Current status of vaccines in veterinary parasitology, I. Protozoa and arthropods

Los avances recientes en inmunologia y biotecnologia han estimulado las investigaciones sobre el control de las enfermedades parasitarias a traves de la vacunacion. Este articulo revisa el estado del arte en relacion a protozoos y artropodos de importancia veterinaria. Todavia existe una vacuna con oocistos vivos contra coccidiosis aviaria pero se ha efectuado abundante trabajo sobre la identificacion, clonaje, y ensayo de antigenos protectores. Los esporozoitos de Eimeria tenella han sido el material preferido y al menos 4 antigenos recombinantes han sido ensayados con exito parcial. La premunizacion contra babesiosis es aun utilizada ampliamente en America Latina y una vacuna viva con parasitos atenuados en Australia. Por lo menos 3 antigenos de Babesia bovis y 3 de B. bigemina que generan proteccion parcial han sido producidos como proteinas recombi­nantes. Una vacuna contra babesiosis canina esta en el mercado en Francia. La tecnica de infeccion–tratamiento es aun utilizada para vacunar contra Theileria parva y una vacuna con esquizontes contra T. annulata . Antigenos recombinantes de esporozoitos han sido ensayados con exito parcial contra ambas especies pero la identificacion y administracion de antigenos protectores de esquizontes, considerados como los mas importantes, aun requiere considerable trabajo. El control inmunologico de los tripanosomas africanos todavia esta dificultado por la variacion antigenica que los parasitos experimental durante la infeccion. Aunque existen algunas posibilidades, la mayoria de los especialistas estan pesimistas acerca de la promesa de desarrollar una vacuna en el futuro cercano. El control de las garrapatas Boophilus con un antigeno intestinal oculto aparece prometedor para inhibir la fertilidad del artropodo pero los antigenos salivales parecen ser mas efectivos para inhibir la alimentacion. Vacunacion con una proteina de Hypoderma recientemente clonada ha inducido 90% de proteccion. Es muy probable que tengamos vacunas efectivas contra algunos parasitos de importancia veterinaria en el futuro cercano. Palabras claves : antigenos, Babesia, biotecnologia, Boophilus, coccidia, Eimenia, Hypoderma, inmunizacion, Theiheria, Trypanosoma, vacunas. Abstract The recent advances in immunology and biotech­nology have stimulated much research on the con­trol of parasitic diseases through vaccination. This is a review of the state of the art regarding important protozoan and arthropod veterinary parasites. A live oocyst vaccine for avian coccidiosis is still in use but much work has been done on the identification, cloning, and assay of protective antigens. The sporozoites of Eimeria tenella have been the preferred subject and at least 4 recombinant an­tigens have already been tested with partial success. Premunization against babesiosis is still widely used in Latin America and a live vaccine with at­tenuated parasites in Australia. At least 3 Babesia bovis and 3 B. bigemina antigens that generate par­tial protection have been produced as recombinant proteins. A vaccine against canino babesiosis is being commercialized in France. Infection-treat­ment is still used to vaccinate against Theileria parva and a schizont vaccine against T. annulata. Recombinant sporozoite antigens have been as­sayed with partial success against both species but the identification and administration of protective schizont antigens, regarded as the most important, still requires considerable work. The immunological control of African trypanosomiases is still im­paired by the antigenic variation that the parasites experience during the infection. Although some possibilities exist, most specialists are pessimistic about the promise of developing a vaccine in the near future. Control of Boophillus ticks with an occult tick intestine recombinant antigen seems promising at inhibiting reproduction of the tick but salivary antigens appear to be more effective at inhibiting feeding and pathogen transmission. Vac­cination with a Hypoderma protein, recently cloned, has induced 90% protection against subsequent in­festations. It is very likely that effective vaccines against veterinary parasites will become available in the near future. Key words: antigens, Babesia, biotechnology, Boophilus, coccidia, Eimeria, Hypoderma, immunization, Theileria, Trypanosoma, vaccine.