The 7 stages of HIV Life Cycle or Steps of HIV Replication
- Binding or Attachment stage
- Fusion stage
- Reverse transcription
- Replication
- Integration
- Assembly
- Budding
What are the 4 steps of viral replication?
the virus connects to a specific host cell (1st step.) the virus injects its nucleic acid into the host cell (second step.) the virus nucleic acid takes over the cell and causes the cell to make 100s of new parts (3rd step.) the virus parts are put together (4th step.)
What are the stages of HIV replication?
The HIV life cycle is typically divided into seven distinct stages, from the attachment of the virus to the host cell to the budding of new free-circulating HIV virions ( pictured ). The stages are outlined in sequential orders as follows: 1. Viral attachment. Binding and fusing.
How is the last stage in the viral replication?
The last stage of viral replication is the release of the new virions produced in the host organism. They are then able to infect adjacent cells and repeat the replication cycle. As you have learned, some viruses are released when the host cell dies, while other viruses can leave infected cells by budding through the membrane without directly ...
How to tell the stage of HIV?
- CD4 T cell count. CD4 T cells are white blood cells that are specifically targeted and destroyed by HIV. ...
- Viral load (HIV RNA). This test measures the amount of virus in your blood. After starting HIV treatment the goal is to have an undetectable viral load. ...
- Drug resistance. Some strains of HIV are resistant to medications. ...
What is the replication of HIV?
When viruses reproduce it is called replication. HIV uses CD4 immune cells to replicate. And each infected CD4 cell produces hundreds of new copies of new HIV particles. The process is called the HIV lifecycle.
What are the four steps of HIV?
Stages of HIV InfectionStages of Infection – (assuming no treatment) ... Stage 1: Infection. ... Stage 2: Asymptomatic. ... Stage 3: Symptomatic. ... Stage 4: AIDS/Progression of HIV to AIDS.
Where does HIV replicate in the body?
Replication Because HIV is now integrated into your CD4 cell's DNA, it can use that cell's machinery to generate viral proteins. During this time, it can also produce more of its genetic material (RNA). These two things allow it to create more viral particles.
How does HIV enter cells and replicate?
To infect cells, the HIV protein envelope (Env) binds to the primary cellular receptor CD4 and then to a cellular coreceptor. This sequential binding triggers fusion of the viral and host cell membranes, initiating infection.
What is replication cycle?
Listen to pronunciation. (reh-plih-KAY-shun...) In biology, refers to the reproduction cycle of viruses. A repliction cycle begins with the infection of a host cell and ends with the release of mature progeny virus particles.
How do viruses replicate?
Viruses cannot replicate on their own, but rather depend on their host cell's protein synthesis pathways to reproduce. This typically occurs by the virus inserting its genetic material in host cells, co-opting the proteins to create viral replicates, until the cell bursts from the high volume of new viral particles.
How do virions go through the final stage of replication?
One the virions are assembled, they go through the final stage in which the mature virions literally buds from the infected host cell. Once released into free circulation, these virions go on to infect other host cell and begin the replication cycle yet again. 11
How does HIV reproduce?
HIV uses its genetic material (RNA) to reproduce by hijacking the genetic machine of the host cell. In doing so, it can churn out multiple copies of itself. The process, called viral uncoating, requires that the protective coating surrounding the RNA must be dissolved.
What are the stages of HIV?
The HIV life cycle is typically divided into seven distinct stages, from the attachment of the virus to the host cell to the budding of new free-circulating HIV virions ( pictured ). The stages are outlined in sequential orders as follows: 1 1 Viral attachment 2 Binding and fusing 3 Viral uncoating 4 Transcription and translation 5 Integration 6 Assembly 7 Maturation and budding
How does HIV hijack the host cell?
In order for HIV to hijack the host cell's genetic machinery, it must integrate the newly formed DNA into the nucleus of the cell. Drugs called integrase inhibitors are highly capable of blocking the integration stage by blocking the integrase enzyme used to transfer the genetic material. 8
How many stages are there in the HIV cycle?
