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How Does Hiv Infect The Body

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Interval Of Mild Or No Symptoms

How HIV infects us: Mucous membranes, dendritic cells, and lymph nodes | Khan Academy

After the first symptoms disappear, most people, even without treatment, have no symptoms or only occasionally have a few mild symptoms. This interval of few or no symptoms may last from 2 to 15 years. The symptoms that most commonly occur during this interval include the following:

  • Swollen lymph nodes, felt as small, painless lumps in the neck, under the arms, or in the groin

  • White patches in the mouth due to candidiasis

Some people progressively lose weight and have a mild fever or diarrhea.

These symptoms may result from HIV infection or from opportunistic infections that develop because HIV has weakened the immune system.

How Is Hiv Transmitted

Unprotected sexual intercourse with infected people poses the single most important risk of infection. HIV can also be passed from one partner into the bloodstream of the other through tiny cuts or scratches.

Intravenous drug abusers may contract HIV if they share needles with infected people. Hemophiliacs requiring frequent transfusions or blood products are at risk due to the possibility of receiving contaminated blood. Since 1985, Canada’s Red Cross has been screening all blood donations for HIV antibodies.

If an individual is struck with a HIV-contaminated needle or sharp object can also pose an opportunity for transmission. Health care workers are at high risk for this type of exposure.

HIV can be transmitted from an infected mother to her unborn child before or during birth, or through breastfeeding. Studies indicate infection takes place across the placenta. Therefore, a Cesarean section delivery does not prevent the transmission of HIV from an infected mother to her infant.

Some reports indicate that HIV can be transmitted through heart, pancreas, kidney, liver and bone transplants, and by artificial insemination. All organs are screened for HIV antibodies before transplantation.

Some studies show HIV transmission did not occur after bites from patients infected with the HIV unless the skin is broken. This fact suggests that transmission of HIV through contact with saliva alone is unlikely.

Hiv Invasion Of Immune Cells

HIV infects T cells via high-affinity interaction between the virion envelope glycoprotein and the CD4 molecule. The infection of T cells is assisted by the T-cell co-receptor called CXCR4 while HIV infects monocytes by interacting with CCR5 co-receptor . As illustrated in Figure 2, after gp120 binds to CD4 on the T cell . Nucleocapsids containing viral genome and enzymes enters the target cell . Following the release of viral genome and enzymes from the core protein, viral reverse transcriptase catalyses reverse transcription of ssRNA to form RNA-DNA hybrids . To yield HIV dsDNA the viral RNA template is partially degraded by ribonuclease H and the second DNA strand is synthesized . The viral dsDNA is translocated into the nucleus and integrated into the host genome by the viral integrase enzyme . Transcription factors transcribe the proviral DNA into genomic ssRNA , which is exported to cytoplasm . In the cytoplasm, host-cell ribosomes catalyse synthesis of viral precursor proteins . The viral precursor proteins are cleaved into viral proteins by viral proteases . HIV ssRNA and proteins assemble beneath the host-cell plasma membrane forming virion buds from it . Maturation occurs either in the forming buds or after budding from the host cell . During maturation, HIV proteases cleave the poly-proteins into individual functional HIV proteins. The mature virions are able to infect another host cell.

Figure 1. Figure 2.

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Ways Hiv Is Not Transmitted

How well does HIV survive outside the body?

HIV does not survive long outside the human body , and it cannot reproduce outside a human host. It is not transmitted

  • Through saliva, tears, or sweat.
  • Through other sexual activities that dont involve the exchange of body fluids .
  • Through the air.

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Symptoms Of Hiv/aids And Stages

The science of HIV and AIDS

Many people donât have symptoms at first, and sometimes even for years or decades. But there are signs that can happen, such as flu-like symptoms soon after you become infected with HIV. Even if you donât feel sick, HIV damages the immune system. It hijacks infection-fighting white blood cells called CD4 cells and uses them to churn out thousands of copies of itself. Without treatment, HIV destroys so many of these cells that your body canât protect you from life-threatening infections. If your CD4 count drops below 200, you have AIDS.

There are three stages of HIV infection:

Stage 1: This the earliest stage. You may also hear it called the âacuteâ stage. You might have a fever, rash, fatigue, chills, and other flu-like symptoms. But you might not have any symptoms. If you do, they may start 2-4 weeks after youâre infected. During this time, the virus quickly makes many copies of itself.

Stage 2: During this stage, HIV continues to reproduce, and it slowly damages your immune system over time. You might not feel sick or have symptoms. But HIV isnât gone, and you can still spread it to other people. This stage can last for years or even decades.

Stage 3: This is when you have AIDS. Your immune system has been severely damaged, leaving you vulnerable to other illnesses. With AIDS, many people have symptoms such as chills, fever, sweats, swollen lymph glands, weakness, and weight loss.

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Hiv Effects On The Immune System

Your immune system has many types of white blood cells that fight infection. HIV gets inside a kind called CD4 cells and makes copies of itself. The virus kills the cell, and the new viruses go off to find more.

