WO1986000645A1 - Monoclonal antibodies and their use - Google Patents

Abstract

Monoclonal antibodies to the genus Edwardsiella, the labelled antibodies, compositions and kits containing them, and their use in diagnosis of antigen and treatment.

Description

-i-

MONOCLONAL ANTIBODIES AND THEIR USE This invention relates to monoclonal antibodies and their use.

BACKGROUND OF THE INVENTION Edwardsiella is described in Zinsser Microbiology (17th ed_) 732-3. Edwardsiella tarda is the best known species classified in the tribe Edwardsiellae. Formerly, it was classified in the Asakusa group and the Bartholomew group of organisms. A number of isolates from animal sources, primarily cold-blooded types, have been reported. In man, Edwardsiella infections are rare, but the organism has been isolated from wound infections, sepsis and meningitis- The organism also has been isolated from human faeces in cases of gastroenteritis. Edwardsiella is known to cause bacterial diarrhea, gram-negative sepsis- and urinary tract infections. Bacterial diarrhea is a common and often serious condition manifest as fluid loss from the bowel, leading in many cases to dehydration, and occasionally death. In addition to diarrhea, Edwardsiella is known to cause gram-negative sepsis whictt is a. bloodstream infection. It is one of the major infectious disease problems encountered in modern medical centres. While it can be transient and self-limited, severe gram-negative sepsis constitutes a medical emergency.

Present treatment and diagnosis of Edwardsiella infections vary depending on the locus of the infection. It is estimated that in the United States and Europe many millions of cases of bacterial diarrhea occur annually, of which several million are seen by a physician or admitted to a hospital. Because of the self-limiting nature of the adult disease, most people do not seek treatment. Of the people seeking treatment, bacterial diagnosis of diarrhea is presently made by stool culture techniques. These techniques are generally performed only in hospitals and are slow, requiring one to three days. During this time, the patient is exposed, if treated, to the expense and potential hazard of inappropriate therapy. However, if not treated, the patient is exposed to the hazard of a deteriorating condition pending the test result and initiation of therapy..

At the present time, the test for gram-negative sepsis involves processing blood and urine cultures and other procedures on occasion. In addition to being expensive, blood culture tests are cumbersome. They require a day, and often several days, to return results. They require expert laboratory skills because of the complex nature of human blood which tends to interact non-specifically with many of the test reagents.

Presently, in urinary tract infections, a microscopic examination is made, to determine the presence of micro-organisms as a preliminary screening. The microscopic examination cannot distinguish among the gram-negative bacteria. Accordingly, a second step is a urine culture to identify the organism isolated in the urine sample. A delay in diagnosis and initiation of treatment can result in serious complications.

Thus, existing methods of detection of Edwardsiella with high accuracy in diarrheal or urinary tract infections, or in gram-negative sepsis are less than satisfactory in that they consume large amounts of expensive skilled labour and laboratory time, generally taking one and often several days before returning results.

The production of monoclonal antibodies is now a well-known procedure first described by Kohler and Milstein, Eur. J. Immunol. (1975) 292. While the general technique of preparing hybridomas and the resultant monoclonal antibodies is understood, it has been found that preparing a specific monoclonal antibody to a specific antigen is difficult, mainly due to the degree of specificity and variations required in producing a particular hybridoma. SUMMARY OF THE INVENTION

The present invention provides novel monoclonal - antibodies for use in accurately and rapidly diagnosing samples for the presence of Edwardsiella antigens and/or organisms. Briefly stated, the present invention comprises monoclonal antibodies specific for an antigen of Edwardsiella; in particular, the antigens of Edwardsiella tarda, the antigens of Edwardsiella hoshinae and the antigens of Edwardsiella ictanuri, as well as a monoclonal antibody broadly cross-reactive with an antigen, for each species ox the genus Edwardsie1l .

