Aids Is The Final Phase Of Hiv Infection Biology Essay

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AIDS is the final phase of HIV infection. HIV virus causes to progressive serious damage to immune system. Infections recently spread worldwide. So HIV infection and AIDS are widely distributed via international travelers and their sexual activities and drug habits. Although infection is preventable. It is transmitted rapidly via sexual intercourse, needle and syringe-sharing in field of medical use of blood, blood components, organs or tissue exchange and from an infected mother to her children and also spread via vertical transmission to newborn baby at delivery and via breast milk. Virus is not spread through casual contact air, food and water or through mosquitoes. There is no vaccine for disease. Acquired Immune Deficiency Syndrome referred as AIDS .HIV is also caused by exposure to various body fluids of an infected person through sexual contact or intravenous drug use. HIV infected persons develop AIDS after several years later approximately 9 years. Although incurable some success has been used in lowering the rapid development from HIV to AIDS. AIDS impaired immune system that gives protection against several infections. The immune system is no single thing and it is complex and no body of science yet fully explains how it all works. Microbes cause infection such as bacteria, viruses or fungi. We are surrounded by millions of them every day; we can't see them through our eyes. Virus mainly targets the T-cells, those which have a receptor called a CD4 receptor. The viral attaches onto above receptor can take to the inside of the cell. Eventually have a virus which similar appearance and acts as a CD4 T-cell.

HIV (Human Immune Deficiency Virus):

HIV is a specific type of virus (retro virus) that causes AIDS. It attacks the immune system. The immune system gives body ability to fight infections. HIV finds and finally destroys a type of white blood cell (T cells or CD4 cells) that the immune system must have to fight disease. Infected HIV person is referred to as HIV positive. But HIV positive person looks healthy for a long time after first becoming infected. HIV-1 (human immunodeficiency virus) mainly causes to this and HIV-2 causes a similar illness.


AIDS (Acquired Immune Deficiency Syndrome):

Final stage of HIV infection is AIDS, Which take hours for a person infected with HIV, even without treatment, to reach this stage. Having AIDS means that the virus has weakened powerful immune system to the point at which the body has a difficult time fighting infections such as diarrhea or cold. No cure. Eventually, the virus kills or impairs cells in the immune systems. People who infected AIDS can die from diseases that are usually not dangerous for people with healthy immune systems.

Origin of HIV:

Source of HIV is specialized type of chimpanzees.. This virus most likely transmits to humans when humans hunted these chimpanzees for food and came into contact with their infected blood. The virus slowly spread across Africa and later into other parts of the world. Now the number of tho se living with HIV infection continues to rise, although more slowly. However, the number of those newly infected was lowered from 1996 (3.5 million) to 2008 (2.3 million), due to more frequent treatment with antiretroviral drugs (ART).

number of people living with HIV

Global epidemic and regional patterns:

AIDS was first recognized in 1981.In Sub-Saharan Africa 64% of all person who infected HIV are live. In South Africa live for one-third of AIDS deaths globally. Since 2002, the rapid increases have been seen in East Asia (50%), largely to the epidemic occurring in China, and in Eastern Europe and Central Asia and Ukraine, Latvia and Russia. In Vietnam, Thailand, Cambodia, Nepal and Myanmar, It is now well established. In India, it is about 5.1 million persons are currently infected .So now Asia is home to 60% of the world's population. HIV infection in countries is profound as it affects the most economically productive and fertile ages and is also eroding the health and economic advances made in the last few decades .Fewer than 5% of patients in resource-poor countries are able to Uses antiretroviral drugs. High-risk of sexual is also increasing in many countries. The epidemic in some nations is changing. Heterosexual transmission is become the dominant route, with racial and ethnic minorities representing an increasing fraction.

How is HIV transmitted?

HIV transmits from blood, semen (cum), pre-seminal fluid (pre-cum), vaginal fluid, or breast milk from an infected person to an uninfected person. HIV enter the body through a vein (e.g., injection drug use), the lining of the anus or rectum, the lining of the vagina and/or cervix, the opening to the penis, the mouth, other mucous membranes (e.g., eyes or inside of the nose), or cuts and sores. Intact, healthy skin is a barrier to HIV. HIV can transmit through infected blood or blood clotting factor, and also has a lower risk infected blood comes in contact with a worker's open cut or is splashed into a worker's eyes or inside their nose. Some additional body fluids transmit the virus such as fluids surrounding the spinal cord, brain, bone, joints, and fluid surrounding an unborn baby.HIV is found in the saliva and tears of some persons living with HIV, but in very low amounts. That is why HIV can be transmitted by through body fluid. HIV has not been investigated from the sweat of HIV-infected persons. Contact with saliva, tears, or sweat has never been cleared to result in transmission of HIV. Women can pass HIV to their unborn child during pregnancy, while the baby is being delivered, or through breast-feeding .This is the most common way spread HIV to children .Not all women who infected will give it to their children. Without medication or breastfeeding about 25% (1 in 4) of pregnant women with HIV will transmit the HIV to their babies.

