Eimeria spp. of the domestic fowl: analysis of genetic variability between species and strains using DNA polymorphisms amplified by arbitrary primers and denaturing gradient-gel electrophoresis.

The genetic relatedness of 5 Eimeria spp. of the domestic fowl, including 11 strains of E. acervulina, 2 strains of E. tenella and 1 precocious line of E. acervulina, was assayed by means of random amplified polymorphic DNA (RAPD) and denaturing gradient-gel electrophoresis (DGGE). Seven different oligonucleotides were used to generate similarity coefficients for the species and strains of Eimeria infecting chickens. Between 1 and 13 DNA segments, depending on the species/strain-primer combination, were amplified with the various primers. Amplification products ranged in size from 0.16 to 3.8 kb. E. acervulina strains demonstrated two to four major common bands unique to the species. These strains also exhibited major and minor differences in their DNA patterns. Band-match analyses from both polyacrylamide and denaturing gradient gels were used to calculate similarity coefficients for the Eimeria spp. and strains tested. Species differences, readily detected upon examination of DNA banding patterns, gave similarity coefficients of 4%-38% and 3%-18% when analyzed by polyacrylamide- and denaturing gradient-gel electrophoresis, respectively. A similar analysis of E. acervulina strains, yielded similarity coefficients of 55%-95% and 51%-85%, respectively. The differences observed between both species and strains were greater when the RAPD-assay products were analyzed via DGGE, indicating that a combination of these two techniques may provide a more stringent analysis of the genetic relatedness of these coccidia.