The invention also comprises labelled monoclonal antibodies for use in diagnosing the presence of the Edwardsiella antigens, each comprising a monoclonal antibody against one of the above-mentioned antigens to Edwardsiella or to a particular species thereof and having linked thereto an appropriate label. The label can be, for example, a radioactive isotope, enzyme, fluorescent compound, chemiluminescent compound, bioluminescent compound, ferromagnetic atom or particle. The invention further comprises the process for diagnosing the presence of Edwardsiella antigens or organisms in a specimen, comprising contacting said specimen with the labelled monoclonal antibody in an appropriate immunoassay procedure.

Additionally, the invention is also directed to a therapeutic composition comprising a monoclonal antibody for an antigen of Edwardsiella and a carrier or diluent, as well as kits containing at least one labelled monoclonal antibody to an antigen of a Edwardsiella. DETAILED DESCRIPTION The monoclonal antibodies of the present invention are prepared by fusing spleen cells from a mammal which has been immunised against the particular Edwardsiella antigen, with an appropriate myeloma cell line, preferably NSO (uncloned) , P3NS1-Ag4/1, or Sp2/0 Agl4. The resultant product is then cultured in a standard HAT (hypoxanthine, aminopterin and thymidine) medium. Screening tests for the specific monoclonal antibodies are employed utilising immunoassay techniques which will be described below.

The immunised spleen cells may be derived from any mammal, such as primates, humans, rodents (i.e. mice, rats and rabbits) , bovines, ovines and canines, but the present invention will be described in connection with mice. The mouse is first immunised' by injectio of the particular Edwardsiella antigen chosen, generally for a period, of approximately eleven weeks. When the mouse shows sufficient antibody production against the antigen, as determined by conventional assay, it is given a booster injection of the _.appropriate Edwardsiella antigen, and then killed so that the immunised spleen may be removed. The fusion can then be carried out utilising immunised spleen cells and an appropriate myeloma cell line.

The fused cells yielding an antibody which gives a positive response to the presence of the particular Edwardsiella antigen are removed and cloned utilising any of the standard methods. The monoclonal antibodies from the clones are then tested against standard antigens to determine their specificity for the particular Edwardsiella antigen. The monoclonal antibody selected, which is specific for the particular Edwardsiella antigen or species, is then bound to an appropriate label. Amounts of antibody sufficient for labelling and subsequent commercial production are produced by the known techniques, such as by batch or continuous tissue culture or culture in vivo in mammals such as mice. The monoclonal antibodies may be labelled with various labels, as exemplified above. The present ^• invention will be described with reference to the use of an enzyme-labelled monoclonal antibody. Examples of enzymes utilised as labels are alkaline phosphatase, glucose oxidase, galactosidase, peroxidase and urease.

Such linkage with enzymes can be accomplished by any known method, such, as the Staphylococcal Protein A method, the glutaraldehyde method, the benzoquinone method, or the periodate method. Once the labelled monoclonal antibody is formed, testing is carried out employin one of a wide variety of conventional immunoassay methods. The particular method chosen will vary according to the monoclonal antibody and the label chosen. At^' the present time, enzyme immunoassays are preferred owing to their low cost, reagent stability, safety, sensitivity and ease of procedure. One example is the enzyme-linked immunosorbent assay (EIA) . EIA is a solid-phase assay system which is similar in design to the radiometric assay, but which utilises an enzyme in place of a radioactive isotope as the immunoglobin marker.

Fluorescent-immunoassay is based on the labelling of antigen or antibody with fluorescent probes. A non-labelled antigen and a specific antibody are combined with identical fluorescently-labelled antigen. Both labelled and unlabelled antigen compete for antibody binding sites. The amount of labelled antigen bound to the antibody is dependent upon, and therefore a measurement of, the concentration of non-labelled antigen. Examples of this particular type of fluorescent-imirtunoassay include heterogeneous systems such as Enzyme-Linked Fluorescent Immunoassay, or homogeneous systems such as the Substrate-Labelled Fluorescent Immunoassay. The most suitable fluorescent probe, and the one most widely used, is fluorescein. While fluorescein can be subject to considerable interference from scattering, sensitivity can be increased by the use of a fluorometer optimised for the probe utilised in the particular assay, and in which the effect of scattering can be minimised.

