The virus attaches itself to a thelper cell and releases hiv into the cell. The life cycle of hiv and hiv disease december 2011hiv life cyclehiv illustration cd4 cell illustration 2. Hiv is different in structure from other retroviruses. As the virus replicates and spreads throughout the. Pdf hiv life cycle, innate immunity and autophagy in the. Once activated, the cell divides as does the hiv genetic material and new hiv particles are produced. It allows us to identify how the virus makes copies of itself, which in turn allow us to develop ways to block or inhibit that process.
It is roughly spherical with a diameter of about 120 nm, around 60 times smaller than a red blood cell. Each of these steps is used as a target to make hiv drugs to inhibit the progress of hiv infection. The hiv life cycle defines the steps and changes the virus undergoes from its first contact with a target cell to the production of new infectious viral particles that can initiate the. These special cells help the immune system fight off infections.
The right treatment can prevent hiv from developing into aids and extend life expectancy. Nov 07, 2019 click above to view or download this fact sheet as a pdf slide presentation. Thus, viral life cycle and immune responses are governed by unique mechanisms in brain. Hiv mrna hiv protein chain cd4 receptor hiv glycoprotein hiv envelope ccr5 receptor orcxcr4 receptor the hiv life cycle binding and fusion. Antiretroviral therapy art is the use of hiv medicines to treat hiv. The hiv life cycle defines the steps and changes the virus undergoes from its first contact with a target cell to the production of new infectious viral particles that can initiate the next round of. Depending on the type of nucleic acid, cellular components are used to replicate the viral genome and synthesize viral proteins for assembly of new virions. Hiv replication or hiv life cycle refers to how the hiv virus reproduces itself using the genetic makeup of the host cell human cell. The human immunodeficiency virus hiv is a retrovirus that affects around 34 million people around the world.
The roles played by hiv 1 gag proteins during the life cycle are numerous and complex, involving not only assembly but also virion maturation after particle release and early postentry steps in virus replication. Hiv life cycle, innate immunity, and autophagy in the central. This animation describes the structure of the hiv virus, receptormediated attachment to. After a virus has made many copies of itself, it has usually exhausted the cell of its resources. By printig out this quiz and taking it with pen and paper creates for a good variation to only playing it online. Pdf definitionthe hiv life cycle defines the steps and changes the virus undergoes from its first contact with a target cell to the production of. The shell of the capsid disintegrates and the hiv protein called reverse transcriptase transcribes the viral rna into dna. Sep, 2016 the seven stages of the hiv life cycle are. The main attachment receptor for hiv is the cd4 molecule that is present on. Hiv virology and pathogenetic mechanisms of infection. In this way hiv weakens the bodys natural defences and over time severely damages the immune system. Jul 01, 2019 hiv uses the machinery of the cd4 cells to multiply and spread throughout the body. The main target of hiv is activated cd4 t lymphocytes. Understanding the life cycle of hiv has made it possible to develop the drugs we use to treat the disease.
This turns the cell into a sort of hiv factory so it can make many more copies of itself. It has a complicated life cycle, with its information being stored as rna, then transferred to dna, before new viral particles are made. Over time, hiv can destroy so many of these cells that the body cant fight off infections and disease. There are seven 7 stages or steps of the hiv virus replication cycle. Aids is the leading cause of infectious disease mortality, surpassing tuberculosis and malaria. Follow each stage in the hiv life cycle, as hiv attacks a cd4 cell and uses the machinery of the cell to multiply. This infographic illustrates the hiv replication cycle, which begins when hiv fuses with the surface of the host cell. On the basis of genetic characteristics and differences in the viral antigens, hiv is classified into the types 1 and 2 hiv 1, hiv 2. This animation describes the structure of the hiv virus, receptormediated attachment to cd4 lymphocytes, viral envelope fusion with the. Structure, life cycle, and pathogenecity jonathan richard hughes university of tennessee knoxville. How quickly the virus develops depends on a persons general health, how soon after getting hiv theyre diagnosed and start antiretroviral treatment, and how consistently they take their treatment. A capsid containing the viruss genome and proteins then enters the cell. How hiv infects the body and the lifecycle of hiv avert.
