EXPRESSION OF GENE PRODUCTS FROM GENETICALLY MANIPULATED STRAINS OF BORDETELLA

Abstract: An expression system for expressing gene products from recombinant Bordetella strains and specific nucleic acid molecules useful in transforming Bordetella strains for such expression are described. A nucleic acid molecule may comprise a Bordetella promoter operatively coupled to a heterologous gene encoding a non-Bordetella gene product with the heterologous gene transcriptionally regulated by the Bordetella promoter. The nucleic acid molecule may further comprise a further nucleic acid molecule encoding a leader sequence for secretion of the non-Bordetella gene product. Another nucleic acid molecule may comprise a Bordetella promoter coupled to a nucleic acid sequence encoding a non-Bordetella leader sequence for secretion of a gene product, which may be a Bordetella gene product or a non-Bordetella gene product.

Description: TITLE OF THE INVENTION EXPRESSION OF GENE PRODUCTS FROM GENETICALLY MANIPULATED ..TRAINS OF BORDETELLA FIELD TO THE INVENTION The present invention relates to the field of molecular biology and is particularly concerned with the expression of gene products from strains of Bordetella. REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of United States Patent Application No. 08/393,334, filed February 23, 1995. BACKGROUND OF THE INVENTION Bordetella pertussis f the organism responsible for whooping cough, expresses a number of virulence factors, such as pertussis toxin (PT) , filamentous hemagglutinin (FHA) and pertactin (PRN) . These proteins are secreted by the organism through the use of signal peptides and/or accessory genes (refs. 1 and 2 - Throughout this specification, various references are referred to in parenthesis to more fully describe the state of the art to which this invention pertains. Full bibliographic information for each citation is found at the end of the specification, immediately preceding the claims. The disclosures of these references are hereby incorporated by reference into the present disclosure) . We have previously demonstrated that it is possible to manipulate the expression of these Bordetella proteins through alteration of gene copy number (ref. 3) or the use of hybrid genes with autologous promoters (ref. 4) . For example, the amount of secreted and processed PT holotoxin was increased more than 3-fold by increasing the copy number of the tox operon encoding PT (ref. 5) . The amount of secreted and processed pertactin was increased 8-fold by using a hybrid gene which replaced the native prn promoter with the stronger fha promoter. The yield of pertactin was further increased to 20-fold wild-type levels by adding a second copy of the hybrid gene. Many gene products including proteins and polypeptides of commercial and medical significance are only available in small amounts from their natural sources, are difficult to isolate or require modification of, for example, their primary amino acid sequence for optional use and/or activity. Thus, many genes have been expressed by recombinant DNA means in a variety of microbial hosts, including bacterial hosts. The gene expressed in the microbial host is typically heterologous to the host. Examples of bacterial hosts used for expression of heterologous proteins include strains of Escherichia coli. Salmonella species (ref. 10) and Bacillus subtilis (ref. 11). Particular biological properties of strains of Bordetella make them attractive hosts for the production of certain heterologous gene products. Thus, many of the antigens produced by B. pertussis are large, can be multimeric and may require post-translational assembly or processing. For example, the pertactin antigen is produced as a 93-kDa precursor and the mature protein is produced by excision of the N-terminal signal peptide and removal of a C-terminal fragment. Pertussis toxin is a 105 kDa exotoxin produced by B. pertussis, and is encoded by the TOX operon and consists of five polypeptide subunits (SI to S5) arranged in the typical A-B structure of bacterial toxins. The S2, S3, S4 and S5 subunit form a pentamer (the B oligomer) which, when combined with the SI subunit forms the holotoxin. For PT, for example, such complex assembly cannot be achieved in E. coli (ref. 22) and, for the 69 kd material, protein accumulated as insoluble inclusion bodies in E. coli (ref. 23) . This intracellular expression in E. coli is to be contrasted with the secretion of soluble antigens by B. pertussis strains. FHA is another large molecule (Mwt 220 kDa) secreted by B. pertussis (ref. 24) . Vibrio cholerae is the organism that causes cholera, a severe disease of dehydration caused by diarrhoea. Many of the symptoms of cholera can be attributed to the action of cholera toxin (CT) , which like B. pertussis PT, is an A/B toxin with ADP-ribosyl transferase activity. However, unlike PT which has four different B subunit components comprising a pentamer, CT has a pentameric structure made up of identical subunits (ref. 6) . Cholera toxin has been shown to have considerable use as a mucosal adjuvant and the B subunit alone may be sufficient to generate a mucosal response in some instances (ref. 7) . A response is generated if cholera toxin B (CTB) is either co-administered or chemically coupled to another protein (ref. 8) . Chi eric genes have also been engineered which have foreign epitopes fused to cholera toxin B and the resultant fusion proteins can sometimes induce an immune response to the foreign epitope (ref. 9) . Cholera toxin B has been expressed from recombinant V. cholerae (ref. 12), E. coli (ref. 13), and S^ tvphimurium (ref. 14). H. influenzae species are responsible for a number of serious human diseases such as meningitis, pneumonia, septicemia, epiglotitis, and otitis media. There are six encapsulated forms of H. influenzae which are designated as serotypes a - f. The serotype b strains (Hib) were responsible for a large proportion of bacterial meningitis before the introduction of Hib capsular polysaccharide conjugate vaccines which have nearly eradicated the disease. The non-encapsulated or non-typable H. influenzae (NTHi) strains cause -30% of bacterial otitis media, or middle ear infection. About 70% of NTHi strains express the related high molecular weight proteins, HMWl and HMW2. These proteins are made as large precursors and the mature proteins are 125 kDa and 120 kDa, respectively. Antibodies to these proteins are found in human convalescent sera and the proteins are protective in an active chinchilla model of otitis media. However, the native proteins are made in very small quantities by H. influenzae strains and recombinant proteins expressed from E. coli are also made in relatively low yields. The H. influenzae HMW proteins are antigenically, morphologically, and genetically related to B. pertussis filamentous hemagglutinin (ref. 26) . Anti-HMWl