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95 Cards in this Set
- Front
- Back
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What direction is mRNA read? |
from 5' to 3' |
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How does dsDNA make +RNA? |
- DNA dependent RNA polymerase - the polymerase comes from the host of the vira dependent on the size of the viral genome |
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Eksempel of dsDNA virus with a 5 Kbps genome |
Polyomaviridae |
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Eksampel of dsDNA virus with a larger genome (35 Kbps)? |
Adenoviridae (Respiratory and gastrointestial ingections in humans) |
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Eksampel of dsDNA virus with a even larger genome (100-370 Kbps) |
Poxviridae (disease called smallpox) |
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how does gapped dsDNA make mRNA |
(1) - Viral-associated polymerase to fill out the gaps (2) - DNA dependent RNA polymerase |
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Exampel of Gapped dsDNA |
Hepatitis B viruses (can cause liver damage if not treated, spred through sexual contact) |
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How does ssDNA make mRNA? |
DNA dependent RNA polymerase |
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Eksampel of ssDNA? |
Parvoviuses Mostly known for cat/dog infections - infect cells if intestine, hematopoietic system and fetus |
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dsRNA genomes? |
RNA dependend RNA polymerase and use the - RNA strand as templete the newly (+) RNA strand becomes mRNA |
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Eksempel of dsRNA virus? |
Family: Reoviridase virus: Rotavirus |
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ssRNA |
READY TO GO!!! |
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Where does the RNA-depend RNA polymerase orientates from? |
The vira since host cells do not have RNA-dependende RNA polymerases |
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Eksempel of ssRNA virus? |
Picornaviridae cause paralytic polyomyelitis: inflammation of motor neurons of spinal cord and brain stem |
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ss (+) RNA strand with DNA intermediate |
(1) viral RNA-dependend DNA polymerase (to make DNA out of RNA) (or reverse transcriptase that make DNA out of RNA) (2) DNA dependend RNA polymerase |
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Eksempel of ss(+) RNA genomes with DNA intermediate |
Retroviridae |
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ss (-) RNA genomes |
viral RNA-dependend RNA polymerase |
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Example of ss (-) RNA genomes |
Paramyxoviridae Orthomyxoviridae (influenza virus, resporatory disease, can be deadly) Filoviridae - Ebola virus |
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what is the L-protein? |
The viral RNA-dep RNA polymerase that ss (-) RNA needs to make (+) RNA |
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Viruses replication - describe the different states of the replication circle for a virus |
-Adsorption = Attachment -Exlipse = infectivity disappears due to uncoating -Latent = Relication of genome - protein synthesis -Maturation = assembly of genome and viral proteins -Tages 8-10h VIRUSES MAKES THEIR BITS AND PIECES (USING HOST) AND THEN ASSEMBLE AN INFECTIOUS VIRION!! |
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What does a cell need to "be" to for a virus can replicate its genome inside it? |
Susceptible (functional receptors for virus) and Permissive (allows the virus to replicate) |
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What is a primary cell line? |
Have a limit number of cycles |
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What is a continuous cell line? |
After transformation if a cell acquires the ability to divide indefinitely (unlimit) |
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describe subunit, protamer and capsid |
Subunit is one polypeptid protamer consist of 2 or more subunits capsid is the whole structure of protamers |
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what is a virion |
complete infectious particle |
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What consist the envelope af? |
Lipid bilayer membrane enclosing nucleocapsides. is hot derived |
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what is the downside of electron Microscopy and staining? |
Potential to "destroy" ultrastructural |
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Cryp- Electron Microscopy |
no stain preserve structures 3D construct |
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X-ray crystallography |
ability to viral protein/vision to crystallize (need to have to ability to be crystallized) gives 3D structure |
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NMR |
if crystallization is not able see protein interactions |
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which method gives the best detailed picture of the viral?? which method gives the less detailed picture of the viral?? |
Most - X-ray and NMR Middle - Cry-Electron EM less: Electron Microscopy |
