Temporary Disabled. :) please Go back HIV Structure and Life Cycle www.fgks.org » Address: [go: up one dir, main page] Include Form Remove Scripts Accept Cookies Show Images Show Referer Rotate13 Base64 Strip Meta Strip Title Session Cookies International HIV & AIDS charity DonateFundraising About Us Our Partners Help & Advice Contact Us Facebook Linked in Twitter Newsletter Copyright © AVERT skip to menu HIV Structure and Life Cycle HIV stands for Human Immunodeficiency Virus. Like all viruses, HIV cannot grow or reproduce on its own. In order to make new copies of itself it must infect the cells of a living organism. back to top The structure of HIV What does HIV look like? The proteins gp120 and gp41 together make up the spikes that project from HIV particles, while p17 forms the matrix and p24 forms the core. Outside of a human cell, HIV exists as roughly spherical particles (sometimes called virions). The surface of each particle is studded with lots of little spikes. An HIV particle is around 100-150 billionths of a metre in diameter. That's about the same as: 0.1 microns 4 millionths of an inch one twentieth of the length of an E. coli bacterium one seventieth of the diameter of a human CD4+ white blood cell. Unlike most bacteria, HIV particles are much too small to be seen through an ordinary microscope. However they can be seen clearly with an electron microscope. HIV particles surround themselves with a coat of fatty material known as the viral envelope (or membrane). Projecting from this are around 72 little spikes, which are formed from the proteins gp120 and gp41. Just below the viral envelope is a layer called the matrix, which is made from the protein p17. The viral core (or capsid) is usually bullet-shaped and is made from the protein p24. Inside the core are three enzymes required for HIV replication called reverse transcriptase, integrase and protease. Also held within the core is HIV's genetic material, which consists of two identical strands of RNA. What is RNA? HIV belongs to a special class of viruses called retroviruses. Within this class, HIV is placed in the subgroup of lentiviruses. Other lentiviruses include SIV, FIV, Visna and CAEV, which cause diseases in monkeys, cats, sheep and goats. Almost all organisms, including most viruses, store their genetic material on long strands of DNA. Retroviruses are the exception because their genes are composed of RNA (Ribonucleic Acid). RNA has a very similar structure to DNA. However, small differences between the two molecules mean that HIV's replication process is a bit more complicated than that of most other viruses. How many genes does HIV have? HIV has just nine genes (compared to more than 500 genes in a bacterium, and around 20,000-25,000 in a human). Three of the HIV genes, called gag, pol and env, contain information needed to make structural proteins for new virus particles. The other six genes, known as tat, rev, nef, vif, vpr and vpu, code for proteins that control the ability of HIV to infect a cell, produce new copies of virus, or cause disease. At either end of each strand of RNA is a sequence called the long terminal repeat, which helps to control HIV replication. back to top HIV life cycle Entry You need to install Adobe Flash player to view AVERT's videos. Click on the logo below to install Flash player. HIV life cycle HIV can only replicate (make new copies of itself) inside human cells. The process typically begins when a virus particle bumps into a cell that carries on its surface a special protein called CD4. The spikes on the surface of the virus particle stick to the CD4 and allow the viral envelope to fuse with the cell membrane. The contents of the HIV particle are then released into the cell, leaving the envelope behind. Importantly, HIV infects the cells (T-helper cells) that form the body's immune system. As HIV infects more cells, the immune system becomes weaker - this is known as AIDS. HIV treatment protects the cells and so keeps the immune system strong - preventing AIDS. The type of HIV drugs that can stop this part of the process are called Fusion or Entry Inhibitors. Reverse Transcription and Integration Once inside the cell, the HIV enzyme reverse transcriptase converts the viral RNA into DNA, which is compatible with human genetic material. This DNA is transported to the cell's nucleus, where it is spliced into the human DNA by the HIV enzyme integrase. Once integrated, the HIV DNA is known as provirus. It is at this point that HIV affects the cell in such a way, that it begins to die - weakening the immune system.1 The type of HIV drugs that can stop this part of the process are called NRTIs, NNRTIs and Integrase Inhibitors. Transcription and Translation HIV budding from an infected cell HIV provirus may lie dormant within a cell for a long time. But when the cell becomes activated, it treats HIV genes in much the same way as human genes. First it converts them into