Abstract: In accordance with the present invention, there are provided selection systems and methods for screening for agents that control splicing of inteins in their native host protein (extein) or in homologous exteins. Specifically, there are provided positive genetic selection systems for the screening of agents which inhibit or activate protein splicing which comprise: a host cell containing a chromosomal gene encoding either a drug-resistant form of a target enzyme or a wild-type target enzyme, and a plasmid-borne gene encoding either a drug-sensitive form of the target enzyme, which is dominantly cytotoxic upon interaction with the drug, or a dominantly cytotoxic form of the target enzyme. In these systems the plasmid-borne gene contains an intein, and the inhibition or activation of splicing of the dominant cytotoxic form of the target enzyme by a given reagent results in the survival or death of the host cell. More specifically, positive genetic selection systems which utilize the M. xenopi GyrA intein or M.

Abstract: In accordance with the present invention, a 31-33 kDa glycoprotein of D. immitis (DiT33) is provided which represents another member of the family of putative pepsin inhibitors. Other known members include Ov33 (a.k.a. Ov33.3, Oc3.6, OvD 5B), Bm33 and Av33. These filarial molecules possess significant homology to the known pepsin inhibitor (Aspi3) of A. suum. Using DiT33 or Ov33, in the form of a recombinant fusion or non-fusion protein, antibody responses to DiT33 may be monitored and used in immunodiagnosis of heartworm infection in mammals. Antibodies reactive with the DiT33 or Ov33 may also be used to detect DiT33 antigen as a means of immunodiagnosis of heartworm infection in mammals.

Abstract: In accordance with the present invention, there are provided selection systems and methods for screening for agents that control splicing of inteins in their native host protein (extein) or in homologous exteins. Specifically, there are provided positive genetic selection systems for the screening of agents which inhibit or activate protein splicing which comprise: a host cell containing a chromosomal gene encoding either a drug-resistant form of a target enzyme or a wild-type target enzyme, and a plasmid-borne gene encoding either a drug-sensitive form of the target enzyme, which is dominantly cytotoxic upon interaction with the drug, or a dominantly cytotoxic form of the target enzyme. In these systems the plasmid-borne gene contains an intein, and the inhibition or activation of splicing of the dominant cytotoxic form of the target enzyme by a given reagent results in the survival or death of the host cell. More specifically, positive genetic selection systems which utilize the M. xenopi GyrA intein or M.

Abstract: In accordance with the present invention, there are provided selection systems and methods for screening for agents that control splicing of inteins in their native host protein (extein) or in homologous exteins. Specifically, there are provided positive genetic selection systems for the screening of agents which inhibit or activate protein splicing which comprise: a host cell containing a chromosomal gene encoding either a drug-resistant form of a target enzyme or a wild-type target enzyme, and a plasmid-borne gene encoding either a drug-sensitive form of the target enzyme, which is dominantly cytotoxic upon interaction with the drug, or a dominantly cytotoxic form of the target enzyme. In these systems the plasmid-borne gene contains an intein, and the inhibition or activation of splicing of the dominant cytotoxic form of the target enzyme by a given reagent results in the survival or death of the host cell. More specifically, positive genetic selection systems which utilize the M. xenopi GyrA intein or M.

Abstract: In accordance with the present invention, there are provided selection systems and methods for screening for agents that control splicing of inteins in their native host protein (extein) or in homologous exteins. Specifically, there are provided positive genetic selection systems for the screening of agents which inhibit or activate protein splicing which comprise: a host cell containing a chromosomal gene encoding either a drug-resistant form of a target enzyme or a wild-type target enzyme, and a plasmid-borne gene encoding either a drug-sensitive form of the target enzyme, which is dominantly cytotoxic upon interaction with the drug, or a dominantly cytotoxic form of the target enzyme. In these systems the plasmid-borne gene contains an intein, and the inhibition or activation of splicing of the dominant cytotoxic form of the target enzyme by a given reagent results in the survival or death of the host cell. More specifically, positive genetic selection systems which utilize the M. xenopi GyrA intein or M.

Abstract: In accordance with the present invention, a 31-33 kDa glycoprotein of D. immitis (DiT33) is provided which represents another member of the family of putative pepsin inhibitors. Other known members include Ov33 (a.k.a. Ov33.3, Oc3.6, OvD 5B), Bm33 and Av33. These filarial molecules possess significant homology to the known pepsin inhibitor (Aspi3) of A. suum. Using DiT33 or Ov33, in the form of a recombinant fusion or non-fusion protein, antibody responses to DiT33 may be monitored and used in immunodiagnosis of heartworm infection in mammals. Antibodies reactive with the DiT33 or Ov33 may also be used to detect DiT33 antigen as a means of immunodiagnosis of heartworm infection in mammals.

Abstract: The present invention is directed to modified proteins and methods of their production. The modified proteins comprise a controllable intervening protein sequence (CIVPS) inserted into or adjacent a target protein, the CIVPS being capable of excision from or cleavage of the modified protein under predetermined conditions in cis or in trans, i.e., increase in temperature, exposure to light, unblocking of amino acid residues by dephosphorylation, treatment with chemical reagents or deglycosylation. If desired, the modified protein can be subjected to these conditions. The CIVPS may also be inserted into a region that substantially inactivates target protein activity. The CIVPS may be used in a number of applications including purification of the target protein in a one-step protocol.

Abstract: The present invention is directed to an extremely thermostable enzyme. More specifically, the invention is directed to a thermostable DNA polymerase 9.degree.N-7, as well as the recombinant form of 9.degree.N-7. In another embodiment, there is provided a method for mutagenizing the exo motif I of the 3'-5' exonuclease DNA polymerases from the native conserved DXE in the 3'-5' exo motif I DNA segment to DXD or AXA.

Abstract: The present invention is directed to modified proteins and methods of their production. The modified proteins comprise a controllable intervening protein sequence (CIVPS) inserted into a target protein, the CIVPS being capable of excision from the modified protein under predetermined conditions, i.e., increase in temperature, exposure to light, unblocking of amino acid residues by dephosphorylation or deglycosylation. If desired, the modified protein can be subjected to these conditions. The CIVPS may also be inserted into a region that substantially inactivates target protein activity.