The HIV life cycle is typically divided into seven distinct stages, from the attachment of the virus to the host cell to the budding of new free-circulating HIV virions ( pictured ). The stages are outlined in sequential orders as follows: 1
What drugs block replication?
Drugs called reverse transcriptase inhibitors can block this process entirely. Three types of drug, nucleoside reverse transcriptase inhibitors (NRTIs), nucleotide transcriptase inhibi tors (NtRTIs) and non-nucleoside reverse transcriptase inhibitors (NNRTIs), contain faulty imitations of the proteins which insert themselves into the developing DNA. In doing so, the double-stranded DNA chain cannot be fully formed, and replication is blocked. 7
What happens when HIV is attached to a cell?
Once attached to the cell, HIV injects proteins of its own into the cellular fluids (cytoplasm) of the T-cell. This causes a fusion of the cell membrane to the outer envelope of the HIV vir ion. This is the stage known as viral fusion. Once fused, the virus is able to enter the cell. 4
How many stages of HIV replication?
HIV Replication or HIV Life Cycle refers to how the HIV virus reproduces itself using the genetic makeup of the Host cell (Human cell). There are seven (7) stages or steps of the HIV Virus replication cycle. Each of these steps is used as a target to make HIV drugs to inhibit the progress of HIV infection. This means that there are drugs that have ...
How does HIV replicate?
For a HIV virus to replicate, it must change from RNA (RiboNucleic Acid) to DNA (DeoxyriboNucleic Acid); for HIV to effect this change, it uses a protein (enzyme) called Reverse Transcriptase. This enzyme then changes the HIV RNA to HIV DNA.
Why does HIV only infect CD4 cells?
The HIV virus only infects CD4 cells because these cells express the receptors that help the HIV virus to enter the cells. It is due to this infection that the HIV brings down the immune system of the body because the CD4 cells maintain the immunity of the body.
What is the binding stage of HIV?
Binding stage of HIV Life Cycle. 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. The HIV virus only infects CD4 cells because these cells express ...
What happens after the virus is bound to a CD4 cell?
After binding to the CD4 cell, the HIV virus then fuses its envelope (which serves as the covering of the virus) with the cell membrane of the CD4 cell. This enables the Virus to gain entry into the CD4 cell.
How many stages are there in the HIV cycle?
These are the 7 stages of HIV Replication Cycle and their associated classes of drugs used for blocking the steps in HIV Replication cycle (HIV Life cycle).
Where do HIV long chains move?
Once the HIV long chains proteins are produced, they move out of the Nucleus to the surface of the CD4 membrane to assemble into immature noninfectious HIV.
What is the site of action of protease inhibitors?
Viral RNAs are translated, yielding viral enzymes(including protease) and structural proteins, this is the site of action of protease inhibitor
What is the function of DNA circularize?
DNA circularize (unintegrated provirus) or intergrase functions to incorporate DNA into host cell genome(integrated provirus), this is the site of action of antiretrovial drugs under development
How many stages are there in the HIV cycle?
The seven stages of the HIV life cycle are: 1) binding, 2) fusion, 3) reverse transcription, 4) integration, 5) replication, 6) assembly, and 7) budding. To understand each stage in the HIV life cycle, it helps to first imagine what HIV looks like. Now follow each stage in the HIV life cycle, as HIV attacks a CD4 cell and uses the machinery ...
What is the life cycle of HIV?
What is the HIV life cycle? HIV attacks and destroys the CD4 cells of the immune system. CD4 cells are a type of white blood cell that play a major role in protecting the body from infection. HIV uses the machinery of the CD4 cells to multiply and spread throughout the body.
How does HIV medicine work?
People on ART take a combination of HIV medicines (called an HIV regimen) every day. HIV medicines protect the immune system by blocking HIV at different stages of the HIV life cycle. HIV medicines are grouped into different drug classes according to how they fight HIV. Each class of drugs is designed to target a specific step in the HIV life cycle.
What is the role of CD4 cells in HIV?
CD4 cells play a major role in protecting the body from infection. HIV uses the machinery of the CD4 cells to multiply and spread throughout the body. This process, which is carried out in seven steps or stages, is called the HIV life cycle.
Why is ART important for HIV?