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what methods is visualizing viral structure give FULL virion structures? |
Cry-Electron EM Electron Microscopy X-ray ONLY NMR THAT GIVE PROTEINS STRUCTURE |
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describe the Helical symmetry describe the polyhedral symmetry |
Helical - rod shaped (interact with an identical protein subunit in an identical manner, also interacts with viral genomes) + are nucleocapsids + can be composed of one type or multiple types Polyhedral - round viruses (called icosahedral symmetry) (appear round because of symmetry, have a defined number of proteins - rules: 60, 180, 240, 960 + solid with 20 faces (20*3 subunits) - larger virus has 60*3 (180 identical subunits)) |
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what is the rules for viral symmetry?? |
1) each subunit had identical bonding contacts with neighboring subunits 2) Bonds between subunits are mostly via non-covalent interactions (has to be both stable and un-stable) |
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what nucleoproteins is a helical symmetry virus composed of? |
VP30, 24 and 35 |
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give example of round capsid assembly |
Poliovirus composted of VP1, 2 and 3 bind in identical manner and each virus captain 60 or 180 depending on size of the virus |
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Enveloped virus |
derived from host membranes or acquired by budding nucleocapsid contains viral proteins - glycoproteins that binds to host cell surface membrane (critical) |
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can viruses undergo passive transport? |
NEEEJ to large!!! |
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what initiate the infectious cycle of a virus and the host? |
interactions between the virus and its receptor --> open the door to the obligate intracellular parasite --> release the genome "inside" the host" |
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what is a Co-receptor? |
a seconds-receptor that in some cases is required --> very essential for many viruses (excluding years and plants) |
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what receptor use HIV-1? |
CD4 and chemokine receptor |
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What receptor use Polio? |
PVR |
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What receptor use Adenovirus? |
CAR |
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What determine the mode of attachment? |
the outer "shell" of the virus non-enveloped or enveloped??? |
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attachment of non-enveloped viruses with icosahedral symmetry?? eksample of poliovirus.. |
contain receptors on VP1 that bids to membrane surface of host that induce a conformational change in the capsid proteins that cause the virus the inject its RNA directly across plasma membrane poliovirus: contain 180 subunits (60 of eacg VP1, 2 and 3). each VP1 contain a receptors that binds to host membrane leading to pore formation for injection |
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attachment and infection of enveloped viruses? |
the glycoproteins at the viral surface binds to sialic acid (a suger) at the viral membrane in a 2-3 linkage or 2-6 linkages depending on the virus (human influenza prefer 2-6) /avian influenza prefer 2-3 linkages)
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how move intracellular viruses around? |
along tracks that are powered by molecular motors this active transport applies to virus trafficking inside the cell |
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for genomic release The different locations are at a different pH - what is; the cell surface pH EE pH? LE pH? |
the cell surface pH - 7,0 EE pH - 6,5-6,0 LE pH - 5,5-5,0 |
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membrane fusion |
some viruses can "release" theis genomes at the plasma membrane; also true for enveloped viruses viral fusion proteins will for eksameple "behave" differently depending on the specific pH eks. Paramyxoviridae and measles virus a specific viral protein mediating fusion evented - proteins at the viral surface binding to the surface of the host. more of there bindings due to more proteins pull the membrane in differen direction leading to a pore between the two cells (host and virus) |
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attachment and entering for HIV? |
require two host receptors - CD4 and chemokinine receptor 5 (CCR5) the viral proteins gp120 and viral fusion protein p41 will bind til the host leading to pore for genomic entering |
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trafficking to the nucleus? difference between small and larger viruses |
small viruses can pass through nucleat pore complexes larger viruses use microtubule/motors Herpesviridae |
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what is a inapparent infection? |
a infection we don't know about - no symptoms! - yet immune system has been activated |
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TERMS: viremia primary viremia secondary viremia |
viremia - presence of visions in the blood primary viremia - progeny visions released in blood after initial replication at the site of entry secondary viremia - delayed appearance of visions in the blood |
