Rhabdovirus lecture
Download as PPTX, PDF35 likes22,217 views
Rhabdoviruses are bullet-shaped viruses with a helical nucleocapsid and a single-stranded, negative-sense RNA genome. They infect mammals, fish, insects, and plants. Mammalian rhabdoviruses are classified into the Vesiculovirus and Lyssavirus genera, with rabies virus being the most important lyssavirus. Rabies virus is transmitted via bites or scratches from infected animals and causes fatal encephalitis in humans. Upon entry through a bite, the virus travels through peripheral nerves to the central nervous system. In the brain, it causes symptoms like aggression, hallucinations, and hydrophobia. Post-mortem diagnosis involves detecting Negri bodies
Rhabdovirus lecture
- 2. Rhabdoviruses are – Rod or bullet shaped, enveloped viruses. Have nucleocapsid with helical symmetry. Genome is single stranded, unsegmented, negative sense RNA. ( Rhabdos = rod). Included under family Rhabdoviridae & contain viruses infecting mammals, reptiles,fish, insects & plants. 2
- 3. Rhabdoviruses infecting mammals grouped in family Rhabdoviridae belong to TWO Genera. 1. Vesiculovirus - containing vesicular stomatitis virus & related viruses like Chandipura virus (Arbovirus). 2. Lyssavirus ( lyssa = madness, rage, a synonym for rabies) containing Rabies virus & related viruses. 3
- 4. 4
- 5. Bullet shaped. 180 x 75 nm in size with one end rounded or conical & the other end planar or concave. Outer lipoprotein envelop carrying knob like spikes composed of glycoprotein G 5
- 6. Spikes do not cover the planar end of virion. Beneath envelop is the membrane or matrix (M) protein layer which may be invaginated at the planar end. Membrane may project outwards from the planar end. 6
- 7. Core of virion contains helically arranged nucleoprotein. Genome – unsegmented, linear, negative sense, single stranded RNA. Present in the nucleocapsid is RNA dependent RNA polymerase ( transcriptase) & some structural proteins. 7
- 8. 8
- 9. Sensitive to ethanol, iodine preparations, quaternary ammonium compounds, soap, detergents & lipid solvents such as ether, chloroform & acetone. Is inactivated by phenol, formalin, beta propiolactone, ultraviolet irradiation & sunlight. Thermal inactivation in 1 hr at 500C & 5 min at 600C. 9
- 10. Dies at room temp, can survive for weeks when stabilised by 50% glycerol. Survive at 40C. Can be preserved at - 700C by lyophilisation. For storage in dry ice, the virus has to be sealed in vials as it is inactivated on exposure to CO2 10
- 11. 11 GLYCOPROTEIN – Surface spikes – composed of glycoprotein – imp. In pathogenesis, virulence & immunity. Imp. Properties as follows – Mediates binding of virus to acetylcholine receptors in neural tissue Induces haemagglutination inhibiting (HI) antibodies. Rabies virus has haemagglutinating activity, optimally seen at 0 - 40C & pH 6.2. It is inactivated by heat 560C for 30 – 60 min, ether, trypsin etc. Induces neutralising antibodies ( protective). Stimulates cytotoxic T cell immunity. Purified glycoprotein may act as safe, effective subunit vaccine.
- 12. 12 NUCLEOPROTEIN – Is a nucleocapsid protein Imp. Having following properties – Induces complement fixing antibodies. Antibodies are not protective. Antigen is group specific & cross reactions do occur with rabies – related viruses. Antiserum prepared against the nucleocapsid antigen is used in diagnostic immunofluorescence tests.
- 13. 13 OTHER ANTIGENS – Include - Two membrane proteins. Glycolipid. RNA dependent RNA polymerase.
- 14. 14 ANIMALS – • All mammals are susceptible to Rabies • Cattle, cats & foxes – Highly susceptible. • Skunks, opossums & fowl – relatively resistent. • Humans & dogs occupy an intermediate position. • Pups more susceptible than adults. • Experimental infection can be produced in any lab. Animal but mice is choice.
- 15. Definition: the virus recovered from naturally occurring cases of rabies is called “street virus” Sources: it is naturally occurring virus. It is found in saliva of infected animal. (continue) FIXED VIRUS Definition: the virus which has a short, fixed and reproducible incubation period is called “fixed virus Sources: it is prepared by repeated culture in brain of rabbit such that its I.P. is reduced & fixed 15 TYPES OF RABIES VIRUS -
- 16. 1. It produces Negri bodies 2. Can be demo. In the brain of dying animal. 3. Incubation period is long i.e. 20 to 60 days 4. It is pathogenic for all mammals 5. Cannot be used for preparation of vaccine FIXED VIRUS 1. It does not form Negri bodies 2. Incubation period is constant between 4-6 days 3. It can be pathogenic for humans under certain conditions 4. Is used for preparation of antirabies vaccine 16 TYPES OF RABIES VIRUS -
- 17. • Rabies virus can be grown in chick embryo. • Mode of inoculation – Yolk sac. • Serial propagation in chick embryo – development of attenuated vaccine strains like Flury & Kelev. • Strains adapted to duck egg – give high yields – used for preparation of inactivated vaccine. 17 • Rabies virus can grow in several primary & continuous cell cultures – chick embryo fibroblast, porcine or hamster kidney • Fixed virus strains adapted for growth in human diploid cell, chick embryo & Vero cell cultures – used for the production of vaccine.
