Structure and life cycle of hiv virus pdf

A few viruses increase the risk of certain cancers. This allows the virus to join, or merge, with the cd4 cell in a process. Lesson hiv structurelife cycle 2 and implications for. Structure, life cycle, and pathogenecity tennessee research. The envelope is a lipid bilayer surrounding the viral matrix, which is derived from host cell membrane during budding. 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. This process happens in two stages, attachment and fusion. Hiv infects immune system cells which have a cd4 receptor on the surface. To survive, hiv needs to infect cells in which new viruses can be made.

Virus mutation the virus life cycle hiv and aids as retroviridae viruses to perform well on the medical college admission test mcat, youll need to be able to answer questions correctly and in a. Despite the discovery of hcv over 15 years ago, our knowledge. The life cycle of hiv and hiv disease december 2011hiv life cycle1. List of known viroporins and their known function in viral life cycle. Hiv1 was first isolated in 1983 and hiv2 in 1986 and they represent two different epidemics. Role and function in the virus life cycle jun 23, 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. Hiv virology and pathogenetic mechanisms of infection. Hepatitis c virus hcv infection afflicts more than 170 million people worldwide, with the great majority of patients with acute hepatitis c developing chronic hcv infection. Oncogenesis several viruses are associated with human cancers. Hiv is a virus spread through certain body fluids that attacks the bodys immune system, specifically the cd4 cells, often called t cells. Thus, hiv1 and hiv2 each had a zoonotic origin but now spread directly from human to human. As the virus replicates and spreads throughout the. As the virus replicates and spreads throughout the body, the immune system detects the presence of the virus and mounts an immediate antibody response.

The major serological differences reside in the surface. Hcv genome and life cycle hepatitis c viruses ncbi. The productive life cycle is also often referred to as the lytic life cycle, even though not all viruses cause lysis of their host cell during their replication. Jul 01, 2019 hiv attacks and destroys the cd4 cells of the immune system. This process, which is carried out in seven steps or stages, is called the hiv life cycle.

This usually occurs within two to four weeks of infection and is referred to as seroconversion because antibodies to hiv can be detected in the blood. Two major types of the aids virus, hiv 1 and hiv2, have been identified. Helper t cells play a central role in normal immune responses by producing factors that activate virtually. Current first line regimens are more ef fective and easier to take and tolerate, which helps. Hiv is a spherical virus of about 90 nm in diameter. In the case of the regulator genes, the proteins of tat and rev are composed of two gene regions. Individual subunits are coloured by chain, with the amino and carboxyterminal domains ntd and ctd, respectively of each subunit indicated. The hiv life cycle is typically divided into 7 distinct stages. Hiv mrna hiv protein chain cd4 receptor hiv glycoprotein hiv envelope ccr5 receptor orcxcr4 receptor the hiv life cycle binding and fusion. Structure of human immunodeficiency virus hiv learn. The genome and proteins of hiv human immunodeficiency virus have been the subject of extensive research since the discovery of the virus in 1983. The human immunodeficiency viruses 1 and 2 hiv1, hiv2 originated from the simian immunodeficiency viruses sivs of primates. Epsteinbarr virus with lymphoma, nasopharyngeal carcinoma and. Together, these molecules allow the virus to infect cells of the immune system and force them to build new copies of the virus.

Hiv attacks and destroys the cd4 cells of the immune system. Structure of influenza viruses, connected with influenza. Instead, the virus attaches itself to a t helper cell and fuses with it. It can ultimately result in liver cirrhosis, hepatic failure or hepatocellular carcinoma, which are responsible for hundreds of thousands of deaths each year. During adsorption, an envelope glycoprotein on the surface of hiv called gp120.

The hiv replication cycle hiv entry cd4 as a primary receptor for hiv. The type of hiv drugs that can stop this part of the process are called protease inhibitors. These special cells help the immune system fight off infections. This cis regulatory rna has been shown to be conserved throughout the hiv family and is thought to influence the viral life cycle. Explore virus structure, structure of virus, viral structure types, and functions of virus structure. 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. Follow each stage in the hiv life cycle, as hiv attacks a cd4 cell and uses the machinery of the cell to multiply. How hiv infects the body and the lifecycle of hiv avert. Some viruses, such as hiv and the herpes viruses are able to become latent in certain cell types.

Cd4 is a 58 kda monomeric glycoprotein that can be detected on the cell surface of about 60% of t lymphocytes, on t cell precursors within the bone marrow and thymus, and on monocytes and macrophages, eosinophils, dendritic cells and microglial cells of the central nervous. Hiv uses the machinery of the cd4 cells to multiply and spread throughout the body. The human immunodeficiency virus hiv genome encodes a total of three structural proteins, two envelope proteins, three enzymes, and six accessory proteins. There are seven 7 stages or steps of the hiv virus replication cycle. 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 herpesviridae family includes more than 200 species that infect mammals, birds, reptiles, amphibians, fish, and bivalves. Structure, life cycle, and pathogenecity jonathan richard hughes. Students will gain a greater understanding about the structure and life cycle of hiv students will apply their understanding about the life cycle of hiv to identify targets of interruption students will be able to explain how mutations occur and why they can create challenges to developing effective vaccines. Structure, genome and proteins of hiv online biology notes. 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. Learn about the lifecycle of hiv and understand how different hiv drugs.

That is, viruses infect specific cells or tissues of specific hosts, or specific bacteria, or specific plants. Activity 3 36 hiv life cycle webquest in order to give students a greater understanding of the life cycle. Viroids are the smallest known autonomously replicating. The life cycle of the virus is a series of steps that enable the virus to infect a host and replicate itself. Hiv 1 was first isolated in 1983 and hiv 2 in 1986 and they represent two different epidemics. Below the envelope, there is an icosahedral shell called matrix p17. It is made of many different cells that are spread throughout the body, each playing different roles and moving around the.