In fluorescence polarisation, a labelled sample is excited with polarised light and the degree of polarisation of the emitted light is measured_* As the antigen binds to the antibody, its rotation slows down and the degree of polarisation increases. Fluorescence polarisation is simple, quick and precise. However, at the present time, its sensitivity is limited to the micromole per litre range and upper nanomole per litre range with respect to antigens in biological samples. Luminescence is the emission of light by an atom or molecule as an electron is transferred to the ground state from a higher energy state. In both chemiluminescent and bioluminescent reactions, the free energy of a chemical reaction provides the energy required to produce an intermediate reaction or product in an electronically-excited state. Subsequent decay back to the ground state is accompanied by emission of light. Bioluminescence is the name given to a special form of chemiluminescence found in biological systems, in which a catalytic protein or enzyme, such as luciferase, increases the efficiency of the luminescent reaction. The best known chemiluminescent substance is luminol.

A further aspect of the present invention is a therapeutic composition comprising one or more of the monoclonal antibodies to the particular Edwardsiella antigen or species, as well as a pharmacologically- acceptable carrier or diluent. Such compositions can be used to treat humans and/or animals afflicted with some form of Edwardsiella infection, and they are used in amounts effective to cure; the amount may vary widely, depending upon the individual being treated and the . severity of the infection.

One or more of the monoclonal antibodies can be assembled into a diagnostic kit for use in diagnosing for the presence of an antigen, antigens or species of

Edwardsiella in various specimens. It is also possible to use the broadly cross-reactive monoclonal antibody which can identify the genus Edwardsiella alone or as part of a kit containing antibodies that can identify other bacterial genera or species of Edwardsiella and/or other bacteria.

In the past, there have been difficulties in developing rapid kits because of undesirable cross-reactions of specimens; e.g. faeces with antiserum. The use of monoclonal antibodies can eliminate these problems and provide highly specific and rapid tests for diagnosis. For example, the incidence of significant diarrhea and diarrheal illness is so high that estimates of market size for such a kit are difficult to make, but a "same day" test could be expected to be used at least as often as stool cultures. Large use of such tests in developing countries might be anticipated because of more frequent and severe diarrhea, and other related illnesses. Additionally, a kit could be used in pathology laboratories for the rapid detection of gram-negative bacteria in urine, or on an out-patient basis. Further, conjugated or labelled monoclonal antibodies for antigens and/or species of Edwardsiella and other gram-negative bacteria can be utilised in a kit to identify such antigens and organisms in blood samples taken from patients for the diagnosis of possible Edwardsiella or other gram-negative sepsis. The monoclonal test is an advance over existing procedures in that it is more accurate than existing tests; it gives "same day" results, provides convenience to the patient and improves therapy as a result of early, accurate diagnosis; and it reduces labour costs and laboratory time required for administration of the tests. The kit may be sold individually or included as a component in a comprehensive line of compatible immunoassay reagents sold to reference laboratories to detect the species and serotypes of Edwardsiella.

One preferred embodiment of the present invention is a diagnostic kit comprising at least one labelled monoclonal antibody against a- particular Edwardsiella- antigen or species, as well as any appropriate stains, counterstains or reagents. Further embodiments include kits containing at least one control sample of a Edwardsiella antigen and/or a cross-reactive labelled monoclonal antibody which would detect the presence of any of the given particular Edwardsiella organisms in a particular sample.

