RNA Viruses - Picornaviridae And Rhabdoviridae Flashcards
Smallest RNA Virus
Picornavirus - 27-30nm
Picornaviridae family includes
Rhinovirus
Enterovirus
Route of transmission of Rhinovirus
Inhalation
Enterovirus family includes
Polio virus
Coxsackie
Enterovirus
Echo virus
Route of transmission of Enterovirus
Feco oral
Antigenic types of Polio virus
Type 1,2 and 3
Immunity is type specific
Which antigenic type of Polio virus is most commonly responsible for epidemics
Type 1
Which antigenic type of Polio virus is most antigenic
Type 2
No case reported since 1999
Vaccine derived
Type 3 Antigenic type of Polio virus is associated with
Vaccine associated Paralytic polio
No case reported since 2013
Dense antigen of Polio virus associated with
A/w whole virion
Type specific
Anti D antibodies are protective
Potency of Injectable polio vaccine is measured using which Antigen
Measured using D antigen units
C antigen of Polio virus is
Non protective
Incubation period and transmission route of Polio virus
IP - 7-14 days (1-2 weeks)
Transmission - Feco oral, inhalation
Reservoir, Carrier and Period of communicability of Polio virus
Reservoir - Humans
Carrier - None
Period of communicability - 1 week before and 2-3 weeks after appearance of signs and symptoms
Phases of Polio virus infection
1) Alimentary phase - enters oropharynx - small intestine - feces
2) Lymphatic phase - Cervical LN or Mesenteric LN
3) Viremic phase - enters blood
4) Neural phase - Crosses BBB - Cerebrum, Spinal Cord
How many percent of Polio infection goes subclinical
90% (via feces)
How many percent of Polio infection reaches to blood causing viremia
8% - Abortive polio
Causes fever, malaise, headache, vomiting
How much percent of Polio infection reaches to brain
1% - causes Non paralytic Poliovirus - Symptoms of meningitis
<1% - Causes paralytic Polio
Final site of Polio virus
Motor neurons
Earliest change in case of Polio virus infection
Nissl body degeneration
Assymetric descending flaccid paralysis (ADFP) clinical Features
Proximal > distal muscles
Bigger muscle of hands > smaller muscle of hands
Leg muscles > Arm muscles
Meningoencephalitis
Resp failure
Samples taken in case of Poliovirus infection
Throat swab
Rectal swab/fecal samples
Cell line used for Polio virus
Rhesus kidney cell line (Primary)
Cytopathic effect seen in case of Poliovirus
Shrinkage and Degeneration of cell lines
Antibody detection in case of Poliovirus infection
Paired sera at 1-2 weeks with increasing titre
Molecular methods used for diagnosis of Poliovirus infection
RT PCR
VP1 protein
Can differentiate between wild and the vaccine strains
Types of Coxsackie virus
Coxsackie A and B
Mode of transmission of Coxsackie virus
Feco oral
Serotypes of Coxsackie A and B
A - 1 to 24
B - 1 to 6
Coxsackie A is known to cause
Herpangina
Hand foot mouth disease
Acute hemorrhagic Conjunctivitis (Coxsackie 24) - Also Enterovirus 70
Coxsackie B is known to cause
Carditis
Bornholms disease/Pleurodynia/Devils grip/Epidemic myalgia
Hand foot mouth disease
Coxsackie Viruses can be isolated on
Brain of suckling mice
Coxsackie A - flaccid paralysis
Coxsackie B - Spastic paralysis
Herpangina Clinical features
Vesicular Pharyngitis - Vesicles in post wall of pharynx
Hand foot mouth disease Clinical features
On Child Hand foot and mouth - Papulovesicular lesions
Pleurodynia means
Infection of intercostal muscles - Pain
Enterovirus 70 is known to cause
Acute hemorrhagic Conjunctivitis
Enterovirus 71 is known to cause
Hand foot mouth disease
Enterovirus 72 AKA
Hepatitis A virus
ECHOvirus full form and Serotypes
Entric cytopathogenic human orphan virus
Serotypes - 1 to 33 except 10,22,23,28
Clinical features of ECHO virus
Aseptic meningitis
Encephalitis
Common cold
Rash
Rhinovirus serotypes, Acid stable or labile and immunity
100 serotypes
Acid labile
Immunity is type specific
Rhinovirus comes and attaches to which receptor
ICAM 1 Receptor
Incubation period, mode of transmission and optimal temperature for growth of Rhinovirus
IP - 2-4 days
Mode - inhalation
Optimal temp - 33°
Clinical feature of Rhinovirus
Common cold
Rhabdovirus includes
Lyssavirus - Rabies
Vesiculovirus - Vesicular stomatitis virus
Features of Rabies virus
100% fatal
Bullet shaped virus
Enveloped
Negative sense RNA
Which structure helps Rabies virus in Pathogenesis and neuro invasiveness
Glycoprotein spikes
Features of Glycoprotein G in Rabies virus
Enveloped
Species specific
Plays role in vaccination
Glycoprotein G of Rabies virus binds to which receptors
Binds to Ach receptors and induces neutralizing antibody
Nucleoprotein of Rabies features
A/w viral RNA
Group specific
No role in binding and inducing antibody
Cross react with other rabies related virus
Types of Rabies Virus
Street virus
Fixed virus
Street virus AKA and features
AKA Furious rabies
Negri bodies seen
Fixed virus AKA and used for
AKA Dumb rabies
Grown repeated in brain of rabbits
Used for vaccine preparation
Pathogenesis of Rabies virus
Virus inoculation - viral replication in muscle - virus enters in peripheral nervous system and binds to Ach receptor - Passive ascent via sensory fibres (Retrograde axonal transport) - Replication in dorsal ganglion - Rapid ascent in spinal cord - infection of brainstem, spinal cord, cerebellum and other brain structures (NEGRI BODIES IN BRAIN +ve) - Descending infection via nervous system to eye, salivary gland, skin and other organs
Organs affected by rabies virus other than brain
Salivary gland - M/C submaxillary gland
Eye
Skin and other organs
Spread and source of Rabies virus
Source - Dog, monkey, sheep , goat
Spread - through bite or lick
Lick on abrasion
Inhalation from infected bat aerosol
Corneal Transplantation
Spread of Rabies virus progess in axon at speed of
3mm/hr
Speed of Rabies virus progess can be shorter in which conditions
Shorter height
Upper Limb bite
Children
Clinical spectrum of Rabies virus infection
1)Short prodromal phase - 2 to 5 days
2) Acute neurologic phase - Furious rabies/encephalitis rabies or Dumb paralytic rabies.