- 18. • Primarily a Zoonotic disease of warm blooded animal • such as :- 18
- 19. 19 • Mad Dog biting Humans lead to Rabies. • Latin Rabhas means Frenzy. • Hydrophobia Fear of Water, Saliva of Rabid dogs • Pasture’s success – Vaccination Fixed virus from Rabbit injected into Joseph Meister Injected 13 injection of the cord vaccine.
- 20. 20 1) URBAN RABIES: From Dogs and cats.
- 21. 21 2) WILD LIFE RABIES: From jackals and foxes.
- 22. 22 3) BAT RABIES: Vampire bats which live on the blood of animals and men. These are one of the main causes of the death of bovine, around 0.5 to 1 million per year.
- 23. 23 Saliva of Rabid animal
- 24. HOST FACTORS • All warm blooded animals including man. • Rabies in man is a dead-end infection. MODE OF TRANSMISSION 24 1. ANIMAL BITES 2. LICKS 3. AEROSOL 4. PERSON TO PERSON
- 25. • Normally it is 3 - 8 wks . • May be short that is 4 days. • Or may be prolonged for years. 25
- 26. 26 • Bite by Rabid dog or other animals • Virus are carried in saliva virus deposited on the wound site. • If untreated 50% will Develop rabies. • Rabies can be produced by licks and corneal transplantation. • Virus multiply in the muscle ,connective tissue, nerves after 48 – 72 hours. • Penetrated nerve endings.
- 27. 27 Live virus Epidermis, Mucus membrane Peripheral nerve Centripetally CNS ( gray matter ) Centrifugally Other tissue (salivary glands,…)
- 28. 28
- 29. 29
- 30. 30 • From Brain virus spread to Salivary glands, Conjunctival cell released into tears Kidney Lactating glands and Milk after pregnancy
- 31. 31
- 32. 32 • Virus travels through axoplasam toward the spinal cord, at the rate of 3 mm/hour, • Towards the brain • Spread from brain centrifugally to various parts of the body. • Multiplies in the salivary glands and shed in the saliva. • Cornea, facial tissues skin. • Incubation 1 – 3 months. • May be average from 7 days to 3 years. • Stages of the disease. Prodrome Acute encephalitis. Coma / Death.
- 33. 33 • Furious Rabies • Dumb ( Rage tranquille ) • (Landry/Guillain-Barre Syndrome
- 34. CLINICAL FINDINGS SYMPTOMS 34 • Bizarre behavior. • Agitation • Seizures. • Difficulty in drinking. • Patients will be able to eat solids • Afraid of water - Hydrophobia. • Even sight or sound of water disturbs the patient. • But suffer with intense thirst. • Spasms of Pharynx produces choking • Death in 1 -6 days. • Respiratory arrest / Death / Some may survive. • Headache, fever, sore throat • Nervousness, confusion • Pain or tingling at the site of the bite • Hallucinations – Seeing things that are not really there • Hydrophobia – “Fear of water" due to spasms in the throat • Paralysis – Unable to move parts of the body • Coma and death
- 35. 1 – Non specific prodrome 2 – Acute neurologic encephalitis Acute encephalitis Profound dysfunction of brainstem 3 – Coma 4 - Death ( Rare cases recovery ) Non specific prodrome 1 - 2 days 1 week Fever, headache, sore throat Anorexia, nausea, vomiting, Agitation, depression Parenthesis or fasciculation's at or Around the site of inoculation of virus. 35
- 36. 36 • 1 – 2 days to < 1 week • Excessive motor activity, Excitation, Agitation • Confusion, Hallucinations, Delirium, • Bizarre aberrations of thought, Seizures, • Muscle spasms, Meningismus, • Opisthotonic posturing • Mental aberration ( Lucid period coma ) • Hypersalivation, Aphasia, Pharyngeal spasms • Incordination, Hyperactivity • Fever T > 40.6 • Dilated irregular pupils • Lacrimation, Salivation & Perspiration • Upper motor neuron paralysis • Deep tendon reflexes • Extensor plantar responses ( as a rule ) • Hydrophobia or Aerophobia (50 -70% )
- 37. Demo. Of Rabies virus antigens by immunofluorescence. Direct immunofluorescence is done using monoclonal antibodies tagged with fluorescein isothiocynate. Immunoperoxidase staining used for Ag in tissues. Negri bodies 37
- 38. Negri bodies 38 • Negri bodies round or oval inclusion bodies seen in the cytoplasm and sometimes in the processes of neurons of rabid animals after death. • Negri bodies are Eosinophilic, sharply outlined, pathognomonic inclusion bodies (2-10 µm in diameter) found in the cytoplasm of certain nerve ..
