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86 Cards in this Set

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w/c type of microscope is needed to view viruses?
electron
what is the size of viruses?
most are <0.45microns
_______ is the inactive form of the virus?
virion
when does a virion become a virus?
once inside in the host, it becomes a virus & active
what are the different nucleic acids of viruses?
DNA or RNA w/c can be SS or DS
what is the function of a capsid on viruses?
to protect DNA/RNA against physcal or chemical damage
what is the shape of all viruses?
icosohedron & some are helical
this viral structure is involved in recognizing the host surface?
capsid
what are the 3 functions of capsid?
protects DNA/RNA against physical chemical damage, involved in recognizing the host surface, & facilitates nucleic acid penetration
viral envelops are composed of what?
host lipids & viral proteins
function of viral spikes?
used for recognition & attachment to host
what are the 4 structures a virus can have?
nucleic acid, capsid, envelope, & spike
w/c structures are required for a virus to have?
nucleic acid & capsid
When growing viruses, what is required?
A host
What is a plaque assay?
Host + virus
What are the tissue culture technique?
in the dish, u see the spots. These are where the virus has attacked the host tissue w/c the opaque part on the dish.
The affinity of the virus to its host is known as?
tropism
this term defines taking the virus & passing it thru the host to produce more viruses?
passing
What are the 4 types of infections involved in human viruses?
Lytic, persistent, transforming, & latent
This infection involves the death of the host & release of virus?
Lytic
Define transforming infection?
When virus inserts itself w/n the host chromosome & therefore replicates along w/ the chromosome. This could lead to mutation or transformation w/c is a change in the genetic make up of the cell.
Give an example of a latent infection?
Herpes
2 types of infections that affect the bacteria by viruses?
Lytic & lysogenic
What are the non specific responses of host to virus?
Fever, interferon, low pH of inflammatory exudates, mucous, hyrolytic enzymes
These are major defenses agains viruses & they are the 1st line of defense?
Interferons
What are interferons?
Cytokines that are released by WBC & are a major defense against viruses
How does low pH work in inhbiting viral infection?
some viruses go inside w/ their capsid intact. To uncoat (for the capsid to come off) it requires a certain pH so if u lower the pH, the virus will be able to unooat & therefore cannot release the virus.
How do hyrolytic enzymes work in viral infection?
They destroy viral components. Examples are proteases & nucleases
What are the specific defenses of viral infection?
Ab & CMI
What is the virulence factors of viruses?
To be able to enter the cell & reprogram the host so the host produces more viruses
What are the 2 ways that the host tries to get rid of the virus?
Cytopathology & immunopathology
A host defense where the cell is lysed so it can get rid of the virus by getting rid of the machinery of the cell?
Cytopathology
A host defense where the immune system tries to minimize the damage & tries to get rid of the pool of cells that have the virus w/n them so it gets rid of their own cells?
immunopathology
2 ways a virus can enter into host tissue?
Directly by trauma or insect bite & thru mucous membranes of the respiratory & alimentary tracts
What is the MC way that a virus can get into the host?
respiratory
These are effects that are visual w/c can be seen under microscope or observe the outcome of a viral infection?
Cytopathic effects (CPE)
What are the 4 ways that a virus can damage the host?
1) cell lysis 2) cell transformation where the DNA is altered, 3) toxic products 4) alter host structure
virus enters the blood stream is a condition ka?
viremia
what are the 8 mechanisms of the virus replication cycle?
attachment, penetration, uncoating, provision of energy, synthesis of precursors, nucleic acid & protein synthesis, assembly, & release
attachment of virus to host occurs by what way?
specific; most of the time occurs between the capsid & the host receptors & may also occur between the spkes & the host receptors
what is the function of the synthesis of precursors in virus replication cycle?
earlier proteins are made w/c are enzymes that are needed for replication
what is maturation in virus replication cycle?
virus is produced in pieces first then assembled later
T/F: release or exit of virus in its replication cycle always involves killing the host?
False, not always
what 3 things can lead to cell lysis & therefore host damage w/ viral infection?
Ab-virus-host cell, complement-Ab-virus-host cell, & expression of viral protein on host surface. These will all lead to lysis of the cell.
what is the main weapon of the host in viral infection?
CMI
these cells are important in killing intracellular pathogens or infected cells?
natural killer cells
what are the 7 ways that viruses can evade the immune response of the host?
