ID week 5

four mechanisms for penetration and uncoating

1. fuse directly with PM 2. clatherin dependent endocytosis 3. caveloin dependent pathway 4. clatherin and caveolin independent pathway

what are 6 characteristics to classify viruses?

1. structure 2. biochemical properties 3. disease caused 4. means of transmission 5. host cell 6. tissue or organ

immunopathology often occurs as a result of ______ cell killing virus infected host cells

CD8 T cells

the below are what kind of viruses? Smallpox HSV Adenovirus Hep B Epstein-Barr virus (EBV) Varicella-zoster

DNA viruses

enveloped viruses with bisegmented RNA genome that encodes 4 proteins

LCM

EBV component that inhibits T cell activation

LMP-1

EBV protein localized to exosomes

LMP-1 latent membrane protein

postive strand RNA virus

Togavirus

Asparagine (n-linked) can serve as viral _________ proteins

attachment

four major steps of the infection cycle

attachment and entry translation genome replication assembly/release

__________ tend to have steady growth while _______ tend to have sharp "bursts" of growth

bacteria viruses

reverse transcriptase

converts RNA to DNA

viral mRNA regardless of origin undergoes ______________ modifications knows as __________

covalent RNA processing

mechanism by which viruses kill host by damaging infected cells

direct killing

a tRNA is selected according to the sequence of mRNA codon. peptide bond form between polypeptide chain and incoming AA

elongation

a lipid membrane obtained by budding through host membrane structures

envelope

can derive from nucleus , ER, or plasma membrane

envelope

functions to.... protect internal structures attach to target cells aid in viral entry

envelope

flaviviridae family are ________ and single stranded ______ RNA

enveloped + sense

viral membranes that can host derived are called ______

envelopes

extracellular vesicles that facilitate communication between cells

exosomes

what 3 things are used to generally distinguish between viruses?

family, genera, and species

Adenovirus transmission

fecal, aerosol , fomites

negative strand DNA virus

filovirus

examples of helical viruses

filovirus orthomyxoviruses

zika virus is in_________ family

flaviviridae family like yellow fever, dengue, etc.

viruses with negative strand RNA genomes are typically what shape?

helical

viral capsids can have which 3 symmetries

helical isosahedral complex

enveloped viruses can have what two symmetries?

helical or icosahedral NOT complex

which is smaller: hep c virus or vaccinia virus?

hep c virus

envelopes are derived from host or virus?

host

the process of translation occurs where?

host ribosomes

when does conformational change or cleavage of glycoproteins occur?

late in assembly or after release

in ____________ stage of infection viral gene products are made in low amounts or not at all

latent

these viruses have what pattern of infection? herpes virus

latent

HSV viron is released how?

lysis exocytosis cell to cell bridges

all viruses must produce _______ to be translated by host ribosomes

mRNA

kolplik spot mouth ulcers are seen in what virus?

measles

most eukaryotic mRNAs are _________

monocistronic

only encode a single protein

monocistronic

Adenovirus portal of entry

mouth gets in GI

____________ viruses are resistant to harsh environmental conditions like temperature

naked capsid viruses

does helical structure limit capsid/virus size?

no

generally _____ bonds are formed so that mature viron can enter new target cell

non-covalent

release of most ____________ viruses results in cell lysis/death

non-enveloped

Adenovirus is ______________ and ________ stranded DNA genome

non-enveloped and double stranded

what are the fates of infected cells?

nothing cell lysis (death) permanent change viral latency immune mediated cell death

HSV ________ associates with viral proteins in the cytoplasm the buds into the golgi

nucleocapsid

discrete structural unit consisting of nucleic acid enclosed in capsid (the who package)

nucleocapsid

refers to the development of cancer

oncogenesis

segmented, negative strand RNA virus

orthomixovirus

5 protomers combine to form

pentamer capsomere

NKs release .....

perforins and granzymes

________ cells allow for the completion of the viral life cycle and production of infectious agents

permissive

these viruses have what pattern of infection? measles HIV

persistant: symptoms

these viruses have what pattern of infection? JC virus Lymphocytic choriomeningitis

persistent: asymptomatic

most RNA viruses bud from the _________. why?

plasma membrane so virus is released without killing cells

Examples of RNA modification

poly A tail at 3' end m'GpppN' Cap at 5' end

bacterial mRNA tend to be ________, encoding more than 1 protein

polycistronic

in icosahedral viruses proteins associate to form _______

protomers

what does binding to alpha dystroglycan result in?

receptor mediated ednocytosis

transforming infections alter growth properties in what ways?

reduce requirements for serum growth (lower the bar) loss of contact inhibition

many viruses spread via _________ route in order to remain wet

respiratory or in bodily fluids

permanent change to cells (what virus)

retroviruses

viruses are thought to contribute to 20% of human cancer. which viruses are mostly to blame?

retroviruses and DNA viruses

capsids with helical symmetry appear as _____ shaped

rod shaped

why is the flu able to re-assort so easily?

segmentation

viral genomes must be _________ packaged during assembly

selectively

viral protein "addresses"

signal sequences membrane retentions signals nuclear export signals

zika portal of entry......

skin

IFN Natural Killer CD8

specific to T cells

GP1 and GP2 associate to form ______ proteins

spike proteins

_________ cells express appropriate viral receptors on their surface

submissive

host cells must be ________ and ________ to a virus for entry to occur

susceptible submissive

replication in target tissue causes what?

symptoms

______ link specific AAs with codons in the mRNA

tRNA

stop codon enters the ribosome and cleaves the protein chain

termination

how are more complex icosahedrals formed, such as those in herpes simplex virus?

the addition of more subunits

viruses relay on _______ for metabolism and for ATP required processes

the host

enveloped viruses must remain _____

wet

does icosahedral structure limit capsid/virus size?

yes

the below are what kind of viruses? Measles Flu Rabies Ebola HIV Dengue Zika Hep C Hep A

RNA viruses

what viral properties were considered by the classical system?