Monoclonal diagnostics which detect the presence of Edwardsiella antigens can also be used in periodic testing of water sources, food supplies and food processing operations. Thus, while the present invention describes the use of the labelled monoclonal antibodies to determine the presence of a standard antigen, the invention can have many applications in diagnosing the presence of antigens by determining whether specimens, such as urine, blood, stool, water and milk, contain the particular Edwardsiella antigen. More particularly, the invention could be utilised as a public health and safety diagnostic aid, whereby specimens such as water or food could be tested for possible contamination.

The invention will be further illustrated in connection with the following Examples which are set forth for purposes of illustration only and not by way of limitation.

The monoclonal antibodies of the present invention were prepared generally according to the method of Kohler and Milstein, supra. In the Examples:

API = Analytical Profile Index (ref. Ayerst Laboratories)

DMEM = Dulbeccos Modified Eagles Medium

FCS = Foetal Calf Serum % T refers to vaccine concentrations measured in a 1 cm light path

PBS = Phosphate Buffered Saline Example 1

A. Antigen Preparation Edwardsiella tarda bearing the antigen OC1 was obtained from the National Collection of Type Cultures (NCTC accession No. 10396) and tested against standard reference typing sera to confirm its typing. More specifically, the Edwardsiella tarda was removed from the lyophile, grown on blood agar, and tested by conventional biochemical (API) and agglutination tests with appropri¬ ate antisera to confirm it identity and purity. The cells were then transferred to DMEM, grown, and harvested for use as a source of antigen. The organisms were washed in formol saline by repeated centrifugation and were resuspended in formol saline.

B. Animal Immunisation

Six Balb/c mice were injected with the prepared antigen. They were given one intraperitoneal injection per week for three weeks ^:{0.05 ml 80% T vaccine) followed -10-

by five intravenous injections every week of 80% T boiled killed Edwardsiella tarda antigen prepared as above, for a further three weeks. The mice were bled approximately six days after the last injection and the serum tested for antibodies by assay. The conventional assay used for this serum titer testing was the enzyme-linked immunosorbent assay system. When the mice showed antibody production after this regimen, generally a positive titer of at least 10,000, a mouse was selected as a fusion donor and given a booster injection (0.05 ml of 80% T vaccine) intravenously, three days prior to splenectomy. C. Cell Fusion

The selected donor mouse was killed and surface sterilised by immersion in 70% ethyl alcohol. The spleen was then removed and immersed in approximately 2.5 ml of .DMEM to which had been added 3% FCS. The spleen was then gently homogenised in a LUX homogenising tube until all cells had been released from the membrane and the cells were washed in 5 ml 3% FCS DMEM. The cellular debris was then allowed to settle and the spleen cell suspension placed in a 10 ml centrifuge tube. The debris was then rewashed in 5 ml 3% FCS DMEM. 50 ml of suspension are then made in 3% FCS DMEM. The myeloma cell line used is NS0 (uncloned) , obtained from the MRC Laboratory of Molecular Biology in Cambridge, England. The myeloma cells are in the log growth phase, and rapidly dividing. Each cell line is washed using a tissue culture medium DMEM containing 3% FCS.

The spleen cells are then spun down at the same time that a relevant volume of myeloma cells are spun down (room temperature for 7 minutes at 600 g) , and each resultant pellet is then separately resuspended in 10 ml 3% FCS DMEM. In order to count the myeloma cells, 0.1 ml of the suspension is diluted to 1 ml and used with a haemacytometer with phase microscope to make the count. In order to count the spleen cells, 0.1 ml of the suspension are diluted to 1 ml with Methyl Violet-citric acid solution and used with a haemacytometer and light microscope and the stained nuclei of the cells counted.

