Term
| classification of animal Viruses, taxonomy criteria based on what 3 things |
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Definition
genomic structure
viral particle structure
presence of absence of envelope |
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Term
| genomic structures include |
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Definition
single or double stranded
DNA or RNA |
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Term
| Virus particle structure include |
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Definition
isometric
helical
pleomorphic |
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Term
| Groupoing based in transmission route of the virus, what are 4 groups |
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Definition
enteric virus
respiratory virus
sexually tranmitted virus
zoonotic virus |
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Term
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Definition
generally transmitted via fecal-oral route
often cause gastroenteritis
some can cause system disease |
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Term
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Definition
usually inhaled via infected respiratoy droplet
generally remain localized in repiratory tract |
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Term
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Definition
| transmitted from animal to human via animal vector |
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Term
| sexually transmitted virus |
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Definition
| can cause lesions on genitalia or cause systematic infections |
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Term
| replication cycle of animal viruses is similar to virulent bacteriophage cycle |
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Definition
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Term
| what are the steps of reproduction fro animal viruses |
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Definition
attachment
entry into suseptable cell
targetting the site of viral reproduction
uncoating of viron
syntheis of nucleic acids and proteins
assembly /maturation/release |
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Term
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Definition
| viral surface protein mediate attachment to specific host receptor, spikes attach to glycoproteins most frequently, and often require attachment to two different receptors |
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Term
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Definition
| viruses enter the cell whole, because animal cells do not have a rigifd cell wall |
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Term
| how does the virus achieve penetration |
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Definition
| phagocytosis in which the virus is engulfed by the cell, membrane fusion occurs with the enveloped virus when the viral envelope fuses with the plasma membrane of the host cell |
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Term
| do viruses enter the cell intact? |
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Definition
| yes but the require an uncoating step to release the nucleic acid from the protein coat. |
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Term
| what are early genes jobs in the replication process of DNA virus |
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Definition
| to encode proteins envolved in the take over of the host and in synthesis of viral DNA and RNA |
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Term
| where does viral DNA replication usually occur |
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Definition
| in the nucleus of the host |
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Term
| Early mRNA synthesis is done usually by |
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Definition
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Term
| what are the simplist of DNA viruses |
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Definition
| paroviruses which have one small single stranded DNA (ssDNA) molecule, they have a small genome with overlapping genes that only encode capsid proteins, they use host cell for all biosynthetic processes |
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Term
| when is the viral DNA replicated in paroviruses |
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Definition
| only during the S period of the cell cycle |
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Term
| replication in Herpes Simple Virus |
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Definition
| use host RNA polymerase for synthesis of early viral mRNA Related to regulatory proeints and enzymes required for viral DNA replication |
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Term
| The herpes Simplex virus uses what fir the replication of the genome |
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Definition
| virus encoded DNA polymerase |
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Term
| INfluenza Virus replication |
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Definition
negative strand of ssRNA virus,
use virus associated, RNA- dependant RNA polymerase to synthesis mRNA |
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Term
| Wat does the influenza virus use to form double stranded RNA to transcribe viral RNA genome |
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Definition
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Term
| compare positive strand ssRNA with negative mRNA |
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Definition
| positive strand ssRNA use the viral genome as the mRNA to form massive polypeptide which is then cleaved or processed to produce various proteins |
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Term
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Definition
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Term
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Definition
| it converts its RNA genome into DNA and inserts this into the genome of the host cell |
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Term
| during assembly capsid proteins are encoded by |
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Definition
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Term
| during assembly with naked viruses |
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Definition
empty procapsids form
nucleic acids then insert by some unknown mechanism |
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Term
| during assembly with envelope viruses |
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Definition
| in most cases similar to assembly of naked virus, the site varies either the cytoplasm or the nucleus |
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Term
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Definition
| microdomain in membranes with specific embedded proteins that seem to be involved in virion assembly |
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Term
| naked viruses are usually released by |
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Definition
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Term
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Definition
| usually results in cell death |
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Term
| during cytocidal infection |
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Definition
virus inhibits cellualar DNA, RNA, and protein synthesis, lysosomes are damaged, releasing hydrolytic enzymes, plasma membrane is disrupted or weakened
chromosomal disruption
toxicity from high concentrations viral proteins |
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Term
| can envelope viruses have cytocidal effects? |
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Definition
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Term
| envelope viruses release virions when |
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Definition
the virus encoded proteins encorporated into the host membrane
nucleocapsid buds outward and is surrounded by a modified host membrane |
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Term
| with envelope viruses formation of envelope and release usuallt occur concurrently? |
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Definition
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Term
| relationships of viruses and their hosts are divided into two catagories |
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Definition
acute- rapid onset and usually short duration
persistant- can last many years |
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Term
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Definition
usually short in duartion
host may develope long lasting immunity
results in productive infection
produce large number of viruses during replication
disease systems result in tissue damage and infection of new cells |
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Term
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Definition
| viruses are continuously persistant in the host |
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Term
| what are 3 possible causes to persistant infection |
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Definition
integration of viral genome into host genome
decrease in antigenicity of virus
mutation to less virulent and slower reproducing form |
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Term
| persistant infections can be divided into three catagories distinguished by detection of virus during period of persistance |
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Definition
latent infection
chronic infection
slow infection |
