7. RNA Viruses Flashcards
Comparison of Morphologic Sizes
Plant cells > animal cells > ___ > poxvirus > ___/___ > proteins > ___ > atoms
bacteria
viruses
ribosomes
small molecules
Smallest: ___
___ nm in size, same as a ___.
Largest: ___ and rabies viruses
____ nm or greater.
picornaviruses 28 ribosome paramxyo 150
Small, infectious, obligate intracellular parasites. They hijack the host cell.
• Genome either ____ or ____, not both.
• Virus uses ____ systems for replication.
• All viruses have their genomes wrapped
up in ____ shell, and may either have or not have a ____ membrane.
• Every virus has a protein shell ○ Some go behind, and carry a lipid layer around them § Once they infect cell > the cell membranes surround the capsid layer • Cannot replicate on their own - they are not \_\_\_\_ things
DNA RNA cellular protein lipid living
Two shapes
Viruses have an ____ or ____ Shape
• Icosahedron ○ \_\_\_\_-faceted diamond looking structure
icosahedral
helical
20
Helical shaped virus
• Nucleic acid is within the \_\_\_\_ shell • Each straw is a virus ○ This is a helical virus, and the nucleic acid is within the straw ○ This one doesn't have a \_\_\_\_ bilayer
protein
lipid
Helical Symmetry: ____ viruses only
- Lattice of ____ subunits.
- Think of it as rolling up a flat sheet into a cylinder.
- ____ of the cylinder is sufficient to hold the viral genome
RNA
identical
diameter
Icosahedral Viruses
There are ____ facets (triangles) ____ facets are facing you
20
10
Different replication schemes
- Plus strand RNA viruses
- Minus strand RNA viruses • ds RNA virus
- Retroviruses• Two replication schemes: ____ and ____ strands
○ Won’t be mechanistic on the exams
• Retroviruses are ____
• dsRNA - won’t go into those
HIV
Polarity
Plus and minus RNA viruses
- Plus strand viruses do not carry ____
- Minus strand viruses carry ____• Every virus wants to replicate itself, and they carry polymerase which is the enzyme that synthesizes and incorporates into RNA
○ Either takes along its own, or it makes its own
• Minus strand - carries in its own suitcase (____)
pol
pol
plasmid
Single stranded RNA virus genomes
Plus Strand AUG GCA CGA > met ala arg
Minus Strand UAC CGU GCU
•Positive Sense RNA – is the equivalent of ____ – it binds to ____ and becomes ____ immediately.
•Negative Sense RNA – is the opposite sense as ____.
It needs to be converted (by ____) to become the equivalent of ____ before it is able to be translated.
mRNA ribosomes translated mRNA pol mRNA
Replication of Plus Strand Viruses
A Plus Strand viruses do not carry Polymerase (Pol).
Instead, the Plus RNA Strand serves as its own ____ to make ____.
* Do not need to memorize * However you come in, is how you \_\_\_\_ out
mRNA
pol
come
Picornaviruses Size: \_\_\_\_ Enveloped: \_\_\_\_ Capsid symm: \_\_\_\_ Nucleic acid: \_\_\_\_ Class: IV form: ss + 3'polyA Seg 1 Genes: 6-8 MW: 2.5
Members:
____
____
____
* Icosahedral in shape * Carries own RNA (\_\_\_\_stranded) * Rhino - common cold virus
25 no icos RNA poliovirus rhinovirus coxsackievirus
plus
IMPORTANT FEATURES OF THE PICORNAVIRSUES
• These are the ____ viruses, about the size of ribosomes (25nm). PICO means SMALL.
• They are ____ in shape and have no ____.
• They contain a single ____-strand genome.
• They undergo ____ maturation of polyprotein.
• They cause a variety of diseases including the ____, hand-foot-mouth disease, ____ disease and the common cold.
* Genome is equivalent to a \_\_\_\_ * Hallmark: \_\_\_\_ - very unusual * Structure, small, icosahedral and + strand DNA, polyprotein; from there on, they're very different in the infections they cause
smallest icosahedral envelope plus post-translational polio myocardial mRNA polyprotein
Poliovirus Complication - ____
paralysis
1951 Polio Poster
Read this!
Yay!
Poliovirus epidemiology
Poliovirus is:
• globally ____
• ____ transmitted person to person:
In most cases, poliovirus ____. It can be spread through contact with stool from an infected person (for example, eating food that is contaminated with poliovirus). Poliovirus is can be found in contaminated ____.
Less commonly, polio transmission occurs through contact with ____ or saliva.
disseminated easily ingested sewage water respiratory droplets
The Course of Poliovirus after Ingestion:
SI: invasion multiplication, excretion in feces
Bloodstream: ___ (day 2)
CNS: invasion, multiplication, ___ spread (day 6)
___ (day 11)
* Primary viremia - the virus is in the \_\_\_; they should not be going into your blood stream > can disseminate * Once \_\_\_\_ > paralysis can occur
primary viremia
intraneural
paralysis
CNS
The great paradox of poliovirus spread
In the absence of a vaccine, good hygienic conditions increase ____
susceptibility
What provides protection against poliovirus under poor hygienic conditions?
- ____ Immunity from mother to offspring
- Transmitted ____ from herself (mother) to her infant, passing immunity to the infant
passive
antibodies
An interesting feature of poliovirus is that it makes a Polyprotein that self-cleaves to generate ____ and ____.