Replication and Mutation of HIV:

HIV allows itself to be destroyed by the defense cells and this way it enters into the defense cells of the body. At the same time the virus accompanies along the enzyme "reverse transcriptase" which change the genetic molecule of the virus itself (RNA) into the human genetic molecule (DNA). The virus RNA is then built into the one of the host cell, where it can relay inactive for many years. While replicating, the virus changes the defense cells in the same way. If the defense cell receives a signals to replicate (for example to kill HIV or other viruses or bacteria), this starts the replication of HIV. Not only that while replicating, the virus uses the above host cell for its own purposes, such as extract its nutrients. Huge amount of HIVs are immediately formed to destroying the defense cells and, new HIVs in turn invades other defense cells.

Symptoms of HIV Infection:

Only one source of check whether you are infected or not is testing for HIV. You cannot hopes on symptoms alone because, many people who already infected with HIV do not have clear symptoms for many years. Someone can show and feel healthy but can still be infected. In fact, one quarter of the infected persons in the worlds do not know that they are infected.

Major symptom:

We can identified major symptoms such as, Loss of more than 10% of body weight, chronic diarrhea, and Prolong fever

Minor symptom:

AIDS has several minor symptoms such as cough for more than a month, generalized itchy skin rash, painful group of blisters all over the body, generalized swollen lymph gland and white curd like patched on tongue/throat.

About the Immune System:

Get protection against infections and other invading organism via several stages called the immune response. Immune system fights with organisms or substances which invade body systems. These system is built up of cells, tissues, and some organs that act together to survive the body and several cells that collectively fight and protect the body from infections such as bacterial, parasitic, fungal, viral and from the growing tumor cells.

The Organs of the Immune System:

Bone Marrow

Stem cells that derived from bone marrow translate into either mature immune cells or into precursors of cells that leave out of the bone marrow to keep their maturation. The bone marrow synthesizes B cells, natural killer cells, granulocytes, immature thymocytes' red blood cells and platelets. 


The function is to synthesize T cells. Immature thymocytes go out of the bone marrow and migrate to the thymus gland and final result is release mature T cells to blood. T cells t are important.


 Immunologic filter of the blood is spleen that composes of B cells, T cells, macrophages, dendritic cells, natural killer cells and red cells. It detects foreign materials such as antigens. Macrophages and dendritic cells passage various antigens to the spleen via circulatory blood. Response is started when the macrophage or dendritic cells bear the antigen to B or T cells. So in the spleen, B cells work actively and produce numerous antibodies. 

Lymph Nodes

The lymph nodes act as an immunologic filter for lymph. Build up with T cells, B cells, dendritic and macrophages. Antigens are separated out of the lymph in the lymph node before entering the lymph to the general circulation. The macrophages and dendritic cells that detect antigens to T and B cells and start response.

The Cells of the Immune System:


T lymphocytes are normally categorized into two major divisions. The T helper division, also called the CD4+ T cell, that coordinator of immune regulation by the secretion of specialized factors that enhance other white blood cells to fight against infections T killer/suppressor or CD8+ T cells are other kind of T cells. These cells directly destroy tumor cells, viral-infected cells and parasites and also help in down-regulation of immune responses. They often depend on the lymph nodes and spleen which give activation site but they are also in other tissues such as liver, lung, blood, and digestive and reproductive system. 

Natural Killer Cells

 Also called NK cells that directly kill tumors such as melanomas, lymphomas, viral-infected cells, herpes and cytomegalovirus-infected cells. Unlike the CD8+ T cells, they destroy their targets without lymphoid organs.

B Cells

  B lymphocytes function is the production of antibodies response to proteins of antigens. Antibodies are proteins that bind to one specialize protein after recognition 


Granulocytes are collection of three cell types recognized as neutrophils, eosinophils and basophils. These cells help to remove bacteria and parasites and engulf foreign bodies and destroy them using their potent enzymes. 


Regulate immune responses. Serve as antigen-presenting cells (APC) because they ingest foreign substances and transmit antigens to other cells such as T and B cells.  

Dendritic Cells

Function as antigen presenting cells (APC). Normally found in the structural compartment of the lymphoid organs (thymus, lymph nodes and spleen, bloodstream and other tissues of the body). They detect antigen or passage it to the lymphoid organs where response is started. Dendritic cells join greater proportion of HIV, and serve as reservoir of virus that is passage to CD4+ T cells during an activity.

