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HIV STRUCTURE IMAGE
These
pictures show the structure of the Human Immunodeficiency Virus
(HIV).The outer shell of the virus is known as the viral envelope.
Embedded in the viral envelope is a complex protein known as env
, which consists of an outer protruding cap glyco protein (gp) 120
, and a stem gp41 . Within the viral envelope is an HIV protein
called p17 (matrix) , and within this is the viral core or capsid,which
is made of another viral protein p24 (core antigen) . The major
elements contained within the viral core are two single strands
of HIV RNA,a protein p7 (nucleocapsid), and three enzyme proteins,
p51 (reverse transcriptase),p11 (protease) and p32 (integrase).
View
Image
HIV
Replication
These pictures
are of a cell producing HIV. HIV has a diameter of 1/10,000 of a
millimeter.
HIV belongs to a class of viruses
called retroviruses , which have genes composed of ribonucleic acid
(RNA) molecules. Retroviruses, like all viruses, can only replicate
within a living host cell because they contain only RNA and they do
not contain DNA. In addition, retroviruses use RNA as a template to
make DNA. Infection begins when an HIV particle encounters a cell
with a surface molecule called CD4 . The virus particle uses gp120
to attach itself to the cell membrane and then enters the cell.
Within
the cell the virus particle releases its RNA, and the enzyme reverse
transcriptase then converts the viral RNA into DNA. This new HIV
DNA then moves into the cell's nucleus where with the help of the
enzyme integrase it is then inserted into the host cells DNA. Once
it is in the cell's genes HIV DNA is called a provirus .
The
HIV provirus is then replicated by the host cell, which can then
release new infectious virus particles.
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