• **** Know this! • From this single protein > makes one \_\_\_\_ > makes a giant protein > \_\_\_\_ > individual co-proteins > makes up the \_\_\_\_ ○ VP = viral protein
polymerase viral-coat proteins mRNA self-clipping shell
Poliovirus Replication Cycle
Note: Polio is a ____ RNA virus that makes a ____
• Viruses get in via a \_\_\_\_ mechanism, has to bind a specific receptor ○ If this wasn't apparent, we'd be infected by all the same viruses, but we all have different \_\_\_\_ so one virus doesn't accept all • Receptor for poliovirus > \_\_\_\_*** > binds, and drags in via \_\_\_\_ > protein uncoats (protein shell off) > + strand > make lots of copies, and makes the \_\_\_\_ (mRNA and proteins) that repackages everything and it leaves the cell again
plus polyprotein lock and key receptor poliovirus receptor endocytosis polyprotein
Poliovirus Maturation:
Viral RNA gets inserted into the newly made ____
protein shell
Polio Paralysis
1 in 200 infections leads to ____ (usually in the legs).
Amongst those paralyzed, 5%-10% die when their ____ muscles become immobilized.
Although polio paralysis is the most visible sign of polio infection, fewer than 1% of polio infections ever result in ____.
irreversible paralysis
breathing
paralysis
Two famous victims of poliovirus
____
____
FDR
richard treanor
Images of poliovirus - paralysis
The ____ keeps patient breathing
iron-lung
Two poliovirus vaccine: salk and sabin
Salk Type: \_\_\_\_ Administration: \_\_\_\_ Dosage: \_\_\_\_ Immunity: \_\_\_\_ Difference: \_\_\_\_ Safety: \_\_\_\_
Sabin Type: \_\_\_\_ Administration: \_\_\_\_ Dosage: \_\_\_\_ Immunity: \_\_\_\_ Difference: \_\_\_\_ Safety: \_\_\_\_
inactivated virus intra-muscular injection 3 univalent injections lifelong IgG free from vaccine caused infections
attenuated live virus oral 5 multivalent doses lifelong IgG, IgA small number of infections caused by vaccine
Salk produced the
___ polio vaccine
He used ____
that was delivered by injection
first
killed-virus
SABIN
Produced the ___ polio-vaccine
It is a live vaccine taken ___
second
orally
Background information: coxsackie virus
- discovered and named after hometown of ___, NY in 1948
- was accidentally found during trials to isolate ___ vaccine
- part of the ___ group, which is a subgroup of the ___
coxsackie
polio
enterovirus
picornavirus
Coxsackie virus
- found in adults and children, however it is more prevanlent in children agres ___
- epidemics of coxsackie viruses tend to occur more in the ___ and ___
- transmission is through ____ or ___ routes
1-7 summer early autumn fecal-oral airborne
Coxsackie viruses
Two Types A and B
Features: The Coxsackie A and B viruses are ____. While there are approximately 10 million symptomatic cases in the USA each year, most infections are ____.
There are: ____ Coxsackie A types ____ Coxsackie B types
widespread
subclinical
24
6
Coxsackie A Virus causes:
• ____
•____ disease
herpangina
hand-foot-and-mouth
Herpangina -Oral Cavit
- Commonly 10 - 20 ____-white vesicles with ____ areola surrounding them.
- Vesicles appear in the posterior part of the oral cavity on the ____.
- Vesicles proceed to form punched out ____ with intense ____ (capillary dilation)
- Finally, with herpangina there can be a ____ lasting a few days.
grey red ulcers erythema fever
Herpangina in the Oral Cavity is caused by Coxsackie ____ virus
Painful ulcers on the palate and tongue lead to problems of ____ and ____.
The disease subsides in a few ____.
A
swallowing
vomiting
days
Hand-Foot-Mouth Disease is caused by Coxsackie ____ Virus
- Hand-Foot-and-Mouth disease is characterized by oral and pharyngeal ulcers and a ____ rash on the palms and soles. It spreads to the arms and legs.
- Symptoms are: low-grade ____; headache; ____ pain; diarrhea; ____.
A vesicular fever abdominal malaise
Coxsackie ____ Virus infection has the potential of
progressing to ____
B
myocarditis
Coxsackie B myocarditis pathology
• Viral myocarditis is an inflammatory disease of the heart that affects heart ____. This can result in ____.
Note: The damage to the heart muscle does not occur though blockage of ____ arteries, which is responsible for classic heart attacks.
• Not vessels of the heart
muscle
death
coronary
Coxsackie B - Myocarditis
Symptoms of myocarditis include ____ and shortness of ____.
chest pain
breath
Autopsied heart from patient with ____ cardiac failure. Observe ____ infiltration and necrosis of ____.
Coxsackie ____ virus is suspected.
acute
mononuclear
cardiomyocytes
B
There is no specific ____ for the Coxsackie viruses
• Treatment for polio, but not for this • Polio has only \_\_\_\_ strains - can make a \_\_\_\_ strain ○ A vaccinologist's dream • Coxsackie - many strains - the more strains you have, it becomes extremely difficult to make a \_\_\_\_ ○ This is also why the \_\_\_\_ virus is difficult to make a vaccine ○ 24 A types, 6 B types fro coxsackie
treatment
three
trivalent
vaccine
common cold
