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Field application of a subunit vaccine against an enteric protozoan disease.

Wallach MG, Ashash U, Michael A, Smith NC - PLoS ONE (2008)

Bottom Line: Progeny of immunized hens excreted significantly less oocysts of various species of Eimeria in their faeces than chicks from unvaccinated hens.These results demonstrate that a vaccine composed of antigens purified from the gametocytes of Eimeria can be used safely and effectively to prevent the deleterious effects of coccidiosis.It is the first subunit vaccine against any protozoan parasite to be successfully applied on a commercial scale.

View Article: PubMed Central - PubMed

Affiliation: Institute for the Biotechnology of Infectious Diseases, University of Technology Sydney, Broadway, Australia. michael.wallach@uts.edu.au

ABSTRACT

Background: Coccidiosis is a major global veterinary health problem in intensively reared chickens. It is caused by apicomplexan parasites of the genus Eimeria.

Principal findings: A subunit vaccine composed of purified antigens from the gametocytes of Eimeria maxima was used to stimulate the production and transfer of maternal antibodies between breeding hens and their hatchlings. The vaccine was injected into hens twice before they began laying eggs. Immunization had no adverse affects on egg laying or health of the hens and resulted in high antibody levels throughout the life of the hens. Progeny of immunized hens excreted significantly less oocysts of various species of Eimeria in their faeces than chicks from unvaccinated hens. Furthermore, the offspring of vaccinated hens developed stronger natural immunity to Eimeria, so that they were resistant to challenge infection even at 8 weeks of age, well after all maternal antibodies had left their circulation. Field trials were conducted in South Africa, Brazil and Thailand, involving at least 1 million progeny of vaccinated hens and at least 1 million positive control birds (raised on feed containing anticoccidial drugs or immunized with a live vaccine) in each country. Additionally, trials were carried out in Israel involving 60 million progeny of vaccinated hens and 112 million positive control birds. There were no significant differences in growth rate, feed conversion ratios or mortality in the offspring of vaccinated hens compared with the positive control chickens in any of these countries regardless of different management practices, different breeds of chickens or climate.

Conclusions: These results demonstrate that a vaccine composed of antigens purified from the gametocytes of Eimeria can be used safely and effectively to prevent the deleterious effects of coccidiosis. It is the first subunit vaccine against any protozoan parasite to be successfully applied on a commercial scale.

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Effect of maternal immunization with purified gametocyte antigens of Eimeria maxima on weight loss due to infection with multiple species of Eimeria in progeny chickens.Commercial broiler breeder hens (14,532 vaccinated with purified gametocyte antigens and 7,256 control) were vaccinated twice with purified gametocyte antigens, (at 15 and 20 weeks of age). Eggs were collected from groups of vaccinated and unvaccinated 43 week old hens and incubated to hatching. Three different groups of 100 broiler chickens were raised: (A) chicks from unvaccinated hens, the chicks being raised in wire cages, with care being taken that they were not exposed to coccidian oocysts (i.e. non-exposed control group); (B) chicks from unvaccinated hens, the chicks being raised under normal commercial conditions on floor litter that was seeded with Eimeria oocysts; and (C) chicks from hens vaccinated twice with purified gametocyte antigens (CoxAbic), the chicks being raised under normal commercial conditions on floor litter that was seeded with Eimeria oocysts. When the birds were 10 days old, eight out of one hundred birds were orally infected with a cocktail containing 50 oocysts from each of four species of Eimeria – E. maxima, E. tenella, E. acervulina and E. mitis. Weekly checking of the litter for oocysts confirmed that the infections were successful in all groups of birds, with peaks of between 300,000 and 459,000 oocysts being found in every gram of floor litter. At 34 days of age, the birds were weighed. Results are means±S.E. Group B chicken weight was significantly lower than both Groups A and C (p<0.0001, one-way ANOVA, Student's t-test), which were not significantly different from each other.
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pone-0003948-g002: Effect of maternal immunization with purified gametocyte antigens of Eimeria maxima on weight loss due to infection with multiple species of Eimeria in progeny chickens.Commercial broiler breeder hens (14,532 vaccinated with purified gametocyte antigens and 7,256 control) were vaccinated twice with purified gametocyte antigens, (at 15 and 20 weeks of age). Eggs were collected from groups of vaccinated and unvaccinated 43 week old hens and incubated to hatching. Three different groups of 100 broiler chickens were raised: (A) chicks from unvaccinated hens, the chicks being raised in wire cages, with care being taken that they were not exposed to coccidian oocysts (i.e. non-exposed control group); (B) chicks from unvaccinated hens, the chicks being raised under normal commercial conditions on floor litter that was seeded with Eimeria oocysts; and (C) chicks from hens vaccinated twice with purified gametocyte antigens (CoxAbic), the chicks being raised under normal commercial conditions on floor litter that was seeded with Eimeria oocysts. When the birds were 10 days old, eight out of one hundred birds were orally infected with a cocktail containing 50 oocysts from each of four species of Eimeria – E. maxima, E. tenella, E. acervulina and E. mitis. Weekly checking of the litter for oocysts confirmed that the infections were successful in all groups of birds, with peaks of between 300,000 and 459,000 oocysts being found in every gram of floor litter. At 34 days of age, the birds were weighed. Results are means±S.E. Group B chicken weight was significantly lower than both Groups A and C (p<0.0001, one-way ANOVA, Student's t-test), which were not significantly different from each other.