- 39. Isolation of virus by intracerebral inoculation in mice attempted from brain, CSF, saliva & urine Isolation of virus in tissue culture cell lines ( WI 38, BHK 21, CER ). CPE minimal so identified by immunofluorescence. Demo. Of antibodies by ELISA. Detection of rabies virus RNA by reverse transcriptase PCR is a sensitive method. 39
- 40. • Demonstration of Negri bodies in brain postmortem • Impression smears stained by Seller’s technique (basic fuchsin + methylene blue in methanol). • Demonstration of rabies virus antigen by immunofluorescence in salivary glands. • Isolation of rabies virus by animal inoculation. 40
- 41. 41 1. General consideration:- Aim is to neutralize virus before entering CNS 2. LOCAL WOUND TREATMENT a, Cleansing of wound(soap & water) b, Chemical treatment: • Either Alcohol 400-700 ml /liter • Tincture Iodine • No more treatment with Ammonium compound • No Carbolic acid and Nitric acid as it leave very bad scar c, Suturing avoided. d, Anti Rabies Serum e, Antibiotic and ATS f, Observe the animal for 10 days • 3, Immunization • 1,NERVOUS TISSUE VACCINE (NTV 2, Human diploid cell vaccine (HDCV)
- 42. 42 Definition: it is fluid or dried preparation of Rabies “Fixed” virus grown in the Neural tissue of Rabbits, Sheep, Goats, Mice or Rats OR in embryonated duck eggs OR in cell culture
- 43. 43 Nervous Tissue vaccine Duck embryo vaccine Cell culture vaccine preparation From fixed virus grown in brain of sheep or other animals potency Low or variable Eliminate Neuroparalytic factors More potent more safer Doses Large nos: are required Fewer doses of small volume Side effects Severe & fatal reactions Allergic risks Fewer Uses Exposed subjects Used in UK,USA in past 1, (HDC) safe, potent Pre & post expos:Immunization Suckling mouse brain V Devoid of Neuroparalytic effect Used in Latin America Improvement over adult animal nervous tissue V Now purified DEV developed Improvement over adult animal nervous tissue V Not available in India & Pakistan 2Tissue culture 2nd G (Non-human) Potent, low cost WHO recommendatio
- 44. 44
- 45. 45
- 46. 46 • TISSUE CULTURE VACCINES – • Human diploid cell vaccine (HDCV) Developed by Koprowsky,Wiktor,and Plotkin • Purified chick embryo cell vaccine (PCEC) • Purified Vero cell vaccine (PVRV) • Purified duck embryo vaccine (PDEV)
- 47. 47 • The vaccination is given on 0, 3, 7, 14, 30, and 90th day Immunity lasts for 5 years Injected on deltoid region IM/SC Not to be given in the gluteal region
- 48. 48 • Dosage • Pre- exposure prophylaxis 0 – 7 – 21 – or 28 – 56 days A booster after 1 year, Repeat once in 5 days, Post exposure Prophylaxis Sex doses 0 -3 -7-14 – 30 - 90 days Given IM or SC in the Deltoid region Don't inject in Gluteal region.
- 49. 49 • Given on the following days 0, 7, 21,or 28 and 56th day Generally given to Vet nary personal
- 50. 50 • Human Rabies Immunoglobulin HRIG • High Risk bitten on face and neck • Given a dose of 20 IU /Kg wt • Half at the site of bite and rest IM route. • Active immunization should be initiated with passive immunization.
- 51. 51 • A number of experimental vaccines are under development that may provide alternative safe and potent but less expensive vaccine options. These include DNA vaccines, recombinant viral vaccines, and recombinant protein vaccines. Further testing is needed to determine if and which one of these novel vaccines will make their way into mass production and application in the future.
- 52. 52 • A viral immunizing agent that has been treated to remove traces of viral nucleic acid so that only protein subunits remain. The subunits have less risk of causing adverse reactions. • Several trails in progress
- 53. 53 1. Class I (slight Risk) 07 injection a. Licks on healthy unbroken skin. b. Scratches without oozing of blood. 2. Class II (Moderate Risk) according to the Schedule plus one booster dose after 3 week a. Licks on fresh cuts. b. Scratches with oozing of blood. c. All bites except those on head, neck, face, palms and fingers. d. Minor wounds less than 5 in number. 3. Class III (Severe Risk) according to the Schedule plus Two booster dose one after one week and another 2 week a. all bites or scratches with oozing of blood on neck, head, face, palms and fingers. b. Lacerated wounds on any part of the body. c. Multiple wounds 5 or more in number. d. Bites from wild animals.
- 54. 54