5.4.6 Control Measures Against the Transmission of HIV

AIDS can be controlled by preventing transfer of body fluid (blood, serum, semen, etc.) from patient to unaffected person.

The following behaviour or precautionary measures will prevent AIDS:

• Do not use used syringes and needles.
• For blood transfusion, blood must be used after proper screening for HIV.
• Do not share toothbrushes, blades, and towels with anyone. Special care is to be taken at barber's shop or hair cutting saloons, beauty salons.
• Surgical instruments must be properly sterilized.
• AIDS is primarily a sexually transmitted disease. Refrain from immoral sexual activities and follow Islamic teachings to pass a healthy, neat, and clean life.
• Mother having HIV should not feed their babies.

• Shaking hands, hugging, coughing or sneezing, and swimming in the same pool do not transmit HIV.
• One cannot get AIDS from inanimate objects such as toilets, door knobs, telephones, office machines, and household furniture.
• AIDS is not transmitted by mosquitoes and other insects.

Intermediate Level

Structure of HIV in Detail

Life Cycle of HIV in Detail

Symptoms of AIDS in Detail

Control Measures in Detail

Important Points

• 1. Human immunodeficiency virus (HIV) is the causative agent of acquired immune-deficiency syndrome or AIDS.
• 2. It was identified (in 1984) by research team from Pasteur Institute in France and National Institute of Health in USA.
• 3. The virus was named HIV (in 1986).
• 4. Structure of HIV:
• - HIV is a retrovirus.
• - It is spherical in shape.
• - The outer covering is a lipoprotein envelope which consists of two layers of lipids; different proteins are embedded in the viral envelope, forming "spikes" consisting of the outer glycoprotein gp 120 and the transmembrane gp 41.
• - The lipid membrane is borrowed from the host cell during the budding process (formation of new particles).
• - Beneath envelope another protein shell is present which is made up of matrix proteins. It lies between the envelope and capsid.
• - The HIV capsid is somewhat conical shaped which is composed of capsomeres.
• - The viral core contains two single strands of HIV RNA and the enzymes needed for HIV replication, such as reverse transcriptase, integrase and protease.
• - The reverse transcriptase enzyme is used to convert viral RNA genome into viral DNA genome, integrase enzyme is used to incorporate viral DNA into host DNA while the protease enzyme is used to break large structural proteins into smaller units.
• - These structural proteins are encoded by three out of the nine virus genes.
• 5. Life Cycle of HIV:
• - HIV attacks only specific cells of host called CD4 cells.
• - Helper T cells, macrophages and certain brain cells have CD4 receptors and are called CD4 cells.
• - CD4 receptors are recognized by HIV for attachment.
• - As HIV only attaches with CD4 cells so it has host cell specificity.
• - Following steps are involved in the life cycle of HIV:
• 1. The initial step in the life cycle of HIV is attachment which is characterized by the binding of the virion gp 120 envelope proteins to the CD4 proteins (a receptor) on the surface of T cells.
• 2. Next the fusion of the viral envelope with the cell membrane takes place by using gp 41 and the virion enters the cell by endocytosis.
• 3. Once inside the host cell, the HIV particle sheds its protective coat i.e., uncoating occurs. This leaves the single stranded viral RNA in the cytoplasm along with viral enzymes.
• 4. The enzyme called reverse transcriptase synthesizes a single stranded DNA complementary to virus RNA therefore, called complementary DNA (cDNA).
• 5. After reverse transcription the viral genomic RNA is disintegrated by the ribonuclease (RNAase) enzyme.
• 6. The single stranded cDNA is replicated to form double stranded cDNA.
• 7. The double stranded cDNA then integrates into the host cell DNA. Integration is mediated by a virus encoded enzyme integrase.
• 8. The integrated DNA is now called provirus.
• 9. and 10. Viral mRNA is transcribed from the proviral DNA by the host cell RNA polymerase. During transcription not only viral mRNAs for different protein are formed but viral genomic RNA is also produced.
• 11. The viral mRNAs are translated by host ribosomes into several large proteins, which are then cleaved by the virus-encoded protease to form the virion structural proteins.
• 12. The viral components are assembled and mature virions are produced.
• 13. Finally, the mature virions are gradually released by budding off from the host cell and enclosing a portion of host cell membrane around them. In this way host cell size is decreased enough that it becomes non-functional.
• 6. HIV AIDS naming:
• - Helper T cells are the most important cells of immune system.
• - They help and activate other cells of immune system.
• - Helper T cells activate B cells to secrete antibodies.
• - They also activate cytotoxic T cells to kill virus infected and cancerous cells.
• - Since, helper T cells regulate immunity by enhancing the response of other immune cells.
• - The decrease in the number of helper T cells causes deficiency of the human immune system, therefore, the virus has been named Human Immunodeficiency Virus (HIV).
• 7. Symptoms of AIDS:
• - An HIV infection can be divided into 3 stages: Asymptomatic carrier, AIDS Related Complex (ARC), Full Blown AIDS.
• - In asymptomatic carrier symptoms that may include are fever, chills, aches (continued pain), swollen lymph glands and an itchy rash. These symptoms disappear and there are no other symptoms for nine months or longer. Although the individual exhibit no symptoms during this stage, he or she is highly infectious. The standard HIV blood test for the presence of antibody becomes positive during this stage.
• - The most common symptoms of AIDS related complex are swollen lymph glands in the neck, armpit or groin that persist for months. Other symptoms include night sweats, persistent cough, flu, and persistent diarrhoea, loss of memory and depression.
• - The full blown AIDS is the final stage. In it there is severe weight loss and weakness due to persistent diarrhoea and usually one of several opportunistic infections.
• 8. Opportunistic Diseases:
• - HIV does not cause any disease nor kills any person.
• - It only destroys T cells of immune system.
• - The decrease in the human immune system results in the inability of the body to fight diseases.
• - Due to weak defence system a person suffering from AIDS is attacked by diseases called opportunistic diseases, e.g., skin cancer, fungal infection, viral infection, gastrointestinal diseases, respiratory diseases, nervous system and eye diseases.
• 9. Treatment of AIDS:
• - HIV is treated using a combination of medicines to fight HIV infection.
• - This is called antiretroviral therapy (ART).
• - ART is not a cure, but it can control the virus so that HIV positive person can live a longer, healthier life and reduce the risk of transmitting HIV to others.
• - ART is a highly effective treatment for HIV infection, preventing progression of the disease in the vast majority of recipients.
• - When ART is accessible and started early in the course of infection, the lifespan of HIV-positive people is typically very close to that of comparable HIV-negative people.
• - But ART can have toxicities, is often costly, and requires strict daily pill taking that can be difficult for some people.
• 10. Control Measures Against the Transmission of HIV:
• - AIDS can be controlled by preventing transfer of body fluid (blood, serum, semen, etc.,) from patient to unaffected person.
• - The following behaviour of precautionary measure will prevent AIDS:
• 1. Do not use used syringes and needles.
• 2. For blood transfusion, blood must be used after proper screening for HIV.
• 3. Do not share toothbrushes, blades and towels with anyone. Special cares to be taken at barber's shop or hair cutting saloons, beauty salons.
• 4. Surgical instruments must be properly sterilized.
• 5. AIDS is primarily a sexually transmitted disease. Refrain from immoral sexual activities and follow Islamic teachings to pass healthy, neat and clean life.
• 6. Mother having HIV should not feed their babies.
• - Shaking hands, hugging, coughing or sneezing and swimming in the same pool do not transmit HIV.
• - One cannot get AIDS from inanimate objects such as toilets, door knobs, telephones, office machines and house hold furniture.
• - AIDS is not transmitted by mosquitoes and other insects.

