2. HIV/AIDS
HIV stands for human immunodeficiency virus.
It harms the immune system by destroying the white blood cells that fight
infection.
This leads to serious infections and certain cancers.
AIDS stands for acquired immunodeficiency syndrome.
It is the final stage of infection with HIV.
Not everyone with HIV develops AIDS.
Jegan
3. HIV is a virus spread through certain body fluids that attacks the body’s immune
system, specifically the CD4 cells (T cells).
These special cells help the immune system fight off infections
Over time, HIV destroys so many of these cells that the body can’t fight off infections
and disease.
Untreated, HIV reduces the number of CD4 cells in the body.
This damage to the immune system makes it harder and harder for the body to fight
off infections and some other diseases.
Opportunistic infections or cancers take advantage of a very weak immune system
and signal that the person has AIDS
Jegan
4. AIDS
AIDS is a disease caused by HIV.
It’s the most advanced stage of HIV.
HIV destroys T cells called CD4 cells. These cells helps immune system fight
infections.
Healthy adults generally have a CD4 count of 800 to 1,000 per cubic millimeter. In
AIDS CD4 count falls below 200 per cubic millimeter
AIDS weakens immune system to the point where it can no longer fight off most
diseases and infections Jegan
5. MODE OF TRANSMISSION
HIV most often spreads through unprotected sex with an infected person.
It may also spread by sharing drug needles or through contact with the blood
of an infected person.
Women can give it to their babies during pregnancy or childbirth.
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7. BINDING
Proteins, called envelope proteins,
embedded in the outer membrane of the
HIV virion bind to receptors on the surface
of target cells.
T-cells (white blood cells) have CD4 and
CCR5 receptors to which HIV can bind.
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8. FUSION
Binding of the HIV envelope protein to CD4 and
CCR5 allows the HIV-1 outer membrane to fuse
with the cell’s outer membrane
HIV RNA, reverse transcriptase, integrase and
other viral proteins enter the cell.
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9. REVERSE TRANSCRIPTION
Once inside a CD4 cell, HIV releases and uses
reverse transcriptase (an HIV enzyme) to
convert its genetic material—HIV RNA—into
HIV DNA.
The conversion of HIV RNA to HIV DNA allows
HIV to enter the CD4 cell nucleus and combine
with the cell’s genetic material—cell DNA.
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10. INTEGRATION
The viral DNA enters the nucleus of the host and
becomes integrated into the host’s DNA.
An enzyme called integrase is key in this process.
Once the viral DNA has integrated into the cell’s
DNA, the cell is infected for the remainder of its
life.
The integrated viral DNA is now referred to as a
provirus.
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11. REPLICATION
The provirus DNA serves as a template for the creation of
new viral RNA via a process known as transcription
The newly formed viral RNA moves out of the infected cell’s
nucleus.
The viral RNA carries code for the synthesis of viral proteins
and enzymes.
The code is translated into long chains of amino-acids,
known as a polypeptide chains, which fold to form the
protein and enzyme components of new virus particles.
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12. ASSEMBLY
Components that are required to build new
virus particles, namely viral proteins, enzymes
and genetic material (viral RNA) move to the
cell’s outer membrane where they accumulate
and assemble in the form of a bud.
A variety of host cell proteins are recruited to
assist in virus assembly.
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13. BUDDING
Host-cell proteins cut the virus bud from the
cell’s outer membrane, thereby releasing a
new virus particle
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