Is There A Vaccine For Hiv
Currently, there are no vaccines to prevent or treat HIV. Research and testing on experimental vaccines are ongoing, but none are close to being approved for general use.
HIV is a complicated virus. It mutates rapidly and is often able to fend off immune system responses. Only a small number of people who have HIV develop broadly neutralizing antibodies, the kind of antibodies that can respond to a range of HIV strains.
The first HIV vaccine efficacy study in 7 years was underway in South Africa in 2016. The experimental vaccine is an updated version of one used in a 2009 trial that took place in Thailand.
A 3.5-year follow-up after vaccination showed the vaccine was 31.2 percent effective in preventing HIV transmission.
The study involves 5,400 men and women from South Africa. In 2016 in South Africa, about contracted HIV. The results of the study are expected in 2021.
Other late-stage, multinational vaccine clinical trials are also currently underway.
Other research into an HIV vaccine is also ongoing.
While theres still no vaccine to prevent HIV, people with HIV can benefit from other vaccines to prevent HIV-related illnesses. Here are the CDC recommendations:
Virology Of Human Immunodeficiency Virus
The human immunodeficiency viruses 1 and 2 originated from the simian immunodeficiency viruses of primates. Thus, HIV-1 and HIV-2 each had a zoonotic origin but now spread directly from human to human. HIV-1 was first isolated in 1983 and HIV-2 in 1986 and they represent two different epidemics. The SIV of chimpanzees gave rise to HIV-1 in humans, and the SIV of the sooty mangabey monkey to HIV-2 in humans. It is still uncertain exactly how the transmission of these SIVs to humans occurred, but it may have been during the hunting and preparation of these primates for food, by the indigenous people of these areas in Central and Western Africa, where these primate species live. Studies using molecular clock evolutionary assumptions have suggested that the ancestor virus for HIV-1 appeared in around 1931 and that of HIV-2 in around 1940. After this initial transmission event, it is likely individuals infected with these primate SIVs then transmitted the human form of the viruses to other people in their communities, from where it spread, world-wide.
Mechanism Of Hiv Infection
Once in the body, HIV attaches to several types of white blood cells. The most important are certain helper T lymphocytes involves white blood cells that travel through the bloodstream and into tissues, searching for and attacking microorganisms and… read more ). Helper T lymphocytes activate and coordinate other cells of the immune system. On their surface, these lymphocytes have a receptor called CD4, which enables HIV to attach to them. Thus, these helper lymphocytes are designated as CD4+.
). Once inside a CD4+ lymphocyte, the virus uses an enzyme called reverse transcriptase to make a copy of its RNA, but the copy is made as deoxyribonucleic acid that contain the code for a specific protein that functions in one or more types of cells in the body. Chromosomes are structures within cells… read more ). HIV mutates easily at this point because reverse transcriptase is prone to making errors during the conversion of HIV RNA to DNA. These mutations make HIV more difficult to control because the many mutations increase the chance of producing HIV that can resist attacks by the persons immune system and/or antiretroviral drugs.
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Problems With Resistance Testing
Resistance tests are not available everywhere. They are expensive. However, they are becoming more common, faster and cheaper.
The tests arent good at detecting “minority” mutations Also, they work better when the viral load is higher. If your viral load is very low, the tests might not work. Tests usually cannot be run if the patients viral load is less than 500 to 1,000 copies per ml.
Test results can be difficult to understand. Drugs that should work according to the tests sometimes dont work, and vice versa. Sometimes genotypic and phenotypic tests give conflicting results for the same patient. Some mutations can “reverse” or reduce resistance to some medications.
Recent research suggests that a genotypic resistance test should be done for every patient before they start taking ARVs. This saves money by avoiding putting someone on ARVs that will not work for them.
Cancers Common In People With Hiv Infection
Kaposi sarcoma Kaposi Sarcoma Kaposi sarcoma is a skin cancer that causes multiple flat pink, red, or purple patches or bumps on the skin. It is caused by human herpesvirus type 8 infection. One or a few spots may appear… read more , a cancer caused by a sexually transmitted herpesvirus, appears as painless, red to purple, raised patches on the skin. It occurs mainly in men who have sex with men.
