A capsid containing the viruss genome and proteins then enters the cell. Structure, expression, and regulation of the hiv genome. 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. The life cycle of hiv and hiv disease december 2011hiv life cyclehiv illustration cd4 cell illustration 2. Unlike some other viruses, the human body cant get rid of hiv completely, even with treatment. Structure, life cycle, and pathogenecity jonathan richard hughes. 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. Learn vocabulary, terms, and more with flashcards, games, and other study tools. The early phase begins with the recognition of the target cell by the mature virion and involves all processes leading to and including integration of the genomic dna into the chromosome of the host cell. The life cycle of hiv and hiv disease december 2011timeline of drug development strikethrough discontinued in us. It is roughly spherical with a diameter of about 120 nm, around 60 times smaller than a red blood cell.
Structure of human immunodeficiency virus hiv microbeonline. The human immunodeficiency viruses are approximately 100 nm in diameter. Hiv and aids have emerged as an epidemic of staggering proportions, and one of todays greatest challenges to scientists and health workers. Pdf definitionthe hiv life cycle defines the steps and changes the virus. Hiv medicines protect the immune system by blocking hiv at different stages of the hiv life cycle. It is composed of two copies of positivesense singlestranded rna that codes for the viruss nine genes enclosed by a conical capsid composed of 2,000 copies of the viral protein p24. It is around 120 nm in diameter 120 billionths of a meter. Hiv infects a type of white blood cell in the bodys immune system called a thelper cell also called a cd4 cell.
This unit provides an overview of the human immune system and viral life cycle. Infection is most common in the young adult population between 20 and 30 years of age. It is not possible to understand how hiv causes aids and how aids leads to death without a basic understanding of the immune system. Structure of influenza viruses, connected with influenza life cycle ludmila krejcova1, petr michalek1, david hynek 2, vojtech adam, rene kizek 1 department of chemistry and biochemistry, faculty of agronomy, mendel university in brno, zemedelska 1, 6 00 brno, czech republic. This animation describes the structure of the hiv virus, receptormediated attachment to cd4 lymphocytes, viral envelope fusion with the. Lesson hiv structurelife cycle 2 and implications for. Hiv is different in structure from other retroviruses. The life cycle of hiv and hiv disease december 2011hiv life cycle 4. Hiv can be transmitted sexually, parenterally, or vertically e. Start studying describe the life cycle of hiv, the course of infection, how aids is defined and developed, how aids is treated. Fact sheets about hivaids treatment information, the prevention of mothertochild transmission, and hiv treatment side effects.
The life cycle of hiv and hiv disease december 2011course of hiv disease to aids,untreated 6. Two major types of the aids virus, hiv 1 and hiv2, have been identified. Instead, the virus attaches itself to a t helper cell and fuses with it. The life cycle of the hiv virus is a multistep process. Structure, genome and proteins of hiv structure and properties of hiv shape and size hiv is a spherical virus of about 90 nm in diameter. Basic concepts replication cycle producesfunctional rnas and proteinsgenomic rna or dna and structural proteins 100s1,000s new particles produced by each cyclereferred to as burst sizemany are defectiveend of eclipse phase replication may be cytolytic or noncytolytic steps in viral replication. The crystal structure of hiv1 rt has been determined. Follow each stage in the hiv life cycle, as hiv attacks a cd4 cell and uses the machinery of the cell to multiply. Different types of antihiv drugs target these different steps. 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. Knowing how hiv infects the body helps people understand prevention and treatment options, and why its important to start antiretroviral treatment as soon as possible after testing positive. Instead, the virus attaches itself to a thelper cell and fuses with it.
These vital cells keep us healthy by fighting off infections and diseases. Hiv attacks and destroys the cd4 cells of the immune system. 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. 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 of hiv and hiv disease december 2011hiv life cycle1. The role of tat in the human immunodeficiency virus life cycle indicates a primary effect on. The dna genome is flanked at both ends by ltr long terminal repeat.
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 next round of replication. Knowing the structure of hiv helps you to understand how it works, why the immune system finds it hard to detect, and how antiretroviral drugs can treat it. Cd4 cells are a type of white blood cell that play a major role in protecting the body from infection. Nov 06, 2015 this video helps the learner to understand in detail the concept of aids, explains the structure of the hiv virus and also describes the various stages of development of the virus. In the binding or attachment stage of hiv life cycle, the hiv virus attaches itself to the surface of cd4 cells by using its receptor known as gp120 a glycoprotein to attach to some receptors on the cd4 cells such as ccr5 receptors and cxcr4. After binding of the trna primers, synthesis of proviral dna occurs as a minusstrand polymerization starting at the pbs primer binding site and extending to the 5 repeat region as a short ru5 dna. As a virus, hiv relies on our immune system to sustain itself and make copies. In the 1990s, the time to development of aids after initial infection with the. Each step in the hiv 1 life cycle is a potential target for antiviral intervention 165. Hiv structure morphology of hiv how does hiv look like. All retroviruses, including hiv and siv, show three functional states during their extracellular life cycle. Once activated, the cell divides as does the hiv genetic material and new hiv particles are produced. This huge diversity of hiv 1 is important when diagnostic testing, treatment and monitoring are applied as the results may differ between different subtypes or clades see hiv global genetic diversity and epidemiology below.
