Rhabdoviruses

1
??? ???? ?????? ??????
2
Rhabdoviruses

• Rhabies virus is the medically important member
  of the rhabdovirus.
• It has a single-stranded RNA .
• It has bullet-shaped capsid surrounded by a
  lipoprotein envelope .
• The virion contains an RNA polymerase .
• Rabies virus has a single antigenic type .
• It can infect all mammals .
• Virus isolated directly from infected animals is
  called (street virus).
• Virus passaged in rabbit brains is (fixed virus)
  .

3
(No Transcript)
4
(No Transcript)
5
Factor determine the incubation period

• Virus concentration in the inoculum.
• Proximity of the wound to the brain.
• Severity of the wound .
• Host immune status .

6
(No Transcript)
7
Clinical syndromes of Rabies virus

• Rabies is almost always a fatal disease unless
  treated by vaccination
• The incubation period varies according to the
  site of the bite from 2-16weeks
• Symptoms such as fever,malaise,headache, paine or
  itching at the site of bite .
• Gastrointestinal symptoms ,fatigue anorexia
  typically occure .
• After a prodrome of 2-10 days neurological
  symptoms appear (Hydrophobia) occurs in 20-50 of
  patients , confusion ,increased salivation
  develop.
• Within few days ,the disease may progressess to
  paralysis ,and coma .

8
Postexposure vaccination decision

• The decision depend on
• The type of animal (all wild animal demand
  immunization) .
• The severity of the bite and its location .
• If the attack by domestic animal ,whether the
  animal immunized or available to be observed .
• Whether Rabies is endemic in the area .

9
Types of human rabies vaccine

• Simple vaccine
• Phenole inactivated virus vaccine prepared in
  brains of rabbits ,sheep or goats .,
• Widely used in developing countries .
• Cheape ,liable to cause neuroparalytic reaction .
• Given as 21 injections subcutaneusly .
• Duck embryo vaccine
• Virus in activated with Beta-propiolactone.
• Free from neural tissue .
• Cause allergic reactions , relatively ineffective
  antigen.
• Human diploid cell strain virus (HDCS)
• Virus inactivated with Beta prpiolactone .
• The most widely used vaccine in developed
  countries .Expensive
• 3. Full course of HDCS vaccine consists of 6
  doses given on days 0,3,7,14 , , 30 and 90 days .

10
Treatment and Prevention of Rabies

• Preexposure and post exposure control .
• Preexposure
• Immunization of individuals in high-risk such as,
  zoo keeper ,veterinarians ,travelers to
  hyperendemic areas .
• Postexposure
• Rabies is a viral infection that, if untreated ,
  is always fatal .
• Postexposure immunization involve the use of
  Vaccine and human rabies immune globuline (HRIG).