Your body responds by making more CD4 cells, but after a while, it canât keep up with the virus. This makes your immune system weak. Youâre more likely to get sick, even from common germs. Infections last longer, are more severe, and might come back more often.

If you follow your doctorâs directions with ART, it knocks out HIV, stopping it from infecting more CD4 cells and from weakening your immune system.

How Is Hiv Diagnosed

A doctor may suspect HIV if symptoms last and no other cause can be found.

If you have been exposed to HIV, your immune system will make antibodies to try to destroy the virus. Doctors use tests to find these HIV antibodies or antigens in urine, saliva, or blood.

If a test on urine or saliva shows that you are infected with HIV, you will probably have a blood test to confirm the results.

Most doctors use a blood test to diagnose HIV infection. If the test is positive , a test to detect HIV DNA or RNA will be done to be sure.

HIV antibodies or antigens usually show up in the blood within 3 months. If you think you have been exposed to HIV but you test negative for it:

  • Get tested again. A repeat test may be done after a few weeks to be sure you are not infected.
  • Meanwhile, take steps to prevent the spread of the virus, in case you do have it.

You can get HIV testing in most doctors’ offices, public health clinics, hospitals, and Planned Parenthood clinics. You can also buy a home HIV test kit in a drugstore or by mail order. Make sure it’s one that is approved by the Food and Drug Administration . If a home test is positive, see a doctor to have the result confirmed and to find out what to do next.

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Hiv Effects On The Digestive System

More than half of people who have AIDS report digestive symptoms as the virus or an opportunistic infection targets the walls of their intestines. Diarrhea is the most common one. Over time, the virus can change how your digestive tract works and even how it looks.

Liver

Some HIV medications can damage your liver. Many people with HIV also have a form of inflammation called hepatitis.

Limit how much alcohol you drink, and don’t use recreational drugs. Having diabetes, high cholesterol, or triglycerides and being overweight can lead to fatty liver disease, so keep an eye on the carbs, fats, and calories you eat each day.

Talk to your doctor about getting the hepatitis A and hepatitis B vaccines. Thereâs no vaccine against hepatitis C, but you should get tested for it.

Get regular blood tests to catch any liver problems early.

Mouth

Your mouth might be one of the first places where you notice signs of HIV. Things like dry mouth, fungal infections, gum disease, cold sores, and canker sores can make chewing or swallowing painful. If they go on too long, you might not be able to take your HIV medication or get the nutrients you need.

Good dental habits can help prevent these issues, so brush and floss regularly. See your dentist for checkups, and tell them if youâre having problems. Most mouth conditions tied to HIV are treatable.

Cytopathic Effects Produced By In Vitro Infection With Hivs

Immunology wars: The battle with HIV

The molecular mechanism by which HIV induces cytopathology in susceptible cells is not well understood. In vitro HIV infected cells formed multinucleated giant cells that can produce large amounts of virus before they die, within a period of a few days, normally within 48 hours.81 Syncytia formation in culture results from fusion of infected cells with uninfected CD4+ cells82 and involves the CD4 molecule and HIV gp120 and gp41 proteins.83,84 Although the precise mechanism is still not known, syncytia formation is linked to the V3 loop of gp120 envelope region.85,86 Thus, the differences in the amino acids sequences of the V3 loop determine SI versus NSI isolates and whether an HIV isolate will induce syncytia formation or not. T cell tropic viruses generally have a basic amino acid at one or more of the positions 11, 24, 25 and 32 of the V3 loop, whereas macrophage tropic viruses have either an acidic amino acid or alanine at position 25.

Generally syncytia formation is the most common event preceding cell death in vitro. There is some evidence that syncytia can occur in vivo and syncytia have been observed in the lymph nodes of homosexual men with lymphadenopathy, in lymph nodes and lungs of children with AIDS and in brain tissues of some adult patients who died with AIDS and is therefore possibly important in the pathogenesis of AIDS.87

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Can You Get Hiv From A Blood Transfusion

Receiving a blood transfusion or other products made from blood is safe in the UK as all blood products have been screened for infections such as HIV since 1985.

In countries that dont have strict checks on the safety of their blood supply, receiving contaminated blood can pass the virus on. This can also happen in countries that dont screen other blood products, organs or sperm.

Giving blood has never been a risk.

Simplified Life Cycle Of The Human Immunodeficiency Virus

Like all viruses, human immunodeficiency virus reproduces using the genetic machinery of the cell it infects, usually a CD4+ lymphocyte.

  • HIV first attaches to and penetrates its target cell.

  • HIV releases RNA, the genetic code of the virus, into the cell. For the virus to replicate, its RNA must be converted to DNA. The RNA is converted by an enzyme called reverse transcriptase . HIV mutates easily at this point because reverse transcriptase is prone to errors during the conversion of viral RNA to DNA.

  • The viral DNA enters the cells nucleus.

  • With the help of an enzyme called integrase , the viral DNA becomes integrated with the cells DNA.

  • The DNA of the infected cell now produces viral RNA as well as proteins that are needed to assemble a new HIV.