Cancers of the immune system . Often, lymph nodes in the neck, under the arms, or in the groin enlarge rapidly and painlessly… read more ) may develop, sometimes first appearing in the brain. When the brain is affected, these cancers can cause weakness of an arm or a leg, headache, confusion, or personality changes.
Having AIDS increases the risk of other cancers. They include cancer of the cervix, anus, testes, and lungs as well as melanoma and other skin cancers. Men who have sex with men are prone to developing cancer of the rectum due to the same human papillomaviruses Human Papillomavirus Infection Human papillomavirus causes warts. Some types of HPV cause skin warts, and other types cause genital warts . Infection with some HPV… read more that cause cancer of the cervix in women.
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Adaptive Immune Response To Hiv
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.
Can Hiv/aids Be Prevented
You can reduce the risk of spreading HIV by
- Getting tested for HIV
- Choosing less risky sexual behaviors. This includes limiting the number of sexual partners you have and using latex condoms every time you have sex. If your or your partner is allergic to latex, you can use polyurethane condoms.
- Getting tested and treated for sexually transmitted diseases
- Not injecting drugs
- Talking to your health care provider about medicines to prevent HIV:
- PrEP is for people who don’t already have HIV but are at very high risk of getting it. PrEP is daily medicine that can reduce this risk.
- PEP is for people who have possibly been exposed to HIV. It is only for emergency situations. PEP must be started within 72 hours after a possible exposure to HIV.
NIH: National Institutes of Health
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Associated Types Of Cancer
Kaposis sarcoma herpesvirus, also known as human herpesvirus 8, causes a type of cancer that involves the growth of abnormal blood vessels. These can develop anywhere in the body. The cancer is called Kaposis sarcoma, and if it reaches organs such as the intestines or lymph nodes, it can be extremely dangerous. On the skin, a doctor may recognize characteristic solid, purple or pink spots, which may be flat or raised.
In addition, Hodgkin and non-Hodgkin lymphoma have strong links to HIV infection. These affect the lymph nodes and lymphoid tissues.
Also, a female with HIV should recieve regular checks for cervical cancer. Receiving an early diagnosis can help limit the cancers spread.
Diagnosis Of Hiv Infection
Tests to detect antibodies to the HIV virus in a sample of blood or saliva
Tests to detect HIV RNA in a sample of blood
Early diagnosis of HIV infection is important because it makes early treatment possible. Early treatment enables infected people to live longer, be healthier, and be less likely to transmit HIV to other people.
Doctors usually ask about risk factors for HIV infection Transmission of HIV Infection Human immunodeficiency virus infection is a viral infection that progressively destroys certain white blood cells and can cause acquired immunodeficiency syndrome . HIV is transmitted… read more and about symptoms .
Doctors also do a complete physical examination to check for signs of opportunistic infections, such as swollen lymph nodes and white patches inside the mouth , and for signs of Kaposi sarcoma of the skin or mouth.
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Which Blood Type Is More Resistant To Hiv
Some people are genetically at greater risk of HIV infection than others.
The first genetic mutation associated with HIV susceptibility was identified in the mid-1990s.
Known as the CCR5-Delta32mutation, it seems to confer strong resistance to infection by HIV.
This gene mutation is found most commonly in certain European populations.
That is possible because it was also associated with resistance to other diseases such as smallpox or the Bubonic Plague.
In early 2009, a paper was published announcing that another genetic mutation may also confer some level of resistance to HIV.
This mutation affects the level of expression of a protein known as Pk. Pk is found on the surface of several types of blood cells.
In particular, its found on a wide range of cells that are susceptible to HIV infection.
This small study found that cells with high levels of Pk were significantly harder to infect with HIV than cells with no Pk.
The same scientists have also published a study showing that individuals with a condition that increases their levels of Pk seem to be resistant to one type of HIV.
Interestingly, this genetic resistance has played an important role in functional cure research.
The case of the Berlin patient involved a man who was given bone marrow cells from someone with the CCR5 mutation.
Combined with antiretroviral treatment, this therapy seems to have eradicated the virus from his system.
Virus even seemed to have been eradicated from his viral reservoir.