Remember

• - HIV = Human Immunodeficiency Virus
• - AIDS = Acquired Immune Deficiency Syndrome
• - HIV attacks = Helper T cells (CD4 cells)
• - **Result** = Immunodeficiency
• - Transmission = Blood, semen, vaginal fluids, breast milk
• - Not transmitted by = Hugging, shaking hands, mosquitoes
• - Treatment = Antiretroviral therapy (ART)
• - Prevention = Safe practices, screening blood, sterile instruments
• - Structure: Envelope, gp 120, gp 41, matrix protein, capsid, viral core, reverse transcriptase, integrase, protease
• - Life cycle: Attachment, fusion, uncoating, reverse transcription, integration, provirus, transcription, translation, assembly, budding, release

Common Mistakes

• 1. Thinking HIV and AIDS are the same – HIV is the virus; AIDS is the disease.
• 2. Thinking HIV can be transmitted by hugging or shaking hands – HIV is not transmitted by casual contact.
• 3. Thinking HIV can be transmitted by mosquitoes – HIV is not transmitted by mosquitoes.
• 4. Thinking HIV only affects humans – HIV infects humans; SIV infects other primates.
• 5. Confusing the structure of HIV with other viruses – HIV is enveloped and has gp 120 and gp 41.
• 6. Thinking HIV has DNA as its genetic material – HIV has RNA as its genetic material.
• 7. Forgetting the role of reverse transcriptase – Reverse transcriptase converts RNA to DNA.
• 8. Thinking the immune system can easily fight HIV – HIV attacks the immune system itself.
• 9. Thinking ART is a cure – ART is not a cure; it controls the virus.
• 10. Forgetting the role of protease – Protease cleaves viral proteins.
• 11. Confusing the stages of HIV infection – Asymptomatic carrier, ARC, Full Blown AIDS.
• 12. Thinking HIV can be transmitted by sharing food – HIV is not transmitted by sharing food.