6 x 10 7 spleen cells were then mixed with 5 x 107 myeloma cells, the mixture washed in serumfree DMEM high in glucose and centrifuged and all the liquid removed The resultant cell pellet is placed in a 37°C water bath. Over a period of one minute, 1 ml of a 50% w/v solution of polyethylene glycol 1500 (PEG) in saline Hepes, pH approximately 7.5, is added, and the mixture gently stirred for approximately 1.5 minutes- There are then slowly added 10 ml of serum-free tissue culture medium DMEM, followed by the addition of up to 50 ml of such culture medium, centrifugation and removal of all the supernatant, and resuspension of the cell pellet in 10 ml of DMEM containing 18% by weight FCS. 10 μl of the mixture are placed in each of 480 wells of standard multiwell tissue culture plates. Each well contains 1.0 ml of the standard HAT medium (hypoxanthine, aminopterin and thymidine) and a feeder layer of Balb/c

4 macrophages at a concentration of 5x10 macrophages/well. The wells are kept undisturbed and cultured at 37°C in 9% CO_ air at approximately 100% humidity. The wells are analyzed for growth utilizing the conventional inverted microscope procedure after about 5 to 10 days. In those wells in which growth was present in the inhibiting HAT medium, screening tests for the specific monoclonal antibody are made utilizing the conventional enzyme immunoassay screening method described below. Somewhere around 10 days to 14 days after fusion, sufficient antibody against the Edwardsiella tarda antigen may develop in at least one well. D. Cloning

From those wells which yielded antibody against the Edwardsiella tarda antigen, cells are removed and cloned using the standard dilution method. The agar method is an alternative.

The clones were assayed by the enzyme immunoassay method to determine antibody production. A positive clone may be recloned.

E. Monoclonal Selection The monocronal antibodies from the clones are screened by the standard techniques for binding to Edwardsiella tarda NCTC 10396 prepared as in the immunization, and for specificity in a test battery of Edwardsiella species and related genera bearing different antigens. Specifically, a grid of microtiter plates containing a representative selection of organisms may be prepared, boiled, and utilized as a template to define the specificity of the parent group. The EIA immunoassay noted above may be used. F- Antibody Production

At least one of two methods are usually available for production (and purification) .

In Method A, six Balb/c mice are primed with pristane and injected intraperitoneally with 10 cells of monoclonal antibody specific against Edwardsiella tarda antigen. Then the ascites fluid is harvested after the mice have reached the proper stage; the mice are swollen with fluid but still alive. The cells are then centrifuged at 1200 g for approximately 10 minutes, the cells discarded, and the antibody rich ascites fluid collected.

The fluid is titrated, as noted above, to establish presence and level of antibody, and purified.

Purification can be accomplished using the protein A-Sepharose method, or the ammonium sulphate/DEAE method. More particularly, in the protein A-Sepharose method, about 10 ml of the ascites fluid are filtered through glass wool and centrifuged at 30,000 g for 10 minutes. The ascites is then diluted with twice its own volume of cold phosphate buffer (0.1 M sodium phosphate, pH 8.2) and the diluted ascites is loaded on to a 2 ml column of protein A-Sepharose which had previously been equilibrated with phosphate buffer. The column is washed with 40 ml of phosphate buffer and the monoclonal antibody is eluted with citrate buffer (0.1 M sodium citrate, pH 3.5) into sufficient IM tris buffer, pH 9.0, to raise the pH immediately to about 7.5. The eluate is dialysed in 2 x 1000 ml PBS at +4°C.

In the ammonium sulphate/DEAE method, about 10 ml of the ascites fluid are filtered through glass wool and centrifuged at 30,000 g for 10 minutes. The ascites is then stirred at +4°C and an equal volume of cold, saturated ammonium sulphate added slowly. The mixture is stirred for a further 30 minutes after addition is complete- The precipitate is harvested by centrifugation at 10,000 g for 10 minutes. The precipitate is dissolved in a minimum volume of cold phosphate/EDTA buffer (20 mM sodium phosphate, 10 mM EDTA, pH 7.5, + 0.02% sodium azide) . The solution is dialyzed versus 2x1000 ml of the same buffer at +4°C The dialyzed, redissolved precipitate is centrifuged at 30,000 g for 10 minutes and applied to a 10 ml column of DEAE-cellulose, previously equilibrated in phosphate/EDTA buffer. The monoclonal antibody is eluted with phosphate/EDTA buffer. in Method B, cells of the monoclonal antibody- producing line specific to Edwardsiella tarda antigen are grown in batch tissue culture. DMEM, to which has been added 10% FCS, is used to support growth in mid-log phase, to 1 litre volume. The culture is allowed to overgrow, to allow maximum antibody production. The culture is then centrifuged at 1200 g for approximately 10 minutes. The cell/cell debris is discarded and the antibody-rich supernatant collected.

