| Eimeria maxima is one of the most common farm intensification three kinds ofcoccidia, which mainly infected chickens within3months old, and widely distributedvirulence medium. Small doses of Eimeria maxima infection would not cause severe death,but lower feed conversion rate, lower the chicks body weight gain, cause huge economiclosses.In view of the important harm the coccidiosis to the chicken industry, domestic andforeign scholars have conducted massive research on it. In this experiment, throughisolating coccidia oocysts to establish purebred passaged system, its research includesgeneral biological characteristics, pathogenicity, immunogenicity and molecular biology,etc., which laid the foundation for further study of Eimeria maxima.This study used a single oocyst separation technology,isolating a suspected Eimeriamaxima from chicken feces with hybrid coccidia-infected in a Baoding chicken, andpassaging rejuvenation, which single oocyst infection rate is30%. Through morphologicalidentification, the results show that oocysts parasitic in the middle of intestinal,andoocysts are oval, large eg, golden brown oocyst wall.Size of100oocysts is(32.0-40.8)um×(20.8-31.2)um, and average size is36.4um×26.0um. Morphological indexis1.4.Oocysts narrow side has a strong refraction polar body, no internal and externalresidues. Its shortest spores time is26h, and complete spore time was30h. Its latent periodis128h. According to the results of morphological identification, it is identified as Baodingstrains Eimeria maxima.Using1×104、2×104、5×104、10×104/only sporulated oocysts infected four groups ofhy-line gray male chicks, studying on its pathogenicity, and fifth groups is healthy controlgroup. The clinical symptoms, body weight, mortality, observation of fecal score andoocyst output are regarded as index to study the pathogenicity of Baoding strains Eimeriamaxima. Infection of chickens appear shock group, decreased feed intake,intestinalmucosal bleeding, bloody row and other clinical symptoms. Infected chicken totalexcretion oocysts were3.24×106/g,3.97×106/g,7.10×106/g and17.04×106/g.Relative rate ofweight gain of chickens were81.41%,62.32%,45.27%, and28.42%, observation of fecalscore were1point,1point,2points and3points. Mortality rates were0%,6.67%,13.33% and23.33%.Molecular identification is used to identify the Baoding strains Eimeria maxima. Afterpurification, the extraction of genomic DNA, using the reported species-specific primers todo PCR amplification, we got a clear target band in151bp. Through the PCR products gelextraction, sequencing, and comparing with Eimeria maxima related sequences in Genbank,it is determined as the type of Baoding strains Eimeria maxima. Compared with11Eimeriamaxima strains associated sequence in Genbank, it determined that the isolated strain wasan\Eimeria maxima Baoding strain. Phylogenetic tree analysis revealed Baoding strainand JN113578.1(YZ strain) has a closer relationship, showing that Eimeria maximakinship was not directly related to geographic distribution.The test using Eimeria maxima Baoding live strains and Astragalus polysaccharideimmune boosters immuned chicks. The7-day-old chicks were randomly divided into fivegroups, namely, the healthy control group, astragalus polysaccharide immune boostersgroup, artificial infection immunity group, astragalus polysaccharide immune boosters plusartificial infection immunity group and infection without immune group,30chickens eachgroup.7-day-old chicks got immuned once, artificial infection group with1×103oocysts,astragalus polysaccharide immune boosters group with0.1ml/only, astragaluspolysaccharide immune boosters plus artificial infection immunity group with0.1ml+1×103oocysts/only.14-day-old chicks got immuned to strengthen, artificialinfection group with1×103oocysts, astragalus polysaccharide immune boosters group with0.1ml/only, immune boosters plus artificial infection immunity group with0.1ml+1×103oocysts/only.21-day-old chicks were infected with5.0×105Baoding strains Eimeriamaxima sporulated oocysts to detect blood T lymphocyte proliferation rate and serumantibody level.The results show that, artificial infection immunity group of oocystproduction fell by20.79%, intestinal lesion scores decreased by45.04%. Through detectingperipheral blood T cell proliferation rate of chicks and serum IgG antibody levels, we gotthe result that group C(artificial infection immunity group) and group D(immune boostersplus artificial infection immunity group) were significantly higher then group A (healthycontrol group)(P <0.05). |
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