Microbio Exam 2- Part F
What type of viral NA do coronaviruses have?
(+)RNA
What type of viral NA is found in the poliovirus?
(+)RNA
What type of viral NA do rhabdoviruses have?
(-)RNA
What is the structure of a coronavirus virion?
-enveloped -club-shaped glycoproteins on the surface look like a crown
What are coronaviruses?
-largest RNA viruses -cause respiratory infections (like SARS)
What happens with the herpesvirus after the viral envelope fuses with the host cell membrane?
-nucleocapsid enters the cell, and migrates to the nucleus where the viral DNA is uncoated
How is adenovirus DNA replicated in the host nucleus?
-replicated using both strands, producing one dsDNA and one ssDNA
How are pox viruses structured?
-they have no envelope -the outer surface is covered by a lattice of protein tubules
Rhabdovirus RNA is transcribed to produce what two classes of RNA?
1. mRNA coding for structural proteins 2. full (+)RNA genome for use as a template for viral genomic RNA to be packaged
What is the result of antigenic shift on the influenza virion?
Antigenic shift changes the surface properties of the virion so that it is no longer recognized when host Ab's are released
What are delayed early proteins of the herpesviruses?
DNA replication proteins
Where does coronavirus virion assembly occur in the host cell?
Golgi apparatus
What are the 2 types of protein spikes on the surface of the influenza virus?
Hemagglutinin Neuraminidase
Aside from neuraminidase, what 2 key enzymes do influenza virions possess?
RNA-dependent RNA Polymerase (aka RNA replicase) RNA endonuclease
What is an example of a latent herpesvirus in which symptoms are caused by stress?
Varicella-zoster virus: chicken pox→shingles
What is tegument?
a fibrous structure unique to herpesviruses
What are herpesivruses?
a large group of dsDNA viruses, many of which cause disease
What are adenoviruses?
a major group of icosahedral, linear dsDNA viruses
What are immediate early proteins of the herpesviruses?
a set of 5 regulatory proteins
What is found at the 5' end of adenovirus DNA?
a terminal protein required for the replication of viral DNA
What is antigenic drift?
accumulation of mutations that also change virions surface properties
What happens to the host machinery when the herpesvirus infects?
all macromolecular synthesis in the host is shut down by proteins brought in by the virus, and host machinery is taken over to produce 3 classes of viral mRNA
How is the influenza (-)RNA transcribed?
an RNA-dependent RNA polymerase brought in by the virus transcribes the (-)RNA into (+)RNA
What surrounds the core of the herpesvirus?
an icosahedral nucleocapsid
What occurs faster, antigenic drift or antigenic shift?
antigenic shift occurs faster
How many proteins does the herpesvirus genome code for?
at least 84
How does poliovirus infect the host?
attaches to a specific receptor on the host cell surface
Why do rhabdoviruses bring in their own replication enzymes?
because the host doesn't recognize negative ssRNA
Where does the rhabdovirus acquire its capsid and envelope proteins?
both are synthesized in the host cell cytoplasm
What is the function of neuraminidase?
breaks down sialic acid in membranes, making cells fall apart
How do herpesviruses infect their host?
by attachment (adsorption) to specific host cell receptors followed by fusion of the viral envelope with the host cell membrane. NOT BY ENDOCYTOSIS
How does influenza virus acquire its envelope?
by budding through the host cell membrane
How is the viral envelope of the herpesvirus acquired?
by budding through the inner membrane of the host nucleus
What disease are caused by a herpesvirus?
cold sores venereal herpes chicken pox shingles infectious mononucleosis cancer (Epstein-Barr virus)
How are pox virions released from the host cell?
either by host cell lysis or by actin rockets
What does the viral DNA transcribed in the nucleocapsid code for?
for a protein that uncoats the viral DNA
What is an orthomyxovirus?
group of enveloped (-)RNA viruses in which the viral RNA is present in the virion in a number of separate pieces, and which interacts with the mucus or slime of a host cell surface
What are actin rockets?
host cell contractile filaments that expel virions
What do the 3 classes of herpesvirus viral mRNA code for?
immediate early, delayed early, and late proteins
Where does influenza virus replication occur?
in both the nucleus and the cytoplasm
Where does the coronavirus replicate in the host?
in the cytoplasm
Where does poliovirus replication occur in the host cell?
in the host cytoplasm
Where are viral nucleocapsids of herpesvirus assembled?
in the host nucleus
Where is viral DNA of herpesvirus replicated?
in the host nucleus
Where is viral DNA replicated in the cytoplasm?
inside inclusion bodies that contain viral encoded DNA-polymerase
Where does hemagglutinin get its name?
it agglutinates RBCs, which also happen to have sialic acid on their surface
What is the function of hemagglutinin on the surface of the influenza virus?
it binds to sialic acid in the mucus membrane (adsorption site)
Is the coronavirus (+)RNA read as mRNA?
it can be but most of it is NOT
What happens to the ssDNA strand of adenovirus produced after replication?
it circularizes, a complementary strand is made, and then it becomes linear (?)
