Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
41 Cards in this Set
- Front
- Back
- 3rd side (hint)
|
Classification of Animal Viruses
|
-Superfamilies (DNA, RNA)
-Families (capsid type, presences of envelope, size, # of nucleic acid strands) -Genera (host, target tissue, disease type) |
|
|
|
Reproduction of Animal Viruses
|
Same steps as bacteriophage
1)Adsoption (attachment) 2)Penetration & uncoating 3)Replication of virus nucleic acids 4)Synthesis of viral coat proteins 5)Assenbly of Virons 6)Release |
|
|
|
1)Adsorption of Virons
|
-glycoproteins mediate attachment
-Receptors play role in specificities of host and tissues |
|
|
|
2)Penetration and Uncoating
|
-3 mechs:
A)Endocytosis of naked virus B)Endocytosis of enveloped virus C)Fusion of envelope with host membrane -Uncoating occurs in different areas depending on virus +Cytoplasm (HIV) +Nucleus (Herpes Simplex Virus) +Lysosome (Poxvirus) |
|
|
|
A)Endocytosis of naked virus
|
-Nucleocapsid binds to receptors and is endocytosed
-Insert genome through vessicle membrane |
|
|
|
B)Endocytosis of Enveloped Virus
|
-Receptor-mediated
-Form coated vesicle -Genome released after fusion with organelle |
|
|
|
C)Fusion of envelope with host membrane
|
-Nucleocapsid released into cytoplasm & uncoats
|
|
|
|
3)Replication and Transcription in DNA viruses
|
-Early genes- take over host, controls DNA RNA synthesis of host
-Viral DNA replication (nucleus) -Early mRNA synthesis -Some take control of cell functions |
|
|
|
Replication of ssDNA Viruses
(parvovirus) |
-Naked, icosahedral capsid
-small overlapping genome (3 overlapping genes) -uses host for all biosynthetic processes (only during S period) |
|
|
|
Replication of dsDNA viruses
(herpes simplex virus-1) |
-icosahedral, enveloped
-linear genome (50-100 genes) -host RNA polymerase for synthesis of viral mRNA -Early genes -DNA circularizes after 4 hours, viruses encoded DNA polymerase for replication |
|
|
|
Replication of dsDNA viruses
(poxvirus) |
-Largest (>200 genes)
-uncoating in lysosome -DNA dependent RNA polymerase which synthesizes early mRNA -Viral-associated= packaged in nucleocapsid -starts after 1.5 hrs, spans 24 hrs |
|
|
|
Replication and Transcription in RNA viruses
|
4 types:
1)Positive-sense ssRNA virus 2)Negative-sense ssRNA virus 3)dsRNA virus 4)Retrovirus |
|
|
|
Positive-sense ssRNA viruses
|
look in notes pg122
|
|
|
|
Negative-sense ssRNA viruses
|
look in notes pg 122
|
|
|
|
dsRNA viruses
|
look in notes pg 122
|
|
|
|
Retroviruses
|
look in notes pg 123
|
|
|
|
Why does RNA viruses mutate more than DNA viruses?
