Intro Flashcards
Teach about Virues
What is a Virion?
A viral particle
True or False:
A virus can’t have DNA
False: Viruses exist as both DNA and RNA.
What four types of genome can a virus have?
Double Strand (ds) DNA, Single Strand (ss) DNA, ds RNA, or ss RNA.
A ____ is a structural protein polymer, symmetrical and rigid Surrounding the Nucleic acid of a virus
Capsid
____ a membrane containing viral glycoproteins..
Envelope
Is an Enveloped Virus stronger than a virus without one?
No. Their envelope is essential for their integrity, but it is fragile, it can be destroyed by excessive temperature or pH, dryness, or detergents
True or False:
Enveloped Viruses can more easily fuse with cell walls.
True
These are examples of what?
Structure: size, morphology, and nucleic acid (e.g., picornavirus [small RNA]
Biochemical characteristics: structure and mode of replication
Disease they cause
Means of transmission
Host cell (host range): animal (human, mouse, bird), plant, bacteria
Tissue or organ (tropism)
Virus classifications/names
In Baltimore classification a Class I virus is?
dsDNA
In Baltimore classification a Class II virus is?
ssDNA
In Baltimore classification a Class III virus is?
dsRNA
In Baltimore classification a Class IV virus is?
ssRNA positive
In Baltimore classification a Class V virus is?
ssRNA negative
In Baltimore classification a Class VI virus is?
Retrovirus: single stranded positive RNA virus that replicates via DNA synthesis
In Baltimore classification a Class VII virus is?
dsDNA virus replication through ssRNA intermediate (HBV)
A virus that replicates backwards is called?
Retrovirus
What 2 ways might cell penetration take place?
Surface fusion or Endocytosis, followed by endocytic fusion
Once inside the cell what process must occur?
Uncoating
Where do most DNA viruses replicate?
the nucleus
Where do most RNA viruses replicate?
Cytoplasm
True or False:
All Viruses carry their own enzymes.
False: Most viruses use the cell machinery. Usually only large viruses carry their own enzymes.
What are the phases of virus synthesis?
Early and late, although some viruses have a middle phase as well
In the ____ phase proteins are synthesized before genome replication: these are the non-structural proteins
Early
In the ____ phase proteins are synthesized after genome replication: these are the structural proteins
Late
____ the immediate-early proteins. They are involved in transcriptional regulation and are not found in the mature virion. They are also involved in the control of beta protein synthesis
Alpha Proteins
____ the early proteins involved also in DNA replication (they include the DNA polymerase and transcription factors). Only a few copies of DNA polymerase need to be made for replication to occur
Beta proteins
____ the late proteins and structural components of the virus. The synthesis of gamma proteins is initiated after the start of DNA synthesis
Gamma Proteins
True or False:
RNA is long lived and can be transcribed by RNA polymerase without error.
False
RNA is degraded relatively quickly, the RNAdependent RNA polymerase must be provided or synthesized soon after uncoating to generate more viral RNA,
Most viral RNA polymerases work at a fast pace but are also error prone, causing mutations.
True or False:
ss(-) RNA are complementary to mRNA and thus must be converted to positive-sense RNA.in order to replicate
True
True or False:
ss(+) RNA can start translation right away once inside a cell. whereas ss(-) RNA must first transcribe then translate.
True
(Class III) dsRNA viruses replicate similar to which other RNA virus type? (ClassV) ss(-) or (ClassIV) ss(+)
(Class V) ss(-) in that they need transcription first.
What is a provirus?
A DNA virus that has integrated into the host DNA and remains latent for a time
These characterize what kind of virus replication?
•nucleotide replication occurs in the nucleus using a virus-coded enzyme
- (+) strand RNA’s are synthesized and serve as templates for (-) strand genomic RNA’s.
- mRNA’s are synthesized from each segment. Some segments give rise to primary transcripts which can be alternatively spliced
segmented RNA replication
True of False:
Each segment codes for only one protein.
False: A single segment can code for more than one protein since the virus has access to splicing machinery. The mRNAs are transcribed in the nucleus
How do (Class VI) retroviruses Replicate?
(Class VI) retroviruses replicate through a DNA intermediate by copying their RNA into DNA by reverse transcription, a process requiring the enzyme reverse transcriptase carried in the virions
True of False:
This is the order of (Class VI) retro virus transcription;
ssRNA → ssDNA → dsDNA → mRNA
True
True or False:
Infection by viruses is always intracellular.
True
____ ____ occurs when two viruses co-infect the same cell and share parts of their genome during replication
Genetic recombination
What is Horizontal transmission?
Infection by a person to another person by direct contact or a vector
What is vertical transmission?
Passed though lineage like a mother to child through plancenta
What is meant by saying viremia?
The virus can relocate using the blood
What is cytopathogenesis and what does it tell a person?
Interaction between cells of the target organ and the virus and it determines the outcome of the viral infection
What is the outcome of the lytic cycle of a virus?
Release of the virions due to cell lysis.
What is the outcome of the lysogenic cycle of a virus?
Integration into the host DNA and gets copied every time the cell replicates.
What is an Oncogenic infection?
Induces uncontrolled replication of infected cells (a.k.a. Cancer)
What is a Non permissive cell and how does it effect the infection?
a cell that does not permit the virus in any way and causes no infection or an abortive infection.
Cells that support viral replication are called?
Permissive
What is the virus doing in the eclipse period?
Uncoating and replicating
What happens after the latent period of a virus?
Virions release
True or False:
The latent period , during which extracellular infectious virus is not detected, includes the eclipse period.
True
High levels of IgM signal what about an infection?
Current Infection
High levels of IgG signal what about an infection?
Past or advanced infection
What is a syncytia?
Formation of giant multinucleated cells
What is a Prodrome?
An early symptom indicating the onset of a disease or illness.
