Human immunodeficiency virus HIV for short, is a virus that attacks
a body’s CD4 cells. CD4 cells are white blood cells that perform a vital role
in a maintaining a healthy immune system by defending the body from infections.
Subsequently, once HIV is contracted, the body’s immune system is weakened. In
2016, it was estimated that nearly 37 million people were living with HIV
making it a worldwide health issue (Avert 2017).

HIV can be transmitted through certain bodily fluids such as blood
and semen coming in contact with mucous membranes or a damaged tissue. It can
also be contracted through the sharing of contaminated drug equipment such as
needles with a HIV infected person. Another way HIV can be transmitted is
sexually through anal, vaginal or oral sex without use of medication or condoms.
Also, HIV is transmitted from mother to child through breastfeeding, pregnancy
or childbirth (AIDS info 2017)

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There are 3 stages of HIV, the first stage acute is the initial stage of
HIV developing within just 2-4 weeks after infection. During this period headaches,
fevers, rashes and body pains can be experienced. In this stage, HIV is multiplying
rapidly and therefore a person is at the greatest risk of transmitting HIV at
this time. The second stage is chronic/asymptomatic, during this period HIV is
still multiplying in the body but at considerably lower levels. You are still
able to spread HIV to other people and without medication the chronic infection
can advance to AIDS within 10 years. Some people may not
have any visible symptoms at this stage. AIDS (acquired immunodeficiency syndrome)
is the final stage of HIV. If a person’s CD4 count is lower than 200 cells/mm3, this is diagnosed as AIDS. This can
lead to a range of opportunistic infections such as cancers and candidiasis. During
this stage, the body’s immune system is severely weakened and unable to fight
of simple infections. Symptoms of this stage include recurring fever, long term
diarrhoea and fatigue. If no treatment is received, a person with AIDS may only
live for 3 years (Wu 2017). Methods of preventing
transmission of HIV include abstinence, using a latex condom, never sharing
needles and getting tested regularly (CDC 2017).

HIV comes from
the family Retroviridae and the genus Lentivirus. It is a rounded virus which
is 80-120nm in diameter. The envelope is the outer covering of the virus it is
composed of a bilayer of phospholipids made from the host cell’s membrane.
Extending the envelope are proteins that aid the virus – gp 120 binds the HIV
virus with the host cell’s CD4 receptor and gp 41 fuses the HIV virus with the
membrane of the host’s cell. This allows the HIV virus to infiltrate its
genetic material within the host’s cell ultimately leading to the damage of the
cell (Pancera 2010). Inside the envelope
is the matrix that is made up of p17 which ensures that gp 120 and gp 41 are held
to the virus (Ghanam 2012). The virus also
contains an enzyme called protease, it is responsible for cutting up long
polyproteins into more appropriate sized protein (Yang 2012). The next innermost
part of the HIV is a conical shaped capsid which is built up by capsid protein
which is also known as p24 (Deshmukh et al 2013). The capsid protects the genetic material inside the virus and
contains accessory proteins such as negative regulatory factor, viral protein
R, viral infectivity factor which are all important in the replication of the
HIV virus. It also contains p7 – a peptide that allows reverse transcription. The
HIV virus also contains reverse transcriptase (RT) which transforms RNA genomes
into DNA and the enzyme integrase integrates the viral DNA into the host cell.  

 

One defensive mechanism is the humoral immune response. This is when
B cells are activated in the body by the presence of an antigen (the HIV virus).
B sells secrete antibodies that bind to the epitopes of the HIV virus that
adhere to the CD4 receptors in the body. This causes the virus to be unable to
attach itself to CD4 receptors and prevents infection (Baum
2010).

Dendritic cells (DC) also play a part in helping to fight of the
HIV virus, they are found in the skin and mucous tissues. They capture
pathogens (the HIV virus) and subsequently active the innate and adaptive
immune responses. DC cells help B and T lymphocytes by donating antigens to
them (Borrow 2008).

Although presently there is no cure for HIV, there are a number
of medications to treat it. One treatment is antiretroviral therapy (ART) which
consists of a mixture of HIV drugs to prevent the replication of the HIV virus.
Subsequently, the medication lowers the HIV in the body and the risk of
transmitting it. This compels the body’s immune system to rectify and protect
itself from infections. One advantage of ART is that because a mixture of drugs
are being taken, it is harder for the HIV virus to develop resistance to a
mixture of drugs compared to taking a single HIV drug. A disadvantage of
consuming HIV medication is possible side effects encountered by a person which
can include headaches, dizziness and liver damage (AIDS info 2017).

 

One technique used to detect the HIV virus is the ELISA test
(enzymes-linked immunosorbent assay). The purpose of the ELISA is to identify whether
there are HIV antibodies in a person’s blood. One disadvantage of the ELISA is
that if the test is performed too soon after acquiring HIV as there would not
be enough HIV antibodies for the test to recognise. Futhermore the test may
provide you with a false positive result because the test can say you are
positive after other infections such as lupus. One main advantage of the ELISA
test is that the results are able to be quickly obtained. Another advantage of
the ELISA is that it is specific – binding only occurs between the
antibody/antigen and the epitope of the antibody/antigen and therefore is an
accurate test.