Because an HIV regimen includes HIV medicines from at least two different HIV drug classes, ART is very effective at preventing HIV from multiplying. Having less HIV in the body protects the immune system and prevents HIV from advancing to AIDS.
How does HIV replicate?
HIV replicates by combining its genetic information with the genetic information of your CD4 white blood cells.
How many stages are there in the HIV cycle?
The replication cycle, or life cycle, of HIV can be divided into seven stages. Medications that treat HIV interrupt one of the seven stages of the HIV lifecycle.
What happens during the assembly stage of HIV?
In the assembly stage, new HIV proteins and RNA are sent to the edge of your CD4 cell and become immature HIV. These viruses are non-infectious in their current form.
What allows the virus to enter the cell?
Fusing with the membrane of your CD4 cells allows the virus to enter the cell.
How does HIV affect CD4 cells?
Because HIV is now integrated into your CD4 cell’s DNA, it can use that cell’s machinery to generate viral proteins. During this time, it can also produce more of its genetic material (RNA). These two things allow it to create more viral particles.
What is the goal of antiretroviral therapy?
The primary goals of antiretroviral therapy are to prevent HIV from replicating and suppressing your viral load to a point where it’s no longer detectable.
What is the name of the group of viruses that HIV falls into?
HIV falls into a group of viruses called retroviruses. These viruses are challenging to get rid of because they integrate with the host cell’s DNA as part of their life cycle.
How many stages of the HIV cycle are there?
The 7 stages of the HIV life cycle explained. This is the very first stage of the HIV Lifecycle. The HIV virus attacks the CD4 cell and attaches Itself to the cell on its surface. It does this by first attaching to the CD4 cell’s receptor than the CCR5 or the CXCR4 coreceptor.
What is the second stage of the HIV cycle?
The second stage of the HIV life cycle is called fusion and this is done after the virus has effectively attached itself to the CD4 cell. The entire HIV viral envelope will then fuse with the cell which allows it to gain entry into it. #3 Reverse Transcriptase. The third stage happens once the HIV virus has entered the CD4 cell.
What enzyme is released when HIV enters the cell?
#4 Integration. When the HIV virus has successfully entered the CD4 cells nucleus it releases another HIV enzyme known as integrase.
What is the final stage of HIV?
The final stage of the HIV life cycle is when the immature HIV is released from within the infected CD 4 that produced it. Being an immature HIV, it is unable to infect another CD4 cell, so it releases another HIV enzyme known as a protease. The function of This enzyme is to break up the long chains of proteins forming the immature HIV.
How long does it take for HIV to multiply?
Thus the infection is established. HIV multiply in mucosa and there is 4-11 days between mucosal infection and initial viremia.
What is the pathogenesis of HIV?
Pathogenesis of HIV/AIDS. Pathogenesis of HIV can be described under following headings. 1. Mode of transmission: HIV infection is acquired through one of the following routes. Sexual contact; infected partner. Parental route; infected needles or syringes. Congenital route; infected mother giving birth . 2.
What is the process of integrating viral DNA into host DNA?
This type of integrated viral DNA into host DNA is known as Pro-virus . Once the viral DNA is integrated, infection of HIV is permanent.
How is viral RNA used to synthesize DNA?
Viral RNA is then used to synthesize ds DNA by the enzyme reverse transcriptase (RNA dependent DNA polymerase). The ds DNA is then circularized and enter into host cell nucleus.
What is the test for anti-viral antibody?
Serology: detection of anti-viral antibody using ELISA. This test detects serum antibody against gp120, gp41, P24 etc. The first positive result must be confirmed by at least 2 other different assays with different viral antigen.
What type of cell is HIV?
HIV uses CD4 molecule as a receptor which is present in CD4+ cells such as T-lymphocytes, macrophages, monocytes, dendritic cells other and Antigen presenting cells.
How long does it take for ARS to resolve?
meningitis, encephalitis. All these symptoms resolves within 5-30 days. 2. Clinical latency and incubation to AIDS. ARS is followed by long period of clinical latency which is free of any clinical symptoms. Clinical latency is maintained because of host immune response against HIV.