recognizes FHA on Western blot and an anti-FHA MAb recognizes HMWl and HMW2 by Western blot. Both FHA and the HMW proteins are found as secreted and membrane bound forms. Both HMW and FHA require accessory proteins for secretion and processing of the large precursor proteins to their mature forms and these proteins are encoded on the operons containing the structural genes. Although B. pertussis has been used to over-express autologous proteins by gene manipulation (refs. 4 and 5) , it has not heretofore been used to produce heterologous proteins. SUMMARY OF THE INVENTION The present invention is directed towards recombinant strains of Bordetella which express non- Bordetella gene products. Accordingly, in one aspect of the present invention, there is provided a nucleic acid molecule comprising a promoter functional in Bordetella and operatively coupled to a heterologous gene encoding a non-Bordetella gene product, wherein the heterologous gene is transcriptionally regulated by the promoter in Bordetella. The non-Bordetella gene product may be one of a wide variety of proteins and polypeptides. The protein or peptide may be an enzyme, an enzyme inhibitor, an antigen, an im unogen, an allergen, a hormone, a lymphokine, an immunoglobulin or fragment thereof, a toxin, a toxin subunit, a mammalian protein, a structural protein or a receptor. The invention is illustrated by the expression of a cholera toxin molecule as the non-Bordetella gene product, specifically the B subunit of cholera toxin. The invention is further illustrated by the expression of an outer membrane protein of Haemophilus, particularly a high molecular weight protein of non-typable Haemophilus influenzae. using either the fha or hmw promoter. However, any other protein or polypeptide may comprise the expressed non-Bordetella gene product. The promoter employed in the nucleic acid molecule provided in accordance with this aspect of the invention may be any of the Bordetella promoters, preferably the TOX. PRN and FHA promoters from any Bordetella strain, including B. pertussis, and an hmw promoter. The heterologous gene component of the nucleic acid molecule provided in accordance with this aspect of the invention may further comprise a nucleic acid sequence encoding a leader sequence for secretion of the non- Bordetella gene product. The leader sequence may be any sequence mediating secretion of the Bordetella gene product. In one embodiment, the leader sequence is a leader sequence of a Bordetella protein or subunit thereof or a fragment or analog of the Bordetella protein leader sequence retaining secretion-mediating properties. The leader sequence may be the Bordetella pertactin leader sequence or a pertussis toxin subunit leader sequence, such as that for the SI subunit, of any Bordetella strain, including B. pertussis. Alternatively, in another embodiment, the leader sequence is a leader sequence of a non-Bordetella protein or subunit thereof or a fragment or analog of the non- Bordetella protein leader sequence retaining secretion- mediating properties. The non-Bordetella gene product may be a secreted gene product, in which case the non- Bordetella leader sequence preferably is the native leader sequence of the secreted gene product. In an illustrative example of the latter embodiment of the invention, the secreted gene product may be a cholera toxin molecule, for example, the B subunit thereof and the leader sequence may be the cholera toxin B subunit leader sequence. Specific combinations of promoter, leader sequence and heterologous gene product sequence are provided herein, including those designed toxp/CTB-L/ctb. fhap/CTB-L/ctb, toxp/Sl-L/ctb. toxp/PRN-L/ctb, fhap/Sl- L/ctb, fhap/PRN-L/ctb, fhap/hmwl. fhap/hmw2, hmwp/hmwl and hmwp/hmw2. The nucleic acid molecule provided in accordance with this aspect of the invention may further comprise a first DNA sequence corresponding to a 5' flanking sequence of a selected Bordetella gene and disposed at the 5' end of the nucleic acid molecule and a second DNA sequence corresponding to a 3' flanking sequence of the selected Bordetella gene and disposed at the 3' end of the nucleic acid molecule. The first and second DNA sequences permit specific integration of the nucleic acid molecule into the genome of a Bordetella species, preferably B. pertussis, at a locus corresponding to the selected Bordetella gene. The Bordetella promoter present in the nucleic acid molecule may be that of the selected Bordetella gene providing the flanking sequences. The selected Bordetella gene may be any of the Bordetella genes, including the TOX. PRN or FHA gene of a Bordetella strain, preferably B. pertussis. The nucleic acid molecule with flanking regions as described above may be provided in a plasmid adapted for transformation of a Bordetella strain, preferably a B. pertussis strain. Specific plasmidε have been prepared herein, as described in more detail below and are identified as plasmids DS-546-1, JB-898-2-1, DS-729-1-1, DS-729-2-1, JB-1201-4, JB-1141-5, JB-1957-27, JB-1989-R- 1, DS-1719-28 and DS-1732R-14. Another aspect of the invention provides a recombinant strain of Bordetella. which may be a B. pertussis strain, a B. parapertussis strain, a B_j_ bronchiseptica strain or a B. avium strain, particularly a B. pertussis strain, containing the nucleic acid molecule provided in the above-described aspect of the invention, integrated into the genome thereof and expressing the non-Bordetella gene product. One specific recombinant B. pertussis strain provided herein is B. pertussis strain 694-46, which has been deposited with the American Type Culture Collection, Rockville, Maryland, USA, on January 11, 1995 under the terms of the Budapest Treaty as ATCC Accession number 55,654. The non-Bordetella gene product may be obtained by culturing a recombinant strain provided herein. In a further aspect of the invention, there is provided a nucleic acid molecule comprising a Bordetella promoter coupled to a nucleic acid sequence encoding a non-Bordetella leader sequence for secretion of a gene product. The secreted gene product may be a Bordetella gene product or a non-Bordetella gene product. The Bordetella promoter component of the nucleic acid molecule provided in accordance with this further aspect of the invention may be any of the Bordetella promoters, preferably the TOX. PRN or FHA promoter of a Bordetella strain, preferably B. pertussis. The non-Bordetella leader sequence component of the nucleic acid molecule provided in accordance with this further aspect of the invention may be any of the leader sequences mediating secretion of a gene product, including bacterial (prokaryotic) leader sequences (such as E. coli leader sequences including rlpB, pal ompA, pilin gene leader sequences and H. influenzae leader sequences including the transferrin receptor protein leader sequence) , eukaryotic