messenger RNA (using human enzymes). Then the messenger RNA is transported outside the nucleus, and is used as a blueprint for producing new HIV proteins and enzymes. Assembly, Budding and Maturation Among the strands of messenger RNA produced by the cell are complete copies of HIV genetic material. These gather together with newly made HIV proteins and enzymes to form new viral particles. The HIV particles are then released or 'bud' from the cell. The enzyme protease plays a vital role at this stage of the HIV life cycle by chopping up long strands of protein into smaller pieces, which are used to construct mature viral cores. The type of HIV drugs that can stop this part of the process are called Protease Inhibitors. The newly matured HIV particles are ready to infect another cell and begin the replication process all over again. In this way the virus quickly spreads through the human body. And once a person is infected, they can pass HIV on to others in their bodily fluids. email print tweet more Where Next? AVERT.org has more about: Science of AIDS HIV types, subtypes groups and strains HIV and AIDS vaccine What causes AIDS? Back to top Sign up to our Newsletter Donate Sources back to top NIH Health Topics "Biology of HIV" Nielsen MH, Pedersen FS and Kjems J (2005) "Molecular strategies to inhibit HIV-1 replication", Retrovirology 2:10 - 2005 References back to top NIH News (2013, 5th June) 'NIH Scientists Discover How HIV Kills Immune Cells' english español back to content home pageHIV & AIDS Topics ScienceEpidemicGlobal EpidemicAIDS & HIV Around the WorldAIDS : What is AIDS? 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More than 2,400 young people are newly infected with HIV every day, accounting for 40% of new adult infections. Involving youth in the HIV response is key to lowering new HIV infections among the next generation and the role of technology in doing this is now clearer than ever. A sneak preview of results from an AVERT survey, due to be released on International Youth Day 2013 - 12 August, show that most young people prefer to get their sexual health and HIV/AIDS information online or via mobile, as it's quicker, confidential and cheap. But not all youth are the same, we've found regional variations in the type of technology young people prefer - with 67% of respondents from Africa using mobile phones for health information, compared to just 31% in Europe. To commemorate International Youth Day 2013 - 12 August, share your experiences with others by sending AVERT your story. Raise HIV awareness among youth, check out the hints, tips and quizzes below and share them with your friends. 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HIV stands for Human Immunodeficiency Virus. Like all viruses, HIV cannot grow or reproduce on its own. In order to make new copies of itself it must infect the cells of a living organism.
Outside of a human cell, HIV exists as roughly spherical particles (sometimes called virions). The surface of each particle is studded with lots of little spikes.
An HIV particle is around 100-150 billionths of a metre in diameter. That's about the same as:
Unlike most bacteria, HIV particles are much too small to be seen through an ordinary microscope. However they can be seen clearly with an electron microscope.
HIV particles surround themselves with a coat of fatty material known as the viral envelope (or membrane). Projecting from this are around 72 little spikes, which are formed from the proteins gp120 and gp41. Just below the viral envelope is a layer called the matrix, which is made from the protein p17.
The viral core (or capsid) is usually bullet-shaped and is made from the protein p24. Inside the core are three enzymes required for HIV replication called reverse transcriptase, integrase and protease. Also held within the core is HIV's genetic material, which consists of two identical strands of RNA.
HIV belongs to a special class of viruses called retroviruses. Within this class, HIV is placed in the subgroup of lentiviruses. Other lentiviruses include SIV, FIV, Visna and CAEV, which cause diseases in monkeys, cats, sheep and goats. Almost all organisms, including most viruses, store their genetic material on long strands of DNA. Retroviruses are the exception because their genes are composed of RNA (Ribonucleic Acid).
RNA has a very similar structure to DNA. However, small differences between the two molecules mean that HIV's replication process is a bit more complicated than that of most other viruses.
HIV has just nine genes (compared to more than 500 genes in a bacterium, and around 20,000-25,000 in a human). Three of the HIV genes, called gag, pol and env, contain information needed to make structural proteins for new virus particles. The other six genes, known as tat, rev, nef, vif, vpr and vpu, code for proteins that control the ability of HIV to infect a cell, produce new copies of virus, or cause disease.
