Abstract: Nucleic acid molecules are provided which encode antigenic proteins capable of inducing in a chicken an immune response conferring protection against Eimeria tenella. Expression vectors containing the nucleic acid molecules are also provided. Methods for producing the proteins or antigenic polypeptides having amino acid sequences included within these proteins are also provided.

Abstract: The present invention relates to the isolation and restoration of biological activity to inactive proteins, that is solubilizing, renaturing and restoring activity to proteins which have been partially denatured or inactivated, e.g. during their synthesis in a host cell, such as E. coli, or during isolation. In particular this invention relates to both a means for extracting insoluble eukaryotic proteins from bacteria and to an efficient process for producing active chymosin from an insoluble chymosin precursor isolated from genetically engineered bacteria.

Abstract: A genomic DNA molecule having the nucleic acid sequence set forth in FIG. 1 and encoding an antigenic protein derived from Eimeria tenella has been isolated. The protein has a molecular weight of about 25,000 daltons and is composed of two polypeptides joined by a disulfide bond. One of the polypeptides is characterized by a molecular weight of about 17,000 daltons and by a blocked N-terminal amino acid and having the amino acid sequence set forth in FIG. 1. The other polypeptide is characterized by a molecular weight of about 8,000 daltons and has the amino acid sequence set forth in FIG. 1.A cDNA molecule encoding the 25,000 dalton polypeptide with a continuous amino acid sequence has been inserted into expression vectors capable of expressing the 25,000 dalton polypeptide directly or as a fused polypeptide. The polypeptides produced are used in vaccines to immunize chickens against infection by Eimeria tenella.