Rabies Virus

Rabies Virus


RABIES VIRUS

  • Produce infection that is almost fatal to humans.
  • Neurotrophic 
  • Causes direct zoonosis of warm blooded animals
  • Serotype 2,3, 4 are rabies related virus

Street virus

  • Virus excreted in thesaliva of rabid animals

Fixed virus

  • Serial brain to brain transfer of Street Virui modifies it into fixed virus
  • Short, fixed and reproducible incubation period’
  • Not form Negri bodies and not multiply in extraneural tissues
  • Used in the preparation of anti-rabies vaccine

 Human pathogens of medical importance are found in the genera 

  1. Lyssavirus 
  2. Vesiculovirus.

Type of Rabies

  • Urban rabies
  • Caused by the dog and is responsible for 99% of human cases in India’
  • Sylvatic or wild-life rabies.
  • Bat rabies 

STUCTURE

  • Negative polarity(RNA), non-segmented
  • Enveloped RNA virus and is bullet-shaped.
  • Measuring approximately 60 nm × 180 nm.
  • Helical nucleocapsid composed of a single-stranded negative-sense RNA genome
  • RNA-dependent RNA polymerase enclosed in a matrix  protein
  • Covered by a lipid bilayer envelope containing knob-like glycoprotein.

MODE OF TRANSMISSION

  • Bite of rabid dogs or other animals (Most common)
  • Non bite exposure
  1. Licks or aerosols
  2. Transplantation of cornea. 

VIRION STRUCTURE

  • Genome encodes five proteins
  • nucleocapsid
  • matrix
  • phosphoprotein
  • glycoprotein
  • RNA polymerase
  • Associated with either the ribonucleoprotein (RNP) complex or the viral envelope.
  • RNP complex contain(Viral RNA)
  1. The L (transcriptase)
  2. N (nucleoprotein)
  3. NS (transcriptase-associated) proteins
  • Viral RNA aggregate in the cytoplasm of virus-infected neurons
  • Compose Negri bodies, the characteristic histopathologic finding of rabies virus infection
  • The G protein known to induce virus-neutralizing antibody.

INCUBATION PERIOD

  • The incubation period is exceptionally variable.
  • Ranging from fewer than 10 days to longer than 2 years.
  • Usually 1–3 months.

CLINICAL MANIFESTATIONS

  • Replicates initially in muscle.
  • Then enters peripheral nervous system.
  • It spreads to CNS gray matter.
  •  Negri bodies are  found in neurons.
  • Pathognomonic lesion is the Negri body, an eosinophilic cytoplasmic inclusion in brain.
  • Particularly in the hippocampus, cerebral cortex, cerebellum, and dorsal spinal ganglia.

Five general stages are recognized in humans

  • Incubation
  • Prodrome
  • Acute neurologic period
  • Coma
  • Death

MUTIPLICATION

  • Virus attaches to the host cell membranes via the G protein.
  • Penetrates the cytoplasm by fusion or pinocytosis.
  • Uncoated to RNP
  • Core initiates primary transcription mRNAs by using the virion-associated RNA-dependent RNA polymerase.
  •  Each RNA is then translated into an individual viral protein.
  • Replication of the genomic RNA continues with the synthesis of full length, positive-stranded RNA.
  • Acts as a template for the production of progeny negative-stranded RNA.
  • Speed of rabies virus axon is 3 mm per hour

SENSETIVE TO

  • Ethanol
  • Soap
  • Iodine Preparations
  • Detergents
  •  Quaternary ammonium Compound
  • Lipid Solvents such as ether, chloroform and acetone

INACTIVATED BY

  • Phenol
  • UV irradiation
  • Formalin
  •  Sun Light
  • Beta propiolactone (BPL)
  • Thermal inactivation (one hour at 50C and 5 min at 60°C)

DIAGNOSIS

  • Rabies is diagnosed by detection of rabies virus antigens by immunofluorescence.
Exam Question
 

RABIES VIRUS

  • Produce infection that is almost fatal to humans.
  • Neurotrophic virus
  • There are two types of strains(antigenically similar)
  1. Street virus
  2. Fixed virus 

STUCTURE

  • Negative polarity(RNA), non-segmented
  • Linear single stranded
  • Enveloped RNA virus and is bullet-shaped..

MODE OF TRANSMISSION

  • Bite of rabid dogs or other animals (Most common)
  • Non bite exposure
  1. Licks or aerosols
  2. Transplantation of cornea. 

INCUBATION PERIOD

  • The incubation period is exceptionally variable.
  • Ranging from fewer than 10 days to longer than 2 years.
  • Usually 1–3 months.

CLINICAL MANIFESTATIONS

  • Replicates initially in muscle.
  • Then enters peripheral nervous system.
  • It spreads to CNS gray matter.
  •  Negri bodies are  found in neurons.
  • Pathognomonic lesion is the Negri body, an eosinophilic cytoplasmic inclusion in brain.
  • Particularly in the hippocampus, cerebral cortex, cerebellum, and dorsal spinal ganglia.

Five general stages are recognized in humans

  • Incubation
  •  prodrome,
  • acute neurologic period
  •  coma
  • Death

 Speed of rabies virus axon is 3 mm per hour

SENSETIVE TO

  • Ethanol
  • Soap
  • Iodine Preparations
  • Detergents
  •  Quaternary ammonium Compound
  • Lipid Solvents such as ether, chloroform and acetone

INACTIVATED BY

  • Phenol
  • UV irradiation
  • Formalin
  •  Sun Light
  • Beta propiolactone (BPL)
  • Thermal inactivation (one hour at 50C and 5 min at 60°C)

DIAGNOSIS

  • Rabies is diagnosed by detection of rabies virus antigens by immunofluorescence.
Don’t Forget to Solve all the previous Year Question asked on Rabies Virus

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