Lecture 4 part 1 Flashcards
state the envelope, capsid, and genome of paramyxoviruses
envelope – pleomorphic with specific viral attachment proteins (VAPs)
nucleocapsid – helical
genome – large, ssRNA(-) viruses; LINEAR genome
the 3 genera of paramyxoviruses are distinguished by what?
the VAPs (viral attachment proteins)
paramyxoviruses cause major diseases including……
measles
mumps
RSV
paramyxoviruses invade cells via ____ and are released by _____
invade cells via membrane fusion and released by budding
what is the name of the viral attachment protein on paramyxoviruses for MUMPS?
HN (hemagglutinin-neuraminidase)
what is the name of the viral attachment protein on paramyxoviruses for MEASLES
H (hemagglutinin)
true or false
the mumps and measles viruses have a single serotype
true
what is the name for the measles virus
morbillivirus
paramyxovirus is:
the mumps virus AND parainfluenza virus 1-4
what is the name of the RSV virus
pneumovirus
RSV AND metapneumovirus
explain the replication scheme of paramyxoviruses
genome is ssRNA(-)
to make protein:
ssRNA(-) is converted to ssRNA(+) via viral RNA dependent RNA polymerase. ssRNA(+) is like mRNA. translated into viral proteins
to make genome:
ssRNA(-) is converted to ssRNA(+) by RNA dependent RNA polymerase to serve as a template for generating more copies.
RNA dependent RNA polymerase then converts this ssRNA(+) back into ssRNA(-) to package into newly made virus
what are the 3 classes of proteins associated with paramyxoviruses
nucleocapsid associated proteins
VAP’s (produced in host cell)
matrix protein
name the nucleo-capsid associated proteins in paramyxoviruses and state their function
NP (nucleoprotein) – bind and protect viral RNA
P – polymerase phosphoprotein – facilitates viral RNA replication
L (RNA polymerase)
name the VAPS made by paramyxoviruses and state where they are made
made IN THE HOST CELL
F protein – membrane protein that promotes fusion and viral entry
HN (MUMPS VAP)
H (MEASLES VAP)
m protein – matrix protein – associated with the assembly of virions
state the envelope, capsid, and genome of togaviruses
envelope – has envelope. 2 GLYCOPROTEIN SPIKES
capsid – icosahedral
genome – ssRNA(+) viruses
where do togaviruses replicate?
in the cytoplasm
where does the togavirus infect and does it spread?
togavirus infects the upper respiratory tract.
spreads via viremia (blood) to lymphoid tissue, skin, and other organs
the togavirus causes what disease?
what is another name for this disease?
rubella – german measles
explain the replication scheme of the togavirus
genome of togavirus = ssRNA(+)
to make protein:
ssRNA(+) directly binds to the host ribosome and makes protein
to make genome:
RNA dependent RNA polyermase converts ssRNA(+) into ssRNA(-) as a template for generating copies.
RNA dependent RNA polymerase then converts this ssRNA(-) back into ssRNA(+) for the packaging into newly made viruses
explain the structure of the spikes of the rubella virus
trimer of E1 and E2 glycoprotein
how does the rubella virus get into the cell?
receptor mediated endocytosos
in the case of the rubella virus, explain what happens when it affects the host cell, starting with translation
translated into a POLYPROTEIN called p200 which is processed to form p150 and p90.
the combined action of p150 and p90 transcribes the message to make proteins
is the transmission of measles, mumps, and rubella the same or different?
same – all respiratory
measles, mumps, and rubella all result in this symptom:
fever
do measles, mumps, and rubella all cause a rash?
no
no rash for the mumps
measles has a widespread, maculopapular rash
rubella has a faint macular rash
between measles, mumps, and rubella, which has the longest duration of illness?
mumps (7-10 days)
true or false
both MUMPS and MEASLES are slightly contagious
false – they are both highly contagious
the mumps virus is spread via….
viremia
the measles virus is spread via..
the lymphatic system
true or false
the mumps cause a lytic infection
TRUE
where is the secondary infection site of the mumps virus?
what are the symptoms of a secondary infection?
secondary infection = parotid gland
symptoms = painful swelling
for which virus does a CNS infection occur in ~50% of patients?
the mumps virus
name the primary and secondary infection sites of the measles virus
primary infection – in epithelial cells
secondary – in lymphocytes and monocytes
(remember: spread systematically through the lymphatic system)
what is the cause of the rash seen when a person is infected with measles virus?
T cells targeting skin, and endothelial cells of blood vessels
name the 5 classes of picornaviruses
enteroviruses
(polio, coxsackie A, coxsackie B, echovirus, enterovirus)
rhinovirus (common cold)
cardiovirus
aphthovirus
hepatovirus (hepatitis A)
explain the envelope, capsid, and genome of enteroviruses
envelope – no envelope
capsid – icosahedral
genome – small, ssRNA(+) viruses. LINEAR mRNA genome
where in the cell are enteroviruses replicated and assembled?
in the cytoplasm
true or false
enteroviruses are a large family of viruses
TRUE –polio, coxsackie A and B, echovirus, enterovirus
what is unique about enteroviruses
they are very resistant to harsh conditions (tolerate wide pH range)
how are enteroviruses transmitted?
via oral fecal route
are enteroviruses lytic or not lytic?
lytic
also have specific tissue tropism
for which of the enteroviruses can you develop a rash and fever and why
the enterovirus itself
the enterovirus has a tissue tropism for the skin. the permissive cells are located there
which viruses have a protein cap on their genome and why
enteroviruses have VPG cap on the 5’ side of their genome (ssRNA(+))
-the genome resembles mRNA. needs protection in the cytoplasm
-the cap primes the synthesis of the viral strand ssRNA(-) and primes the synthesis of RNA dependent RNA polymerase
what is the target tissue of the enterovirus (not plural)
the skin – that’s why rash is developed
