AIDS And Retroviruses

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AIDS And Retroviruses

Today, tens of millions of people around the world are going to die young
because they are infected by HIV, the virus that causes AIDS. The primary AIDS
virus is HIV-1, which can be spread via sexual intercourse or drug use
(activities, which result in body fluid exchange like blood and semen). HIV can
also be passed from mother to child and can also be acquired during blood
transfusions. AIDS, Acquired Immune Deficiency Syndrome, is a virus that causes
a loss of protection against disease causing microorganisms. People who are
infected by AIDS usually have a decline in the number of T-cells that are
responsible for their immune system. Because the virus reproduces by a reversed
transcriptase enzyme, it can quickly make a copy of its virus and so, it is
difficult to treat with its infinite reproductions. However, scientists have now
came up with a combination of drug called "cocktail drugs" to slow
down the development of the virus in different life cycles. Introduction HIV,
the Human Immunodeficiency Virus, is a disease that merits international
concern, study, and research. The diseases that infect individuals over the
world are causing theme to lose the functionality of their immune system and
finally succumb to one or more opportunistic diseases. AIDS viruses are
unbelievably small particles, invisible under an ordinary microscope, but
observable with an electron microscope. All the viruses are tiny packets of
genetic material, composed of either DNA or RNA and are surrounded by a
protective envelope of protein. HIV belongs to a group of especially tricky
viruses called retrovirus. It reverses the usual flow of genetic information
within the host cell. Retroviral RNA is copied, using its reverse transcriptase
enzyme, into a complementary single strand of DNA. This single-strand retroviral

DNA is then copied into double-stranded retroviral DNA inside the cell's
cytoplasm. This retroviral DNA migrates into the host cell's nucleus and becomes
integrated into the host cell DNA. It is then a provirus. (Hyde & Forsyth,

1996) 1.0 Retroviruses 1.1 History There are two strains of HIV, HIV-1 and

HIV-2. HIV-1 is the more prevalent form and also the one that causes the greater
pathology. HIV-2 is a lesser found strain that is endemic to countries in West

Africa. Presently, the majority of those infected with HIV are infected with the

HIV-1 strain. When the infection progresses, the patient is diagnosed with
acquired immunodeficiency syndrome (AIDS). The first well-documented case of

AIDS was found in San Francisco and New York in 1981. A young gay man in San

Francisco was found to be suffering from a severe fungal infection to which he
had little immune reaction. In fact, his immune system did not appear to respond
to any disease. Then he developed Pneunocystis carinii pneumonia (PCP), a type
of pneumonia that is caused by parasite. This disease is usually found only
among severely malnourished individuals or people whose immune systems have been
impaired by drugs such as those used in the treatment of cancer or in connection
with organ transplants. The young man died by the end of the year. Retroviruses
are classified into many different categories, but Lentivirus is responsible for
human immunodeficiency virus (HIV-1). (Armstrong, 1990) 1.2 T-Cells A
characteristic feature of AIDS is the progressive decline in the number of
circulating CD4 T lymphocytes . Various strains of HIV are cytopathic for cells
from cultured CD4 cell lines suggesting that direct killing, among other
mechanisms, may contribute to depletion of CD4 T-cells in HIV-infected persons.

Cell killing may also be involved in other aspects of HIV pathogenesis,
including the induction of neurological dysfunctions. The molecular events that
mediate HIV-induced cytopathology have not yet been elucidated, although env
gene products have been implicated by many lines of evidence. Studies funded in
the previous years of this grant indicate that HIV, like several other cytolytic
viruses, mediates changes in plasma membrane-associated ion transport systems.

Scientists proposed studies focus on defining HIV proteins, which mediate the
changes in ion flux. Their study found out that one of the HIV proteins may be
involved is the transmembrane protein (TM). Among the regions of TM, there are
carboxyl terminal sequences involved. These sequences have the potential to form
a strongly amphipathic helix enriched in arginine, a motif shared with
monovalent cation channels. HIV also have affects the potassium and sodium ion
transport systems. (Armstrong,1990) 1.3 Structure of AIDS virus There is
considerable diversity between various types of retrovirus; the following is a
generalized description of the particle. There is a universal nomenclature for
retrovirus proteins: Protein Function Matrix matrix protein (gag

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