At either end of each strand of RNA is a sequence called the long terminal repeat, which helps to control HIV replication.
You need to install Adobe Flash player to view AVERT's videos. Click on the logo below to install Flash player.
HIV life cycle
HIV can only replicate (make new copies of itself) inside human cells. The process typically begins when a virus particle bumps into a cell that carries on its surface a special protein called CD4. The spikes on the surface of the virus particle stick to the CD4 and allow the viral envelope to fuse with the cell membrane. The contents of the HIV particle are then released into the cell, leaving the envelope behind.
Importantly, HIV infects the cells (T-helper cells) that form the body's immune system. As HIV infects more cells, the immune system becomes weaker - this is known as AIDS. HIV treatment protects the cells and so keeps the immune system strong - preventing AIDS.
The type of HIV drugs that can stop this part of the process are called Fusion or Entry Inhibitors.
Once inside the cell, the HIV enzyme reverse transcriptase converts the viral RNA into DNA, which is compatible with human genetic material. This DNA is transported to the cell's nucleus, where it is spliced into the human DNA by the HIV enzyme integrase. Once integrated, the HIV DNA is known as provirus. It is at this point that HIV affects the cell in such a way, that it begins to die - weakening the immune system.1
The type of HIV drugs that can stop this part of the process are called NRTIs, NNRTIs and Integrase Inhibitors.
HIV provirus may lie dormant within a cell for a long time. But when the cell becomes activated, it treats HIV genes in much the same way as human genes. First it converts them into messenger RNA (using human enzymes). Then the messenger RNA is transported outside the nucleus, and is used as a blueprint for producing new HIV proteins and enzymes.
Among the strands of messenger RNA produced by the cell are complete copies of HIV genetic material. These gather together with newly made HIV proteins and enzymes to form new viral particles. The HIV particles are then released or 'bud' from the cell. The enzyme protease plays a vital role at this stage of the HIV life cycle by chopping up long strands of protein into smaller pieces, which are used to construct mature viral cores.
The type of HIV drugs that can stop this part of the process are called Protease Inhibitors.
The newly matured HIV particles are ready to infect another cell and begin the replication process all over again. In this way the virus quickly spreads through the human body. And once a person is infected, they can pass HIV on to others in their bodily fluids.
english español
Play our games to test your knowledge and skills, while learning new facts. See how much you know about HIV/AIDS and sexual health, with our AIDS Game, Sex Education Game, Pregnancy Game and Condom Game. Use your mouse to collect the right letters while avoiding the baddies for a chance to appear on our HI-scores table.
Give our games a try now, and see how well you can do!
Our media gallery contains hundreds of HIV and AIDS related photos, videos and graphics. You can have a look around, use the search feature, or take a look at some photo selections.
Try our quizzes to test your knowledge on all aspects of sexual health and HIV and AIDS. We have a Sex Quiz, Pregnancy Quiz, Condom Quiz and an HIV and AIDS Quiz.
Just a beginner? Then try the quizzes' easy levels. Think you're an expert? Well try the hard quizzes.
I went through kind of a phase shift from just getting feelings towards this one guy, to be being confused and feeling kind of bi... - Submitted by Wesley Read more >>
Giving young people a platform to share their thoughts and experiences raises awareness among their peers and gives an invaluable insight into the needs of this high-risk group. More than 2,400 young people are newly infected with HIV every day, accounting for 40% of new adult infections.
Involving youth in the HIV response is key to lowering new HIV infections among the next generation and the role of technology in doing this is now clearer than ever.
A sneak preview of results from an AVERT survey, due to be released on International Youth Day 2013 - 12 August, show that most young people prefer to get their sexual health and HIV/AIDS information online or via mobile, as it's quicker, confidential and cheap. But not all youth are the same, we've found regional variations in the type of technology young people prefer - with 67% of respondents from Africa using mobile phones for health information, compared to just 31% in Europe.
To commemorate International Youth Day 2013 - 12 August, share your experiences with others by sending AVERT your story. Raise HIV awareness among youth, check out the hints, tips and quizzes below and share them with your friends.