1) inhibition of MHC class I, 2) inhibition of MHC II, 3) downregulation of CD4 by HIV, 4) inhibition of NK cell lysis, 5) interference w/ apoptosis, 6) inhibition of cytokine action (interferons), 7) evasion of humoral immunity
how can a virus evade the humoral immunity of the host?
evade by mutation, antigenic shift or drift
for viral infection, the site of infection is the _______ ________ of infection?
primary site
what is the MC way of viral infection spread in the body?
subepithelial invasion & lymphatic spread
secondary viremia can happen by what 3 ways?
virus enters the lymph system, virus enters the blood stream, or virus enters the NS. This is how the virus spreads thru the rest of the body
virus entering the lymph system is ka?
lymphotropic
virus entering the NS is ka?
neurotropic
what are the different ways that viruses can shed?
respiratory or oropharyngeal secretions, feces, skin, urine, milk, genital secretions, blood
T/F: all viruses shed to be able to infect others organisms?
False, not all viruses are involved in virus shedding.
all of the visual damages to the host by the virus is ka?
cytopathic effects or CPE
T/F: usually viruses don't want to kill their host so lysis is not the preferred method for a virus?
True
what are permissive or productive virus cell interaction infections?
Permissive or productive infection: go in, make viruses & then get out
what are the types of virus cell interactions in viral infections?
permissive or productive, abortive or non productive, persisten, latent, & CPE
what is the normal outcome for virus cell interactions for a viral infection?
permissive or productive infection
define abortive or non productive infection in viral infection?
virus enters the cell then a few genes are turned on but no further expression occurs
when does lysogeny of the virus become lytic?
under some kind of stress, it will become lytic & start doing damage
what happens in persistent viral infection?
there are a few cells that produce the virus after the permissive cells die & release the virus. At this point, interferon inhibits the infection but Ab do not clear it from the body
what happens in latent viral infection?
Some viruses, instead of reproducing, enter into a latent state from which they can later be reactivated
give 2 examples of latent infection & how they work?
herpes where DNA is methlyated but is not integrated w/n the host chromosome. Adeno-associated where it integrates into the host genome & therefore can replicate when host genome replicates.
Give some examples of CPE?
1)Changes in structure of nucleus, 2)Changes in membrane, fibroblast and viral budding & 3)Cell fusion
in viral infection, cell fusion is aka?
syncytia formation
what makes up the one step growth cycle?
attach or adsorb to cell, penetration of virus, eclipse, & rise
penetration of virus into host can occur by what 2 ways?
fusion or endocytosis
what happens in the eclipse part of the one step growth cycle?
infecitous virus is not detectable
what happens in the rise stage of the one step growth cycle?
infectious particles are detectable
what are the viral replication steps?
what is a clatherin coated pit?
once a virus enters by endocytosis, it becomes surrounded by this coated vesicle
clartherin coated pits require what?
low pH in the cytoplasm for the virus to release its particles
Define viral syndrome. Give some examples of viral syndromes
a. Viral Syndrome: the pathogenic manifestation of a viral infection.
b. Examples include: oral and respiratory tract infections, infections of the eye, hepatitis, and etc.
A process by which cells internalize molecules (endocytosis) by the inward budding of plasma membrane vesicles containing proteins with receptor sites specific to the molecules being internalized.
receptor mediated endocytosis
how does a virus replicate in the host?
it uses host cell enzymes & structural components such as actin fibers, membranes & ribosomes
what enzymes can be used by the virus to undergo transcription?
cellular transcriptase & viral transcriptase
T/F: viruses use only the host cellular enzymes to undergo transcription?
false, some viruses have their own viral transcriptase enzymes to help them undergo transcription
Influenza virus is what type of virus?
a) RNA virus
b) DNA virus
A) RNA virus
Be familiar w/ infections associated w/ viral syndromes
w/c viruses can trigger fusion of neighboring cells called syncytia?
paramyxoviruses, herpesviruses, & retroviruses
What the important features of AZT?
Azine group instead of hydroxyl – acts as a chain terminator
Why is it so difficult to develop vaccine for HIV
HIV has a high mutation rate
The disease is spread by so many different transmission routes,
vaccine against the mucosal lining is difficult, and so many subtypes
exist
What is the possible origin of HIV? What are the clads, groups and subtypes of HIV
a. Simian (SIV). Origin is from the simian lentiviruses. More specifically, HIV-1 from
SIV- CPZ and HIV-2 from SIV-SM.
Groups > Subtypes > Clads
In HIV, what is the MC transmission? what is the most effective transmission?
The most common is sexual, but the most EFFECTIVE is blood transfusion.