01 Influenza & HIV Virus Replication Flashcards
____ is a contagious respiratory infection caused by influenza
viruses. Like all viruses, influenza must gain entry into host
cells to replicate.
Flu
The process involves several stages:
○ attachment and entry to viral RNA
○ protein production
○ assembly and release from the host cell
An influenza virus attaches to a cell when ____,
one type of protein in its viral envelope binds to a host
receptor.
hemagglutinin
recognizes receptor polysaccharides that terminate with cyanic acid – the cell then takes up the virus by endocytosis
Hemagglutinin
contains digestive enzymes and an acidic interior, and typically digests contents taken
in from outside the cell.
Lysosome
For the host, the virus uses the ____ to its advantage. An
ion channel allows protons to enter the virus. The ___
inside the viral particle disrupts protein-protein interactions
causing matrix proteins to detach from proteins covering the
viral RNA genome.
○ This detachment is the beginning of the _____
process. One type of anti influenza drug blocks
this ion channel.
acidity
uncoating
The acidity also triggers ______ to make a structural change and insert itself into the vesicle membrane. In this new form ____ stimulates membrane fusion.
hemagglutinin
The RNA genome and associated proteins can flow freely away from the matrix proteins into the ____, completing the uncoating process
cytoplasm
The 8 RNA segments of the influenza genome are covered
with _________and attached to several other proteins that make up the viral RNA polymerase. These RNA protein units enter the nucleus via the nuclear pores,
Nucleocapsid Proteins (NP)
RNA segments are ______, each of the eight segments needs to be copied into a complementary plus strand by the viral RNA polymerase before it can be used for translating proteins.
minus (-) strand RNA (non-coding
strands)
To make a messenger RNA for translation by host ribosomes, the virus needs to add a structure called ___.
5’ cap
At the beginning of the mRNA transcript, virus performs a
stealthy act known as ______ in which the viral RNA
polymerase cuts off the cap from one of the host cells own
mRNA molecules and uses the cap to start transcription of viral RNA. The new plus strand viral RNA gets a _____
that aids in mRNA stability.
cap snatching
Poly A tail
The new viral mRNA leaves the nucleus for the cytoplasm
where the host cells _____ translate the mRNA
ribosomes
In this example, the mRNA codes for the ____ protein that will code future viral RNA molecules
nucleocapsid
Several other mRNAs code for viral envelope proteins.
_______ are made by ribosomes on the host cells endoplasmic reticulum. This particular mRNA codes for hemagglutinin.
Envelope proteins