The fluid may then be titrated, as noted above, to establish presence and level of antibody, and purified. Purification can be accomplished by a combination of batch ion-exchange chromatography, ammonium sulphate precipitation and either column ion-exchange chromatography or protein A-Sepharose chromatography. More particularly, to one litre of culture supernatant is added one litre of 0.05M sodium acetate buffer, pH 4.5, and 40 ml of SP-Sephadex, previously equilibrated in 0.IM sodium acetate buffer, pH 5.0. The suspension is stirred at +4°C for one hour. The SP-Sephadex is allowed to settle and the supernatant is decanted- The SP-Sephadex is packed in a column, washed with 60 ml of 0.1M acetate buffer, pH 5.0, and eluted with 60 ml of the same buffer plus IM sodium chloride. The eluate is stirred at +4°C, and an equal volume of saturated ammonium sulphate added slowly. The suspension is stirred for a further 30 minutes. The precipitate is then harvested by centrifugation at 10,000 g for 10 minutes. The precipitate is dissolved in a minimum volume of either cold phosphate/EDTA buffer (20mM sodium phosphate, lOmM EDTA, pH 7.5, + 0.02% sodium azide) for DEAE-cellulose chromatography, or phosphate buffer (0.1M sodium phosphate, pH 8.2 -t- 0.02% sodium azide) for protein A-Sepharose chromatography. The dissolved precipitate is dialysed versus 2 x 1000 ml of the dissolution buffer at +4°C, and the appropriate chromatography step carried out as previously described in Method A.

G. Enzyme-Monoclonal Linkage

The monoclonal antibody specific against Edwardsiella tarda antigen, prepared (by Method B) and screened as described above, is then bound to an appropriate enzyme; in this case, a highly purified alkaline phosphatase. This can be accomplished by any known method, e.g. the one-step glutaraldehyde method or benzoquinone conjugation-

In the glutaraldehyde method, monoclonal antibody (3 mg in about 1 ml of solution) is dialyzed with 10 mg of alkaline phosphatase (Sigma Type VII-T) against 2x1000 ml of phosphate buffered saline, pH 7.4 (PBS) at +4°C After dialysis the volume is made up to 2.5 ml with PBS and 25 μl of a 20% glutaraldehyde in PBS solution added. The conjugation mixture is left at room temperature for 1.5 hours. After this time, gluteraldehyde is removed by gel filtration on a Pharmacia PD-10 (Sephadex G-25M) column, previously equilibrated in PBS. The conjugate is eluted with 3.5 ml PBS and then dialyzed against 2x2000 ml of TRIS buffer (50 mM TRIS, 1 mM magnesium chloride, pH 8.0 plus 0.02% sodium azide) at +4°C- To the dialyzed conjugate is added 1/lOth its own volume of 10% BSA in TRIS buffer. The conjugate is then sterile filtered through a 0.22 μm membrane filter into a sterile amber vial and stored at +4°C.

In the benzoquinone method, 24 mg alkaline phosphatase (Sigma Type VII-T) are dialysed against 2 x 500 ml of 0.25M sodium phosphate buffer, pH 6.0, at +4°C. Para-benzoquinone, 18 mg, is dissolved in warm AR ethanol, 0.6 ml, and added to the dialysed alkaline phosphatase. The benzoquinone/alkaline phosphatase mixture is left in the dark at room temperature for 1 hour. After this time, unreacted benzoquinone and reaction by-products are removed and the buffer exchanged, by gel filtration on a Pharmacia PD-10 (Sephadex G-25M) column, previously equilibrated in 0.15M sodium chloride. The benzoquinone-activated alkaline phosphatase thus produced is sufficent for three 3 mg antibody conjugations.