Mentions: Weight gain is the most important performance parameter for a chicken meat farmer and coccidiosis is recognised as one of the major causes of weight loss in broilers. To test the effect of maternal immunization with purified gametocyte antigens on growth of broiler chickens, we raised groups of 100 broilers of the Ross breed on litter that was deliberately seeded with oocysts of E. maxima, E. tenella, E. acervulina and E. mitis (see Figure 2). We chose this approach as a prelude to larger scale field trials because we can control the level of seeding of the litter to guarantee an exposure level that will have an affect on weight gain, whilst otherwise mimicking commercial conditions. We were also able to include negative control groups of chickens in these experiments, which was not possible for the large-scale field trials (see below).


Field application of a subunit vaccine against an enteric protozoan disease.

Wallach MG, Ashash U, Michael A, Smith NC - PLoS ONE (2008)

Effect of maternal immunization with purified gametocyte antigens of Eimeria maxima on weight loss due to infection with multiple species of Eimeria in progeny chickens.Commercial broiler breeder hens (14,532 vaccinated with purified gametocyte antigens and 7,256 control) were vaccinated twice with purified gametocyte antigens, (at 15 and 20 weeks of age). Eggs were collected from groups of vaccinated and unvaccinated 43 week old hens and incubated to hatching. Three different groups of 100 broiler chickens were raised: (A) chicks from unvaccinated hens, the chicks being raised in wire cages, with care being taken that they were not exposed to coccidian oocysts (i.e. non-exposed control group); (B) chicks from unvaccinated hens, the chicks being raised under normal commercial conditions on floor litter that was seeded with Eimeria oocysts; and (C) chicks from hens vaccinated twice with purified gametocyte antigens (CoxAbic), the chicks being raised under normal commercial conditions on floor litter that was seeded with Eimeria oocysts. When the birds were 10 days old, eight out of one hundred birds were orally infected with a cocktail containing 50 oocysts from each of four species of Eimeria – E. maxima, E. tenella, E. acervulina and E. mitis. Weekly checking of the litter for oocysts confirmed that the infections were successful in all groups of birds, with peaks of between 300,000 and 459,000 oocysts being found in every gram of floor litter. At 34 days of age, the birds were weighed. Results are means±S.E. Group B chicken weight was significantly lower than both Groups A and C (p<0.0001, one-way ANOVA, Student's t-test), which were not significantly different from each other.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2596963&req=5

