A retrovirus is a single-stranded RNA virus that stores its nucleic acid in the form of an mRNA genome and targets a host cell as an obligate parasite. The virus uses an enzyme reverse transcriptase to make DNA from its RNA strand as it enters the host cell. The newly formed virus DNA is incorporated in the host’s DNA using an enzyme called integrase. After it is inserted in the host’s genome, it is called a provirus. The cell then unknowingly transcribes the virus’ DNA and translated proteins necessary for the virus.
As the number of B cells increases, helper T cells signal them to start producing antibodies. Meanwhile, some of the viruses have entered cells of the body - the only place they are able to replicate. Killer T cells will sacrifice these cells by chemically puncturing their membranes, letting the contents spill out, thus disrupting the viral replication cycle. Antibodies then neutralize the viruses by binding directly to their surfaces, preventing them from attacking other cells. Additionally, they precipitate chemical reactions that actually destroy the infected cells.
2) A protein which is extremely important in a hazardous virus because is provides a strong, protective barrier as the virus passes from cell to cell.2 Viruses do not contain the enzymes and metabolic pressures needed for self-duplication. The missing components are taken from the host cells they infect. Replication begins when the virus enters the cell. The enzymes remove the coat of the virus, and the RNA or DNA particles come in contact with the ribosomes in the cell. The virus then finds the protein by using the nucleic acid.
As Joe Palca a science specialist says, Viruses are a cheaper way to provide gene therapy. The virus can be transfused into the patient’s blood where they will deliver the new genes to the cells. After the virus is injected it will do all the work. Someday genetic therapy will be as easy as modifying a virus and injecting it into the patient. Indeed, as Andrea Pavirani, a molecular biologist, says, "Viruses exist to remake themselves.
With this information scientists are able to learn how the individual viruses are able to cause disease in humans such as AIDS. Once the virus is decoded, scientists are then able to use computers to compare the virus to other viruses. This allows us to identify molecules in the virus that are worth targeting. There are stages that every virus must go through in order for it to infect the cell. During these steps the virus is extremely vulnerable and can be disrupted by pharmaceuticals.
Viruses: Complex Molecules or Simple Life Forms? Viruses have been defined as "entities whose genomes are elements of nucleic acid that replicate inside living cells using the cellular synthetic machinery, and cause the synthesis of specialised elements that can transfer the genome to other cells." They are stationaryand are unable to grow. Because of all these factors, it is debatable whether viruses are the most complex of molecules or the simplest life forms. While the definition of living organisms must be adapted, the majority of evidence leads to the classification of viruses as living organisms.
As they lack many structures that are needed for growth and replication like ribosomes, they are an obligatory intracellular parasites and need to invade living cells to produce their basic materials like proteins, amino acids and fats. Viruses invade living cells and use their machinery to produce specific proteins and synthesise their own genetic materials by integrating their DNA into host cells genome (Molecular Expressions, 2005). To achieve this, viruses need to be capable of recognising specific receptors on host cell surface which is the first step of viral invasion and pathogenesis. This recognition permits viral attachment to take place and facilitate viral entry into the host cell. This attachment occur between viral specific fusion proteins (ligands) ,such as M2 pore proteins on Influenza viruses and the trimeric rabies virus glycoprotein (RVG) on rabies virus, and the host cellular surface proteins (receptors) such as CD4 and CCR5 proteins on T helper cells.
In most gene therapy studies, a "normal" gene is inserted into the genome to replace an "abnormal," disease-causing gene. A carrier molecule called a vector must be used to deliver the therapeutic gene to the patient's target cells. Currently, the most common vector is a virus that has been genetically altered to carry normal human DNA. Viruses have evolved a way of encapsulating and delivering their genes to human cells in a pathogenic manner. Scientists have tried to take advantage of this capability and manipulate the virus genome to remove disease-causing genes and insert therapeutic genes.
While outside of a host cell, it is known as a virion. It will not be known as a virus until it infects a host. A virus depends on this ‘host cell’. The capsid of the virus captures either Deoxyribonucleic acid or Ribonucleic acid, which it then uses to “code” it’s actions. It uses the host cell to produce more of its viral proteins and other products for the virus rather than what the cell should be making.
After a virus has gained control of the cells, it influences those same cells to make new imitations of the virus. Viruses are largely composed of protein, which grants protection for its genomic operator restricted in a DNA, most commonly known as RNA, molecule. (Sodora & Silvestri, 2008). Viruses enclose an insignificant number of genes, the average virus possessing from about 10 to 15 genes, some additional complex viruses are known to possessing up to two hundred genes. Virus infections often generate a response by the immune system after detection and antibodies are manufactured, these antibodies tend to be are specific for the particular virus attacking the body.