Types of immune system:

1) Innate (non-adaptive)

Non adaptive immunity gives first line of immune response and relies on mechanisms that exist before infection.

2) Acquired (adaptive)

Acquired immunity is the Second line of response (if innate fails) and also relies on mechanisms that adapt after infection. It is regulated by T and B lymphocytes.

Impaired immunity in AIDS:

The immune system fighting invaders and give protection against infections and prevents cancer by lowering the body's own damaged or degenerate cells. After HIV infections thousands of millions of helper cells are killed. So 2-3 weeks within infection, the acute HIV infection can occur, which suppressed again after 6 weeks, when the immune system has great duty in the first battle. Kills numerous HIV as are synthesized, keeping equilibrium year upon year. After immune system becomes damaged and the amount of virus readily increases AIDS appear. Final result from HIV makes increasing vulnerable, to infections and cancer. The inability of CD4+ T cells of HIV-1-infected patients to mount an effective immune response is widely believed to explain the increased susceptibility of these patients to opportunistic infections. Reduction of CD4+ T cells and quality of CD4+ T-cell dysfunction independent of T-cell reduction. Many patients with reduced T-cell responses to recall antigens prior to significance CD4+ T-cell depletion, and among the proposed explanations for this phenomenon are gp120-mediated interference with T-cell activation by inhibition of CD4-class II histocompatibility complex (MHC) determinant interactions, gp41-mediated inhibition of protein kinase C-dependent T-cell activation, formation of gp41 cross-reactive antibodies that react with MHC class II determinants, transforming growth factor-beta (TGF-beta)-mediated immunosuppression, and decreased functions of antigen-present and antigen-processing cells HIV-1-infected patients, these T cell defects do not inform the onset of life-threatening situations.Depletion of CD4+ T cells are direct result of HIV-1 infection that occurs because of syncytia formation. The thymus is seriously damaged in patients with late phase of disease and that is why that has the inability of the thymus to synthesize new T cells contributes to T-cell depletion in patients with AIDS. Chronic suppression of virus replication may be achieved with newer anti-HIV drugs or combinations of several drugs.

Diagnosis of HIV infection

Disease can't be diagnosed via a physical examination or via disease symptoms. It is only possible on the determine of the virus or antibodies in blood or body fluid. Usually the presence of antibodies is checked.

The diagnostic window

It takes some time before sufficient amounts of antibodies keep in the blood for the test. This period of infection to proof of infection is referred as the diagnostic window. It dependents on several factors such as transmission track, amount of transferred viruses, and immune system and also vary with person to person. The diagnostic window may be decreased by an average of 3 weeks with the use of virus test or a combination of antigen -antibody tests. Most patients taken time between infection and diagnosis is about 3 months but it may sometime.

diagnostic window

HIV infection and anti-body reaction

The left curve shows the antibodies concentrations against the HIVs in the blood. The right line shows the HIV concentration in the infected blood.

Therapy of Aids:

Antiviral therapy-

Reverse transcriptase inhibitors and the protease inhibitors are the drugs that combat virus.. The reverse transcriptase inhibitors indirectly inhibit viral genome from becoming related in the DNA of host cell, because of drugs block DNA synthesis enzyme reverse transcriptase. The protease inhibitor inhibits protease, an especial enzyme response for synthesizing new viruses. Both lowered amount of virus in the blood and lymph nodes. St

Drugs for Prophylaxis in cases of AIDS-

Prophylaxis is used to preventing opportunistic infections in the disease. It prevents the symptoms and not causes to cure infection. This depends upon stage of disease.


Sexual relationship among two healthy partners and infection do not occur. But danger of infection risk is increased by performing another sexual contact. So faithfulness is one of reducing method of AIDS


Even though AIDS incurable it is recommended to have an HIV.

No unprotected sexual contacts

Only single sexual partner is recommended. Several partners always give greater risk.


Now a days younger generation have not well experience and knowledge about condoms. That is why they face higher risk with these fetal disease

Vaccination against cervical cancer and genital warts-

Recently vaccine is recommended for everyone even though advisable is vaccination against HPV types 6, 11,1 6 and 18 to prevent genital warts and cervical cancer. Girls before starting their sexual behaviors are well advisable for above vaccine.

Vaccination against Hepatitis B-

Medical staff, dialysis patients, intravenous drug addicts or someone staying a long period in a developing country those who have somewhat risk about hepatitis B vaccination against it is advisable.

Response of treatment:  

Measure viral quantity and CD4 counts. This must check commencement of treatment and during every 3 to 6 months. Treatment decline viral amount but doesn't mean risk is gone and just means test is not powerful to detect it.