Evaluation of an Experimental Irradiated Oocyst Vaccine to Protect Broiler Chicks Against Avian Coccidiosisby Raymond H. Fetterer, Mark C. Jenkins, Katarzyna B. Miska, Ruth C. Barfield

Avian Diseases

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Year
2014
DOI
10.1637/10679-092613-reg.1
Subject
Immunology and Microbiology (all) / Food Animals / Animal Science and Zoology

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Evaluation of an Experimental Irradiated Oocyst Vaccine to Protect Broiler

Chicks Against Avian Coccidiosis

Author(s): Raymond H. Fetterer, Mark C. Jenkins, Katarzyna B. Miska, and Ruth C. Barfield

Source: Avian Diseases, 58(3):391-397. 2014.

Published By: American Association of Avian Pathologists

DOI: http://dx.doi.org/10.1637/10679-092613-Reg.1

URL: http://www.bioone.org/doi/full/10.1637/10679-092613-Reg.1

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Evaluation of an Experimental Irradiated Oocyst Vaccine to Protect Broiler Chicks

Against Avian Coccidiosis

Raymond H. Fetterer,AC Mark C. Jenkins,A Katarzyna B. Miska,B and Ruth C. BarfieldA

AAnimal Parasitic Diseases Laboratory and

BAnimal Bioscience and Biotechnology Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Beltsville, Maryland 20705

Received 16 December 2013; Accepted 19 March 2014; Published ahead of print 19 March 2014

SUMMARY. The current study investigates the use of irradiated oocysts to protect broiler chicks, raised on litter, from infection with multiple species of Eimeria. In order to determine the optimum radiation dose for each Eimeria species, 1-day-old chicks were immunized with oocysts of Eimeria maxima, Eimeria acervulina, or Eimeria tenella exposed to gamma radiation ranging from 0–500 Gy. The litter oocyst counts at 7 days postimmunization, and the effect on weight gain following a challenge infection, decreased with an optimum dose between 150–200 Gy. Based on this finding, broiler chicks were immunized with a mixture of E. maxima, E. acervulina, and E. tenella that had been exposed to 150 or 200 Gy. This resulted in more than a 100-fold reduction in litter oocyst counts and significant protection from a challenge infection, as measured by improved weight gain and feed conversion ratio (FCR). Immunization of birds with oocysts receiving 200 Gy was less effective in providing protection from a challenge infection. An additional formulation of vaccines containing two different oocyst doses of the three species that had been irradiated with 150 Gy were evaluated in their ability to attenuate oocyst output and convey protection to challenge. Results were similar with both high and low numbers of irradiated oocysts. Immunized chicks shed less oocysts at 7 days postimmunization and were protected from negative effects of challenge infection as measured by FCR, changes in weight gain, lesion scores, and measurement of body composition. However, the level of protection was somewhat less than that achieved by immunization with nonirradiated oocysts. The overall conclusion is that an irradiated oocyst vaccine developed in this study can effectively protect chicks that are raised on litter from challenge infection with multiple species of Eimeria, comparable to vaccines with virulent or precocious strains.

RESUMEN. Evaluacio´n de una vacuna experimental con ooquistes irradiados en la proteccio´n de pollos de engorde contra la coccidiosis aviar.

El presente estudio investigo´ el uso de ooquistes irradiados para proteger pollos de engorde criados sobre cama, contra la infeccio´n con mu´ltiples especies de Eimeria. Con el fin de determinar la dosis o´ptima de radiacio´n para cada especie de Eimeria, pollitos de un dı´a de edad fueron inmunizados con ooquistes de Eimeria maxima, Eimeria acervulina, o de Eimeria tenella expuestos a la radiacio´n gamma que fue desde 0 hasta 500 Gy. Los conteos de ooqistes en la cama a los siete dı´as despue´s de la inmunizacio´n y el efecto sobre el aumento de peso despue´s del desafı´o disminuyeron con una dosis o´ptima de entre 150–200 Gy. Con base en este hallazgo, se inmunizaron pollos de engorde con una mezcla de E. maxima, E. acervulina, y de E. tenella que habı´an sido expuestas a 150 o 200 Gy.

Esto dio lugar a una reduccio´n de ma´s de 100 veces en los recuentos de ooquistes en la cama y a una proteccio´n significativa contra el desafı´o, tal como se determino´ por la mejora de la ganancia de peso y de la conversio´n alimenticia (FCR). La inmunizacio´n de las aves con ooquistes que recibieron 200 Gy fue menos eficaz en la proteccio´n contra el desafı´o. Una formulacio´n adicional de vacunas que contenı´an dos dosis diferentes de ooquistes de las tres especies que habı´an sido irradiados con 150 Gy fue evaluada en su capacidad para atenuar la produccio´n de ooquistes y para transmitir proteccio´n contra el desafı´o. Los resultados fueron similares con nu´meros de ooquistes irradiados altos y bajos. Pollos inmunizados eliminaron menos ooquistes a los siete dı´as despue´s de la vacunacio´n y estuvieron protegidos contra los efectos negativos del desafı´o, determinados por la conversio´n alimenticia, por los cambios en la ganancia de peso, por las puntuaciones de lesiones y por la medicio´n de la composicio´n corporal. Sin embargo, el nivel de proteccio´n fue ligeramente menor que el alcanzado por la inmunizacio´n con ooquistes no irradiados. La conclusio´n general es que la vacuna de ooquistes irradiados desarrollada en este estudio puede proteger eficazmente a pollos criados sobre cama contra el desafı´o con mu´ltiples especies de Eimeria, de manera comparable con las vacunas con cepas virulentas o precoces.