leader sequences (including mammalian) and viral leader sequences. Some appropriate leader sequences for use in aspects of the present invention are described in reference 25. In an illustrative example of this further aspect of the invention, the non-Bordetella leader sequence may be that for the cholera toxin B subunit. A recombinant strain of Bordetella. such as a B. pertussis strain, a B. parapertussis strain, B. bronchiseptica strain or a B. avium strain, preferably a B. pertussis strain, may contain the nucleic acid molecule provided in accordance with this further aspect of the invention and secrete the gene product. Such recombinant strain of Bordetella may be cultured under a range of appropriate conditions to secrete the gene product. In an additional aspect of the invention, the heterologous gene may be provided with optimized codons for Bordetella expression. One example of such heterologous gene has the nucleic acid sequence of Figure 1, which encodes the B subunit of cholera toxin and constitutes an embodiment of this additional aspect of the invention. The present invention, therefore, provides an expression system for expressing gene products from recombinant Bordetella strains and specific nucleic acid molecules useful in transforming Bordetella strains for such expression. The expressed gene products have a variety of uses, depending on the form and nature of the product produced, as will be evident to a person skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be further understood from the following detailed description and examples with reference to the accompanying drawings, in which: Figure 1 shows the sequence of a synthetic cholera toxin B subunit gene (SEQ ID NO: 1) and its derived amino acid sequence (SEQ ID NO: 2), based upon strain 569B of V. cholerae; Figure 2 shows the construction scheme for plasmid DS-546-1 which contains the toxp/CTB-L/ctb gene; Figure 3 shows the sequences of oligonucleotides (SEQ ID NOS: 3 to 16) used for the construction of plasmid DS-546-1; Figure 4 shows the construction scheme for plasmid JB-898-2-1 which contains the fhap/CTB-L/ctb gene; Figure 5 shows the sequences of oligonucleotides (SEQ ID NOS: 17 to 20) used to construct plasmid JB-898- 2-1; Figure 6 shows the construction scheme for plasmid DS-729-1-1 which contains the toxp/Sl-L/ctb gene; Figure 7 shows the sequences of oligonucleotides (SEQ ID NOS: 21 to 30) used to construct plasmid DS-729- 1-1; Figure 8 shows the construction scheme for plasmid DS-729-2-1 which contains the toxp/PRN-L/ctb gene; Figure 9 shows the sequences of oligonucleotides (SEQ ID NOS: 31 to 40) used to construct plasmid DS-729- 2-1; Figure 10 shows the construction scheme for plasmid JB-1201-4 which contains the fhap/Sl-L/ctb gene; Figure 11 shows the sequences of oligonucleotides (SEQ ID NOS: 41 to 48) used to construct plasmid JB-1201- 4; Figure 12 shows the construction scheme for plasmid JB-1141-5 which contains the fhap/PRN-L/ctb gene; Figure 13 shows the sequences of oligonucleotides (SEQ ID NOS: 49 to 56) used to construct plasmid JB-1141- 5; Figure 14 shows the chromosomal maps of the genes at the fha and tox loci and the corresponding Southern blot showing the correct chromosomal integration. Chromosomal DNA was digested with Bgl II and hybridized with the approximately 300 bp ctb probe indicated in the figure. Lane 1, strain 694-46 (fhap/PRN-L/ctb); lane 2, strain 694-54 (fhap/Sl-L/ctb) ; lane 3, strain 694-12 (toxp/PRN- L/______) ; lane 4, strain 694-4 (toxp/Sl-L/ctb) ; lane 5, strain 10536 (wild-type B. pertussis) ; and Figure 15 shows the SDS PAGE and corresponding Western blot of recombinant B. pertussis strain 694-46 which expresses CTB. Lane 1, acetone precipitated supernatant from strain 694-46 (fhap/PRN-L/ctb. , boiled in SDS; lane 2, acetone precipitated supernatant from strain 694-46, unboiled; lane 3, cell pellet from strain 694-46, boiled in SDS; lane 4, cell pellet from strain 694-46, unboiled; lane 5, acetone precipitated supernatant from strain 10536 (wild-type B. pertussis) ; lane 6, cell pellet from strain 10536; lane 7, purified cholera toxin (Sigma), boiled in SDS; lane 8, purified cholera toxin, unboiled; Figure 16 shows the construction scheme for pUC / 5 ' fha / hmwp / hmw l abc / 3 ' fha a nd pUC/5'fha/fhap/hmwlabc/3'fha. Restriction enzymes are indicated as B, BamH I; Bg, Bgl II; Bsm, Bsm I; H, Hind III; Ps, Pst I; R, EcoR I; Sa, Sal I; Sm, S a I; Xb, Xba I. CAP refers to dephosphorylation using calf alkaline phosphatase; Figure 17 shows the construction scheme for pUC/5'fha/hmwp/hmw2abc/3'fha. Restriction enzymes are indicated as Bg, Bgl II; H, Hind III; R, EcoR I; Ps, Pst I; Sm, Sma I; Xb, Xba I. CAP refers to dephosphorylation using calf alkaline phosphatase; Figure 18 shows the construction scheme for pUC/5'fha/fhap/hmw2abc/3'fha. Restriction enzymes are indicated as B, BamH I; Bg, Bgl II; Bsm, Bsm I; H, Hind III; Ps, Pst I; R, EcoR I; S, Sal I; Sm, Sma I; Xb, Xba I. CAP refers to dephosphorylation using calf alkaline phosphatase; Figure 19 shows a dot blot analysis of recombinant B. pertussis strains containing hmwlabc or hmw2abc genes. Figure 20 shows a western blot analysis of the expression of HMWl from recombinant B. pertussis strains containing the fhap/hmwlabc and hmwp/hmwlabc genes. Figure 21 shows a western blot analysis of the expression of HMW2 from recombinant B. pertussis strains containing the fhap/hmw2abc and hmwp/hmw2abc genes. In some of the above figures, the following abbreviations are used: toxp is the B. pertussis tox promoter fhap is the B. pertussis fha promoter ctb is the synthetic cholera toxin B gene (SEQ ID N0:1) CTB-L is the sequence encoding the cholera toxin B subunit leader sequence Sl-L is the sequence encoding the pertussis toxin subunit SI leader sequence PRN-L is the sequence encoding the pertussis pertactin leader sequence h wl is the gene encoding the high molecular weight protein HMWl of non-typable Haemophilus influenza hmw2 is the gene encoding the high molecular weight protein HMW2 of non-typable Haemophilus influenza Restriction enzyme recognition sites are B, BamH I; Bg, Bgl II; H, Hind III; K, Kpn I; R, EcoR I; S, Sac I; and Hf, Hinfl CAP is calf alkaline phosphatase. GENERAL DESCRIPTION OF THE INVENTION Bordetella pertussis 10536 is the vaccine production strain of the assignee hereof and it has been used as the initial strain for all the work detailed by the inventors herein. The genes for B. pertussis PT, FHA and pertactin, V. cholerae CT and non-typable H. influenzae h wl and hmw2 have been cloned and sequenced (Refs. 15 to 19 and WO 93/19090) and the promoter regions and transcriptional starts of the structural genes have been determined. The inventors have generated hybrid genes by substituting the B. pertussis native structural genes encoding a leader sequence and/or mature protein by gene segments encoding