Which Type Of Cell Does Hiv Infect

What Are The Stages Of Hiv

HIV has three stages:

Stage 1: Acute HIV

Some people get flu-like symptoms a month or two after theyve been infected with HIV. These symptoms often go away within a week to a month.

Stage 2: Chronic stage/clinical latency

After the acute stage, you can have HIV for many years without feeling sick. It’s important to know that you can still spread HIV to others even if you feel well.

Stage 3: AIDS

AIDS is the most serious stage of HIV infection. In this stage, HIV has severely weakened your immune system and opportunistic infections are much more likely to make you sick.

Opportunistic infections are ones that someone with a healthy immune system could typically fight off. When HIV has advanced to AIDS, these illnesses take advantage of your weakened immune system.

Youre more likely to get certain cancers when you have AIDS. These cancers and opportunistic infections together are called AIDS-defining illnesses.

To be diagnosed with AIDS, you must be infected with HIV and have at least one of the following:

• Fewer than 200 CD4 cells per cubic millimeter of blood .
• An AIDS-defining illness.

Whatpart Of The Body Does Hiv Infect

HIV infects our immune system. This is the part of our body that stops us getting sick. HIV infects a type of white blood cell in our immune system called a T-helper cell . These cells keep us healthy by fighting off infections and diseases. However, HIV hides inside these cells, tricking the body so that the immune system canât find and destroy it.

Preventing Transmission By Blood Transfusions And Organ Transplants

In the United States, the following have almost eliminated transmission of HIV infection by organ transplantation or blood transfusion:

• Screening donors of organs or blood for risk factors for HIV infection

• Screening donated blood for HIV

Risk is reduced further by asking people with risk factors for HIV infection, regardless of their test results for HIV, not to donate blood or organs for transplantation.

However, developing countries have not consistently used sensitive HIV screening tests and have not restricted donors. Consequently, transmission by these routes is still a problem in these countries.

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Pathophysiology Of Cd4+ T

• Division of HIV/AIDS, Department of Clinical Research, National Institute for Research in Tuberculosis , Chennai, India

The hall mark of human immunodeficiency virus infection is a gradual loss of CD4+ T-cells and imbalance in CD4+ T-cell homeostasis, with progressive impairment of immunity that leads ultimately to death. HIV infection in humans is caused by two related yet distinct viruses: HIV-1 and HIV-2. HIV-2 is typically less virulent than HIV-1 and permits the host to mount a more effective and sustained T-cell immunity. Although both infections manifest the same clinical spectrum, the much lower rate of CD4+ T-cell decline and slower progression of disease in HIV-2 infected individuals have grabbed the attention of several researchers. Here, we review the most recent findings on the differential rate of decline of CD4+ T-cell in HIV-1 and HIV-2 infections and provide plausible reasons for the observed differences between the two groups.

Donor Testing And Significance

In Germany, both HIV antibody and HIV NAT testing are mandatory.

2.3.1 HIV Antibody Testing

Initial testing of a donation is carried out with antibody screening test systems approved in Europe according to the German Medicinal Products Act in connection with the In Vitro Diagnostics Directive . Tests used in Germany recognise antibodies to all known HIV-1 groups and HIV-2. Reactive screening test results must be followed by a serologic confirmation test or a NAT assay. An additional second blood sample has to be investigated for confirmation of an HIV infection . Until the results are clarified, the donation is separated and should be preserved for additional investigations. The donor is deferred until the final results are available . According to current knowledge, the vast majority of reactive HIV antibody screening test results of blood donors are non-specific, i.e. false-positive, and have other causes, e.g., immune complexes in the specimen .

2.3.2 Detecting HIV RNA by NAT

The diagnostic window period, which is between 3 and 6 weeks for antibody screening tests, can be shortened by application of NAT. Depending on the level of viraemia, the sensitivity of the assay used and the infecting HIV, an infection can be detected as early as about 11 days post infection . The HIV NAT enables sensitive detection also of non-HIV-1 M:B. Reference materials for the detection of different HIV-1 genotypes are available .

Cost-Benefit Calculation

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Contributors To Cd4+ T

CD4+ T-cells are known to be the central facilitators for both cellular and humoral immune responses against exogenous antigens and are kept constant in the human body by homeostatic mechanisms .HIV binds to the CD4 molecule on the surface of helper T-cells and replicates within them. This results in destruction of CD4+ T-cells and leads to a steady decline in this population of T-cells. The definition of progressive and slow loss of CD4+ T-cells is not clear. In order to understand the correlation between CD4+ T-cell depletion and immunopathogenesis, and its relationship with disease progression, a number of dynamic models have been put forward. Two of the most acknowledged mechanisms are discussed in detail in this review. These include direct virus attack leading to cytolytic effect and chronic immune activation resulting in apoptosis.

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:

• A CD4+ cell count of less than 200 cells per microliter of blood.
• A certain kind of infection called an opportunistic infection that is common in people who have weakened immune systems, such as Kaposi’s sarcoma or Pneumocystispneumonia.