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Term
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Definition
| infection is followed by symptonless period, virus stops reproducing and remains dormant for some time. During this perios symptoms, antivirus-antibodies, and viruses are not detectable |
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Term
| during reactivation of latent infections what happens |
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Definition
infectious particles can be detected
symptoms of reactivation and inital disease may differ
examples herpes simplex virus ( cold sores)
shingles (zoster) |
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Term
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Definition
| infectious virus can be detected at all times, disease may be present or absent during extended times or may develope late clinical symptoms mild or absent for long periods |
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Term
| best example of chronic infection |
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Definition
| hepititis B aka serum hepititas |
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Term
| best example of reactivation od a latent disease |
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Definition
herpes ( cold sores)
shingles (zoster) |
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Term
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Definition
infectious agent gradually increase in amount over long periods of time
no significant symptoms apparent during this time |
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Term
| what two groups of infectious agents cause slow infections |
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Definition
| lentiviruses ( retroviruses0 which includs HIV And prions |
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Term
| how can viruses alter genes |
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Definition
| mutation- virus may become more virulent, virus might also become easliy transmitted |
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Term
| how else can viruses alter genes |
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Definition
genetic reassortment - occurs in segmented viruses
these have genomes divided into different segments - each coding for different information |
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Term
| during genetic reassortment-- viruses infect the same cell |
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Definition
| 2, each virus encorporated segments of viral DNA, one segment comes from one virion the rest comes from the other virion |
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Term
| what is responsible for antigenic shift and antigenic drift in influenza virus |
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Definition
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Term
| does the number of plant diseases caused by viruses have a major economic importance? |
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Definition
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Term
| how can infection be recognized by plant viruses? |
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Definition
pigment loss
markes on leafs and fruits
tumors
stunted growth |
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Term
| plants usually recover from viral infections? |
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Definition
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Term
| all infections from plants are bad? |
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Definition
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Term
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Definition
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Term
| plant viruses differ alot from animal and bacterial viruses |
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Definition
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Term
| plant virus transmission usually causes damage to plant |
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Definition
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Term
| do viruses attach to specific receptor site on plants? |
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Definition
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Term
| how do viruses infect plants |
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Definition
| through wound in plant cell wall |
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Term
| how are plant viruses traferred by |
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Definition
| wind, animals seeds, tubers, soil and pollen grafting healthy plants to infected plants |
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Term
| what are the most important agents of transmission in plant viruses |
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Definition
| insects, they act as vectors, their feeding by- passes cell wall protectiion, also leaves a wound which viruses can infect |
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Term
| many plant viruses are resistant to inactivation |
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Definition
| once started infection spreads from cell to cell through plasmodesmata |
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Term
| replcation of plant viruses is similar to bacteria and animals except |
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Definition
| capsid remains outside the cell, tobacco mosaci virus, filamentous, RNA virus |
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Term
| RNA replication is unclear if replicated by host ----- or virus encoded enzyme |
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Definition
| host RNA dependant RNA polymerase |
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Term
| protein synthesis in plant viruses |
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Definition
| processed viral genome serves as mRNA and new virions assemble spontaneously |
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Term
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Definition
| define group of pathogens much smaller and distinclty different from viruses |
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Term
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Definition
| small, circular, single- stranded RNA molecule |
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Term
| do virions have a protein coat? |
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Definition
| no, therefore resistant to proteases |
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Term
| do virions act as mRNA molecules |
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Definition
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Term
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Definition
| anonomously in suseptable cells |
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Term
| RNA might be replicated in virions by |
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Definition
| rolling circle method using host RNA polymerase |
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Term
| are single virions capable of infecting a cell |
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Definition
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Term
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Definition
| circular and resistant to nuclease digestion |
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Term
| all identified virions infect plants |
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Definition
| true, mechnaisms are unknown some cause latent infections |
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Term
| diseases include from virions |
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Definition
potatoe spindle tuber
chrysanthemum stunt
cadang-candang |
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Term
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Definition
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Term
| what are linked to a number of fatal diseases |
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Definition
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Term
| all afflictions of prions cause what |
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Definition
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Term
| how does prions cause brain degeneration |
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Definition
| the brain tissue developed sponge like holes, disease termed transmissible spongiform encephalopathies symptoms may not appear for many years after infection |
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Term
| currently thought that PrP( prion proteins) is present in " normal" form in host animal but ------- is what is thought to cause diease |
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Definition
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Term
| how did the altered prion arise |
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Definition
| by the gene that encodes for normal prion protein, the mutation caused protein to have different folding properties, the mutated protein resistant to preteases |
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Term
| prions are resistant to Uv light and nucleases due to |
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Definition
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Term
| how are prions inactivated |
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Definition
| by chemicals that denature proteins |
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Term
| normal prion proteins are sensative, but prions are resistant to what enzyme |
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Definition
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