native, autologous, or heterologous leader peptides and a mature foreign protein. This was accomplished by fusing the promoters with the gene segment encoding the leader peptide at the ATG start codon, followed by the structural gene for the mature foreign protein joined at the natural cleavage site of the signal sequence. Such fusions result in a native promoter, a native, autologous, or heterologous leader peptide, and a heterologous structural gene. The resultant hybrid genes then have been integrated by homologous recombination into the chromosome of B_j_ pertussis at the loci corresponding to the gene from which the promoters were derived. As examples of the use of hybrid genes expressing foreign proteins, genes have been created containing a tox promoter with the cholera toxin B leader peptide and mature cholera toxin B sequence; a tox promoter with the pertussis toxin subunit SI leader peptide and mature cholera toxin B sequence; a tox promoter with the pertactin leader peptide and mature cholera toxin B sequence; an fha promoter with the cholera toxin B leader peptide and mature cholera toxin B sequence; an fha promoter with the pertussis toxin subunit SI leader peptide and mature cholera toxin B sequence; and an fha promoter with the pertactin leader peptide and mature cholera toxin B sequence; and an fha promoter or the hmw promoters and the non-typable H.influenzae high molecular weight outer membrane proteins HMWl and HMW2. A number of B. pertussis strains have been generated to demonstrate the success of this strategy. The efficiency of expression of the foreign CTB protein is dependent upon both the promoter and the leader peptide which precede the structural ctb gene. The use of the fha promoter in the hybrid genes results in a higher level of expression of the foreign protein than when the tox promoter is used. This phenomenon was also observed when hybrid genes were used to express autologous proteins from B. pertussis (ref. 4) . For the leader peptides, expression levels varied as follows: pertactin > PT subunit SI > cholera toxin B. The best combination of promoter and leader peptide in the hybrid genes expressing foreign proteins was the fha promoter with the pertactin leader peptide. The CTB expressed by the recombinant B. pertussis strains is produced and is a pentamer as demonstrated by SDS PAGE and Western blot analysis of unboiled (pentameric) and boiled (monomeric) samples. The CTB binds to GM1 as demonstrated by ELISA. Thus, a complex foreign protein which has authentic structure and binding functions can be secreted by the recombinant Bordetella strains of the invention. B. pertussis strain (590-508; fhaB and tox deleted) has been used as host to express the H. influenzae hmwlabc and hmw2abc genes. Recombinant strains have been generated which contain the hmwlabc or hmw2abc genes driven by the fha or hmw promoters. All strains contain the inserted genes at the fhaB locus. Recombinant B_j_ pertussis strains can express H. influenzae HMWl and HMW2 proteins. Strains containing the hmw genes under the influence of the fha promoter produce more HMW proteins than those using the hmw promoters. The HMW proteins are found in both the supernatant and cellular fractions. The recombinant B. pertussis strains containing the hmwp/hmw2abc genes appear to secrete HMW2 into the medium while HMWl appears to be made in negligible amounts from its own promoter. The expression of non-typable H. influenzae high molecular weight outer membrane proteins HMWl and HMW2 by genetically manipulated strain of Bordetella is shown in Figures 20 and 21. It has been clearly demonstrated that the structural gene of a foreign protein may be fused to a B. pertussis promoter through a gene fragment encoding a native, autologous, or heterologous leader peptide to express foreign proteins. BIOLOGICAL DEPOSITS B. pertussis strain 694-46 which contains the fhap/PRN-L/ctb hybrid gene at the fha locus has been deposited with the American Type Culture Collection (ATCC) located at Rockville, Maryland, USA, pursuant to the Budapest Treaty and prior to the filing of this application. The ATCC access number is 55,654. Samples of the deposited strain will become available to the public upon the grant of a patent based on this United States patent application. The invention described and claimed herein is not limited in scope by the strain deposited, since the deposited embodiment is intended only as an illustration of the invention. Any equivalent or similar strains to that deposited are within the scope of the invention. EXAMPLES The above disclosure generally describes the present invention. A more complete understanding can be obtained by reference to the following specific Examples. These Examples are described solely for the purposes of illustration and are not intended to limit the scope of the invention. Changes in form and substitution of equivalents are contemplated as circumstances may suggest or render expedient. Although specific terms have been employed herein, such terms are intended in a descriptive sense and not for purposes of limitations. Methods of molecular genetics, protein biochemistry, and immunology used but not explicitly described in this disclosure and these Examples are amply within the ability of those skilled in the art. Example 1 This Example illustrates the construction of a synthetic gene encoding the cholera toxin B subunit. A gene encoding the cholera toxin B subunit was synthesized from a number of oligonucleotides. The oligonucleotides were synthesized on an ABI model 380B DNA synthesizer and purified by gel electrophoresis. Nucleotide sequences were confirmed by automated DNA sequencing on the ABI model 370A DNA sequencer using dye terminator chemistry. For construction of the synthetic gene encoding cholera toxin subunit, codons preferred by B. pertussis were selected. The nucleotide sequence of the hybrid gene is shown in Figure 1 (SEQ ID NO: 1) . Example 2 This Example illustrates the construction of plasmid DS-546-1 containing the toxp/CTB-L/ctb gene. Oligonucleotides 2769.SL (SEQ ID NO: 3), 2770.SL (SEQ ID NO: 4), 2771.SL (SEQ ID NO: 5), 2780.SL (SEQ ID NO: 14), 2781.SL (SEQ ID NO: 15) and 2782.SL (SEQ ID NO: 16) (Figure 3) contain part of the tox promoter, encode the cholera toxin B leader peptide, and contain -70 bp of the 5'-end of the ctb gene encoding the mature cholera toxin B subunit protein. Plasmid S-3616-2 is an 8.6 kb pBR322-based plasmid containing 2.5 kb of the 5'- and 1.3 kb of the 3'-flanking regions for the fha structural gene between Bgl II and Kpn I sites (Figure 2) . Oligonucleotides 2769.SL, 2770.SL, 2771.SL, 2780.SL, 2781.SL, and 2782.SL were kinased, annealed, and ligated with the 4.8 kb vector fragment of S-3616-2 which had been digested with Bgl II and Kpn I to form plasmid JB- 867-1-1, which contains a toxp/CTB-L/5'ctb gene insert on a -220 bp