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Severity And Course Of The Disease

The course of an HIV infection is always chronic, ending fatally without antiretroviral therapy. CD4 cell disintegration and clinical symptoms can be decelerated or suppressed by antiretroviral therapy for decades . In untreated HIV-1 infections, AIDS-defining symptoms appear after a mean of about 10 years, with a range of 2-25 years. HIV-2-induced AIDS becomes apparent after a mean of approximately 15 years . With antiviral therapy it is possible to extend the phase without or with only slight symptoms for many years .

The Intersection Of Viral Fitness And Immune Control

Although most of the focus on immune control and lack of control has been on CD8+ T-cell function and differential induction of negative immunoregulatory molecules, an increasing body of data suggests that immune-mediated mutations within CD8+ T-cell epitopes lead to reduced viral fitness. These data include assays in which replication of virus containing a B57-selected mutation is out-competed by wild-type virus , evidence of reduced viral fitness in Gag-PR in persons who control virus spontaneously , and evidence of compensatory mutations leading to restoration of fitness . Importantly, mutations in Env do not lead to reduced fitness, suggesting that structural constraints are likely key to this effect . More recent studies have shed further light on this, by demonstrating that there are multidimensional constraints on HIV evolution because certain combinations of mutations must occur in a coordinated manner to maintain virus viability, and thus constrain immune escape pathways . Persons who spontaneously control HIV without medications preferentially target sites that are most constrained, providing further evidence that the specific sites targeted by the immune system may have a major impact on overall control .

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Hivs Affect On Receptor Usage

To speculate as to why HIVs have evolved plasticity in their interactions with co-receptors is important. The ability to use multiple functionally redundant contacts with co-receptors could conceivably facilitate immunological escape.5460 Thus, in the face of a neutralising antibody response , the selection of variants with altered envelope sequences would be permitted without compromising the ability of the virus to use a given co-receptor.39 Furthermore, changes in envelope sequence, that enable the virus to use additional co-receptors while retaining the ability to interact with CCR-5, could be tolerated. It appears that dual-tropic strains that use both CCR-5 and CXCR-4 are less tolerant of perturbations in CCR-5 sequence than are M-tropic strains,66,67 suggesting that acquisition of the ability to utilise CXCR-4 might involve the sacrifice of a degree of functional redundancy and/or affinity in the envelope/CCR-5 interaction.39

Home Test Kits For Hiv

A home test kit for HIV has been approved by the U.S. Food and Drug Administration . For the test, you rub your gums with a swab supplied by the kit. Then you place the swab into a vial of liquid. The test strip on the swab indicates if you have HIV or not.

Another type of test kit for HIV is a home blood test kit. This type of kit provides instructions and materials for collecting a small blood sample by sticking your finger with a lancet. The blood is placed onto a special card that is then sent to a lab for analysis. You get the results over the phone using an anonymous code number. Counseling is also available over the phone for people who use the test kit.

If the results from a home test kit show that you have an HIV infection, talk with a doctor.

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Frequency Of Administration Type And Amount Of Blood Products

Blood components: Since 2004 only 2 HIV transmissions through blood components have been reported in Germany . HIV is transmitted if 1 HID is present in the administered blood component . There is evidence that immediate initiation of HIV post exposure prophylaxis can prevent an infection after needle stick injury in individual cases .

Plasma derivatives: Transmission of HIV by plasma derivatives occurred between 1979 and 1989 primarily via factor VIII, factor IX and prothrombin complex concentrates . HIV has never been transmitted via albumin, antithrombin III and i.m. or i.v. immunoglobulin preparations, not even before the introduction of specific process steps for the depletion and inactivation of viruses. The implementation of donor selection, antibody screening and inactivation procedures has made a transmission of enveloped viruses no longer possible.

Does Hiv Go Away

HIV doesnt go away on its own. It inserts itself into your DNA so your cells think that its a part of you. There can be many years without symptoms after initial infection, but HIV can still be damaging your immune system even if you dont feel sick.

There may be periods while on medication where the virus is not detectable by an HIV test. In these cases, HIV can be hiding in your body, undetected. It can wake up and start destroying your cells again in the future.

This is why continuing to take HIV medication, even if you dont feel sick or the virus is undetectable, is extremely important. Without treatment, HIV will weaken your immune system until you cant fight off other serious illnesses.

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Prevalence And Incidence Of Blood

Prior to the introduction of compulsory testing for HIV antibodies in May and October 1985, about 1,380 haemophiliacs and about 200 transfusion recipients were infected in Germany with HIV by blood donations and plasma derivatives . With the introduction of antibody screening tests and obligatory virus inactivation procedures in the production process of plasma derivatives, the number of HIV and hepatitis virus infections by transfusion declined significantly, especially in the first 2 years. Since 2004, HIV antibody testing and HIV NAT further reduced the potential HIV burden of the source material . Since 1990/1991 no HIV infections have been transmitted by plasma derivatives .

