Poliovirus is of ____ family. What other virus is within the same family?
Picornaviridae – an enterovirus
Coxsackie A and B
Echovirus
Poliovirus genome:
ssRNA +
non-segmented
no envelope
replicate in cytoplasm
T/F: humans are the only reservoir for poliovirus
How many antigenic serotypes for poliovirus?
3 antigenic serotype – outer capsid proteins
T/F: antibodies against 1 antigenic serotype of poliovirus has cross-protection for the other 2 antigenic serotypes
False; there is no cross-protection, need to make antibodies against each type
T/F: Poliovirus is transmitted fecal-orally and it is a very efficient at infecting, if swallowed from say contaminated water or surfaces, will get infected
True
Polio virions accumulate in the cell’s _____, and are released upon ____.
Cytoplasm
Lysis and death of the cell
(does NOT bud off from the cell membrane, it causes cell death)
T/F: most poliovirus infection are asymptomatic
True
Abortive poliomyelitis presents with _______, without _______
Flu like symptoms
Without CNS symptoms – hence “abortive”
T/F: Aseptic meningitis is paralytic
False; it is non-paralytic. Paralytic poliomyelitis is paralytic
What is Paralytic poliomyelitis?
Flaccid paralysis of limb muscles. Though rare, <2% of infections result in this
Paralysis of respiratory muscles 2/2 bulbar poliomyelitis affecting medulla oblongota
What is post-polio syndrome?
Progressive muscle weakness, fatigue and atrophy about 30-40 years after poliomyelitis episode as a child due to reinnervated motor neuron dying off causing muscle to atrophy
Poliomyelitis risk factors goes up with _____, and ______ women
Age
Pregnant
T/F: Poliovirus enters the body and attack muscle cells by killing myocytes causing paralysis
False; virus attack and kill motor neurons, not direct attack to muscles.
Where in the spinal cord does poliovirus infect?
Anterior horn, replicates in the motor neurons
T/F: no permanent carrier state occurs following infection by poliovirus, but virus excretion in the feces can occur for several months
True
How is polio diagnosed?
Viral isolation using stool, throat swab or CSF
Antibody titer (though won’t show antibody in minor illness)
T/F: polio can be treated with acyclovir
False; acyclovir targets DNA virus, polio is ssRNA+. Only treatment is supportive care, there is vaccine that can prevent
Injected polio vaccines are _____, will not revert to become pathogenic; while Oral vaccines are ____ and may revert to virulence and cause disease in immunocompromised
Inactivated- injected (salk)
Live, attenuated – oral (sabin)
Live (Sabin)/Oral polio vaccine _____ IgA, _____ IgG, and _____ transmission
What allows rhabdoviridae virus to have cell contact?
Glycoproteins on their envelope
T/F: like poliovirus, rabies kill the infected host cell
False; unlike poliovirus, rabies do not kill the infected cell, instead it buds off
Typical negative sense ssRNA shit
Incubation period of rabies in human:
1-3 months
Depending on host age, immune status, viral strain, etc
T/F: bit by a face with a rabied dog is worse than getting bit on the foot
Yes, because the face is closer to the brain
Presentation of rabies in human (progressive encephalitis):
Agitation, paralysis, anxiety, hallucination
Hydrophobia (hates water)
Hypersalivation
Aerophobia (fear of flying)
Wil reservoirs of rabies:
Raccoons
Skunks
Bats (most cases of human rabies in the US have had bat exposure)
Foxes
Coyotes
Domestic mammals reservoir for rabies?
Cats, dogs, cattle
(sylvatic-urban rabies)
T/F: contact with saliva, brain/ nervous system tissue of an infected animal is how Rabies is transmitted
True; usually though a bite wound
Where does the rabies virus replicate in our body?
Muscles or connective tissue at the site of inoculation (bite site)
Diagnosis of rabies in human:
Saliva test for virus isolation or RT-PCR (if found in saliva though = bad news)
Serum and spinal fluids for antibodies
Skin biopsy for rabies antigen
Negri bodies, think:
Rabies!
What are negri bodies?
Specific eosinophilic cytoplasmic inclusion found in rabies-infected nerve cells
Post-exposure therapy for Rabies:
Rabies immune globulin (HRIG) near the wound – passive immunization
Inactivated rabies vaccines in four doses (away from the wound)- active immunization to develop long term protection
JC virus causes ____
Progressive multifocal leukoencephalopathy (PML)
can have hydrocephalus
JC virus is of the ___ Family. With genome:
Polyomaviridae
Double-stranded Circular DNA
Non-enveloped
T/F: Like poliovirus, JC virus is also cytolytic, meaning that it kills the infected cell
True
T/F: 80% of people have been exposed to JC virus in childhood (likely through inhalation of the virus) but this is asymptomatic, and the virus remains quiescent in kidneys, bone marrow, lymphoid tissues
True
How is JC virus activated from its quiescent state?
Severe immunosuppression such as HIV or organ transplant
What happens with the brain in progressive multifocal leukoencephalopathy caused by JC virus?
Demyelinating disease of the White matter, killing oligodendrocytes
Fatal
What Is Creutzfeldt-Jakob Disease?
Caused by prions.
Prion is a _____ and it ____ nucleic acid
Protein- proteinaceous infectious particle
Does not have
How does a regular protein become a prion?
Misfolded beta sheets proteins aggregate; “self-propagate” converting normal proteins into these bad ones
T/F: prions are not living, not a virus and resistant to proteases
True
Normal cellular protein is PrP__and spontaneous mutation occurred, causing post-translational conformational change changing it to PrP___
PrPC
To become PrPSc – aka Scrapie
PrPSc (arises from either spontaneous mutation or inculated) starts converting normal endogenous PrPc protein from mostly _____ to having _____
Alpha-helices (normal PrPc)
Beta sheets (mutated PrPsc)
What eventually happens when there is accumulation of PrPSc ?
Causes cell death, death of brain tissue
Spongiform encephalopathy- huge gaps in neuronal tissue
T/F: formation of PrPsc prion proteins yield minimal immune response, not enough to combat the rate at which these proteins are aggregating
False; there is no immune response at all because these are still considered “self” proteins so body can’t do anything about it
3 ways to get prion:
Sporadic (for unknown reason, random ass mutation)
Inherited (super rare)
Acquired (from medical procedure or contaminated food like mad cow)