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entering points for viruses? |
Conjunctiva --> the layer of cells that cover the eye, blink is a defence mechanism, certain types of adenoviruses can infect respiratory --> aerosolized droplets alimentary --> come down with food - must survive harsh acidic environments urogental anus -- > do not have to withstand harsh environment of upper alimentary tract (HIV) viruses have evolved to enter via mucosal linings of the respiratory, alimentary and urogenital tracts + can enter via the outer surface of the eyes + skin could break |
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how can viruses be inactivated? |
acidic (pH = 5,5) in skin surface anti-viral peptides dryness |
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what is Rhinovirus?? |
common cold, influenza virus, lungs has 140m^2 of surface area available for adsorption of visions |
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Eksampel of alimentary virus? |
Reoviruses - enter as non-enveloped entry |
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methods of virus shedding? |
aerosol secreations: coughing, talking, sneezing feces blood milk urine, semen skin lesion |
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transmission of non-enveloped viruses? |
withstand a lot including low pH mostly transmitted in respiratory, fecal-oral route or FOMITES: objects contaminated by virus |
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transmission of enveloped viruses? |
more fragile, mostly aerosol transmisstion. sensitive to low pH |
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name of the HIV virus? |
famaly: Retroviridae subfamaly: Lentiviruses - humans HIV-1 and HIV- 2 IS ENVELOPE has ssRNA but goes the "complicated" way to get incorporated into the host genome |
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describe the structure of the HIV virus |
contain Surface proteins (SU) - pg120 -"VIRAL RECEPTOR" Transmembrane proteins - pg41 "FUSION PROTEIN" Capsid protein p24 CAPSID protein has hexagonal lattice - long structure but not icosahedral symmetry |
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whats the role of SU (surface proteins) of HIV pq120 |
to interact with sepcific host receptors |
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why is every "found" HIV virus genetic different? |
Because viruses lacks 3'-5' exonuclease activity (proofreading) results in 1-10 nucleotide errors per synthesis this heterogeneity in retrovirus populations results in a collection of variants or quasispecies |
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is retrovirus enveloped or non-enveloped? |
Enveloped |
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what genes does a retrovirus contain? what els about retroviruses? |
Gag + Pol + Env +strand RNA |
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what is a proviral? |
Viral that becomes integrated into the host genome - at a random site integrase removes two 3'-terminal nucleotides on each strand - free 3'OH ends are ligated into a cleaved segment of host genome carried out by viral enzyme integrase, present in core |
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HIV-1 deiversity (based on sequence alignments) |
groups - 20% differences in sequence are group changers - M is major (99%) - each group represents a transfer from an animal to a human - M contain 9 subtypes (C. most prevalent, africa) (B high in North America) (D Quicker death) (CRFs usually sex workers that have been infected many times, circulating - mixture of various subtypes) - lifestyle can dictate subtypes - HIV-2 does not progress to AIDS as quickly, not transmissible, nat as deadly HIV-1 is very similar to another lentivirus - SIV from chimpanzees (lentivirus is a retrovirus with long incubation time) + SIV from Pan troglodytes troglodytes is closest to HIV-1 |
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HIV-1 is what? |
whimpy |
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Retrovirus? |
Enveloped viruses that replicate in the host ss (+) RNA with DNA intermediate use its own reverse transcriptase Eksampel: HIV |
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Non pathogens viruses? |
(1) - Wasps lays it eggs inside a lark - deposits eggs inside a caterpillar + deposits her polydnavirus visions (otherwise innate system would kill the eggs) - polydnavirus suppress the innate system (2) - fungus Curvularia protuberate permits plant survival but cannot survive at high temp so the fungal thermotolerance is mediated by the curvularia thermal tolerance virus (CThTV) (3) - nicer flowers - potyvirus (tulip breaking virus) (TBV) results in the pattern |
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the 2 major themes in virology? |
1 - viral genomes are obligate molecular parasites. They can only function after the replicate in a host cell 2 - Viruses must make mRNA that can be translated by host ribosomes. Thus, they use the host protein synthesis machinery to make viral proteions NO VIRUS CAN TRANALATE PROTEINS FROM mRBA OF THEIR OWN!!!! |
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obligate molecularparasites |
they can only function after they replicate in the host |
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TAKE HOME #1 |