|
-DNA has proofreading ability
-RNA no proofreading ability |
|
|
|
4)Synthesis of virus capsids
|
-Capsid proteins (encoded by late genes)
-Naked virus +procapsids formed then nucleic acid inserted -Enveloped viruses +same as naked, envelope acquired when released (budding) -Matrix on some |
|
|
|
5)Assembly of Virons
|
site of assembly and morphogenesis varies
|
|
|
|
6)Viron released
|
Naked virus
-lysis of host cell Envelope viruses -budding -virus encoded protein incorperated into host membrane -most release form plasma membrane but some from different membranes |
|
|
|
HIV reproductive cycle
|
1)GP120 bind to CD4 of T cell, GP41 to accessory receptor
2)Fusion with PM 3)Reverse transcriptase (viral-assoc) makes dsDNA, enters nucleus, integrates using integrase (viral-assoc) -Pos.-sense RNA made for genomes 4)mRNA transcribed & translated into polypeptide -Protease (viral-assoc) cleaves into individual proteins 5)Assembles in cytoplasm 6)Buds from PM |
|
|
|
HSV-1 reproductive cycle
|
1)Spike attaches to heparan sulfate on cell mem
2)Receptor-mediated endocytosis -Vessicle fuses with outer nuc mem, envelope fuses with inner nuc mem to insert genome directly into nucleus 3)Early genes transcribed -DNA circularizes, Viral DNA copied 4)Late mRNA transcribed -Viral proteins made 5)Assembly in cytoplasm 6)Buds from PM |
|
|
|
Influenza Reproductive cycle
|
1)Spike attaches to sialic acid containing glycoproteins
2)Receptor-mediated endocytosis -vessicle fuses with endosome -RNA released in the cytoplasm 3)Transcriptase (viral-assoc) transcribes mRNA -Viral replicase make ds replicative form and -ssRNA 4)Late mRNA transcribed -Viral proteins made in cytoplasm and rough ER 5)Assembly in cytoplasm 6)Buds from plasma membrane |
|
|
|
Cytocidal Infections
|
7 types:
1) Inhibition of host mechs (DNA, RNA, Protein) 2)Lysosome damage 3)Alteration of plasma membrane 4)Toxicity from high concentrations of certain viral proteins 5)Formations of inclusion bodies (too many cells) 6)Chromosomal disruptions due to prophage insertion 7)Transformation of host cell into malignant cell |
7 types
|
|
|
Tumor
|
Growth and lump of tissue
|
|
|
|
Neoplasia
|
Abnormal cell growth and replication due to regulation loss
|
|
|
|
Anaplasia
|
Reversion to a more primitive/ differentiated state
|
|
|
|
Metaplasia
|
spread of cancer cells throughout the body
|
|
|
|
Causes of cancer
|
5 types:
1)Spontaneous mutations 2)Chemicals (carcinogens) 3)Diet (30-60% of cancers) 4)Viruses 5)Radiation |
5 types
|
|
|
Oncogenes
|
-cancer-causing genes
-most are proto-ocogenes (soon to be) |
|
|
|
Possible Mechs by which Viruses Cause Cancer
|
4 mechs
1)Carry oncogene into cell and insert into genome 2)Altered cell regulations due to changes in kinase activity or production of regulatory proteins 3)Insertion of promoter or enhancer next to cellular oncogene 4)Insert into host chromosome and disrupt normal functioning proto-oncogene |
4 mechs
|
|
|
Types of infections
|
3 types:
1)Acute 2)Persistent 3)Slow |
|
|
|
1)Acute
|
Rapid onset and relatively short duration (ex flu)
|
|
|
|
2)Persistent
|
can last many years
2 types: A)Chronic B)Latent |
|
|
|
3)Slow
|
Symptoms may take years to develop (ex HIV, Measles)
|
|
|
|
A)Chronic Infection
|
Virus is almost always detectable (diff from latent)
antibodies detected slow repro w/o causing disease symptoms symptoms mild or absent for long periods |
|
|
|
B)Latent Infections
|
Remains dormant for some time
not detectable (HSV, MONO, CHIC POX,) |
|
|
|
Viroids
|
Infectious agents made only of circular ssRNA
cause disease in plants |
|
|
|
Prions
|
-Infectious agent composed of only proteins
-Cause Neogenerative diseases (animals and humans) -Transmissible Spongioform Encephalopathies (TSEs) -microscopic holes in brain tissue -Symptoms= dementia, mycolonia, cerebellar ataxia |
|
|
|
PrP
|
prions protein, found in normal form of host animal
-protease sensitive -alpha-helix -soluble altered PrP^Se(PrP-Res) -protease resistant -beta-sheet -insoluble |
|
|
|
PrP interaction and conversion
|
occurs at cell surface or in endocytic pathway
blocking interaction and conversion may lead to therapy theories of conversion still not sure yet |
|
