Abstract: The field of this invention is the development of therapeutic agents having immunogenic efficacy against Campylobacter. The present invention is directed to a method of producing monoclonal antibodies that are highly specific for epitopes of Campylobacter jejuni outer membrane proteins; to specific monoclonal antibodies made by using the epitopes; and to uses thereof. The invention is drawn further to immunogens comprising certain outer membrane proteins or portions thereof from C. jejuni.

Abstract: The present invention provides a mutant C. fetus strain in which one or more sapA homologs are altered by an inserted DNA cassette so that the encoded S-layer proteins represent a chimera between the native S-layer proteins and a heterologous peptide encoded by the inserted cassette. Preferably, the heterologous peptide is an immunogen of a pathogen and the mutant strain can be used to immunize a host to develop mucosal and systemic immune responses to such immunogen.

Abstract: A purified IceA protein of Helicobacter pylori is provided. The protein is expressed as either an IceA 1 or an IceA 2 variant. A purified polypeptide fragment of the IceA protein is also provided. An antigenic fragment of IceA is provided. An isolated nucleic acid that encodes an IceA protein of H. pylori is provided. A nucleic acid that encodes an IceA 1 variant and a nucleic acid that encodes an IceA 2 variant is also provided. Fragments of the iceA gene are provided. A method of detecting the presence of an antibody against H. pylori in a sample is provided. The method comprises the following steps: a) contacting the sample with a purified IceA protein of H. pylori or a H. pylori-specific fragment thereof; and b) detecting the binding of the antibody in the sample to the protein or fragment, the detection of binding indicating the presence in the sample of antibodies against H. pylori.

Abstract: A purified IceA protein of Helicobacter pylori is provided. The protein is expressed as either an IceA 1 or an IceA 2 variant. A purified polypeptide fragment of the IceA protein is also provided. An antigenic fragment of IceA is provided. An isolated nucleic acid that encodes an IceA protein of H. pylori is provided. A nucleic acid that encodes an IceA 1 variant and a nucleic acid that encodes an IceA 2 variant is also provided. Fragments of the iceA gene are provided. A method of detecting the presence of an antibody against H. pylori in a sample is provided. The method comprises the following steps: a) contacting the sample with a purified IceA protein of H. pylori or a H. pylori-specific fragment thereof; and b) detecting the binding of the antibody in the sample to the protein or fragment, the detection of binding indicating the presence in the sample of antibodies against H. pylori.

Abstract: A purified IceA protein of Helicobacter pylori is provided. The protein is expressed as either an IceA 1 or an IceA 2 variant. A purified polypeptide fragment of the IceA protein is also provided. An antigenic fragment of IceA is provided. An isolated nucleic acid that encodes an IceA protein of H. pylori is provided. A nucleic acid that encodes an IceA 1 variant and a nucleic acid that encodes an IceA 2 variant is also provided. Fragments of the iceA gene are provided. A method of detecting the presence of an antibody against H. pylori in a sample is provided. The method comprises the following steps: a) contacting the sample with a purified IceA protein of H. pylori or a H. pylori-specific fragment thereof; and b) detecting the binding of the antibody in the sample to the protein or fragment, the detection of binding indicating the presence in the sample of antibodies against H. pylori.

Abstract: An isolated nucleic acid encoding the Helicobacter pylori recombinase is provided. Also provided is an isolated nucleic acid that hybridizes with the recombinase-encoding nucleic acid under stringent conditions and has at least 70% complementarity with the segment of the nucleic acid of SEQ ID NO:1 to which it hybridizes. Also provided is a mutant strain of H. pylori that does not express a functional recombinase (recA.sup.- mutant). An isolated nucleic acid encoding the Helicobacter pylori enolase is provided. Also provided is an isolated nucleic acid that hybridizes with the nucleic acid that encodes a H. pylori recombinase under stringent conditions and has at least 70% complementarity with the segment of the nucleic acid of SEQ ID NO:9 to which it hybridizes. Also provided is a mutant strain of H. pylori that does not express a functional enolase (eno.sup.- mutant). A method is provided for immunizing a subject against infection by H.

Abstract: An isolated nucleic acid encoding the Helicobacter pylori recombinase comprising the nucleotide sequence defined in the Sequence Listing as SEQ ID NO:1 is provided. Also provided is an isolated nucleic acid that selectively hybridizes with the nucleic acid of claim 1 under stringent conditions and has at least 70% complementarity with the segment of the nucleic acid of SEQ ID NO:1 to which it hybridizes. Also provided is a mutant strain of H. pylori that does not express a functional recombinase (recA.sup.- mutant). An immunogenic amount of the recA.sup.- mutant H. pylori in a pharmaceutically acceptable carrier is provided. A method of immunizing a subject against infection by H. pylori comprises administering to the subject an immunogenic amount of mutant H. pylori in a carrier for the mutant.