How hiv infects the body and the lifecycle of hiv avert. Dec 01, 2017 structure, genome and proteins of hiv structure and properties of hiv shape and size hiv is a spherical virus of about 90 nm in diameter. Jul 01, 2019 hiv medicines protect the immune system by blocking hiv at different stages of the hiv life cycle. Despite decades of research, the interactions between hiv 1 and host proteins that underlie some steps in the viral life cycle, for example the import of the preintegration complex into the nucleus fig. On the basis of genetic characteristics and differences in the viral antigens, hiv is classified into the types 1 and 2 hiv1, hiv2. Each class of drugs is designed to target a specific step in the hiv life cycle.
Human immunodeficiency virus knowledge for medical. The hiv particles are then released or bud from the cell. Rna secondary structures have been proposed to affect the hiv life cycle by altering the function of hiv protease and reverse transcriptase, although not all elements identified have been assigned a function. Structure, life cycle, and pathogenecity tennessee research. Hiv virology and pathogenetic mechanisms of infection. Understanding the life cycle of hiv has made it possible to develop the drugs we use to treat the disease. It is the virus that can lead to acquired immunodeficiency syndrome or aids if not treated.
Hiv infects cells of the immune system and aids is predominantly a disease due to failure of the immune system. The type of hiv drugs that can stop this part of the process are called protease inhibitors. Fact sheets about hivaids treatment information, the prevention of motherto child transmission, and hiv treatment side effects. The how treatment works leaflet in our illustrated series, the basics, looks at hiv treatment in relation to the hiv lifecycle. Each step in the hiv1 life cycle is a potential target for antiviral. Structure, genome and proteins of hiv online biology notes. 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. Structure of influenza viruses, connected with influenza life.
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. The introductory reading in section 1 was general information about some of the practical issues about hiv resistance. This process, which is carried out in seven steps or stages, is called the hiv life cycle. The shell of the capsid disintegrates and the hiv protein called reverse transcriptase transcribes the viral rna into dna. The human immunodeficiency virus hiv is grouped to the genus lentivirus within the family of retroviridae, subfamily orthoretrovirinae. To find out more about hiv treatment, you may find some of the pages in our hiv treatment section helpful. Overhead projector or lcd projector optional computer lab for students. If youd like to find out more about the hiv lifecycle, take a look at our science of hiv and aids section. It has a complicated life cycle, with its information being stored as rna, then transferred to dna, before new viral particles are made. Structure of influenza viruses, connected with influenza life cycle ludmila krejcova1, petr michalek1, david hynek 2, vojtech adam, rene kizek 1 department of chemistry and biochemistry, faculty of agronomy, mendel university in brno, zemedelska 1.
This video helps the learner to understand in detail the concept of aids, explains the structure of the hiv virus and also describes the various stages of. Unlike some other viruses, the human body cant get rid of hiv completely, even with. Pendergraph, phd, jd, mlsascpsm, hcldccabb received his msph from the university of kentucky in lexington, his phd in medical parasitology and mycology from the university of north carolina in chapel hill, and his law degree with a concentration in health care law from concord law school, purdue university. This infographic illustrates the hiv replication cycle, which begins when hiv fuses with the surface of the host cell.
The combination of reverse transcription of viral rna into dna and integration. Because an hiv regimen includes hiv medicines from at least two different hiv. Despite decades of research, the interactions between hiv1 and host proteins that underlie some steps in the viral life cycle, for example the import of the preintegration complex into the nucleus fig. Infection with the human immunodeficiency virus hiv leads to a complex disease pattern which ultimately results in chronic immunodeficiency. Next, it familiarizes students with types of vaccines and with. This huge diversity of hiv1 is important when diagnostic testing, treatment and monitoring are applied as the results may differ between different subtypes or clades see hiv global genetic diversity and epidemiology below. Host cells infected with hiv have a shortened life span as. And each infected cd4 cell produces hundreds of new. It has a lipid envelope, in which are embedded the trimeric. Mar 22, 2019 the life cycle of the hiv virus is a multistep process. After fusion, the virus releases rna, its genetic material, into the host cell. General features of the hiv replication cycle are shown in figure 2. Immune system and how vaccines work in the immune system.
Hiv is an approximately 100 nm icosahedral structure with 72 external spikes that are formed by the two major envelope glycoproteins gp120 and gp41. Human immunodeficiency virus hiv is a complex rna virus of the genus lentivirus within the retroviridae family. Another rna structure that has been identified is gag stem loop 3 gsl3, thought to be involved in viral packaging. Hiv medicines are grouped into different drug classes according to how they fight hiv. Its by interrupting these processes that we are able to reduce the amount of hiv in a persons body.
598 759 1179 1507 1505 889 1311 441 1067 1238 519 429 1206 304 241 688 549 1246 822 59 1373 1427 966 110 451 1151 1079 1176 604