The Threat Of Human Immune System

Viruses are microscopic particles that invade and take over both eukaryotic and prokaryotic cells. They consist of two structures, which are the nucleic acid and capsid. The nucleic acid contains all genetic material in the form of DNA or RNA, and is enclosed in the capsid, which is the protein coating that helps the virus attach to and penetrate the host cell. In some cases, certain viruses have a membrane surrounding the capsid, called an envelope. This structure allows viruses to become more stealthy and protected. There are two cycles in which a virus can go into: lytic and lysogenic. The lytic cycle consists of the virus attaching to a cell, injecting its DNA, and creating more viruses, which proceed to destroy the host. On the other hand, the lysogenic cycle includes the virus attaching to the cell, injecting its DNA, which combines with the cell’s DNA in order for it to become provirus. Then, the provirus DNA may eventually switch to the lytic cycle and destroy the host.

The immune system plays a vital role in helping the body to fight diseases, as well as pathogens, the disease-causing factors. It is mainly composed of the tonsils and adenoids, the lymph nodes and lymphatic vessels, the spleen, appendix, and bone marrow. The main purpose of the immune system is to assist the body in its struggle to maintain optimal health.

On encountering a host cell, the retrovirus attaches itself to receptors on the surface of the host cell’s membrane. Once inside the cell, the capsid opens, releasing RNA and reverse transcriptase into the cell’s cytoplasm.

The virus fuses with the cell’s plasma membrane. The capsid proteins are removed, releasing the viral proteins and RNA. Reverse transcriptase catalyzes the synthesis of a DNA strand complementary to the viral RNA. Reverse transcriptase catalyzes the synthesis of a second DNA strand complementary to the first. The double-stranded DNA is incorporated as a provirus into the cell’s DNA. Proviral genes are transcribed into RNA molecules, which serve as genomes for the next viral generation and as mRNAs for translation into viral proteins. The viral proteins include capsid proteins and reverse transcriptase (made in the cytosol) and envelope glycoproteins (made in the ER). Vesicles transport the glycoproteins from the ER to the cell’s plasma membrane. Capsids are assembled around viral genomes and reverse transcriptase molecules. New viruses bud off from the host cell.

CD4 is a glycoprotein found on the surface of immune cells such as T helper cells, monocytes, macrophages, and dendritic cells. HIV infects cells of the immune system called T lymphocytes (T cells) and macrophages. HIV has an envelope and contains two copies of single-stranded RNA as the genome. Within the viral capsid are important viral enzymes called reverse transcriptase, integrase, and protease. The HIV virus has a spike protein that is called gp120, and the host cell receptor is CD4+. HIV belongs to a class of viruses called retroviruses. Retroviruses are RNA viruses, and to replicate or reproduce, they must make a DNA copy of their RNA through transcription and translation. It is the DNA genes that allow the

Entering human body is not easy. The bacteria and other harmful materials can enter human body either via food or cuts and injuries on the skin. However, there foreign agents are not always welcomed in the human body. There are immune cells that fight harmful agents. The immunity system in the human body identifies harmful microbes like bacteria, viruses, and others and provides defense to the body against these substances. There are antigens present in viruses, fungi, or bacteria and these antigens are normally proteins or toxins, chemicals, drugs, etc. that show the presence of foreign harmful agent. The immunity system of man identifies these antigens and fights the microbes producing them.

The virus starts by getting a host cell and either uses it right away then kills it or kills right away usually they use it first. When the virus invades a body, It collides with the cell that spicks and propherances then they brush against each other and it if they fit together become one. The viruses is also able to hide from the immune system therefore avoiding being killed so it can reproduce. Then the virus gains control of a cell by injecting its genes into the cell and makes it do whatever it wants for the benefits of the virus not the cell. Of course while you have a cell doing the dirty work for you. The viruses make is own offspring/ copies of itself and takes of over and invading surrounding cells.

Some viruses also have an outer bag of lipo-protein called an envelope. After a virus attaches to a living cell, it either enters the cell to release the genetic information, or, the virus injects the information through the cells outer lining. Thus changing the cells natural functions and forcing the cell to spend its energy to create copies of the virus. The cell will go on making copies of the virus until the cell is used up and dies. The virus then leaves the dead cell and invades a nearby cell and the process starts all over. There are five types of human herpes virus: Varicella zoster which causes chickenpox, Epstein Barr virus which causes infectious mononucleosis, cytomegalovirus which can cause cytomegalic inclusion disease in infants, and herpes simplex viruses 1 and 2.