According to reports to the Paul Ehrlich Institute, 2 HIV transmissions by cellular blood components have occurred after the introduction of NAT screening in 2004 . Both transmissions were due to very recent infections and a failure of the NAT systems used. In the case of 2007, presumably a low viral load and mutations in the primer binding region were responsible for the false-negative test results . Regarding the transmission reported in 2009, the HIV-positive donor sample was repeatedly tested negative with the NAT system used .

As recommended for HIV-infected donors, plasma and lymphocytes of the HIV-infected recipient should also be stored in order to possibly clarify the origin of infection and the transmission using molecular methods .

Screening And Diagnostic Tests

If doctors suspect exposure to HIV infection, they do a screening test for HIV. Doctors also recommend that all adults and adolescents, particularly pregnant women, have a screening test regardless of what their risk appears to be. Anyone who is concerned about being infected with HIV can request to be tested. Such testing is confidential and often free of charge.

The current combination screening test tests for two things that suggest HIV infection:

Antibodies are proteins produced by the immune system to help defend the body against a particular attack, such as that by HIV. Antigens are foreign substances that can trigger an immune response.

The body takes several weeks to produce enough antibodies to be detected by the test, so results of the antibody test are negative during the first few weeks after the virus enters the body . However, results of the p24 antigen test can be positive as early as 2 weeks after the initial infection. The combination tests can be done quickly by a laboratory. Also, a version of these tests can be done in a doctor’s office or clinic . If results are positive, doctors do a test to distinguish HIV-1 from HIV-2 and a test to detect the amount of HIV RNA in the blood .

The newer combination screening test is quicker and less complex than older screening tests, which use enzyme-linked immunosorbent assay to detect HIV antibodies and then confirm positive results using a separate, more accurate, specific test such as the Western blot test.

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Where Does Virus Entry Occur

The entry of viruses into cells is controlled in both time and space, with these parameters being regulated by host cell factors that serve to unlock the membrane fusion potential of viral membrane proteins. Many viruses require delivery by the host cell into an acidic, intracellular compartment where low pH triggers membrane-fusion-inducing conformational changes . HIV entry does not require low pH instead it is triggered by receptor engagement . The fact that HIV does not require low pH for cellular entry does not imply that fusion occurs at the cell surface. In fact, no spatial information is provided by the triggering mechanism. Despite this, it was often assumed that HIV fuses at the cell surface owing to several observations . First, Env expression on the cell surface can mediate cell-to-cell fusion, indicating not only that Env is the only viral membrane protein needed to elicit fusion but that low pH is clearly not required. Second, very early studies on HIV entry showed that lysomotropic agents, which increase endosomal pH, do not inhibit HIV infection . Third, inhibiting endocytosis of CD4 in cell lines by mutating its cytoplasmic domain does not affect HIV infection . Together, these studies show that HIV entry is not pH dependent, but they provide no definitive information as to whether fusion occurs at the cell surface or from within endocytic vesicles, albeit in a pH-independent fashion.

How Can I Take Care Of Myself While Living With Hiv

It’s very important to take your medications as prescribed and to make sure you dont miss appointments. This is called treatment adherence.

If you miss medications, even by accident, HIV can change how it infects your cells , potentially causing your medications to stop working. If your schedule prevents you from taking medications on time or making it to appointments, talk to your healthcare provider.

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Distinguishing Features Of Cd4+ T

One of the best ways of elucidating the intriguing nature of immunopathogenesis of HIV infection is studying naturally occurring HIV infection with different clinical outcomes. HIV-2 infection provides an ideal situation for this investigation as it has a lower degree of pathogenicity as compared to HIV-1. Although HIV-2 also eventually causes immunodeficiency syndrome indistinguishable from HIV-1-induced AIDS , many HIV-2-infected individuals do not develop immunodeficiency during their lifetime and retain stable CD4+ T lymphocyte counts and low levels of viremia for many years . This striking difference has prompted the search for the reason for variations in T-cell homeostasis and imbalances in cytokine production and identification of factors that contribute to an effective immune response that delays progression of disease during infection.

What Questions Should I Ask My Doctor

• Am I at high risk for HIV?
• What can I do to reduce my risk of HIV?
• How can I make sure I take my medications correctly?
• What can I do to protect myself from other illnesses?
• How can prevent the spread of HIV?
• What do my test results mean?
• What do my blood counts mean?
• What vaccinations should I get?

A note from Cleveland Clinic

Treatments have come a long way since the height of the AIDS epidemic. You have the best chance of living a long life if youre diagnosed early and are able to get on and stick with ART medications. People living with HIV today are able to work, have active social lives and families, and pursue fulfilling relationships. In fact, this can have a positive impact on your well-being.

While weve come a long way with treatments, unfortunately, social stigmas around HIV still persist. In addition to the feelings of fear and uncertainty a new diagnosis can bring, you may wonder how those around you will respond. If youre hesitant to get tested or get treatment, or if you just arent sure what your next steps are, you can reach out to a community organization that specializes in HIV. Remember that you are deserving of support, compassion and high-quality healthcare.

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