Korean J Parasitol.  2013 Apr;51(2):147-154. 10.3347/kjp.2013.51.2.147.

Efficacy of a DNA Vaccine Carrying Eimeria maxima Gam56 Antigen Gene against Coccidiosis in Chickens

  • 1Ministry of Education Key Lab for Avian Preventive Medicine, Yangzhou University, Yangzhou, Jiangsu Province 225009, P. R. China. xmjsc@sina.com


To control coccidiosis without using prophylactic medications, a DNA vaccine targeting the gametophyte antigen Gam56 from Eimeria maxima in chickens was constructed, and the immunogenicity and protective effects were evaluated. The ORF of Gam56 gene was cloned into an eukaryotic expression vector pcDNA3.1(zeo)+. Expression of Gam56 protein in COS-7 cells transfected with recombinant plasmid pcDNA-Gam56 was confirmed by indirect immunofluorescence assay. The DNA vaccine was injected intramuscularly to yellow feathered broilers of 1-week old at 3 dosages (25, 50, and 100 microg/chick). Injection was repeated once 1 week later. One week after the second injection, birds were challenged orally with 5x10(4) sporulated oocysts of E. maxima, then weighed and killed at day 8 post challenge. Blood samples were collected and examined for specific peripheral blood lymphocyte proliferation activity and serum antibody levels. Compared with control groups, the administration of pcDNA-Gam56 vaccine markedly increased the lymphocyte proliferation activity (P<0.05) at day 7 and 14 after the first immunization. The level of lymphocyte proliferation started to decrease on day 21 after the first immunization. A similar trend was seen in specific antibody levels. Among the 3 pcDNA-Gam56 immunized groups, the median dosage group displayed the highest lymphocyte proliferation and antibody levels (P<0.05). The median dosage group had the greatest relative body weight gain (89.7%), and the greatest oocyst shedding reduction (53.7%). These results indicate that median dosage of DNA vaccine had good immunogenicity and immune protection effects, and may be used in field applications for coccidiosis control.


Eimeria maxima; coccidiosis; DNA immunization; DNA vaccine; Gam56 antigen; control

MeSH Terms

Antibodies, Protozoan/blood
Antigens, Protozoan/genetics/*immunology
Cell Proliferation
Coccidiosis/immunology/pathology/*prevention & control
Disease Models, Animal
Injections, Intramuscular
Protozoan Vaccines/administration & dosage/genetics/*immunology
Vaccines, DNA/administration & dosage/genetics/*immunology
Antibodies, Protozoan
Antigens, Protozoan
Protozoan Vaccines
Vaccines, DNA
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