  • A new virus is assembled from RNA and short pieces of protein.

  • The virus pushes through the membrane of the cell, wrapping itself in a fragment of the cell membrane and pinching off from the infected cell.

  • To be able to infect other cells, the budded virus must mature. It becomes mature when another HIV enzyme cuts structural proteins in the virus, causing them to rearrange.

Drugs used to treat HIV infection were developed based on the life cycle of HIV. These drugs inhibit the three enzymes that the virus uses to replicate or to attach to and enter cells.

HIV also infects other cells, such as cells in the skin, brain, genital tract, heart, and kidneys, causing disease in those organs.

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How Is Aids Diagnosed

AIDS is the last and most severe stage of HIV infection. It is diagnosed if the results of your test show that you have:

Stages Of Hiv Infection

The science of HIV and AIDS

About a month after you get HIV, you might feel like you have the flu. This is the first stage, called primary or acute HIV infection. Symptoms include:

  • Swollen lymph nodes

The next stage is called clinical latency, or chronic infection. You might have no symptoms, or only mild ones, for 10 years or more.

Without treatment, as HIV keeps multiplying inside your body, youâll move into the third stage, which is AIDS. A person who has HIV is diagnosed with AIDS when they have fewer than 200 CD4 cells per cubic millimeter of blood or when they get whatâs called an AIDS-defining condition.

AIDS-defining conditions are certain cancers and illnesses called opportunistic infections.

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How Is Hiv Not Spread

HIV is not spread by:

  • Mosquitoes, ticks, or other insects
  • Saliva, tears, sweat, feces, or urine that is not mixed with the blood of a person with HIV
  • Shaking hands hugging sharing toilets sharing dishes, silverware, or drinking glasses or engaging in closed-mouth or social kissing with a person with HIV
  • Drinking fountains
  • Other sexual activities that dont involve the exchange of body fluids .

Preventive Treatment After Exposure

People who have been exposed to HIV from a blood splash, needlestick, or sexual contact may reduce the chance of infection by taking antiretroviral drugs for 4 weeks. These drugs are more effective when they are started as soon as possible after the exposure. Taking two or more drugs is currently recommended.

Doctors and the person who was exposed typically decide together whether to use these preventive drugs. They base the decision on the estimated risk of infection and the possible side effects of the drugs. If they do not know whether the source is infected with HIV, they consider how likely the source is to be infected. However, even when the source of the exposure is known to be infected with HIV, the risk of infection after exposure varies, depending on the type of exposure. For example, risk from a blood splash is less than that from a needlestick.

Immediately after exposure to HIV infection, what is done depends on the type of exposure:

  • If skin is exposed, it is cleaned with soap and water.

  • Puncture wounds are cleaned with antiseptic.

  • If mucous membranes are exposed, they are flushed with large amounts of water.

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Treatment To Prevent Hiv Infection

Health care workers who are at risk for HIV because of an accidental needlestick or other exposure to body fluids should get medicine to prevent infection.footnote 11

Also, medicine may prevent HIV infection in a person who has been raped or was accidentally exposed to the body fluids of a person who may have HIV.footnote 12 This type of treatment is usually started within 72 hours of the exposure.

And studies have shown that if you are not infected with HIV, taking antiretroviral medicines can protect you against HIV.footnote 13, footnote 14, footnote 15 But to keep your risk low, you still need to use safer sex practices.

Adaptive Immune Response To Hiv

How HIV infects us: CD4 (T-helper) lymphocyte infection | NCLEX-RN | Khan Academy

Cellular immune response to HIV. The cellular immune response is induced upon the entry of HIV into the target cells and synthesis of viral proteins . MHC class I on the cell surface displays the intracellularly degraded HIV peptide fragments for recognition by T-cell receptors on CD8+ T cells . CD8+ T cells lyse HIV infected cells and secrete cytokines, i.e. interferon- , tumor necrosis factor , and chemokines, i.e. MIP-1 , MIP and RANTES, that inhibit virus replication and block viral entry into CD4+ T cells. Development of CD8+ T cells is crucial for control of HIV replication. This results in declining viraemia after primary infection. In the early stages of infection, CD4+ T cells lose their proliferative capacity and therefore their contribution to viral control is minor. However, during chronic infection CD4+T cells are present and secrete interleukin-2 or cytokines, such as IFN-, to control viraemia.

Figure 3.

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What Is The Treatment For Hiv

Individuals who are HIV positive will likely need to see a specialist. As with many other conditions, early detection offers more options for treatment. Today, there are medical treatments that can slow down the rate at which HIV weakens the immune system. However, there are other treatments that can prevent or cure the conditions associated with HIV. Anti-retroviral drug therapy may be given to a pregnant woman, which has proven to greatly reduce the chance of an infant developing HIV. A cesarean section may be recommended to reduce infant transmission from the birth canal. In the U.S., where other feeding options are available, an infected mother should be discouraged from breastfeeding her infant. Consult your child’s doctor for more information regarding various drug therapies.

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