Vaccine development against viruses

An example of the use of an attenuated virus is the administration of the measles vaccine to an individual who has not had measles. The m easles (rubeola) vaccine contains the live, attenuated measles virus. The individual receiving the vaccine develops a mild or modified measles infection, which then produces immunity against the rubeola virus. The measles vaccine protects 95% of the recipients for several years or, for some individuals, for life. An example of a killed virus used for immunization is the cholera vaccine. This vaccine protects those who receive the vacdne for about 3 to 6 months. 

Ideally, the most effective prevention of HIV infection would be a vaccine that blocks virus infection in individuals. Indeed, effective vaccines have been developed against most human viruses that cause serious diseases. While several different possible vaccines against HIV are under development, there are some theoretical reasons why it may be difficult to develop an effective one. First, HIV has the unique ability to evade the immune system in an infected individual. Briefly, this results from (1) the high mutation rate of the virus, particularly in the env gene (2) the ability of the virus to establish a latent state in some cells and (3) the ability of the virus to spread by cell-to-cell contact. The object of the vaccine is to raise a protective immune response to the infectious agent. Since HIV evades the immune system so efficiently, it may be difficult for a vaccine to prevent HIV infection in an individual, even if it can induce production of neutralizing antibodies or cell-mediated immunity. 

The main objective of immunization against viruses is the prevention or modification of the disease. However, most of the existing classical vaccines are able to prevent the disease but are not so efficient in preventing infection (Sandhu, 1994 Ellis, 1999). The development of the recombinant DNA technology made possible the creation of vaccines that do not present the typical side effects of the vaccines of attenuated or inactivated viruses. Virus-like particles (VLPs) are one of the new vaccine strategies arising from recombinant DNA technology. 

Effective vaccines have been developed against which virus... 

Pasteur s further research included investigating the diseases that plagued the French silk industry. He developed a means of vaccinating sheep against infection by Bacillus anthracis and a vaccine to protect chickens against cholera. Pasteur s most impressive achievement may have been the development of a treatment effective against the rabies virus for people bitten by rabid dogs or wolves. 

Chemical research is driven by many goals, and it progresses in many different ways. The essential traits of a good researcher are curiosity, creativity, flexibility, and dedication. Some chemical advances come from a direct assault on a known problem. A classic example is the development of the Hall process for refining aluminum from its ores, which we describe in Chapter 21,. As a contemporary example, many scientists around the world are working at a feverish pace to develop a vaccine against the AIDS virus. 

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