2. • Acquired Immune Deficiency Syndrome (AIDS) is a type
immune suppression which cripples the human immune
system and the ability of the human body to resist infections
diseases.
• It is caused by the human immunodeficiency virus (HIV).
• HIV is a type of retrovirus of an comprises of an envelope
studded with glycoprotein. This envelope surrounds a protein
coat which contains the viral genetic material
• The enzyme reversed transcriptase enables the virus to make
DNA from its RNA template, and thus earns its name as a
retrovirus.
• HIV destroys large portions of the T4 cells by using the
glycoproteins in its envelope to recognize and bind to receptor
molecules (CD4) on the T4 cells (host cells)
Two molecules of single-stranded RNA and an enzyme is reversed transcriptase
6. • During infection, HIV enters the body of a person and attaches
to CD4 receptor on the membrane of the T4 cell and fuses with
the plasma membrane of these host cells.
• The coat proteins are removed by enzymes and the RNA
molecules and reverse transcriptase of HIV enter the host
cells.
• Reversed transcriptase catalyzes the synthesis of a single
DNA strand complementary to the viral RNA strand. A second
DNA strand complementary to the first is then formed
catalyzed by the same enzyme.
• The double-stranded complementary DNA (cDNA) is
incorporated as a provirus into the T4 cell’s chromosomal DNA,
where it may lie dormant for many years.
This is where the HIV virus busy spreading and killing other lymphocytes
7. • The provirus is transcribed into RNA when the
T4 cells become activated as the body of the
infected person responds to certain infection.
• This Viral RNA serves as both messenger
RNA for the formation of HIV proteins and as
genetic material for the new generations of
viruses formed.
• Protein coats form around the viral RNA and
reverse transcriptase molecules to form new
viruses.
8.
9.
10. • Viruses bub from the host cell, acquiring envelopes from the
plasma membrane of the host cell ? as they leave.
• The new generations of viruses are released into the blood of
the infected person
• This new population of HIV then attacks other T4 cells,
particularly those in the lymph nodes.
• As more and more of the T4 cells are destroyed, the immune
system of the infected person deteriorates, making that
person susceptible to various infections. This will eventually
lead to death.
• HIV also infects the brain cells of the infected person causing
them to be gradually damaged. The retrovirus also attacks
the bone marrow and causes the precursor cells in blood
tissue to become a “pool” for HIV .
12. SYMPTOMS DESCRIPTION
1. No symptoms as a carrier During the initial stages of the infection, the
infected person does not show any
symptoms of the disease
(HIV STILL SPREADING)
2. (i) Fever
(ii) Drastic loss of weight
(iii) cough
(iv) Fatigue
(v) Diarrhea
(vi) Candidiasis
(vii) Swollen lymph nodes
These occur at the 2nd stage of the infection
3. (i) Pneumonia
(ii) Kaposi’s sarcoma
(iii) Lymphoma
(iv) Mental disturbance
These occur at the 3rd stage of the infection.
4. Death X_X Occurs within the next two years after the
infected person has develop full-blown AIDS
in five years.
21. • HIV is found in the blood , semen or vaginal fluids of
the carrier.
• Transmission can occur during blood transfer,
transfer of semen or vaginal from the carrier to
person through the following ways :-
(i) By having multiple sex partners who could be HIV
carriers.
(ii) By sharing of needles or syringes with an HIV
carrier.
(iii) Transfer of HIV by a mother who is a carrier to her
fetus through the placenta before birth.
(iv) Blood transfusions from a carrier the recipient.
23. • Reverse transcriptase inhibitors such as
Azidothymidine (AZT) and Dideoxyinosine
(DdI) are used to inhibit the reproduction of
virus by blocking the formation of DNA from
viral RNA.
• Protease inhibitors such as Ritonavir and
Indinavir are used to block cleavages that
convert new viral proteins into building blocks
for new viruses.
27. • Use of condoms during intercourse for people with
multiple sex partners which can prevent the virus
from infecting others.
• Restriction to one sexual partner only that is, sex
between husband and wife.
• Prevent drug abuse and avoid sharing needles and
syringes.
• Screen all donated blood for the presence of anti-
HIV antibodies.
• Avoid sharing shaving razor or toothbrushes or any
personal stuff which could be contaminated with
HIV-infected blood.
• Educate the public about the disease .