Kpn I/Bgl II fragment. Oligonucleotides 2772.SL to 2779.SL (SEQ ID Nos: 6 to 13) (see Figure 3) encode the remaining -250bp of the ctb gene. They were kinased, annealed, and ligated with the 6.1 kb vector fragment from plasmid S-3616-2, which had been digested with Bgl II and EcoR I, to generate plasmid DS-525-1-1. The Kpn I/Bgl II fragment from plasmid JB-867-1-1 and the Bgl II/EcoR I fragment of plasmid DS-525-1-1 were ligated into pUC18, which had been digested with Kpn I and EcoR I, to generate plasmid DS-534-1 which thus contains the entire toxp/CTB-L/ctb gene. Plasmid S-3484-3-27 is a 14.2 kb pUC-based plasmid containing a mutant tox gene between the 5'- and 3'-tox flanking regions. Digestion with Kpn I and BamH I excised -4.7 kb of the tox structural gene. The -470 bp Kpn I/BamH I hybrid gene fragment from DS-534-1 was ligated into the Kpn I/BamH I vector fragment from S- 3484-3-27 to generate plasmid DS-546-1 (Figure 2) which contains the toxp/CTB-L/ctb hybrid gene between the tox flanking regions. This plasmid was used for insertion of the tox /CTB-L/ctb gene into the tox locus of B. pertussis, generating strain 492-320. Example 3 This Example describes the construction of plasmid JB-898-2-1 containing the fhap/CTB-L/ctb gene. Plasmid S-3658-1 contains a -210 bp EcoR I/Hinf I fragment of the fha promoter (Figure 4) . Oligonucleotides 2821.SL to 2824.SL (SEQ ID NOS: 17 to 20) (see Figure 5) encode the remaining 36 bp of the fha promoter and encode most of the cholera toxin B leader peptide. Oligonucleotides 2821.SL to 2824.SL were kinased, annealed, and ligated with the EcoR I/Hinf I fha promoter fragment from S-3658-1 into pUC18 which had been digested with EcoR I and Sac I. Plasmid JB-881-2 thus contains a portion of the fhap/CTB-L hybrid gene on a 290 bp EcoR I/Sac I fragment. Digestion of plasmid DS-534-1, which contains the complete toxp/CTB-L/ctb gene, with EcoR I and Sac I excised a -340 bp fragment of the ctb gene. Ligation of the EcoR I/Sac I fragments from DS- 534-1 and JB-881-2 into S-3616-2, which had been digested with EcoR I and dephosphorylated, generated plasmid JB- 898-2-1 (Figure 4) which contains the entire fhap/CTB- L/ctb gene between the fha flanking regions. This plasmid was used to insert the fhap/CTB-L/ctb hybrid gene into the fha locus of B. pertussis, generating strain 492-363. Example 4 This Example illustrates the construction of plasmid DS-729-1-1 which contains the toxp/Sl-L/ctb hybrid gene. Plasmid DS-534-1 contains the complete toxp/CTB- L/ctb gene on a -470 bp Kpn I/EcoR I fragment (Figure 6) . Oligonucleotides 2769.SL (SEQ ID NO: 21), 3220.SL (SEQ ID NO: 22), 3221.SL (SEQ ID NO: 23), 3222.SL (SEQ ID NO: 24), 3212.SL (SEQ ID NO: 25), 2782.SL (SEQ ID NO: 30), 3225.SL (SEQ ID NO: 29), 3224.SL (SEQ ID NO: 28), 3223.SL (SEQ ID NO: 27) and 3213.SL (SEQ ID NO: 26) (see Figure 7) contain part of the tox promoter, encode the pertussis toxin subunit SI leader peptide, and contain -70 bp of the 5'-end of ctb encoding the mature cholera toxin B subunit protein. The oligonucleotides were kinased, annealed, and ligated with the 3 kb Kpn I/Bgl II vector fragment from DS-534-1 (Figure 6) to generate plasmid DS- 700-2-1 which thus contains the complete toxp/Sl-L/ctb gene on a -505 bp Kpn I/BamH I fragment. The Kpn I/BamH I tox structural gene was excised from plasmid S-3484-3- 27 and the toxp/Sl-L/ctb gene inserted, to generate plasmid DS-729-1-1 which contains the toxp/Sl-L/ctb gene between the tox flanking regions (Figure 6) . This plasmid was used to insert the toxp/Sl-L/ctb hybrid gene into the tox locus of B. pertussis, generating strain 694-4. Example 5 This Example illustrates the construction of plasmid DS-729-2-1 which contains the toxp/PRN-L/ctb hybrid gene. Oligonucleotides 2769.SL (SEQ ID NO: 31), 3210.SL (SEQ ID NO: 32), 3217.SL (SEQ ID NO: 33), 3211.SL (SEQ ID NO: 34), 3212.SL (SEQ ID NO: 35), 3213.SL (SEQ ID NO: 36), 3214.SL (SEQ ID NO: 37) , 3215.SL (SEQ ID NO: 38) , 3218.SL (SEQ ID NO: 39) and 2782.SL (SEQ ID NO: 40) (see Figure 9) contain part of the tox promoter, encode the pertactin leader peptide, and contain -70bp of the ctb gene encoding the mature cholera toxin B subunit protein. The oligonucleotides were kinased, annealed, and ligated into DS-534-1 (Figure 8) which had been digested with Kpnl and Bgl II to delete -220 bp of the 5'-end of the toxp/CTB-L/ctb hybrid gene (Figure 5A) . Plasmid DS-707-6 contains the complete toxp/PRN-L/ctb hybrid gene on a -505 bp Kpn I/BamH I fragment. S-3484-3-27 was digested with Kpn I and BamH I to excise the tox structural gene and the hybrid gene was inserted. The resulting plasmid DS-729-2-1 contains the toxp/PRN-L/ctb gene between the tox flanking regions (Figure 8) and was used for insertion of the hybrid gene into the tox locus of B. pertussis, generating strain 694-12. Example 6 This Example illustrates the construction of plasmid JB-1201-4 which contains the fhap/Sl-L/ctb hybrid gene. Plasmid S-3658-1 contains a -210 bp EcoR I/Hinf I fragment of the fha promoter (Figure 10) . Oligonucleotides 3226.SL (SEQ ID NO: 41) , 3221.SL (SEQ ID NO: 42), 3222.SL (SEQ ID NO: 43), 3212.SL (SEQ ID NO: 44), 3213.SL (SEQ ID NO: 45), 3223.SL (SEQ ID NO: 46), 3224.SL (SEQ ID NO: 47) and 3227.SL (SEQ ID NO: 48) (Figure 11) contain part of the fha promoter, encode the pertussis toxin subunit Si leader peptide, and contain the first -70 bp of the ctb gene encoding the mature cholera toxin B subunit protein. Plasmid pUC8/BgXb is a pUC8 derived plasmid with extra restriction enzyme sites for Bgl II and Xba I in the multiple cloning site (Figure 10) . The oligonucleotides were kinased, annealed, and ligated with the EcoR I/Hinf I fha promoter fragment into pUC8/BgXb which had been digested with EcoR I and Bgl II. Plasmid JB-1190-1 thus contains the fhap/Sl-L/5'ctb hybrid gene on a -414 bp EcoR I/Bgl II fragment. Plasmid DS-534-1 was digested with Bgl II and EcoR I to excise the -250 bp 3'-ctb fragment, which was ligated with the EcoR I/Bgl II hybrid gene fragment into S-3616-2, which had been digested with EcoR I and dephosphorylated. The resulting plasmid JB-1201-4 thus contains the complete fhap/Sl-L/ctb hybrid gene between the fha flanking regions, in a reverse orientation with respect to the flanking regions (Figure 10) . This plasmid was used to introduce the fhap/Sl-L/ctb hybrid gene into the fha locus of B. pertussis, generating strain 694-54. Example 7 This Example illustrates the construction of plasmid JB-1141-5 which contains the fhap/PRN-L/ctb hybrid gene. Oligonucleotides 3216.SL (SEQ ID NO: 49), 3217.SL (SEQ ID NO: 50), 3211.SL (SEQ ID NO: 51), 3212.SL (SEQ ID NO: 52), 3213.SL (SEQ ID NO: 53), 3214.SL (SEQ ID NO: 54), 3215.SL (SEQ ID NO: 55) and 3219.SL (SEQ ID NO: 56) contain part of the fha promoter, encode the pertactin leader peptide, and contain the first -70 bp of the ctb gene encoding the mature cholera