The virus is now travelling inside a sac made from your cell 's membrane. The virus’s genetic material enters the nucleus, and the virus is cloned. Now thousands even millions of new virus’ are in now your body, and taking over

The virus replicates in the cytoplasm of the host cell. DNA replication and transcription may start immediately as the virus itself contains enzymes for replication and transcription. It does not rely on the host cell enzymes to begin replication (Koplow 2003). First, the DNA and RNA polymerase are made, along with other transcription

The G protein binds to cells and starts the infection. The virus __uncoats__ inside the cell, which means that the RNP is released into the cytoplasm where viral replication take place. The first step is for the virus to make its proteins. The viral RNA is used as a template for the L protein to transcribe messenger RNAs (mRNAs). These mRNAs tell the cell's ribosomes to make viral proteins instead of the cell's proteins. Once enough viral proteins are made, the L protein starts to make new copies of the viral genome. This RNA is bound by new copies of the L, P, and N protein forming new RNPs. These are covered with M protein and then gain an envelope with the G protein as it leaves the cell forming a new infectious

Targeting mainly the non-ciliated epithelial cells of lung, airway and alveoli do to the spike and its specific receptors. The Coronavirus goes through six steps; the first step is called attachment. This step involves the spike, where it bonds to a specific receptor on the membrane of the host cell, like the MERS-CoV and the lung cells. Second step is penetrating, which involves the endocytosis or fusion between the viral and cell membranes and the release of the nucleocapsid into the cell. The third and fourth step are Biosynthesis and Maturation which is explain in detail by Susan and Sonia, After receptor interaction and fusion of viral and plasma membranes, virus-specific RNA and proteins are synthesized, probably entirely in the cytoplasm. Expression of coronaviruses starts with translation of two polyproteins, pp1a and pp1ab, which undergo translational proteolysis processing into the proteins that form the replicas complex. This complex is used to transcribe a 3′-coterminal set of nested subgenomic mRNAs, as well as genomic RNA, that have a common 5′ “leader” sequence derived from the 5′ end of the genome. Proteins are translated from the 5′ end of each mRNA. New virions are assembled by budding into intracellular membranes and released through vesicles by the cell secretory mechanisms. Once the viral is released then it can go and infect others cells in the body or just that specific cell. Although the main

b) Fusion is another way viruses can enter the host cell, however only an enveloped virus can do so in this process. To enter the cell an enveloped virus has a structure known as the spikes, the spikes will than need to attach on the receptor cell to gain entry to the cell. capsid and chromosome are allowed entry in the cell and the spikes are left behind. 1111111

The protective capsid helps the virus escape detection and destruction during the invasion of the host. When the virus reaches the target cell, biochemical reactions between the capsid and cell wall allow the virus to latch on and inject its genome into the cell’s interior. Once inside, the viral genetic material insinuates itself into the host’s DNA or RNA. In an efficient feat of natural bioengineering, the host cell’s genetic machinery now does the rest of the work for the virus. The cell, which had already been making copies of its own genome, now also replicates that of the virus. Coded within the viral material is the blueprint for making more copies of the viral genome. Further instructions command the production of capsids and directions for assembly of new viruses. After the host cell becomes engorged with viruses, it explodes, sending the new

The HIV-1 virion is approximately 120 nm in diameter, roughly spherical, and is composed of two copies of a single stranded positive sense RNA enclosed by a capsid (24). The HIV-1 genome is less than 10 kb and encodes for more than nine different gene products. It encodes for 3 major structural protein genes: gag (group-specific antigen), pol (DNA polymerase), and env (Envelope), which code for major structural proteins and essential enzymes. Gag generates the mature Gag protein matrix (MA or p17), capsid (CA or p24), nucleocapsid (NC or p7), and p6, which encompass proteins for the basic infrastructure of the virus such as the inner core of the viral particle (25). Pol encodes for reverse transcriptase (RT), which enables the virus to reproduce, integrase (IN), which is necessary to integrate the viral double stranded DNA into the host genome, RNAse H, and HIV protease, which are all encapsulated in the core of the inner particle formed by the viral capsid protein p24 (25). Env encodes for glycoproteins of the outer membrane such as outer gp120 (which enables the virus to attach and fuse to cells of the host), and transmembrane gp41 that anchors the glycoprotein complex to the surface of the virion (25). Between the core and the envelope is the HIV matrix proteins which are composed of the viral protein p17 (23). HIV-1 also encodes for proteins with important regulatory elements (tat (Trans-Activator of Transcription) and rev