg vaccine Discontinued - Discontinued
2 Tissue culture vaccine Fixed virus grown in
HDCS eg. WI-38
BPL Highly Agenic,
free from side
effects, costly
3 Chick embro vaccine
i) Low egg passage
(LEP)
By 40-50 passage Live
attenuated
For dogs above
3 months
ii) High egg passage
(HEP)
By 180 passage Live
attenuated
For cattle and
cats
Subunit vaccine Surface glycoprotein cloned &
recombinant vaccine
Experimental
stage

40. 1. Semple vaccine
– Developed by semple (1911) at the
Central Research Institute (CRI),
Kasauli, India.
– 5% suspension of infected sheep
brain and inactivated by 5% phenol
at 370C, leaving no residual live virus.
2. Beta propiolactone (BPL) vaccine
– Modified semple vaccine with BPL as
ainactivationg agent instead of
phenol.
– Believed to be more Agenic.

41. Non-neural Vaccine
• Egg Vaccines
1. Duck egg vaccine
– BPL inacitivated
– Poor immunogenicity
– Discontinued
2. Live attenuated chick embryo vaccine
a) Low egg passage (LEP)
b) High egg passage (HEP)

42. • Cell cullture vaccines
a) Human diploid cell strain (HDCS)
– Growing fixed rabies virus on human diploid cells
(WI 38 or MRC 5)
– Inactivated with BPL
– Highly antigenic
– Free from side effects
– high cost

43. b) Purified chick embryo
cell culture (PCEC)
vaccine
– Equally effective as HDCS
vaccine
– Economical
– Brand name Rabipur
– Purified vero cell (PVC)
vaccine another
economical cell culture
vaccine.

44. Commonly used Non-neural
Antirabic vaccines
Vaccine Substrate to grow
fixed virus
Type
HDCS Human diploid cell Inactivated by BPL
PCEC vaccine Chick embryo cells Inactivated by BPL
PVC vaccine Vero cells Inactivated by BPL

45. Vaccination Schedules
• Pre-exposure vaccination
– For lab personnel
– 1 ml on days 0, 7 and 21 given intramuscularly
– Booster dose after 1yr and then one every five years.
• Postexposure vaccination
– 1 ml on days 0, 3,7,14 and 30 given intramuscularly
– Booster dose (optional) on day 90.
– Gives protection for at least 5 years, during which period any
further exposure may require only one to two doses (on days
0, 3).