pone-0003948-g002: Effect of maternal immunization with purified gametocyte antigens of Eimeria maxima on weight loss due to infection with multiple species of Eimeria in progeny chickens.Commercial broiler breeder hens (14,532 vaccinated with purified gametocyte antigens and 7,256 control) were vaccinated twice with purified gametocyte antigens, (at 15 and 20 weeks of age). Eggs were collected from groups of vaccinated and unvaccinated 43 week old hens and incubated to hatching. Three different groups of 100 broiler chickens were raised: (A) chicks from unvaccinated hens, the chicks being raised in wire cages, with care being taken that they were not exposed to coccidian oocysts (i.e. non-exposed control group); (B) chicks from unvaccinated hens, the chicks being raised under normal commercial conditions on floor litter that was seeded with Eimeria oocysts; and (C) chicks from hens vaccinated twice with purified gametocyte antigens (CoxAbic), the chicks being raised under normal commercial conditions on floor litter that was seeded with Eimeria oocysts. When the birds were 10 days old, eight out of one hundred birds were orally infected with a cocktail containing 50 oocysts from each of four species of Eimeria – E. maxima, E. tenella, E. acervulina and E. mitis. Weekly checking of the litter for oocysts confirmed that the infections were successful in all groups of birds, with peaks of between 300,000 and 459,000 oocysts being found in every gram of floor litter. At 34 days of age, the birds were weighed. Results are means±S.E. Group B chicken weight was significantly lower than both Groups A and C (p<0.0001, one-way ANOVA, Student's t-test), which were not significantly different from each other.
Mentions: Weight gain is the most important performance parameter for a chicken meat farmer and coccidiosis is recognised as one of the major causes of weight loss in broilers. To test the effect of maternal immunization with purified gametocyte antigens on growth of broiler chickens, we raised groups of 100 broilers of the Ross breed on litter that was deliberately seeded with oocysts of E. maxima, E. tenella, E. acervulina and E. mitis (see Figure 2). We chose this approach as a prelude to larger scale field trials because we can control the level of seeding of the litter to guarantee an exposure level that will have an affect on weight gain, whilst otherwise mimicking commercial conditions. We were also able to include negative control groups of chickens in these experiments, which was not possible for the large-scale field trials (see below).

Bottom Line: Progeny of immunized hens excreted significantly less oocysts of various species of Eimeria in their faeces than chicks from unvaccinated hens.These results demonstrate that a vaccine composed of antigens purified from the gametocytes of Eimeria can be used safely and effectively to prevent the deleterious effects of coccidiosis.It is the first subunit vaccine against any protozoan parasite to be successfully applied on a commercial scale.

View Article: PubMed Central - PubMed

Affiliation: Institute for the Biotechnology of Infectious Diseases, University of Technology Sydney, Broadway, Australia. michael.wallach@uts.edu.au

ABSTRACT

Background: Coccidiosis is a major global veterinary health problem in intensively reared chickens. It is caused by apicomplexan parasites of the genus Eimeria.

Principal findings: A subunit vaccine composed of purified antigens from the gametocytes of Eimeria maxima was used to stimulate the production and transfer of maternal antibodies between breeding hens and their hatchlings. The vaccine was injected into hens twice before they began laying eggs. Immunization had no adverse affects on egg laying or health of the hens and resulted in high antibody levels throughout the life of the hens. Progeny of immunized hens excreted significantly less oocysts of various species of Eimeria in their faeces than chicks from unvaccinated hens. Furthermore, the offspring of vaccinated hens developed stronger natural immunity to Eimeria, so that they were resistant to challenge infection even at 8 weeks of age, well after all maternal antibodies had left their circulation. Field trials were conducted in South Africa, Brazil and Thailand, involving at least 1 million progeny of vaccinated hens and at least 1 million positive control birds (raised on feed containing anticoccidial drugs or immunized with a live vaccine) in each country. Additionally, trials were carried out in Israel involving 60 million progeny of vaccinated hens and 112 million positive control birds. There were no significant differences in growth rate, feed conversion ratios or mortality in the offspring of vaccinated hens compared with the positive control chickens in any of these countries regardless of different management practices, different breeds of chickens or climate.

Conclusions: These results demonstrate that a vaccine composed of antigens purified from the gametocytes of Eimeria can be used safely and effectively to prevent the deleterious effects of coccidiosis. It is the first subunit vaccine against any protozoan parasite to be successfully applied on a commercial scale.

Show MeSH
Related in: MedlinePlus