3 mg monoclonal antibody are dialysed against 2 x 500 ml of 0.15M sodium chloride at +4°C. Dialysed antibody is added to 8 mg of benzoquinone-activated alkaline phosphatase, immediately followed by sufficient IM sodium bicarbonate to give a final concentration of 0.1M. The conjugation-mixture is left in the dark at +4°C for 48 hours. After this time, sufficient IM lysine is added to give a final concentration of 0.1M. After 2 hours in the dark at room temperature, the conjugate is dialysed against 2 x 1000 ml of phosphate buffered saline + 0.02% sodium azide at +4°C. An equal volume of glycerol is added. The conjugate is sterile-filtered through a 0.22 μm membrane filter into a sterile amber vial and stored at +4°C- H. Monoclonal Antibody Conjugate Testing

The enzyme immunoassay method is used for testing. This assay method comprises coating the wells of a standard polyvinyl chloride (PVC) microtiter tray with the antigen, followed by addition of monoclonal antibody enzyme conjugate, and finally addition of the enzyme substrate, para-nitrophenyl phosphate.

In this case, the monoclonal antibody, found to be specific for the antigen of Edwardsiella tarda can then be tested.

If deemed necessary, the particular epitopic site to which the antibody attaches to the antigen can also be determined. The same enzyme immunoassay method can also be used to determine whether diagnostic specimens such as urine, blood, stool, water or milk contain the antigen. In such cases, the antibody can first be bound to the plate.

Tests using the present invention are superior to the existing tests based on the following advantages: (i) greater accuracy; (ii) same day results, within an hour or two; (iii) reduction in amount of skilled labor required to administer laboratory procedures, resulting in reduced labor costs; (iv) reduction in laboratory time and space used in connection with tests, resulting in reduced overhead expense; and (v) improved therapy based upon early, precise diagnosis.

While the invention has been described in connection with certain preferred embodiments, it is not intended to limit the scope of the invention to the particular form set forth, but, on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A monoclonal -antibody specific for an antigen or species of Edwardsiella.

2. The antibody of Claim 1 specific to the antigen of Edwardsiella tarda.

3. A monoclonal antibody broadly cross- reactive with an antigen of all species of the genus Edwardsiella.

4. A labeled monoclonal antibody consisting essentially of a monoclonal antibody of Claims 1-3 and an appropriate label.

5. The labeled monoclonal antibody of Claim 4, wherein said label is a member of the group selected from a radioactive isotope, enzyme, fluorescent compound, bioluminescent compound, chemiluminescent compound, or ferromagnetic atom, or particle.

6. The labeled monoclonal antibody of Claim 5, wherein said label is an enzyme capable of conjugating with a monoclonal antibody and of being used in an enzyme-linked immunoassay procedure .

7. The labeled monoclonal antibody of Claim 6, wherein said enzyme is alkaline phos¬ phatase, glucose oxidase, galactosidase, or peroxidase.

8. The labeled monoclonal antibody of Claim 5, wherein said label is a fluorescent compound or probe capable of being used in an immuno-fluorescent or fluorescent immunoassay procedure, enzyme fluorescent immunoassay, or fluorescence polarization immunoassay, photon counting immunoassay, or the like procedure.

9. The labeled monoclonal antibody of Claim 8, wherein said fluorescent compound or probe is fluorescein.

10. The labeled monoclonal antibody of Claim 5, wherein said label is a chemiluminescent compound capable of being used in a luminescent or enzyme-linked luminescent immunoassay.

11. The labeled monoclonal antibody of Claim 10, wherein such chemiluminescent compound is luminol or a luminol derivative.