toxin B subunit protein (Figure 13) . The oligonucleotides were kinased, annealed, and ligated with the 210 bp EcoR/Hinf I fha promoter fragment from S-3658-1 (Figure 12) , into pUC8/BgXb which had been digested with EcoR I and Bgl II. Plasmid JB-1076-1-2 contains the fhap/PRN-L/5'ctb hybrid gene on a -414 bp EcoR I/Bgl II fragment and was ligated with the remainder of the ctb gene, excised from DS-534-1 on a -250 bp Bgl II/EcoR I fragment, into the S-3616-2 vector which had been digested with EcoR I and dephosphorylated. The resulting plasmid JB-1141-5 (Figure 12) thus contains the complete fhap/PRN-L/ctb gene between the fha flanking regions and was used to insert the hybrid gene into the fha locus of B_ ι . pertussis, generating strain 694-46. Example 8 This Example illustrates the generation of recombinant B. pertussis strains. B. pertussis strain 29-8 (ATCC 53,973) is a tox- deleted derivative of strain 10536 and is described in ref. 20. This strain was used as the host strain for genomic introduction of plasmids DS-546-1 ftoxp/CTB- L/Ctb. , DS-729-1-1 .toxp/Sl-L/ctb. and DS-729-2-1 (toxp/PRN-L/ctb) . B. pertussis strain 590-508 is an fha- and tox-deleted derivative of strain 10536 and was used to genomically introduce plasmids JB-898-2-1 .fhap/CTB- L/ctb. , JB-1201-4 (fhap/Sl-L/ctb. , and JB-1141-5 (fhap/PRN-L/ctb) . Plasmids were introduced into the B. pertussis strains by electroporation as described by Zealey et al. (ref. 5 and 20). A single cross-over event resulted in integration of the entire plasmid generating st_- s Ap Λ ctJ + strains. Selecting on streptomycin (100 μg ml" ') resulted in a second homologous recombination event which deletes all plasmid sequences and generated strains 694-4, 694-12, 694-46, and 694-54 respectively. Strain 694-46 has been deposited with ATCC (ATCC 55,654). The second cross-over did not occur for strains 492-320 and 492-363, thus these strains include the entire plasmids DS-546-1 and JB-898-2-1 respectively. The identification of the recombinant B. pertussis strains obtained and their derivations are summarized in Table 1 below. Example 9 This Example illustrates a Southern blot analysis of recombinant B. pertussis strains to confirm the correct chromosomal location of the integrated genes. Chromosomal DNA was isolated from B. pertussis strains 10536, 694-4, 694-12, 694-46, and 694-54, digested with restriction enzyme Bgl II, electrophoresed, and transferred to Gene Screen Plus (Dupont) . The blot was hybridized with a -300 bp Bgl II/BamH I ctb-specific probe and the results are shown in Figure 14. The appearance of a ctb-specific 1.5 kb Bgl II fragment confirmed the correct location of integration of the toxp/Sl-L/ctb and toxp/PRN-L/ctb genes at the tox locus of B. pertussis strains 694-4 and 694-12 respectively. The appearance of a specific 11 kb Bgl II fragment confirmed the correct location of the fhap/Sl-L/ctb and fhap/PRN-L/ctb hybrid genes at the fha locus in B. pertussis strains 694-54 and 694-46 respectively. Example 10 This Example illustrates the growth of recombinant B. pertussis strains and expression of cholera toxin B subunit. Recombinant B. pertussis strains were grown in modified Stainer-Scholte medium containing 0.2% heptakis(2,4-0-dimethyl)3-cyclodextrin (ref. 21) in 10 ml culture. 1 ml of culture was centrifuged at 12,000 x g for 4 min and the resulting supernatant was analysed by ELISA, SDS PAGE, and/or Western blot. The cell pellets were resuspended in 1 ml of media and lysed by sonication at 25μ for 45 sec, on ice with a Soniprep model 150 sonicator. Then, the cell debris was removed by centrifugation at 12000 x g for 4 min, and the supernatant removed and analysed by ELISA. The level of expression of cholera toxin B subunit from various B. pertussis strains is shown in Table 2 below. Example 11 This Example illustrates the ELISA assay used for the quantitation of cholera toxin B expression. Nunc Maxisorp 96 well plates were coated with monosialoganglioside - GM1 (Sigma) and incubated overnight at room temperature. The plates were washed and blocked with PBS containing 0.1% BSA for 45 min at room temperature. Two-fold serial dilutions of samples were added and the plates incubated for 1 h at room temperature. Cholera toxin B (List Biologicals #103C) , growth media, wild-type B. pertussis supernatant and cell pellets were used as standard and controls. CTB was detected using goat anti-choleragenoid (anti-CTB, List Biologicals #GAC-01C) as primary antibody and HRP- conjugated affinity purified rabbit anti-goat IgG as secondary antibody. Example 12 This Example illustrates the analysis of the expressed recombinant proteins by SDS-PAGE and Western blot. Culture supernatants were acetone-precipitated and resuspended in 0.1 volume of SDS lysis buffer. An equal volume of 2 x Laemmli sample buffer was added and the samples were either resolved directly on a 17.5% SDS PAGE gel or boiled for 5 min, before being resolved to convert the CTB pentamer to the monomeric form. Cell pellets were resuspended in 0.1 volume of SDS lysis buffer, an equal volume of 2 x Laemmli sample buffer added, and the samples treated as above. For Western blot analysis, proteins were transferred onto Gene Screen Plus nylon membranes (Dupont) and probed with goat anti-choleragenoid IgG antibody (anti-CTB, List Biologicals #GAC-01C) . Detection was performed with alkaline phosphatase-conjugated donkey anti-goat IgG, using dig che iluminescence (Boehringer Mannheim) . A cholera toxin standard (Sigma) contained both CTA and CTB. Figure 9 shows the expression of CTB as a pentamer in culture supernatants of strain 694-46 (fhap/PRN- L/ctb) . The identity of the cholera toxin is indicated by the correct molecular weight; specific-reactivity with anti-CTB antiseru and the conversion of the pentameric form of cholera toxin B subunit protein to the monomeric form by boiling. Example 13 This Example describes the construction of a plasmid for the introduction of a gene expressing hmwl from the hmwl promoter at the fha locus of the B. pertussis genome. Plasmid S-3616-2 contains the 5'- and 3'-fha flanking regions on a pBR322 based plasmid. Using oligonucleotides, a multiple cloning site containing EcoR I, Xba I, and Pst I sites was added at the EcoR I site to generate plasmid JB-1883-1, which has lost the 5'-fha flanking region. This 5'-fha sequence is re-introduced in plasmid JB-1901R-3. Plasmid S-3259-2 is a pUC8 based plasmid which contains Bgl II and Xba I sites in its MCS, but has had the EcoR I site deleted. The 4.2 kb Bgl II- Hind III fragment containing the 5'- and 3'-fha flanking regions with the MCS, was cloned into S-3259-2 to generate a pUC-based plasmid containing the fha flanking regions, JB-1926-3. The sequences between the BamH I and Bgl II sites of the MCS were removed by ligation to generate plasmid JB-1935-1. Plasmid pHMWl-15 is a pUC-based plasmid containing