Virus Lecture 1 Flashcards
What is the first animal virus?
foot and mouth disease 1898
what is the first human virus?
yellow fever virus in 1901
Viruses are smaller than ___, ___, & ___ ____
bacteria, fungus, and other microorganisms
Virus means what in greek?
poison
Vrisuses are what in nature?
ubiquitous
What are the two theories of virus origin?
cellular and autopoietic origin
what is cellular origin?
proposes that viruses were once cellular components but over time they evolved separately
what is the autopoietic origin?
proproses that viruses, once autopoietic entities, became dependent on cells for replication?
What are the 3 events of viruses in history?
Measles in Boston
Yellow fever in US
1918 pandemic
what are the 5 attributes of virus clasification
virus particle structure genome replication features serology stability
what are the 3 components of particle structure for viruses
composition
shape
size
define nucleocapsid
RNA or DNA in a core that is protected by a protein coat
Virus is defined by the ___ ___
nucleocapsid structure
Nucleocapsid is comprised of repeating protein subunits called
capsomeres
define envelope structure
virus- modified cellular membranes acquired upon exit from host
Exposure to ___ solvents in the laboratory renders enveloped viruses ____
lipid
noninfectious
Enveloped viruses may have ____ with different structures
nucleocapsids
What is the smallest size of virus particle
18 nm
What is the largest size of virus particle
300 nm
What are the advantages of a large size particle?
Carry a lot of stuff (DNA, etc) EX: herpes
What are the disadvantages of large particle?
turnover time isn’t quick (takes a long time to replicate)
What 2 types of DNA are in the genome?
single and double stranded
What are the 2 types of RNA
double strandard and single stranded
What are the 3 types of single stranded RNA?
plus sense
minus sense
ambisense
Define plus sense RNA
ready for translation
Define minus sense RNA
not ready for translation
Define ambisense RNA
a part is ready for translation but another part isn’t
What are the 4 different types of structure for virus gemone
Linear
circular
segmented
diploid
What are the advantages of a large genome?
Make more proteins
What are the disadvantages of a large genome?
More things can go wrong
More time for the host to attack
Harder to replicate
What do RNA viruses need that DNA virus do not?
RNA dependent RNA polymerase
Virus replication process
Attachment ENtry Transcription Translation Replication Assembly Release
Define attachment
binding of a virus receptor to a cellular receptor
What can change the cellular reception?
Genetic engineering
What are the 3 cellular receptors?
signaling molecules
cell adhesion
transport
how does a virus usually get into the cell?
cell mediated endocytosis
do viral receptors sometimes need co-receptors?
Yes
Viral receptors mimic cell receptor’s normal ligands T/F
FALSE
What do the viral receptors look like on the particle surface?
spike like projections
Envelope viruses like to go into the cell by what?
receptor penetration of plasma membrane
influenza, poliovirus, adenovirus
What is the other pathway a virus can go into the cell by?
Direct penetration of plasma membrane
HIV, herpes virus, newcastle disease virus
How is a virus different from a bacterium?
size
How is a virus different from a toxin?
toxin doesn’t replicate
whats serology?
antibody recognition
what is required for replication features?
requires access to cell nucleus
what are 2 viruses that are envelopes?
ebola virus and influenza
what replication example is dsDNA rolling circle?
herpes virus
what are the 2 types of DNA replication?
dsDNA
ssDNA
what are the types of RNA replication?
(+)ssRNA
(-)ssRNA
what do most DNA viruses need that RNA viruses do not?
DNA- usually needs access to nucleus
What are some aspects of the attachment process for viruses?
- Binding of a virus receptor to a cellular receptor
- Cellular receptors
- Viral receptors
- Genetic engineering (can change receptor recognition)
What are the 3 aspects of cellular receptors
signaling molecules
cell adhesion
transport
what is virus tropism?
host range. how much can it infect
attachment is a major determinant of ___ ___
virus tropism
host range is a major factor in ____
eradication
smallpox virus, what host?
only humans
yellow fever, what host?
mosquitoes and humans
what are the two mechanisms for non-enveloped virus entry?
pores: picornavirus
membrane disruption: adenovirus & reovirus
what pathway does an enveloped virus go through?
membrane fusion CELL MEDIATED ENDOCYTOSIS (placed into an endosome)
whats an example of enveloped virus?
influenza
What are two aspects of the receptor conformational change for entry?
Low pH
receptor induced
