Submitted to: Vaccine
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/9/2005
Publication Date: 8/12/2005
Citation: Ding, X., Lillehoj, H.S., Dalloul, R.A., Min, W., Sato, T., Yasuda, A., Lillehoj, E.P. 2005. In ovo vaccination with the eimeria tenella etmic2 gene induces protective immunity against coccidiosis. Vaccine. 23:3733-3740. Interpretive Summary: Avian coccidiosis is caused by several different intestinal protozoan parasites which infect different areas of gut damaging its ability to absorb nutrients. At present coccidiosis cost US industry more than $ 1 million annual economic loss. Although traditionally coccidiosis has been controlled by prophylactic medication, increasing regulation of chemical use in poultry production and the high cost for new drug discovery are pushing industry to develop alternative control strategy to control avian coccidiosis. In this new report, ARS scientists in collaboration with scientists at Zeon vaccine company and University of Maryland demonstrate new concepts and method to elicit protective local immunity to coccidia using embryo vaccination of recombinant protein obtained from Eimeria parasites. This study demonstrates for the first time that thr immunization of chicken embryos with a gene carrying MIC2 antigen to 18-day-old chicken embryos induced significant protection against coccidiosis challenge infection. This information will be useful for developing new disease control strategy against coccidiosis for vaccine industry worldwide and will lead to novel, drug-free approach toward coccidiosis control .
Technical Abstract: An Eimeria tenella microneme recombinant gene (EtMIC2) and encoded protein were evaluated as potential vaccines against avian coccidiosis. In ovo inoculation with the EtMIC2 gene increased anti-EtMIC2 antibody titers at days 10 and 17 following E. tenella infection. In addition, vaccinated birds developed protective immunity against infection by E. tenella as assessed by significantly increased body weight gain and decreased fecal oocyst shedding compared with non-vaccinated controls. Vaccination with the EtMIC2 gene also led to protective immunity against infection by E. acervulina, but not E. maxima. Combined in ovo DNA vaccination plus post-hatch boosting with EtMIC2 DNA or protein did not improve antibody titers or protective immunity beyond that achieved with in ovo vaccination alone. These results provide evidence that in ovo immunization with a recombinant Eimeria microneme gene stimulates protective intestinal immunity against coccidiosis.