New hope for vaccine against schistosomiasis

Article Abstract:

A report is presented from a recent meeting concerning vaccines under development against schistosomiasis, a parasitic disease that affects as many as 200 million people worldwide. Andre Capron, an immunologist, is planning to inject himself and colleagues with a new version he has developed to demonstrate its safety. Although the World Health Organization (WHO), who convened the meeting, formerly advocated control of sanitation and use of praziquantel (a drug that kills the adult form of the parasite) to fight the disease, it has now assigned vaccine development a high priority. Even though the parasite is problematic because of its many strategies for foiling the host's immune system, the fact that some people develop resistance to the infection indicates that a vaccine could work. Moreover, even a significant reduction in the number of worms in the body would be of considerable health advantage, since it is large numbers of parasites that cause severe consequences: a vaccine does not have to eradicate all infectious agents. Capron's group has cloned several genes that encode proteins produced by the parasite. The most promising for use as a vaccine is p28GST, excreted by the adult worm. Other research groups also have candidate vaccines; their efforts are described. WHO expressed concern over whether a vaccine would be more effective than a yearly dose of praziquantel, an expensive drug that currently reaches a small proportion of the people who need it. An undesirable consequence of vaccination could be a loss of effectiveness of praziquantel. Capron's vaccine could also cause autoimmune diseases (in which the body attacks its own proteins); the researcher has found no signs of such reactions. If the safety of his vaccine is assured, it will probably be tested first in Senegal, site of a schistosomiasis outbreak. The European Community funds a research project for schistosomiasis, involving 10 laboratories, a treatment center in Senegal, and a five-year program. Capron hopes his vaccine will be part of these efforts. (Consumer Summary produced by Reliance Medical Information, Inc.)

Conferences, meetings and seminars, Schistosomiasis, Parasite vaccines, Capron, Andre

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Hope for AIDS vaccines

Article Abstract:

Scientists who once thought an AIDS vaccine would be very difficult to develop are now growing more optimistic. Researchers are pursuing several new approaches, any one of which might prove successful. One vaccine has been tested on human volunteers and its only side effect was a mild stinging while it effectively stimulated the immune system. The vaccine was made from one of the proteins of the human immunodeficiency virus (HIV) grown in yeast cells. Another group of researchers is giving simian immunodeficiency virus (SIV) from African monkeys to Asian macaque monkeys; the virus cells have been killed beforehand. The killed SIV has protected the recipients so far from the live AIDS virus that was injected afterwards. The question is whether the monkeys will develop AIDS in the near future, since the vaccine may only be delaying onset of the disease. AIDS researchers agree that the most promising animal model for testing human AIDS vaccines is a strain of mouse called scid-hu. These mice have a genetic disease with effects similar to AIDS called severe combined immune deficiency (scid). Scientists are transplanting human immune cells into the mice to set up a tiny model of the human immune system. Experimental vaccines could be tested in the mice before giving them to human volunteers. Other investigators are using genetic engineering techniques to create a version of HIV that will prompt the human immune system to fight it more quickly and vigorously than the original HIV. This more virulent (potent) virus could act as a vaccine, stimulating the immune system to build up protection against subsequent exposure to the real AIDS virus. Scientists are concerned that they will have difficulty finding human volunteers for any tests of AIDS vaccines.

Models, HIV (Viruses), HIV, Control

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A perspective on AIDS vaccines

Article Abstract:

Questions are answered that may help scientists determine if more basic research on AIDS vaccines should be undertaken before phase III trials of specific HIV vaccines are implemented. Questions pertain to topics such as the need for an AIDS vaccine and the difficulty of developing one.

AIDS research

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