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Protegen IntoductionHuman and animal health is threatened by various diseases every day. Acquired as a result of pathogenic microbial agents, infectious diseases are still a major source of mortality throughout the world, contributing to 26% of global mortality in 2001. Of these mortalities, 90% are caused by illnesses such as acute respiratory infections, diarrhoeal diseases, malaria, AIDS, tuberculosis, and measles. Cancer, allergy, and many other diseases also cause significant mortality and morbidity in human and animal victims. Vaccines stimulate the immune system and confer protection against pathogenic microorganisms, offering a safe effective method to prevent disease. Vaccines are among the most useful and cost-effective tools for reducing the morbidity and mortality caused by infectious diseases. Vaccination programs have succeeded in eliminating smallpox from the world population as well as in drastically reducing the incidences of other diseases such as polio. Measles, one of the six major illnesses responsible for mortality mentioned above, can now be prevented by vaccination. Vaccines are also being developed for fighting against other diseases such as cancer and allergy. At the forefront of this vaccine development are protective antigens. Protective antigens are those antigens that are specifically targeted by the acquired immune response of the host, and when introduced into the host body, are able to stimulate the production of antibodies and/or cell-mediated immunity against certain pathogens or the causes of other diseases. Protective antigens can be used in many research areas. First, identification of protective antigens is a major component of research for new and improved vaccines against infection diseases. Using these protective antigens, researchers are able to develop vaccines, especially DNA and subunit vaccines, which use targeted DNA or proteins of a pathogen to elicit a protective immune response. These vaccines have shown great potential in the fight against diseases such as malaria for which there is no current vaccine. Protective antigens are also useful in the control of allergies through the use of allergen immunotherapy. This process uses repeated exposure to allergenic antigens in order to create immunologic tolerance in an individual to the allergen. Many cancer vaccines are currently in clinical trials. In addition, protective antigens can often be used as biological markers for to diagnosis of diseases such as AIDS based on the presence or absence of the protective antigen. Furthermore, the identification of protective antigens and the study of their roles in the induction of host immunity against various diseases are crucial to the better understanding of fundamental host immune mechanism. While intensive research has been conducted and resulted in identification of many protective antigens, these is no reported central resource that allows storage, annotation, comparison, and analysis of protective antigens across different pathogens and within different hosts. To address this challenge, we have developed Protegen (http://www.violinet.org/protegen), a web-based protective antigen database and analysis system. Protegen stores manually curated protective antigens and associated information. It also allows bioinformatics analysis and comparison of various protective antigens. We believe that Protegen is a timely repository and will have significant impact for vaccine research and development. Currently, Protegen has included more than 500 protective antigens for over 90 pathogens, for example, Bacillus anthracis (anthrax), Brucella spp. (brucellosis), Yersinia pestis (Plague), Human immunodeficiency virus (HIV, the causative agent of AIDS), Ebola virus (hemorrhagic fever), and Plasmodium spp. (malaria). Protegen also stores more than 50 protective antigens for cancer and allergy. Many of the annotated protective antigens are currently under internal review and will be posted soon. Protegen is expected to become a central and vital source of protective antigens and will support researchers in the areas of vaccinology, microbiology, and immunology with curated data and bioinformatics tools.
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