12. The labeled monoclonal antibody of Claim 5, wherein said label is a bioluminescent compound capable of being used in an appropriate bioluminescent immunoassay.

13. The labeled monoclonal antibody of Claim 12, wherein such bioluminescent compound is luciferase or a luciferase derivative.

14. A process for diagnosing for the pre¬ sence of an antigen of Edwardsiella in a specimen comprising contacting at least a portion of said specimen with a labeled monoclonal antibody of Claim 4 in an immunoassay procedure appropri¬ ate for said label-

15- The process of Claim 14, wherein the appropriately labeled immunoassay procedure is selected from immuno-fluorescent or fluorescent immunoassay, immuno-electron microscopy, radio- metric assay systems, enzyme-linked immunoassays, fluorescence polarization, photon-counting bio¬ luminescent, or chemiluminescent immunoassay.

16. The process of Claim 15, wherein said label is an enzyme capable of being used in an enzyme-linked immunoassay procedure.

17. The process of Claim 16, wherein said enzyme is selected from alkaline phosphatase, glucose oxidase, galactosidase, or peroxidase.

18. The process of Claim 15, wherein said label is a fluorescent compound or probe capable of being used in an immuno-fluorescent or fluores¬ cent immunoassay procedure, enzyme fluorescent immunoassay, or fluorescence* polarization immuno¬ assay, or photon-counting immunoassay, or the like procedure-

19- The process of Claim 18, wherein said fluorescent compound or probe is fluorescein.

20. The process of Claim 15, wherein said label is a chemiluminescent compound capable of being used in a luminescent or enzyme-linked luminescent immunoassay.

21. The process of Claim 20, wherein said chemiluminescent compound is luminol or a luminol derivative.

22. The process of Claim 15, wherein said label is a bioluminescent compound capable of being used in ^r-a bioluminescent or enzyme-linked bioluminescent immunoassay.

23. The process of Claim 22, wherein said bioluminescent compound is luciferase or a lucif¬ erase derivative.

24- A therapeutic composition comprising one or more of the monoclonal antibodies of Claims 1-3 and a pharmaceutically acceptable carrier or diluent.

25. A therapeutic composition comprising one or more of the labeled monoclonal antibodies in Claim 4 and a pharmaceutically acceptable carrier or diluent.

26. A method of treating Edwardsiella infections comprising administering an effective amount of a monoclonal antibody of Claims 1-3.

27. A kit for diagnosing for the presence of an antigen or species of Edwardsiella in a diagnostic specimen comprising at least one monoclonal antibody of Claims 1-3.

28. The kit of Claim 27, wherein said at least one antibody is labeled.

29. The kit of Claim 28, wherein said at least one monoclonal antibody is labeled with a fluorescent compound.

30. The kit as in Claim 28, wherein said at least one monoclonal antibody is labeled with an enzyme.

31. The kit as in Claim 28, wherein said at least one monoclonal antibody is labeled with a member of the group consisting of a radio¬ active isotope, chemiluminescent compound, bio¬ luminescent compound, ferromagnetic atom, or particle.

32. The kit of Claims 28, 29, 30, and 31 additionally containing at least one known Edwardsiella antigen as a control.

33. The kit of Claims 28, 29, 30, 31, and 32 containing each known antigen of Edward- siella.

34. The kit of Claims 28, 29, 30, 31, and 32 containing the antigen or antigens of Edwardsiella tarda.

35. A kit for diagnosing for the presence of an antigen or species of Edwardsiella in a diagnostic specimen comprising at least one monoclonal antibody of Claims 1-3 and a control.

36- The kit of Claim 35, wherein said at least one antigen is labeled and said control is at least one known antigen of Edwardsiella.

37. A kit for diagnosing for the presence of a gram-negative bacterial infection comprising at least one monoclonal antibody of Claims 1-3.

38. The kit of Claim 37, wherein said at least one monoclonal antibody is labeled.