The present invention provides an isolated nucleic acid comprising a nucleotide sequence encoding a 250 kDa polypeptide from Sporozoites/Merozoites of Eimeria maxima, or encoding a homolog of the polypeptide, or a complement of the nucleic acid and a method of producing a recombinant 250 kDa polypeptide of the same. The present invention also provides an isolated nucleic acid comprising a nucleotide sequence encoding an immunodominant portion of a 250 kDa polypeptide from Sporozoites/Merozoites of Eimeria maxima having the amino acid sequence described herein, or encoding a homolog of the polypeptide, or a complement of the nucleic acid. The subject invention also provides a vaccine against Eimeria tenella, Eimeria maxima, Eimeria acervulina, Eimeria necatrix, Eimeriapraecax, Eimeria mitis or Eimeria brunetti, or a microorganism expressing an immunologically cross-reactive antigen, comprising the isolated nucleic acid comprising a nucleotide sequence encoding a 250 kDa polypeptide from Sporozoites/Merozoites of Eimeria maxima or the immunodominant portion of a 250 kDa polypeptide from Sporozoites/Merozoites of Eimeria maxima, or encoding a homolog of the polypeptide, or a complement of the nucleic acid which may also contain a 56 kDa, 82 kDa or 230 kDa protein isolated from the gametocytes of Eimeria maxima and a method of immunizing a subject against infection by Eimeria tenella, Eimeria maxima, Eimeria acervulina, Eimeria necatrix, Eimeria praecox, Eimeria mitis or Eimeria brunetti, or a microorganism expressing an immunologically cross-reactive antigen, comprising the step of administering to the subject any of the aforementioned vaccines.