What is the function of the RNA endonuclease brought in by the influenza virion?
it cuts a primer from the host's capped mRNA precursors
What does it mean that the influenza virus is polymorphic?
it has no defined shape
What is the size and shape of poliovirus?
it is an icosahedral picornavirus with only 7433 nucleotides
What happens to the rhabdovirus (+)RNA that is made as a complement to the viral (-)RNA?
it is read as mRNA that codes for structural proteins
How is viral RNA replicated in the host cell?
it is replicated in the nucleus by viral replicase and viral endonuclease brought in by the virus
How does the influenza virion infect the host?
it is taken up by endocytosis
How many proteins does the poliovirus make?
it makes on giant polyprotein that self-cleaves into 20 smaller proteins
What is the function of the viral RNA replicase brought in by the influenza virion?
it synthesizes a (+)RNA from a (-)RNA
What form of viral NA is found in the pox virus?
linear dsDNA
How many start codons does the poliovirus have?
one
How is the complementary coronavirus (-)RNA strand used?
parts of the (-)RNA strand are used as a template make small (+)RNAs which DO get read as mRNA to make viral proteins
What type of viral NA does the influenza virus contain?
segmented genome present in 8 separate pieces of (-)RNA that code for 10 proteins
What is a picornavirus?
small (pico) RNA virus
How does the coronavirus replicate?
some genomic (+)RNA is read to produce viral replicase which then synthesizes a full-length complementary (-)RNA strand
What happens inside the nucleocapsid of the pox virus?
some viral DNA is transcribed into mRNA by viral-encoded RNA polymerase brought in by the virus
What are late proteins of the herpesviruses?
structural proteins for capsomeres, tegument, and spikes
What is the structure of the herpesvirus?
structurally complex with 4 units: Core Nucleocapsid Tegument Envelope
What does the poliovirus do in the host cell once the viral NA is uncoded?
the (+)RNA is read as mRNA and all host RNA and protein synthesis is shut down
How does the host defend itself from the protein spikes of the influenza virus?
the host makes antibodies against hemagglutinin, which neutralize the virus
What strand of the coronavirus is used as a template for viral RNA to be packaged?
the large (-)RNA strand
What happens once the influenza virus is inside the host?
the nucleocapsid separates from the envelope and migrates to the nucleus
What structural proteins are included among the 20 smaller proteins from the poliovirus polyprotein?
the poliovirus capsid RNA replicase a protease that cuts the polyprotein
What surrounds the herpesvirus nucleocapsid?
the tegument
How is the pox virus DNA unique?
the two strands of DNA are covalently cross-linked at the ends by phosphodiester bonds
How do adenoviruses infect their hosts?
the virion is taken up by endocytosis and moves to the nucleus
What is the structure of rhabdoviruses?
they are enveloped and helical (rod-shaped), with capsomeres in a helix and Nas in the middle
How are rhabdovirus envelope proteins structured?
they are glycoproteins, similar to host cell membrane glycoproteins; have hydrophobic AA leader sequences at the terminus attached to sugars
What does the size of pox viruses compare to other animal viruses?
they are relatively large, and can be seen under a light microscope
How are mature herpesvirus virions released from the cell?
they are released through the ER to the outside of the cell
How do pox virions infect a host?
they are taken up by endocytosis and the nucleocapsid is released in the cytoplasm
How are coronavirus virions released from the host cell?
they are transported from the Golgi to the cell surface for release
How do rhabdoviruses replicate in the host?
they bring in several enzymes, including RNA-dependent RNA polymerase
How do rhabdovirus envelope proteins attached to the cell membrane?
they migrate to the cell membrane where the leader sequence is cleaved off, and the protein is inserted into the host cell membrane
How do the rhabdovirus nucleocapsids acquire an envelope?
they migrate to viral glycoproteins on the host membrane, recognize them, and then bud through them, getting enveloped in the process
What pox virus processes occur in inclusion bodies?
transcription, replication, and encapsidation
What is on the surface of influenza virus that interacts with the host cell?
two types of protein spikes
How many (+)RNA strands are synthesized in one poliovirus cycle?
up to one million
What happens once adenovirus virions move to the host cell nucleus?
viral DNA is released and transcribed using host RNA polymerase
What is in the core of a herpesvirus?
viral linear dsDNA
What causes antigenic shift in the influenza virus?
when virions assemble in the host cytoplasm, different RNA segments from different flu viruses can be packaged together
