Microbio Week 9 - Nature of Human Viruses (Exam 3) Flashcards
Viruses are ____________ agents
filterable
Are viruses alive?
NO
Can viruses replicate in broth?
NO
Do viruses divide by binary fission?
NO
What do viruses do after they infect a susceptible cell?
Take over cellular machinery
Make cell into a virus-making factory
What do viruses require to replicate?
Living cells
Do antibiotics and antifungals work on viruses?
NO
How do viruses initiate a new infection?
They disassemble in the newly infected cell
What do viruses use to complete their life cycle?
Host cell machinery
What is the genetic material of viruses?
RNA or DNA
New virus particles are made from newly made _________ ___________ in the host cell
viral proteins
Infectious virus particle
Virion
What are the 2 types of capsids?
Helical
Icosahedral
Which capsid varies in length depending on the size of the viral RNA?
Helical
All (-)RNA viruses contain which capsid?
Helical
All enveloped viruses contain which capsid?
Helical
Helical capsids containing human viruses have what?
Lipid envelope
T/F: Most helical capsids have a rigid stucture
FALSE, most do NOT have a rigid structure, they are spaghetti-like
Viruses with icosahedral capsids can be ___________ or ___________
enveloped; naked
What are icosahedral capsids formed from?
Viral capsid proteins
What is inside the icosahedral capsid?
Nucleic acid of the virus
The structure of icosahedral capsids need to be strong enough to withstand ___________ ________ but still be able to open up once the virus has infected a new cell
stomach acid
What is needed to form the icosahedral capsid?
Viral capsid protein
What happens once a sufficient amount of viral capsid protein is present?
Icosahedron spontaneously forms
The property of icosahedral capsid self-assembly is used to make what?
Virus-like particles in HPV vaccine
What does a “naked” virus mean?
No envelope lipid bilayer
What are viral envelopes derived from?
Infected cell membranes
The viral envelope ____________ are incorporated into the lipid bilayer.
glycoproteins
What are the viral envelope glycoproteins that are incorporated into the lipid bilayer required for?
Entry into a cell
T/F: If you disrupt the lipid bilayer, the virus cannot enter cells
True!
T/F: If a virus is enveloped, it is, on the whole, more fragile and cannot withstand agents that disrupt the envelope, such as stomach acid, detergents, solvents, heat, and drying agents
True
Which viruses are more resistant to agents such as stomach acid, detergents, solvents, heat, and drying - enveloped or naked?
Naked viruses
Some (naked/enveloped) viruses can withstand stomach acid and are transferred through the oral-fecal route
Naked viruses
Name 4 ways naked viruses can be transmitted
Respiratory
Sex
Congenitally
Oral-fecal
Name 3 ways enveloped viruses can be transmitted
Respiratory
Sex
Blood
Can enveloped viruses be spread via oral-fecal route?
NO
T/F: If an enveloped virus is on a surface in a liquid, like blood or mucus, it can retain some infectivity. However, once the liquid dries, the virus loses infectivity
True
What prevents a virus from infecting a cell?
Neutralizing ABs
What do neutralizing ABs recognize?
Surface proteins on the virion
What do neutralizing ABs for naked viruses bind?
Capsid proteins
What do neutralizing ABs for enveloped viruses bind?
Envelope glycoproteins in the lipid bilayer
What is the name of the genome for single-stranded RNA viruses?
+ssRNA
What genome is the same as messenger RNA (mRNA)?
+ssRNA
What is the name of the genome for negative-sense RNA viruses?
-ssRNA
What do negative-sense RNA viruses use as a template to make mRNA?
-ssRNA
What does BOAR stand for?
Bunyavirus, Orthomyxovirus, Arenavirus, Reovirus
What type of genome do BOAR viruses have?
Segmented
Linear ssDNA members
Parvovirus
Linear dsDNA members
Adenovirus, Herpesvirus, and Poxvirus
Closed-circular dsDNA members
Papillomavirus and Polyomavirus
Circular, most of the circle is double-stranded, but a small part is single-stranded (circular ds/ssDNA)
member
Hepadnavirus
+ssRNA members
Hepevirus, Picornavirus, Calicivirus, Togavirus,
Coronavirus, Flavivirus, and Retrovirus
-ssRNA members
Filovirus, Paramyxovirus, and Rhabdovirus
segmented -ssRNA members
Arenavirus, Bunyavirus, and Orthomyxovirus
Segmented dsRNA member
Reovirus
Circular -ssRNA member
Deltavirus-This is the Hepatitis D virus (HDV)
(It is not replication-competent and needs the help of the Hepatitis B Virus to replicate)
In this infection, the virus does not kill the cell but does produce virus
Steady state
This infection is productive. The virus is made and is non-cytocidal; the virus does not kill the cell
Steady state
The virus kills the cell as part of its life cycle; cell death is needed to release the virus.
Lytic/cytocidal
The virus kills the cell but not as part of its normal replication. It just makes the cell so sick that it cannot live
Cytopathic/cytocidal
This infection is productive and cytocidal. It also produces virus and kills the cell
Lytic/cytocidal
Cytopathic/cytocidal
The virus infects cells and does not produce any virus but can reactivate
Latent
This is non-productive (no virus made) and non-cytocidal (the cell is not killed)
Latent
The ability to become latent is an important feature of which virus?
Herpesviruses
The infected cell can fuse membranes of neighboring uninfected cells to form a large multinucleated cell
Syncytia forming
If a virus can transform a cell, it makes the virus more likely to cause cancer.
Cell-transforming
Transforming a cell makes them immortal and able to grow on top of each other (no contact inhibition like most cells)
Cell-transforming
Name the 6 viruses that cause cancer
EBV
HPV
HHV8
HTLV
HBV
HCV
What cancers does EBV cause?
Burkitt lymphoma
Nasopharyngeal carcinoma
Oral hairy leukoplakia
What cancers does HPV cause?
Cervical
Anal
Oropharynx
What cancer does HHV8 cause?
Kaposi’s sarcoma
What cancer does HTLV cause?
Adult T cell leukemia and lymphoma
What cancer does HBV and HCV cause?
Hepatocellular carcinoma
All DNA viruses are ____________
icosahedral
For the RNA viruses, only the –ssRNA viruses are ________
helical
(except for coronavirus)
for the RNA viruses, only the –ssRNA
viruses are helical, except for which one?
Coronavirus