Quick Revision

• Human immunodeficiency virus (HIV) is the causative agent of acquired immune-deficiency syndrome or AIDS.
• It was identified (in 1984) by research team from Pasteur Institute in France and National Institute of Health in USA.
• The virus was named HIV (in 1986).
• Structure of HIV:
• HIV is a retrovirus.
• It is spherical in shape.
• The outer covering is a lipoprotein envelope which consists of two layers of lipids; different proteins are embedded in the viral envelope, forming "spikes" consisting of the outer glycoprotein gp 120 and the transmembrane gp 41.
• The lipid membrane is borrowed from the host cell during the budding process (formation of new particles).
• Beneath envelope another protein shell is present which is made up of matrix proteins. It lies between the envelope and capsid.
• The HIV capsid is somewhat conical shaped which is composed of capsomeres.
• The viral core contains two single strands of HIV RNA and the enzymes needed for HIV replication, such as reverse transcriptase, integrase and protease.
• The reverse transcriptase enzyme is used to convert viral RNA genome into viral DNA genome, integrase enzyme is used to incorporate viral DNA into host DNA while the protease enzyme is used to break large structural proteins into smaller units.
• These structural proteins are encoded by three out of the nine virus genes.
• Life Cycle of HIV:
• HIV attacks only specific cells of host called CD4 cells.
• Helper T cells, macrophages and certain brain cells have CD4 receptors and are called CD4 cells.
• CD4 receptors are recognized by HIV for attachment.
• As HIV only attaches with CD4 cells so it has host cell specificity.
• Following steps are involved in the life cycle of HIV:
• HIV AIDS naming:
• Helper T cells are the most important cells of immune system.
• They help and activate other cells of immune system.
• Helper T cells activate B cells to secrete antibodies.
• They also activate cytotoxic T cells to kill virus infected and cancerous cells.
• Since, helper T cells regulate immunity by enhancing the response of other immune cells.
• The decrease in the number of helper T cells causes deficiency of the human immune system, therefore, the virus has been named Human Immunodeficiency Virus (HIV).
• Symptoms of AIDS:
• An HIV infection can be divided into 3 stages: Asymptomatic carrier, AIDS Related Complex (ARC), Full Blown AIDS.
• In asymptomatic carrier symptoms that may include are fever, chills, aches (continued pain), swollen lymph glands and an itchy rash. These symptoms disappear and there are no other symptoms for nine months or longer. Although the individual exhibit no symptoms during this stage, he or she is highly infectious. The standard HIV blood test for the presence of antibody becomes positive during this stage.
• The most common symptoms of AIDS related complex are swollen lymph glands in the neck, armpit or groin that persist for months. Other symptoms include night sweats, persistent cough, flu, and persistent diarrhoea, loss of memory and depression.
• The full blown AIDS is the final stage. In it there is severe weight loss and weakness due to persistent diarrhoea and usually one of several opportunistic infections.
• Opportunistic Diseases:
• HIV does not cause any disease nor kills any person.
• It only destroys T cells of immune system.
• The decrease in the human immune system results in the inability of the body to fight diseases.
• Due to weak defence system a person suffering from AIDS is attacked by diseases called opportunistic diseases, e.g., skin cancer, fungal infection, viral infection, gastrointestinal diseases, respiratory diseases, nervous system and eye diseases.
• Treatment of AIDS:
• HIV is treated using a combination of medicines to fight HIV infection.
• This is called antiretroviral therapy (ART).
• ART is not a cure, but it can control the virus so that HIV positive person can live a longer, healthier life and reduce the risk of transmitting HIV to others.
• ART is a highly effective treatment for HIV infection, preventing progression of the disease in the vast majority of recipients.
• When ART is accessible and started early in the course of infection, the lifespan of HIV-positive people is typically very close to that of comparable HIV-negative people.
• But ART can have toxicities, is often costly, and requires strict daily pill taking that can be difficult for some people.
• Control Measures Against the Transmission of HIV:
• AIDS can be controlled by preventing transfer of body fluid (blood, serum, semen, etc.,) from patient to unaffected person.
• The following behaviour of precautionary measure will prevent AIDS:
• Shaking hands, hugging, coughing or sneezing and swimming in the same pool do not transmit HIV.
• One cannot get AIDS from inanimate objects such as toilets, door knobs, telephones, office machines and house hold furniture.
• AIDS is not transmitted by mosquitoes and other insects.

60-Second Revision

• HIV = Human Immunodeficiency Virus
• AIDS = Acquired Immune Deficiency Syndrome
• HIV attacks = Helper T cells (CD4 cells)
• **Result** = Immunodeficiency
• Transmission = Blood, semen, vaginal fluids, breast milk
• Not transmitted by = Hugging, shaking hands, mosquitoes
• Treatment = Antiretroviral therapy (ART)
• Prevention = Safe practices, screening blood, sterile instruments
• Structure: Envelope, gp 120, gp 41, matrix protein, capsid, viral core, reverse transcriptase, integrase, protease
• Life cycle: Attachment, fusion, uncoating, reverse transcription, integration, provirus, transcription, translation, assembly, budding, release
• Warning: HIV and AIDS are not the same. HIV is the virus; AIDS is the disease. HIV is not transmitted by casual contact or mosquitoes. HIV attacks helper T cells. Reverse transcriptase converts RNA to DNA. ART is not a cure. Prevention is better than cure.