all of the hmwlabc operon, its flanking regions, and a T7 promoter upstream of the hmwl genes. The entire -10.6 kb insert was cloned into pUC8-BgXb in order to flank the coding sequence by Xba I sites, as in plasmid JB-1945R-1- 6. The 10.2 kb Xba I fragment from JB-1945R-1-6 was cloned into JB-1935-1 to generate plasmid JB-1957-27 which is pUC/5'fha/hmwp/hmwlabc/3'fha. Example 14 This Example describes the construction of a plasmid for the introduction of a hybrid gene expressing hmwl from the fha promoter at the fha locus of the B. pertussis genome. Oligonucleotides were used to introduce a synthetic fha promoter and the extreme 5'-end of hmwl into pUC8- BgXb, to generate plasmid JB-1936-2. The oligonucleotides include all of the fha promoter and the sequence of hmwla from the ATG start codon to the Bsm I s i t e - 4 5 b p d o w n s t r e a m : [GAATTCCTGCGCTGGCACCCGCGGCGGGCCGGGGAGCGGGTTGTCGGCGCACGC CTATACGTGCCGGACAGGGTTTGATGGTTTGACTAAGAAATTTCCTACAAGTCTT GTATAAATATCCATTGATGGACGGGATCATTACTGACTGACGAAGTGCTGAGGTT TATCCAGACTATGGCACTGGATTTCAAAACCTAAAACGAGCAGGCCGATAACGGA TTCTGCCGATTACTTCACTTCGCTGGTCGGAATATGAACAAGATATATCGTCTCA AATTCAGCAAACGCCTGAATGCT - SEQ ID No: 57] The 2.2 kb 5'- fragment of hmwl was subcloned from JB-1945R-1-6 to generate plasmid JB-1959-1. The hmwl promoter region of JB-1945R-1-6 was replaced by the synthetic fha promoter from JB-1936-2 to generate plasmid JB-1972-1. The 1.7 kb fhap/5'hmwl fragment from JB-1972-1 was inserted between the fha flanking regions to generate JB-1980-1 and the remainder of the hmwl genes was added in plasmid JB-1989R-1, pUC/5'fha/fhap/hmwlabc/3'fha. Example 15 This Example describes the construction of a plasmid for the introduction of a gene expressing hmw2 from the hmw promoter at the fha locus of the B. pertussis genome. Plasmid JB-1935-1 (described in Example 13) is a pUC-based plasmid containing the fha flanking regions and a multiple cloning site. pHMW2-21 is a pUC-based plasmid containing the entire hmw2abc operon, its flanking regions and a T7 promoter upstream. A 3 kb fragment containing the hmw promoter and 5'hmw2 sequences was cloned between the fha flanking regions in plasmid DS- 1702-2-1. The remainder of the hrow2 gene sequences were a d d e d i n p l a s m i d D S - 17 19 - 2 8 , pUC/5'fha/hmwp/hmw2abc/3'fha. Example 16 This Example describes the construction of a plasmid for the introduction of a hybrid gene expressing hmw2 from the fha promoter at the fha locus of the B. pertussis genome. Oligonucleotides were used to create a synthetic fha promoter and the extreme 5'-end of the hm 2 gene in plasmid DS-1658-1-1. The oligos included the entire fha promoter and the hmw2a gene from the ATG start codon to the Bsm I site -45 bp downstream and were identical to those used in Example 14 except that there was a 5'- terminal BamH I site instead of an EcoR I site. The sequence between the BamH I and Bgl II sites of the pUC8- BgXb MCS was deleted in plasmid DS-1591-1 and the 3 kb Xba I fragment of pHMW2-21 containing the hmw2 promoter and 5'-end of hmw2 was inserted to generate plasmid DS- 1614-6. BamH I-Bsm I fragments were used to replace the hmw promoter in DS-1614-6 with the synthetic fha promoter to generate plasmid DS-1674-1. The 2.3 kb fhap/5'hmw2 fragment of DS-1674-l replaces the hmwp/5'hmw2 fragment of DS-1719-28 to generate DS-1732R-14, pUC/5'fha/fhap/hmw2abc/3'fha. Recombinant B. pertussis strains containing fhap/hmwlabc. hmwp/hmwlabc. fhap/hmw2abc. or hmwp/hmw2abc genes were produced using the two-step double cross-over procedure described in Example 8 above and are summarized in Table 3 below. TABLE 3 Recombinant strains of Bordetella producing high molecular weight outer membrane proteins from non- typable H. Influenzae. Example 17 This Example describes the dot blot analysis of recombinant B. pertussis strains. Streptomycin resistant recombinant B. pertussis strains were grown in modified Stainer Scholte medium containing cyclodextrin and 10 μl of culture was dotted onto GeneScreen membrane and allowed to air dry. The filters were processed and hybridized with a dig-labelled 1.0 kb Bsm-Bsm probe generated from plasmid JB-1972-1. This probe recognizes both the hmwla and hmw2a genes in a region of conserved sequence. B. pertussis 590-508 cells were used as a negative control and plasmid JB- 1972-1 was used as a positive control. All of the recombinant B. pertussis strains were positive indicating the presence of the hmwla or hmw2a genes. The results are shown in Figure 19. Example 18 This Example describes the Western blot analysis of recombinant B. pertussis strains expressing high molecular weight outer membrane proteins of non-typable H. influenzae. One ml aliquots of cultures were spun at 14,000 x g for 4 minutes and the supernatant transferred as 2 x 0.5 ml aliquots to clean tubes. The cell pellet was resuspended at 20 OD/ l in Laemmli sample buffer. 0.5 ml of supernatant was precipitated with 1 ml of acetone and the pellet was resuspended in 10 μl of Laemmli sample buffer. For SDS PAGE gels and Western blots, 1 μl of cell pellet and 5 μl of acetone precipitate was heated at 100°C for 5 minutes, then loaded onto an 11.5% gel. Western blots were developed using a monoclonal antibody to HMWl and the results are shown in Figures 21 and 22. SUMMARY OF THE DISCLOSURE In summary of this disclosure, the present invention provides a novel gene product expression method having particular application to Bordetella species. Modifications are possible within the scope of this invention. TABLE 1 Recombinant B. pertussis strains cc TABLE 2 Cholera toxin B expression from recombinant B. pertussis strains REFERENCES 1. Johnson and Burns. 1994. J. Bacteriol. 176: 5350. 2. Locht et al. 1992. EMBO J. 11: 3175. 3. EP patent application 523 976. 4. EP patent application 453 216. 5. Zealey et al. 1992. Appl. Environ. Microbiol. 58: 208. 6. Burnette. 1994. Structure 2: 151. 7. Holmgren et al. 1993. Vaccine 11: 1179. 8. Wu and Russell. 1994. Vaccine 12: 215. 9. Dertzbough and Elson. 1993. Infect. Immun. 61: 384. 10. Cardenas and Clement. 1993. Vaccine 11: 126. 11. Airaksinen et al. 1991. Biotechnology Lett 13: 305. 12. Lebens et al. 1993. Bio/Technology 11: 1574. 13. Burnette et al. 1991. Infect. Immun. 59: 4266. 14. Klauser et al. 1990. EMBO J. 1991. 15. Nicosia et al. 1986. Proc. Natl. Acad. Sci. (USA) 83: 4631. 16. Loosmore et al. 1989. Nucleic Acid. Res. 17: 8365. 17. Relman et al. 1989. Proc. Natl. Acad. Sci. (USA) 86: 2637. 18. Charles et al. 1989. Proc. Natl. Acad. Sci. (USA) 86: 3554. 19. Da s et al. 1991. Biochen. Biophys. Acta. 1090: 139. 20. Zealey et al. 1990. Bio/Technology 8: 1025. 21. Imaizumi et al. 1983. Infect. Immun. 41: 1138. 22. Nicosia et al. 1987. Infect. Immun. 55: 963. 23. Makoff et al. 1990. Bio/Technology 8: 1030. 24. Domenighimi et al. 1990. Molec. Microbiol. 4: 787. 25. Watson, M. 1984. Nucl. Acids. Res. 12: 5145.

