History Snake venom is a potentially lethal and complex mixture of

History Snake venom is a potentially lethal and complex mixture of hundreds of functionally diverse proteins that are hard to purify and hence hard to characterize. victim thus increasing the risk of anaphylactoid and serum sickness adverse effects. Here we exploit recent molecular sequence R306465 analysis and DNA immunization tools to design more rational toxin-targeted antivenom. Methods and Findings We developed a novel bioinformatic strategy that recognized sequences encoding immunogenic and structurally significant epitopes from an expressed sequence tag database of a venom gland cDNA library of the most medically important viper in Africa. Focusing upon snake venom metalloproteinases (SVMPs) that are responsible for the severe and frequently lethal hemorrhage in envenomed victims we recognized seven epitopes that we predicted would be represented in all isomers of this multimeric toxin and that we engineered into a single synthetic multiepitope DNA immunogen (epitope string). We compared the specificity and toxin-neutralizing efficacy of antiserum raised against the string to antisera raised against a single SVMP toxin (or domains) or antiserum raised by standard (whole venom) immunization protocols. The SVMP Rabbit Polyclonal to HSF2. string antiserum as predicted in silico contained antibody specificities to numerous SVMPs in venom and venoms of several other African vipers. More significantly the antiserum R306465 cross-specifically neutralized hemorrhage induced by and venoms. Conclusions These data provide valuable sequence and structure/function information of viper venom hemorrhagins but more importantly a new opportunity to design toxin-specific antivenoms-the first major conceptual switch in antivenom design after more than a century of production. Furthermore this approach may be adapted to immunotherapy design in other cases where targets are numerous diverse and poorly characterized such as those generated by hypermutation or antigenic variance. Editors’ Summary Background. Of the 3 0 species of snakes worldwide about 600 are poisonous; poisonous snakes are a particular problem in Africa and Southeast Asia. Because not all victims of snake bites get to hospital estimates of illness and death caused are very approximate. However one estimate quoted by the World Health Organization is usually that 2.5 million snake bites occur each year and 125 0 are fatal. The effects of snake bites vary obviously depending on which snake does the biting but immediate effects include swelling (round the bite or of other parts of the body) death of the area round the bite and blood clotting problems. Nowadays snake bite is usually treated with “antivenoms ” which are usually made from immunizing horses or sheep with snake venom. However these antivenoms contain many different proteins that can themselves trigger unpleasant reactions in the recipient. One problem with developing antivenoms is usually that venoms contain many hundreds of different proteins many of which may contribute to the harmful effect. Why Was This Study Done? Recent scientific discoveries have led to new ways of obtaining which parts of an animal’s genetic sequence are active in any one specific part of the body and also whether the proteins produced from these genes are likely to cause illness. A snake’s venom gland where R306465 the venom is made can be analysed this way. The experts wanted to R306465 use this information to develop R306465 a more rational way of designing antivenoms. What Did the Researchers Do and Find? They analyzed the venom glands of the carpet viper the most medically important snake in West Africa. They isolated expressed sequence tags (ESTs) produced by the venom glands. Each EST is usually a small part of the active a part of a gene. They then focused on one group of genes that make proteins called snake venom metalloproteinases (SVMPs) which eliminate other proteins and which cause many of the severe symptoms such as bleeding seen after snake bite. They recognized seven parts of these SVMPs that were likely to be clinically important and designed them into a single string of DNA. This product is known as an immunogen-that is it can produce an immune response in an animal. And when this immunogen was injected into mice the experts found that the serum (the part of the blood that contains antibodies) from these mice did have a specific effect against the SVMPs in snake venom. It also had some effect again in mice against bleeding caused by small doses of snake venom. What Do These Findings Mean? These results suggest that it is possible to use some of the newest genetic techniques to design immunogens that can be used to make highly.