As far as the
phrasing goes: Know your enemy and know your enemy well in order to win the
day. It's a little cliche but a touche ^^
In order to fully fathom the premise of HIV treatment or possibly
cure, we must first be able to understand how this little midget works
Entry (This virus do know how to make an entrance^^): [1]
HIV
infection is specific to certain human immune cells (helper T-cell) due to the
presence of the protein CD4 (exclusive to helper T cells) which acts as a
receptor that allow the virus to enter the cell; other than the CD4 receptor, a
secondary receptor CCR5*
(Chemokine Co-receptor) is also needed. After the virus attaches itself to
these cell-surface receptors, it then fuses the viral membrane and the cell
membrane and inject the viral particles into the cell while leaving its
membrane protein behind.
Reverse Transcription
and Integration
After
the virus make its way into the cell, its matrix and capsid protein break down
to release the viral genetic material. Then the enzyme, reverse transcriptase* that the
virus brings along with it starts acting on the viral mRNA to transcribe a
complementary DNA or cDNA. Now, another enzyme that the virus brought along, integrase* would bring the
viral DNA into the cellular nucleus and integrate that piece of viral DNA into
the human DNA, which dawns upon the start of a life-long infection as the virus
take advantage of the cellular machinery to create more copies of itself and
infect neighboring cells. Once integrated, the HIV DNA is known as provirus.
Transcription and
Translation
HIV
provirus may lie dormant within a cell for a long time. But when the cell
becomes activated, it treats HIV genes in much the same way as human genes.
First it converts them into messenger RNA (using human enzymes). Then the
messenger RNA is transported outside the nucleus, and is used as a blueprint
for producing new HIV proteins and enzymes.
[2]Interesting tidbits: While
HIV only has 9 genes, it’s able to take advantage of mRNA slippage and a change
in reading frame to generate different protein from the same message
(Programmed frameshifting in biosynthesis of HIV protein). A single mRNA,
designated gag-pol, encodes for two polyproteins that overlap by about 200
nucleotides and are in different reading frames. The gag polyprotein is
translated from the initiation codon to an in-frame termination codon near the
gag-pol junction.; gag polyprotein is then cleaved to generate several
structural proteins of the virus. However about 5% of the time a one-nucleotide
frameshift occurs within the overlapping segment of the mRNA and the
termination codon is bypassed because it is no longer in the reading frame. A
gag-pol fusion polyprotein is produced; proteolytic cleavage of the pol
polyprotein produces the viral reverse transcriptase and other proteins needed
in virus replication.
Assembly, Budding and Maturation
Among the strands of messenger RNA produced by
the cell are complete copies of HIV genetic material. These gather together
with newly made HIV proteins and enzymes to form new viral particles. The HIV
particles are then released or 'bud' from the cell. The enzyme protease* plays a vital role at
this stage of the HIV life cycle by chopping up long strands of protein into
smaller pieces, which are used to construct mature viral cores.
The newly matured HIV particles are ready to
infect another cell and begin the replication process all over again. In this
way the virus quickly spreads through the human body. And once a person is
infected, they can pass HIV on to others in their bodily fluids.
If you are too
lazy to read the whole process, here's an olive branch ^^:
References:
[2] Glitz, D.(2006). Textbook of Biochemistry With
Clinical Correlations Sixth Edition. Canada: Wiley-Liss.
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