Review articleVaccines for prevention of cysticercosis
Introduction
Neurocysticercosis due to Taenia solium is well recognised as an important cause of human morbidity and mortality. Currently available measures for control of the disease are inadequate and there is a need for new and improved interventions. A strong argument can be made for vaccination playing a key role in T. solium control (Lightowlers, 1999). The vision to which we aspire is of a vaccine which can prevent T. solium being transmitted by pigs, the parasite's natural intermediate host; a highly effective vaccine, able to prevent infections in neonates as well as older pigs, an inexpensive vaccine which can be delivered via an edible biscuit, without the need for equipment or trained personnel. Through the combined use of anthelmintic treatment of tapeworm carriers, vaccination of pigs and public education about the disease, the parasite could be eradicated. This is a vision for the future, because the vaccine required does not currently exist. However, these are good reasons to believe that such a vaccine will be achievable and the recent demonstration of complete protection against cysticercosis in pigs using a recombinant oncosphere antigen (discussed below) highlights the rapid progress being made towards the development of a practical vaccine.
Several approaches are being used by different research groups towards the development of a vaccine to prevent porcine cysticercosis. These approaches are reviewed here with emphasis on the application of recombinant oncosphere antigens for vaccine development.
Section snippets
General aspects of the immunobiology of taeniid cestode infections
T. solium belongs to the cestode family Taeniidae which comprises two genera, Taenia and Echinococcus. There are a number of species, including several which infect humans, causing disease, or infect domestic livestock and cause economic loss. The economic and medical significance of these parasites has stimulated a substantial amount of research into the biology of the group, and their immunobiology in particular. Many of the immunological characteristics of the host–parasite relationship
Development of recombinant vaccines against cysticercosis in sheep and cattle
The recombinant antigen vaccine which was developed against cysticercosis caused by T. ovis in sheep (Johnson et al., 1989) was the first effective, defined antigen vaccine against a parasitic infection and has been recognised as a milestone in the history of parasitology (Cox, 1993). The T. ovis vaccine received provisional registration as a commercial vaccine in New Zealand in August 1990 although this was not followed by marketing due to commercial considerations (Rickard et al., 1995); the
Protection against cysticercosis in pigs using oncosphere antigens
In common with all other taeniid cestodes which have been investigated, oncosphere antigens of T. solium have been found to be a rich source of host-protective antigens (Pathak and Gaur, 1990, Plancarte et al., 1999, Verastegui et al., 2002). The rapid success which had been achieved with identifying host-protective recombinant antigens for T. saginata, encouraged the adoption of a similar approach for development of a vaccine against T. solium cysticercosis in pigs.
Investigations using
Other approaches to development of a vaccine against T. solium
Antigens derived from the rodent parasite Taenia crassiceps are being used as a potential source of host-protective antigens for T. solium. This concept is based on the well-established immunological cross-reactivity between host-protective antigens derived from different taeniid cestode species. Toledo et al. (1999) investigated recombinant antigens of T. crassiceps and identified proteins which could be used to vaccinate mice against an intraperitoneal challenge with the parasite's
Concluding remarks
The prospects are bright for the successful development of an effective, practical vaccine to assist with control of transmission of T. solium. The vision for a vaccine with the features expressed at the beginning of this article may not be attained for some time, however, the crucial beginnings have already been accomplished successfully and now vaccine delivery looms as a critical issue for implementation of a vaccine for T. solium cysticercosis. The vision for an edible, non-living vaccine
Acknowledgments
The author wishes to acknowledge the contributions made to the research program on taeniid vaccine development made by Charles Gauci and also by collaborating scientists with a special interest in development of a vaccine against T. solium, particularly Ana Flisser, Hector Garcia, Armando Gonzáles, André Zoli and Stanny Geerts. Charles Gauci made valuable comments in reviewing the manuscript. Funding to the author's laboratory is acknowledged from the National Health and Medical Research
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2013, Trends in ParasitologyCitation Excerpt :Owing to the loss of income, villagers are aware of cysticercosis and ask for treatment of pigs via a single dose of oxfendazole [98]. In the same line, vaccination of pigs with recombinant antigens could also be a promising approach proposed to villagers [9,105]. However, the detection of cysticercosis by a rapid test, available at the farm gate, might be the simplest asset in autocontrol of the quality of the meat by producers themselves.
The highly antigenic 53/25kDa Taenia solium protein fraction with cathepsin-L like activity is present in the oncosphere/cysticercus and induces non-protective IgG antibodies in pigs
2012, Veterinary Immunology and ImmunopathologyCitation Excerpt :Oncosphere antigens are currently the most effective vaccine candidates in preventing porcine cysticercosis (Assana et al., 2010; Flisser et al., 2004; Gonzalez et al., 2005; Lightowlers et al., 2003; Pathak and Gaur, 1990; Plancarte et al., 1999; Verastegui et al., 2002). T. solium oncospheral protein TSOL18 is currently the best antigen able to induce near total protection against a T. solium proglottid oral challenge in pigs (Lightowlers, 2003). TSOL18 is an oncosphere protein homologue to Taenia saginata HP6.
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