Yellow Fever Vaccination Travel Centre
Travel vaccines are non-dangerous agents, thought of as enemies
. These molecules, mostly proteins but not always, they get a response from your immune system providing immunity against a potential pathogen. While the pathogen can be a bacterium or even a eukaryotic protozoan, most successful vaccines raised against viruses and here we shall deal mostly with anti-viral vaccines.All vaccinations work of presenting a foreign antigen to the immune system to evoke an immune response, but there are several ways to do this. Three of the most found types are:
* Inactivated vaccine consists of virus particles grown in culture and then killed using a method such as heat or formaldehyde. Virus particles are destroyed and can not replicate, but the virus capsid proteins are intact enough to be recognized by the immune system and elicit a response. When constructed correctly, the vaccine is not infectious, but improper inactivation can result in intact and infectious particles. Since the properly produced vaccine not reproduce, booster shots are required periodically to boost the immune system.
* An attenuated vaccine, live virus particles very low virulence are administered. They will reproduce very slowly. As the reproduce continually presenting antigens beyond the initial inoculation, booster injections are required less often. These vaccines are produced by culturing the virus in tissue cultures that choose to less virulent strains or by mutagenesis or targeted deletions in genes required for virulence. As always there are risks but a small risk of reversion to virulence, this risks are smaller in vaccine injections with deletions. Attenuated vaccines cant be used by people with poor immune systems.
* While an antigen is presented by a subunit vaccine without introducing viral particles to the immune system, whole or otherwise. Involve A method for producing the isolation of a specific protein from a virus and manage this by themselves. A weakness of this technique is that individual proteins can be denatured and will then bind to different antibodies than the proteins of the virus. Another method of subunit vaccine is the recombinant vaccine, which implies that a protein gene from the targeted virus into another virus. The second virus will express the protein, but will not pose a risk to the patient.
O Killed vaccines: These are preparations of the normal (wild type) infectious, pathogenic virus that has been made non-pathogenic, usually by chemical treatment, such as with formaldehyde cross-links viral proteins.
O-attenuated vaccines: These are live viruses that grow in the vaccine but do not cause disease because the vaccine virus has been altered (mutated) to a non-pathogenic form, for example, has its tropism modified so that it does not grow longer in a place can cause illness.
O sub-unit vaccines: This is the cleaned parts of the virus, such as a surface antigen.
Vaccination development comes with problems:
Many inherent problems while developing a good protective anti-viral vaccine.
Quite allot of these will be:
* Various types of the virus can cause similar diseases - eg G Cold. As a result, a single vaccine is not possible for such a disease
* antigenic drift and shift - Viruses with segmented genomes and especially RNA viruses.
* Compounds containing large animals - If these occur, reinfection after elimination from the human population can be
* With Viral DNA And Integration. latent virions are not affected by vaccines unless antigens are found on the cell surface. In addition, if the vaccine virus integrates into the host cell's chromosomes, can cause problems (This is, for example, a problem with the possible use of anti-HIV vaccines based on attenuated virus strains-see later )
* Transmission from cell to cell via syncytia - This is a problem for potential AIDS vaccines, since the virus can spread from cell to cell without the virus entering the circulation.
* Mutation of the vaccine and recombination of the vaccine virus in an attenuated vaccine.
Despite these problems, anti-viral vaccines, in some cases, spectacularly successful (Figure 1) has in one case (smallpox) to the elimination of the disease of the human population. The smallpox vaccine is an example of a weakened vaccine, but not of the original pathogenic smallpox virus. Another successful polio vaccine is the vaccine that could lead to the elimination of this disease in a human population in the coming years. There are two different forms of this vaccine. While the Slak vaccine is dead, as it has been killed, the Sabin is a live attenuated vaccine.
Polio is now restricted to parts of the UK and South Asia.
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