A virus is a vary small, infectious, obligate, intracellular parasite that needs a cellular host |
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what is a virion? |
an vehicle to transmit virus elements to a net host |
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describe the 3 cytopathic effects that a virus can induce inside a cell |
Cell lysis syncytia - fusion of adjacent plasma cell membranes. Results in a multinucleate array of cells Transformation - cells are no longer flat but divide uncontrollably to become piles or round cells |
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who to tell that a viruses are doing to cells when cell fail to display cytopathic effects |
1 - measure infectivity - plaque assay after virus infection of bacteria - plaques: are where bacteria have been infected a) add virus b) overlay cells with a ager c) when infected cells release progeny; spread is halted by agar or stain plaque assay with crystal violet - stain cells that are alive particle-to-PFU ration: are all viral particles infectious? - #of virus particles/number of infectious particles (200 - for every virus only 1 infected) THE 3 ABOVE ARE MEASURE INFECTIVITY 2 - transformation assay cartain viruses do not form plaques but form foci - so count foci and get forming unit per/ml if we cannot measure infectivity using plaque assay or transformation assays we can use measure virus particles ----- measure virus particles after bursting a) Physical measurement: Hemaglutination assay - cartain viruses contain proteions that bind to red blood cells - coat the side of the tube b) viral enzyme activity: Retroviruses (such as HIV) captain active enzymes such as reverse transcriptase - open op virus and ass radioactively labeled ATPs c) Immunostaining - use direct or indirect immunustaining d) immunoblotting e) sequencing. useful for low viral abundance genes f) Flourescent proteins |
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Reverse transcriptase do what ? |
Make DNA from RNA |
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Non-enveloped viruses with icosahedral symmetry |
Picornaviridae (ss + RNA) Poliovirus (ss + RNA) Ready to go VP1, VP2 and VP3 (60*3=180) 60 faces VP1 binds to receptor on host and release their genome (RNA) |
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Hemagglutinin |
viral envelope glycoprotein binds to host receptors |
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Silica Acid |
host cell receptor human virus use 2-6 linkages |
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Paramyxoviridae contains e.g. Measles Virus |
release their genomes at the plasma membrane: they are non-enveloped but the same is true for envelopes viruses receptors in viral bind to host membrane and pull the membrane from each other require TWO host receptors CD4 CCR5 which |
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Reoviruses |
Reoviruses are non-enveloped and have an icosahedral capsid attach to host membrane and enter through receptor mediated endocytosis |
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enveloped virus entry? |
Viral proteins pg120 and pg41 binds to host receptors CD4 CCR5 og release genome |
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Ebola uptake |
NPC1 (cholesterol transporter): essential for ebola virus infection in late endosome SO: ebola virus is taken up by receptor mediated endocytosis and fused into late endosome where NPC1 ???? |
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how does Herpesviridae enter nucleus? |
use microtubule/motors to enter since its a larger virus (smaller viruses can pass through nuclear pore complexes)
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eksampel of inapparent infection |
Flaviridae West Nile virus (spread by mosquitoes) +RNA with envelope |
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Skin and virus stopping point? (when not breached) |
outer layer (the epidermis) is dead so virus cannot replicate virions will also be inactivated by acidic (pH=5) on skin surface anti-viral peptides dryness |
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Respiratiry tract |
Mucosal membrane are lined with "live" cells eksampel of virus: Rhibivirus (common cold) |
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Example for virus that enter through the Urogenital tract? |
Retrovirus (HIV) human Papilloma virus |
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Example for virus that enter through the Alimentary tract / or anus? |
HIV does not have to withstand harsh environment |
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Conjunctiva entry |
eyes Blinking is a defence mechanism certain types of adenoviruses can infect the conjuctiva |
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Does HIV contain nucleocapsid? |
Yes .. not the normal icosahedral symmetry plus is enveloped |
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how does HIV enter host? |
pg120 and pg41 binds to CD4 and CCR5 (chemokine receptors) and 2 things can happen 1 - viral envelope fuses directly with the plasma membrane (conformational shift in SU inserting TM into host cell membrane and virione core is then released) 2 - virus undergo receptor mediated endocytosis |
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d |
d |