RNA vs DNA, size, protein shell symmetry, presence vs absence of envelope

mRNA strands and DNA strands equivalent to the mRNA are considered to be what sense? why?

+ easily translatable

RNA and DNA strands that complement + strands have what sense?

-

modes of control for viruses

1. Quarantine 2. vector elimination 3. vaccination 4. antiviral treatments 5. lifestyle changes 6. hygiene and sanitation

what are the 3 conditions in the Baltimore system?

1. Whether it is RNA or DNA 2. if genome is ss or ds 3. whether rNA ss is positive or negative sense

in what two ways do viruses cause cancer?

1. activating cellular transduction pathways 2. disruption of cell cycle control pathways

6 unique properties of viruses you should know for quiz!

1. viruses are filterable agents 2. viruses are obligate intracellular parasites 3. viruses cannot make energy or proteins independent to host cell 4. viral genomes can be DNA or RNA, but NOT both 5. viruses have a naked capsid (envelope morphology) 6. viral components are assembled, but do not "replicate" by division

chain of infection stage where entry into a susceptible host occurs

Acquisition

virus with double strand DNA

Adenovirus

LCMV is a member of _______ virus family

Arenaviridae

most viral glycoproteins have ______ carbohydrates

Asparagine (n-linked)

focuses on genome type, and that all viruses must produce mRNA that host can translate

Baltimore system

the viral genome encodes protein synthesis machinary like ribosomes and tRNA, and proteins for metabolism true or false?

FALSE they do not

non-enveloped viruses tend to survive harsher environments, and are therefore often found in the _________

GI

in LCM, a protein called ______ is translated by ER-bound ribosomes

GP-C

GPC is cleaved into _________ and ________

GP1 and GP2

the flu infects many hosts, relying on _______ protein on cell surfaces in order to infect

HA

mutation of the CCR5 gene is a co-factor in __________ entry

HIV

the _________ nucleocapsid assembles in the nucleus an buds into, adn then out of, the ER

HSV

measles reduce levels of _______ cytokine, meaning not as much viral clearance occurs

IL-12

why must enveloped viruses remain wet? what are they disrupted by?

acids detergents drying heat

these viruses have what pattern of infection? Rhinovrius Flu Rotavirus

acute

adenovirus is part of what family?

adenoviridae

LCM virion binds to what receptor?

alpha dystroglycan

disadvatage of this mechanism is that high volume of molecules needs to synthesized to increase chance encounters between them

assembly from individual protein

assembly or proteins shells/capsids have 3 techniques

assembly from individual protein assembly from polypeptide chaperon assisted assembly

perk of this mechanism is that individual proteins dont need to find eachother at an assembly sie

assembly from polypeptide

polioviruses uses what kind of assembly for capsids/ protein shells?

assembly from polypeptide

best way to control Adenovirus is through......

better hygiene and sanitation

protein coat of a virus

capsid

this protein structure protects viral genomes and in some cases mediates attachment

capsid

genomes are packed into ______

capsids

many viruses spread ________ without passing into extracellular space. others can also spread extracellularly

cell to cell

______ assist in protein folding and can be host or virus derived. this one happens often.

chaperon assisted assembly

______ are most susceptible Adenovirus

children

___________ was based on the idea that viruses should be classified by shared traits rather than those of what cells they infect

classical system

viruses like HIV, flu, and polio require _______ or ___________ to be fully infectious / mature

conformational change cleavage of glycoproteins

parvoviruses and picornaviruses contain capsids of what structure?

icosahedral

stage in chain of infection where virus is amplified and moves from primary to secondary site (usually through blood or lymph)

incubation period

most common portal entry for viruses?

inhalation

formation of complex of mRNA, ribosome, and initiator tRNA

initiation

where does translation begin and end?

initiation codons and termination codons

chain of infection stage that occurs at a primary site where proper receptors/ machinary are needed to establish infection

initiation of infection

three stages of protein translation

initiation, elongation, termination

skin, tears, mucous, and immune cells like macrophages and dendritic cells are a part of what immune response

innate immunity

interferon production and apoptosis are ________ responses

instrinsic

catalyzes insertion of viral double strand DNA into host DNA

integrase

both ______ and __________ enzymes are encoded intro viral genomes of retroviruses

integrase and reverse transcriptase

most non-enveloped viruses (and some enveloped) do what to cell upon exiting?

kill

_______ genomes tend to encode proteins for viral replication, nucleic acid metabolism, and evasion of host immune system

larger

Paroviridae viruses contain ss DNA genomes. what is their pathway to mRNA?

the ss DNA is synthesized into double strand the double strand is then translated to mRNA

rabies has limited __________ tropism

tissue tropism

example of capsid with helical symmetry

tobacco mosaic virus

cancer related viruses cause _______________ infections, leading to cell proliferation

transforming

in general, enveloped viruses attach via ______ and non-enveloped viruses attach via _________

transmembrane glycoproteins capsid surface or projections

HSV blocks peptide uptake into the ER true or false

true

adenovirus E3 blocks MHCI transport to golgi true or false

true

sometimes, immunopathology causes death of host true or false

true

the viral genome contains all the info needed for a virus to replicate/ spread true or false

true

viruses with larger genomes are less dependent on the host true or false

true

mRNA contains 5 and 3 ______ and an _______

untranslated regions (UTR) open reading frame (ORF)

best way to control zika?

vector control/ reservoir elimination

process by which viruses causes disease

viral pathogenesis

______ contains a nucleic acid genome packed into a protein capsid

virion (virus particle)