Mar 22, 2019 the life cycle of the hiv virus is a multistep process. Pdf documents can be viewed with the free adobe reader. Next, the virus is uncoated within the cytoplasm of the cell when the capsid is removed. The main cellular target of hiv is a special class of white blood cells critical to the immune system known as helper t lymphocytes, or helper t cells. Viral dynamics in human immunodeficiency virus type 1 infection x. Covid19 is an emerging, rapidly evolving situation. The process by which virus progeny are released to find new hosts, is called shedding. This video lecture explains the life cycle of hiv virus and the infection strategy of hiv in causing aids. Once hiv is in the body, it targets and infects a certain type of white blood cell called a cd4 cell. Different antihiv drugs target different steps in the process of hiv. Pathophysiology of the human immunodeficiency virus bipai. The hiv life cycle and antiretroviral drugs part 1 duration. Firstphase hiv rna decay halflife of 17 h over all drugs seemed to slow as the stage being inhibited by the drug was further from viral.
Estimated number of people living with hiv in 2012 and trends in the incidence of new infections from 2001 to 2012 by global. The gag proteins of hiv 1, like those of other retroviruses, are necessary and sufficient for the assembly of virus like particles. Definitionthe hiv life cycle defines the steps and changes the virus undergoes from its first contact with a target cell to the production of new infectious viral particles that can initiate the. May 14, 2014 this video lecture explains the life cycle of hiv virus and the infection strategy of hiv in causing aids. Once hiv binds to an immune cell, it hides its dna inside the cells dna. Structure, life cycle, and pathogenecity tennessee research. The life cycle of hiv and hiv disease december 2011hiv life cycle1. As a result, when the cellular dna is transcribed, so is the viral dna to form an rna. Knowing the secrets of how the virus functions and reproduces itself a process called its life cycle can help scientists design new drugs that are more effective at suppressing hiv and have. Timing of the components of the hiv life cycle in productively.
After fusion, the virus releases rna, its genetic material, into the host cell. A capsid containing the virus s genome and proteins then enters the cell. This process, which is carried out in seven steps or stages, is called the hiv life cycle. The infective agent, human immunodeficiency virus hiv, has already infected more than 60 million people around the world. To survive, hiv needs to infect cells in which new viruses can be made. The outside of hiv has an outer shell envelope of proteins, fats and sugars. One of the hallmarks of hiv infection is the integration of viral genes into the infected persons genome which causes persistent infection because the immune system is unable to clear the virus. Hiv medicines protect the immune system by blocking hiv at different stages of the hiv life cycle. The life cycle of bacteriophages has been a good model for understanding how viruses affect the cells they infect, since similar processes have been observed for eukaryotic viruses, which can cause immediate death of the cell or establish a latent or chronic infection.
This worksheet is in pdf format and holds a printable version of the quiz hiv virus life cycle. Hiv virus life cycle printable worksheet purposegames. Effectively, the virus has now hijacked the host cells own replication system. Nov 28, 2019 the life cycle of viruses with prokaryote hosts. And each infected cd4 cell produces hundreds of new.
Being a retrovirus, it uses it viral rna ribonucleic acid and the host dna deoxyribonucleic acid to produce viral dna. Hiv uses the machinery of the cd4 cells to multiply and spread throughout the body. Basic concepts viruses are obligate intracellular parasites viruses carry their genome rna or dna and sometimes functional proteins required for early steps in replication cycle viruses depend on host cell machinery to complete replication cycle and must commandeer. The life cycle begins with the penetration of the virus into the host cell. Each of these steps is used as a target to make hiv drugs to inhibit the progress of hiv. Hiv is a virus spread through certain body fluids that attacks the bodys immune system, specifically the cd4 cells, often called t cells. Similarly, vpx viral protein x is found in hiv2 and not hiv1. A better understanding of the steps in the viral life cycle, especially the. The human immunodeficiency virus hiv is grouped to the genus lentivirus within the family of retroviridae, subfamily orthoretrovirinae. Today, a person with hiv who adheres to antiretroviral therapy can expect to live a nearnormal life span. Art in pictures overdrive graphic2 like other living things, viruses need to be able to reproduce. It is composed of two copies of positive sense singlestranded rna that codes for the virus s nine genes enclosed by a conical capsid composed of 2,000 copies of the viral protein p24. Fact sheets about hivaids treatment information, the prevention of mothertochild transmission, and hiv treatment side effects. These concepts are of critical importance for both eradication.
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