12th Zoology

AIDS – HIV

AIDS – HIV

AIDS (HIV) and its control

The disease Acquired Immuno Deficiency Syndrome (AIDS) was
identified in the year 1981 (December). Early epidemiological studies have
established that it is a communicable disease transmitted through sexual
contact or through blood and blood products.

In 1983 Luc Montagnier at Pasteur Institute, Paris and Gallo at National Institute of Health (NIH) USA isolated the virus that caused AIDS. In 1986, the committee on taxonomy of virus coined the term HIV or Human Immunodeficiency Virus
to avoid confusion due to different names being given by different reasearchers.

HIV is new member of the Lentivirinae subfamily of human
retroviruses. Retroviruses are RNA viruses, which have the capacity to
convert their RNA into DNA with the help of an enzyme called reverse
transcriptase.

Structure of HIV

HIV is spherical in shape. Its size is about 100-140 nm. Like any
other virus, it is made up of a central icosahedral capsid core containing the
genetic material surrounded by a protein envelope. The protein envelope is
attached several spicules of glycoprotein, Like other retroviruses the
glycoprotein sticks out on both sides (inside and outside) of its protein coat.
The outer position of glycoprotein called gp120 is attached to the gp 41
situated on the inner side of the viral coat. gp 41 is an unusually long protein
with over 100 amino acids. gp 120 appears like a knob. Electron
microscopic studies have revealed that the distribution of proteins of the viral
surface is very much like a soccer ball made of 12 pentagons and 20
hexagons, stitched together to make a sphere. The envelope of HIV also
contains other proteins including some HLA antigens (Human Leucocyte
Antigen).

The genome of HIV contains two helix of RNA molecules in folded
form. The enzyme reverse transcriptase is attached to RNA.

Pathogenesis

HIV causes profound immunodepression in humans. It is due to the
depletion of one type of WBC, which is involved in the formation of
antibodies called CD4 plus T-helper cells (lymphocytes). In addition other cells such as B-lymphocytes and macrophages are destroyed by HIV
infection. The infected macrophages serve as the reservoir of viruses and
dissiminate to all tissues in the body. HIV is found besides blood, in all body
fluids such as semen, vaginal secretion, cervical secretion, breast milk, CSF,
synovial fluid, pleural fluid, peritoneal fluid, pericardial fluid and amniotic
fluid. HIV can even destroy the brain cells.

Symptoms

The following symptoms have been defined by WHO.
1. Weight loss at least 10% body weight
2. Chronic diarrhoea for more than a month
3. Prolonged fever for more than one month
4. Night sweats and persistent coughs

5. Opportunistic infections such as tuberculosis, oropharyngeal
candidiasis (fungal infection in mouth and throat)
6. recurrent herpes zoster (viral) infection
7. Meningitis and nerve damage
8. Loss of memory and intelligence
9. An unusual cancer, kaposis sarcoma which produces scattered
purplish lesions over the chest and abdomen.

Diagnosis

ELISA test (Enzyme Linked Immuno Sorbent Assay) is a sensitive
preliminary blood test used to detect HIV antibodies.
Western Blot is the confirmatory test, which is highly specific and
based on specific antibodies to viral core proteins.

Control and Management

1. Screening of blood and blood products.
2. Education to people about do’s and don’ts in AIDS contraction and
bringing more awareness among the public.
3. Education about protected sexual behaviour and practices
4. Participation of voluntary agencies, teachers, NGOs, paramedical
workers, several other voluntary health organizations, in AIDS awareness
programmes
5. Making the antiretroviral drugs such as AZTs (Azidothymidine/Zidovudin)
and saquinovir etc., available to patients.

The management of HIV infection involves the above general
measures, treatment of opportunistic infections and cancer, antiretroviral
drugs, immunomodulators and supportive treatment and counselling.

Related Topics in Zoology:

Bio Zoology All Important Topics


  1. Microbiology Introduction and History of Medical Microbiology

  2. Pasteur, Koch, Lister

  3. Structure of Viruses

  4. Viral genetics

  5. Virus Culture

  6. Viral Diseases

  7. Bacteria Structure Culture

  8. Bacterial Genetics

  9. Bacterial Diseases

  10. Protozoan microbiology

  11. Pathogenecity of Microorganisms

  12. Antimicrobial Resistance

  13. Antibiotics and Chemotherapy

  14. AIDS – HIV

Unit 3 – Immunology Topic List Zoology

  1. IMMUNOLOGY

  2. Acquired Immunity

  3. Structure and Functions of the Immune System

  4. Peripheral Lymphoid Organs

  5. Secondary Lymphoid Organs

  6. Antigenic determinants and epitopes

  7. Antibodies – Immunoglobulins

  8. Transplantation immunology

  9. Genetic basis of organ transplants

  10. Immune system disorders

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