Claims: CLAIMS What we claim is: 1. A nucleic acid molecule comprising a promoter functional in Bordetella and operatively coupled to a heterologous gene encoding a non-Bordetella gene product, wherein the heterologous gene is transcriptionally regulated by the promoter in Bordetella. 2. The nucleic acid molecule of claim 1 wherein the non-Bordetella gene product is selected from the group consisting of proteins and peptides. 3. The nucleic acid molecule of claim 2 wherein the protein or peptide is selected from the group consisting of an enzyme, an antigen, an immunogen, an allergen, an enzyme inhibitor, a hormone, a lymphokine, an immunoglobulin or fragment thereof, a toxin, a toxin subunit, a mammalian protein, a structural protein and a receptor. 4. The nucleic acid molecule of claim 2 wherein the protein is a cholera toxin molecule. 5. The nucleic acid molecule of claim 4 wherein the cholera toxin molecule is the B subunit thereof. 6. The nucleic acid molecule of claim 3 wherein the antigen is a high molecular weight outer membrane protein a non-typable Haemophilus influenzae strain. 7. The nucleic acid molecule of claim 6 wherein the outer membrane protein is HMWl or HMW2. 8. The nucleic acid molecule of claim 1 wherein the Bordetella promoter is selected from the group consisting of the TOX. PRN, FHA and hmw promoters. 9. The nucleic acid molecule of claim 1 wherein the heterologous gene further comprises a nucleic acid sequence encoding a leader sequence for secretion of the non-Bordetella gene product. 10. The nucleic acid molecule of claim 9 wherein the leader sequence is a leader sequence of a Bordetella protein or subunit thereof or a fragment or analog of the Bordetella protein leader sequence retaining secretion- mediating properties. 11. The nucleic acid molecule of claim 10 wherein the leader sequence is selected from the group consisting of the Bordetella pertactin leader sequence and a pertussis toxin subunit leader sequence. 12. The nucleic acid molecule of claim 10 wherein the heterologous gene encodes a cholera toxin molecule. 13. The nucleic acid molecule of claim 12 wherein the cholera toxin molecule is the B subunit thereof. 14. The nucleic acid molecule of claim 9 wherein the leader sequence is a leader sequence of a non-Bordetella protein or subunit thereof or a fragment or analog of the non-Bordetella protein leader sequence retaining secretion-mediating properties. 15. The nucleic acid molecule of claim 14 wherein the non-Bordetella gene product is a secreted gene product and the non-Bordete1la leader sequence is the native leader sequence of said secreted gene product. 16. The nucleic acid molecule of claim 15 wherein the secreted gene product is a cholera toxin molecule. 17. The nucleic acid molecule of claim 16 wherein the cholera toxin molecule is the B subunit thereof. 18. The nucleic acid molecule of claim 1 selected from the group consisting of toxp/CTB-L/ctb. fhap/CTB-L/ctb. toxp/Sl-L/ctb. toxp/PRN-L/ctb. fhap/Sl-L/ctb and fhap/PRN-L/ctb. fhap/hmwl and fhap/hmw2. hmwp/hmwl and hmwp/hmw2. 19. A nucleic acid molecule comprising a Bordetella promoter coupled to a nucleic acid sequence encoding a non-Bordetella leader sequence for secretion of a gene product, operatively coupled to acid leader sequence. 20. The nucleic acid molecule of claim 19 wherein said Bordetella promoter is selected from the group consisting of the TOX. PRN and FHA promoters. 21. The nucleic acid molecule of claim 20 wherein the non-Bordetella leader sequence is selected from bacterial leader sequences, eukaryotic leader sequences and viral leader sequences. 22. The nucleic acid molecule of claim 21 wherein the non-Bordetella leader sequence is the leader sequence for the cholera toxin B subunit. 23. The nucleic acid molecule of claim 1 having a first DNA sequence corresponding to a 5' flanking sequence of a selected Bordetella gene and disposed at the 5' end of the nucleic acid molecule and a second DNA sequence corresponding to a 3 ' flanking sequence of the selected Bordetella gene and disposed at the 3' end of the nucleic acid molecule, the first and second DNA sequences permitting specific integration of the nucleic acid molecule into a Bordetella genome at a locus corresponding to the selected Bordetella gene. 24. The nucleic acid molecule of claim 23 wherein the Bordetella promoter is that of the selected Bordetella gene. 25. The nucleic acid molecule of claim 24 wherein the selected Bordetella gene is selected from the group consisting of the TOX. PRN and FHA genes. 26. A plasmid adapted for transformation of a Bordetella strain comprising the nucleic acid molecule of claim 23. 27. The plasmid of claim 26 which selected from the group consisting of DS-546-1, JB-898-2-1, DS-729-1-1, DS- 729-2-1, JB-1201-4, JB-1141-5, JB-1957-27, JB-1989-R-1, DS-1719-28, DS-1732R-14. 28. A recombinant strain of Bordetella containing the nucleic acid molecule of claim 1 and expressing said non- Bordetella. gene product. 29. A recombinant strain of Bordetella containing the nucleic acid molecule of claim 19 and secreting said gene product. 30. A recombinant strain of Bordetella containing the nucleic acid molecule of claim 23 integrated into the genome thereof and secreting said non-Bordetella gene product. 31. The strain of claim 30 wherein the Bordetella strain is a selected from the group consisting of a B. pertussis strain, a B. parapertussis strain, a B. bronchiseptica strain and a B. avium strain. 32. The strain of claim 31 wherein the Bordetella strain is a strain of B. pertussis. 33. The strain of claim 32 which is B. pertussis strain 694-46 having ATCC deposit No. 55,654. 34. A method of expression of a non-Bordetella gene product, which comprises culturing a recombinant strain of claim 30. 35. A method of expression of a gene product, which comprises culturing a recombinant strain of claim 29. 36. A nucleic acid molecule having the nucleotide sequence shown in Figure 1.

Inventors: KLEIN MICHEL H, LOOSMORE SHEENA M, YACOOB REZA KHAYYAM, ZEALEY GAVIN R, KLEIN, MICHEL, H., LOOSMORE, SHEENA, M., YACOOB, REZA, KHAYYAM, ZEALEY, GAVIN, R.
Applicants: CONNAUGHT LAB, KLEIN MICHEL H, LOOSMORE SHEENA M, YACOOB REZA KHAYYAM, ZEALEY GAVIN R, CONNAUGHT LABORATORIES LIMITED, KLEIN, MICHEL, H., LOOSMORE, SHEENA, M., YACOOB, REZA, KHAYYAM, ZEALEY, GAVIN, R.
Application year: 1996
Main classification: C12N15
IPC codes: C07K14, C12N15