Emergency Hiv Pills: Pep
72 hours should speak with a healthcare provider about PEP. This medication may be able to stop the infection, especially if a person takes it as soon as possible after the potential exposure.
A person takes PEP for 28 days, and a doctor monitors the person for HIV afterward. PEP is not 100% effective, so it is important to use prevention techniques, such as barrier protection and safe injection practices, including while taking PEP.
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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.
Hiv Natural History And Immunopathogenesis
The pathology of HIV infection can be generally characterised by declining peripheral blood CD4 lymphocyte counts, wasting disease and neurological disease. This latter feature of the AIDS syndrome is related to infection of macrophages and microglia. In primary HIV infection, only about 50% of infected individuals are symptomatic with fever and lymphadenopathy. After seroconversion , there follows an asymptomatic period of 2-15 years. During this period, viral replication is continuing at a high rate of up to 1010 infectious virions/day, leading to approximately 108-109 lymphocytes/day being infected, which are replaced almost as quickly. It is therefore remarkable that the rate of CD4 lymphocyte depletion is not more rapid than observed. This rapid turnover of HIV and its enormous diversity underlie the difficulty in producing antiretroviral drugs with long-term efficacy, and is one of many problems facing the development of an effective vaccine against HIV.
Depletion of HIV-infected lymphocytes occurs through several mechanisms, viz: direct cytopathic effect of HIV, including the formation of syncytia by SI X4 HIV lymphotropic strains, immune destruction of HIV-infected cells by cytotoxic CD8 T lymphocytes that recognise HIV antigens presented on major histocompatibility complex molecules, apoptosis due to lymphocyte activation in the presence of specific cytokines.
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What Are The Symptoms Of Hiv/aids
The first signs of HIV infection may be flu-like symptoms:
- Swollen lymph nodes
- Mouth ulcers
These symptoms may come and go within two to four weeks. This stage is called acute HIV infection.
If the infection is not treated, it becomes chronic HIV infection. Often, there are no symptoms during this stage. If it is not treated, eventually the virus will weaken your body’s immune system. Then the infection will progress to AIDS. This is the late stage of HIV infection. With AIDS, your immune system is badly damaged. You can get more and more severe infections. These are known as opportunistic infections .
Some people may not feel sick during the earlier stages of HIV infection. So the only way to know for sure whether you have HIV is to get tested.
Treatment Options For Hiv
Treatment should begin as soon as possible after a diagnosis of HIV, regardless of viral load.
The main treatment for HIV is antiretroviral therapy, a combination of daily medications that stop the virus from reproducing. This helps protect CD4 cells, keeping the immune system strong enough to take measures against disease.
Antiretroviral therapy helps keep HIV from progressing to AIDS. It also helps reduce the risk of transmitting HIV to others.
When treatment is effective, the viral load will be undetectable. The person still has HIV, but the virus is not visible in test results.
However, the virus is still in the body. And if that person stops taking antiretroviral therapy, the viral load will increase again, and the HIV can again start attacking CD4 cells.
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A Note About Treatment
While theres currently no cure for HIV, treatments have come an incredibly long way since the virus was first identified. Due to advances in treatment, people living with HIV can have long, healthy lives.
There are now many types of antiretroviral drugs available to treat HIV. According to the National Institutes of Health , taking antiretroviral medications each day as directed can reduce viral load to undetectable levels in 6 months or less .
Not only can having an undetectable viral load keep the immune system healthy, but it can also prevent transmission of HIV to others. People with an undetectable viral load have no risk of transmitting HIV to their partners via sex.
The Three Categories Of Viruses
There are three different virus types that are made distinct by their shape. The cylindrical helical virus type is associated with the tobacco mosaic virus. Envelope viruses, such as influenza and HIV come covered in a protective lipid envelope. Most animal viruses are classified as icosahedral and are nearly spherical in shape.
The viruses within these categories share similar characteristics. Theyre composed of RNA or DNA, and are coated with either a protein, lipid or glycoprotein. Theyre also parasitic, meaning they cant replicate without a host. Viruses are also the most abundant biological form of life on the planet. While they cant be cured, a vaccination can prevent their spread.
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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.
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.