3) Coma and death - 100% Fatal
Phases seen in Furious rabies/encephalitis rabies
In 80% patients
Phase of Encephalitis - Hyperexcitability
Phase of lucidity - Slight improval
Phase of autonomic disturbances - Hypersalivation, Goosereflex, Arrythmias, Hydrophobia
Dumb paralytic rabies features
Seen in partially vaccinated or Rat bite
Paralytic symptoms +
Cardiac symptoms not seen
Antigen detection method used in Rabies Virus
By direct immunofluorescence
Best specimen first Rabies infection in early and late stages
Early - from Nape of neck - hair follicles atleast 10
In later stages - Corneal impression smear
Most sensitive and specific assay for diagnosis of Rabies
RT PCR
Viral isolation methods used for diagnosis of Rabies
Animal inoculation
Cell lines
Animal inoculation and finding in case of Rabies
On Brain of suckling mice - Negri bodies (intracytoplasmic bodies)
Cell lines used for Diagnosis of Rabies
Chick embryo fibroblast (Primary)
BHK Cell line (Continous (
W138(sec.)
When Antibodies are seen in CSF and blood sample in case of Rabies
CSF - More vulnerable , not seen in vaccinated person
Blood - appears late, A/b + in vaccinated person’s
Antibody detection methods in case of Rabies infection
MNT (Mouse neutralisation test)
RFFIT (Rapid fluorescent focus inhibition test)
FAVN (Fluorescent Antibody virus neutralisation test)
IFA (indirect fluorescence test)
HAI (Haemgluttination inhibition)
CFT (Complement fixation)
Autopsy finding and Stain used for diagnosis of Rabies
Negri body
Stain - Seller stain
Immunoperoxidase stain
Category A Patients and Prophylaxis for Rabies
Category A -; Touching/feeding, Intact skin contact with rabid animal
Prophylaxis - wound toilet
Category ii and Prophylaxis of Rabies
Category ii - Minor scratches/abrasions without bleeding
Prophylaxis - wound toilet + vaccine
Category ii and Prophylaxis of Rabies
Category ii - Minor scratches/abrasions without bleeding
Prophylaxis - wound toilet + vaccine
Category iii and Prophylaxis for Rabies
Category iii - Transdermal scratch/bite, Licks on abraded skin/mucus, exposure to wild animals
Prophylaxis - Wound toilet + vaccine + Ig
Wound toilet procedure in case of Rabies infection
Wash - soap, H20 for 15-20min
After Povidone I2 (Topical)
Vaccine type and site of administration in Rabies infection
Type - Human diploid cell culture vaccine
Site - Adult - Deltoid
Child - Anterolateral part of thigh
Regimes given for Rabies vaccine
IM - Essen regime
ID - Thai red Regime
Essen Regime
Intramuscular
5 visits
1-1- 1- 1 - 1 (5 doses)
0-3-7-14-28 day
Thai red Regime
Intradermal
4 visits
2-2-2-0-2 (8 doses)
0-3-7 and 28th day (not on 14th)
Preexposure prophylaxis for Vet/Forest workers
1-1-1 (3 doses)
0-7-21 or 28th day im/id
Reexposure prophylaxis criteria
If reexposure within 3 months - Wound toilet
If reexposure > 3 months - Vaccine.
1- 1
0- 3 day
Immunoglobulins used for Rabies virus infection
Equine RIg @40IU/kg - more S/E
Human RIg @20IU/kg - less S/E
Usually infiltrated in or around wound
Vector of Vesicular stomatitis virus
Sandfly
Reservoir and clinical features of Vesicular stomatitis virus
Reservoir - Domestic animals
C/F - Vesicles in and around mouth
Sandfly is Vector for which infections
Leishmania/Kala azar
Bartonella Bacilliformis (Oroya fever)
Vesicular stomatitis virus
