RNA viruses Flashcards
RNA virus are divided to
- helical nucleocapsid
2. icosahedral nucleocapsid
RNA virus - helical nucleocapsid - diagram
helical nucleocapsid –> enveloped:
- SS- segmented:
a. Bunyaviridae)
b. Arenoviridae (Arenovirus)
c. Orthomycoviridae (Influenza A,B,C) - SS+ nonsegmented
a. Coronoviridae –> Coronovirus - SS- nonsegmented
a. Filoviridae (filovirus)
b. Rhbdoviridae (lyssavirus)
c. Paramyxoviridae (Parainfluenza, RSV, Measles, Mumps)
RNA virus - icosahedral nucleocapsid - diagram
- Nonenveloped
A. SS+ non-segmented
- Picornaviridae –> a. Rhinovirus B. enterovirus (Poliovirus, Hepatitis A virus, coxsackievirus, echovirus)
- Caliciviridae –> Clicivirus (Norovirus, Hepatitis E)
B. DS segmented –> Reoviridae (Rotavirus, Coltivirus) - Enveloped
A. SS+ diploid –> Retrovirus (HIV, HTLV-1, HTLV-2)
B. SS+ non-segmented
- Flaviviridae (Flavivirus)
- Togaviridae (rubella, Eastern equine encephalitis, Western equine encephalitis)
C. SS- circular –> Deltavirus (NOT EXACTLY icosahedral nucleocapsid)
which RNA virus helical nucleocapsid are enveloped
all
RNA SS+ non segmented helical nucleocapsid virus
coronovirus
coronovirus - characteristics
RNA virus, helical nucleocapsid, enveloped, SS+ non-segmented
coronovirus causes
- common cold
- Severe acute respiratory syndrome (SARS)
- Middle East Respiratory Syndrome (MERS)
RNA virus, helical nucleocapsid enveloped, SS- segmented
a. Bunyaviridae
b. Arenoviridae (Arenovirus)
c. Orthomycoviridae (Influenza A,B,C)
Orthomycoviridae - characteristic and virus
RNA virus, helical nucleocapsid enveloped, SS- segmented (8)
Influenza A,B,C
Influenza viruseses - family and characteristics
Orthomycoviridae
RNA virus, helical nucleocapsid enveloped, SS- segmented
Influenza viruses - specific antigens and actions
- hemagglutinin –> promotes viral entry
2. neuraminidase –> promotes progeny virion release
Influenza viruses infection increases the risk for
fatal bacterial superinfection (Most commonly S. aureus, S. pneumonia, H. influenzae)
Influenza viruses - vaccines - characteristics, rout of administration, structures etc
Reformulated vaccine (“the flu shot”) contains viral stains most likely to appear during the flu season
- Killed viral is most frequently used –> (injected)
- Live attenuated vaccine contains temperature sensitive mutant that replicates in the nose but not in the lung –> intranasally
Influenza viruses - types of vaccines (and route of administration) (Most freq use?)
killed –> injected (MC)
Live attenuated –> intranasally
Influenza viruses - special characteristic of live cycle
Rapid genetic changes
causes of influenza virus Rapid genetic changes - ways
- Genetic shift/antigenic shift
2. Genetic drift/antigenic drift
genetic shift/antigenic shift mechanism
Reassortemnt of viral genome segments
Genetic drift/antigenic drift mechanism and example
Minor changes based on random mutation in hemagglutinin or neuraminidase
genetic shift/antigenic shift example
segments of human flu A virus reasort with swine flu A virus
Genetic drift/antigenic drift vs genetic shift/antigenic shift according to resutls
- genetic shift/antigenic shift causes pandemics
- genetic drift/antigenic drift causes epidemics
Arenoviruses characteristics and viruses
RNA virus, helical nucleocapsid enveloped, SS- segmented (2)
- Lassa virus
- LCMV - lymphocytic choriomeningitis virus
Lassa virus causes
Lassa fever ecephalitis (a form of hemorrhagic fever)
Lassa virus transmission
- spread by rodents (contaminated food or water by rodent urine
- person to person via bodily fluids
Bunyaviridae - characteristics and viruses
RNA virus, helical nucleocapsid enveloped, SS- segmented (3)
- california encephalitis virus
- Rift valley river virus
- Crimean Congo hemorrhagic fever virus
- Hantavirus
Hantavirus - characteristics clinical manifestation
hemorrhagic fever, pneumonia
RNA virus, helical nucleocapsid, enveloped SS- nonsegmented
a. Filoviridae (filovirus)
b. Rhbdoviridae (lyssavirus)
c. Paramyxoviridae (Parainfluenza, RSV, Measles, Mumps)
Filoviridae (filovirus) characteristics and viruses and their resevoir
RNA virus, helical nucleocapsid, enveloped SS- nonsegmented
- Marburg virus –> monkey reservoir
- Embola virus –> unknown, maybe bats
Embola virus - mechanism
targets epithelial cells, phagocytes, hepatocytes –> incubation period of up to 21 days –> symptoms
Embola virus - course
abrupt onset of flu-like symptoms, diarrhea/vomiting, high fever myalgia –> DIC, diffuse hemrrhage, shock –> high mortality rate
Filoviridae (filovirus) viruses and their outcome
- Marburg virus
- Embola virus
HIGH MORTALITY
Embola virus - treatment
no definitive treatment, supportive care
Strict isolation of infected individuals and barrier practices for health care workers are key to preventing transmission
Embola virus - transmission
requires direct contact with bodily fluids or fomites (including dead bodies)
Embola virus - nosocomial infections
HIGH INCIDENCE
Embola virus - diagnosis
RT-PCR within 48hr of symptoms onset
lyssavirus - characteristics
RNA virus, helical nucleocapsid, enveloped SS- nonsegmented - Rhbdoviridae
Rabies virus - appearance
Bullet shaped virus (electrical microscope) Negri bodies (commonly found in Purkinje cells of cerebellum and hippocampal neurons)
Rabies virus - negri bodies commonly found in
Purkinje cells of cerebellum and hippocampal neurons
Rabies virus - source in US
More commonly from bat, raccoon and skunk than from dog bites in the US
- aerosol also possible
Rabies virus - progression of disease
Long incubation period (weeks to months) –> fever, malaie, agitation, photophobia, hydrophobia, hypersalivation –> paralysis and coma –> death
Rabies virus - pathophysiology
Travels to the CNS by migrating in a retrograde fashion up nerve axons after binding to nicotinic ACH receptors