This animation describes the structure of the hiv virus, receptormediated attachment to. 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 human immunodeficiency virus hiv is grouped to the genus lentivirus within the family of retroviridae, subfamily orthoretrovirinae. The process of producing new viruses begins when hiv gains entry to a cell.

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. 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. 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. Hcv genome and life cycle hepatitis c viruses ncbi bookshelf. Different antihiv drugs target different steps in the process of hiv infecting cells. Hiv is different in structure from other retroviruses. Cd4 cells are a type of white blood cell that play a major role in protecting the body from infection. Viral membrane channels role and function in the virus life cycle. The hiv particles are then released or bud from the cell. Human immunodeficiency virus hiv 1, and coronaviruses cov table. General description, life cycle, and replication general description of herpesviridae family. It is roughly spherical with a diameter of about 120 nm, around 60 times smaller than a red blood cell. Fact sheets about hivaids treatment information, the prevention of motherto child transmission, and hiv treatment side effects.

A flea is a parasite to a dog and is harmful to the dog. The main target of hiv is activated cd4 t lymphocytes. Hiv human immunodeficiency virus is composed of two strands of rna, 15 types of viral proteins, and a few proteins from the last host cell it infected, all surrounded by a lipid bilayer membrane. Jun 08, 2019 a virus is an infectious nonliving particle that cannot survive on its own. Hiv is an approximately 100 nm icosahedral structure with 72 external spikes that are formed by the two major envelope glycoproteins gp120 and gp41. At this stage of the life cycle the retroviral genome is a dna element integrated into and covalently attached to the dna of the host cell. To understand each stage in the hiv life cycle, it helps to first imagine what hiv looks like.

The genome of the virus is of approximately 812 kilobases of dna depending upon the retroviral species. Shown are the reading frames of the genes coding for structural and regulatory proteins see table table1. It then takes control of the cells dna, replicates itself inside the cell, and finally releases more hiv into the blood continuing the multiplication process. A virus is an infectious nonliving particle that cannot survive on its own. A virus is an infectious agent made up of nucleic acid dna or rna wrapped in a protein coat called a capsid viruses have no. Lytic and lysogenic life cycles dna viruses rna viruses influenza hiv prions mad cow disease figure 18. Next, the virus is uncoated within the cytoplasm of the cell when the capsid is removed. Over time, hiv can destroy so many of these cells that the body cant fight off infections and disease. Structure of influenza viruses, connected with influenza life. This animation describes the structure of the hiv virus, receptormediated attachment to cd4 lymphocytes, viral envelope fusion with the. Each step in the hiv 1 life cycle is a potential target for antiviral intervention 165. Depending on the type of nucleic acid, cellular components are used to replicate the viral genome and synthesize viral. The life cycle of the hiv virus is a multistep process.

Examples include hiv, hepatitis b virus and hepatitis c virus. The retroviral life cycle begins in the nucleus of an infected cell. Compans, georg herrler, in mucosal immunology third edition, 2005. The human immunodeficiency viruses 1 and 2 hiv 1, hiv 2 originated from the simian immunodeficiency viruses sivs of primates. 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.

Key points the immune system is the bodys natural defence system. Although there are currently no hiv drugs that block this stage, several drugs are in. It has a complicated life cycle, with its information being stored as rna, then transferred to dna, before new viral particles are made. Estimated number of people living with hiv in 2012 and trends in the incidence of new infections from 2001 to 2012 by global. 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. Definitionthe hiv life cycle defines the steps and changes the virus. Together, these molecules allow the virus to infect cells of the immune. The life cycle begins with the penetration of the virus into the host cell. Structure classification multiplication cultivation and replication nonviral infectious agent teratogeniconcogenic viruses have a host range. After fusion, the virus releases rna, its genetic material, into the host cell. Human immunodeficiency virus hiv is a complex rna virus of the genus lentivirus within the retroviridae family. These states have been elucidated by transmission electron microscopy tem and closely correlated to viral functions using wildtype virus as well as a variety of functional.

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. Although the structure of hiv1 ma has been well characterized, several. Mar 22, 2019 the life cycle of the hiv virus is a multistep process. Understanding the life cycle of hiv has made it possible to develop the drugs we use to treat the disease. It requires the presence of hepatitis b virus to complete its replication cycle. Each of these steps is used as a target to make hiv drugs to inhibit the progress of hiv infection. The hiv virus only infects cd4 cells because these cells express the receptors that help the hiv virus to enter the cells. Aim of this article is provide an overview of the structure of influenza virus and linking of the individual structures in the life cycle of influenza virion. Click above to view or download this fact sheet as a pdf slide presentation. The core consists of cylindrical capsid p24 which surrounds the genome. Effectively, the virus has now hijacked the host cells own replication system. The life cycle of hiv and hiv disease december 2011possible benefits of starting at 350500 an increasing number of observational results and early clinical studies suggest lower rates of aids and other healthrelated conditions and death. Viral specificity refers to the specific kinds of cells a virus can. The initial event in the viral life cycle is the interaction of one or more viral surface proteins with specific components present on the cell surface.

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. Thus, hiv 1 and hiv 2 each had a zoonotic origin but now spread directly from human to human. Virus structure forms of viruses virus structure types. As a result, when the cellular dna is transcribed, so is the viral dna to form an rna. Two major types of the aids virus, hiv 1 and hiv 2, have been identified. An rna secondary structure determined by shape analysis has shown to contain three stem loops and is located between the hiv protease and reverse transcriptase genes. The structure of the human immunodeficiency virus hiv.