MXPA97001372A - Adnc and fra fragment of antibody bcf2 and its use in neutralizing pharmaceutical compositions of alac venom - Google Patents

Abstract

The present invention relates to the field of obtaining and applying monoclonal antibodies that recognize scorpion toxins and more particularly to the generation of the peptide chains of the variable region of the FAb fragments of sequence SEQ ID No. 1 and SEQ ID No. 2 specifically, the invention relates to obtaining Fab fragments of monoclonal antibodies capable of recognizing the venom of the scorpion Centruroides noxius Hoffmann and its application in pharmaceutical compositions to neutralize the toxic effect of the venom of alacr

Description

ADNC AND FRAGMENTO Fab OF ANTIBODY BCF2 AND ITS USE IN NEUTRALIZING PHARMACEUTICAL COMPOSITIONS OF POISON SCORPION FIELD OF THE INVENTION The present invention relates to the field of obtaining and applying monoclonal antibodies that recognize scorpion toxins and more particularly to the generation of the variable region peptide chains of the Fab fragments of sequence SEQ ID No. 1 and SEQ ID No 2. Specifically, the invention relates to obtaining Fab fragments of monoclonal antibodies capable of recognizing the scorpion venom Centruroides noxius Hoffmann, and their application in pharmaceutical compositions to neutralize the toxic effect of scorpion venom.

BACKGROUND OF THE INVENTION Scorpion venom is a complex mixture of peptides, which can be classified into two groups based on the number of amino acids: long-chain toxins, 60-70 amino acids, which block the Na + channels of excitable cells, and those of short chain of 37-39 amino acids that affect the K + channels. \ 2? 4 Toxins that modify Na + channels, in turn, are classified as a and? Toxins5. The a-toxins mainly modify the mechanism of inactivation of the Na + channels, while the β-toxins preferentially modify the activation mechanism of the Na + channels. 6 The scorpion venom is composed of several peptides that can be toxic to a great variety of organisms, some are for mammals, others for insects, others for crustaceans, etc. There are approximately 221 species and subspecies of scorpions in Mexico, but only eight are medically important and belong to the genus Centr? Roides, highlighting the species Centruroides noxius Hoffmann, C. limpidus limpidus and C. suffusus suffusus, as some of the most dangerous7 . From 1981 to 1990 Approximately 250,000 cases of stings in humans have been reported, with around 300 deaths8 so that alacrism is considered a public health problem in Mexico. The symptoms after a scorpion sting are among others: pain, cough, hypersensitivity, hyperexcitability, excessive salivation and vomiting. When two or more of the above symptoms are present, the anti-lactic acid serum is supplied to counteract the effects since cases of poisoning or severe cases can cause heart and / or lung failure, 9 which can cause the death of the chopped individual. In order to obtain control and prevention for poisoning by scorpion venom, some strategies have been proposed. One of them is to obtain adequate vaccines. To date, experimental vaccines have been developed through the detoxification of scorpion venom peptides. { Centr? Roides noxius Hoffmann, for example) by means of its chemical modification with glutaraldehyde10, or by means of chemical synthesis of the primary polypeptide structure corresponding to scorpion toxins11. However, such vaccines have not been convenient for the following reasons: 0 a) It is difficult (if not impossible) to obtain adequate quantities of the poison of interest to prepare about 13 million doses required of the vaccine in the country12. b) The control of biological material (modified venom) for vaccination, is extremely difficult to obtain in a reproducible way, to have the quality required for its use in humans. c) The previous situation worsens, due to the fact that synthetically prepared peptides produce a sensitization phenomenon in pre-immunized mice13. Another strategy is the use of hyperimmune sera or antibodies or monoclonal antibodies capable of neutralizing or delaying the toxic effect of scorpion toxins (serotherapy). In this sense, serotherapy studies have been carried out with polyclonal14 and monoclonal15; likewise, commercially available hyperimmune horse anti-scorpion sera exist in the market (for example, the one prepared by the National Hygiene Institute of the Ministry of Health, Mexico). However, these sera are made in horses, which in turn are immunized with a maze of the scorpion telson. Once this maceration is had, it is centrifuged and the horse is inoculated with the soluble part. This procedure is done with the maceration of a mixture of telsons from several species of scorpions, such as C. noxius, C. limpidus limpidus and C. suffusus suffusus (in Mexico). After several immunizations, the horse serum is obtained and a purification of the total immunoglobulins of the equine is carried out, later a digestion of the antibodies with trypsin is performed to obtain the fragments of the immunoglobulins F (ab ') 2 the ones in charge to neutralize the poison. The above preparation has the disadvantage of containing a very varied mixture of antibodies, since as mentioned above, the venom of scorpions is composed of dozens of peptides of which only a few have activity against mammals (mainly the toxins Cn13 and Cn2). , in the case of Centr? roides noxius Hoffmann). In such a way that the antibodies directed against these toxins are in a very small proportion with respect to the total protein, that is, it is necessary to apply a high dose of the preparation in order to neutralize the effect of the toxins, given that it is a large The amount of exogenous protein increases the risk of causing anaphylactic shock in patients, and with greater possibility of causing this side effect to those who are more than once applied this neutralizing preparation. Therefore, there is a need to remove immunoglobulins not associated with the neutralizing effect of these sera, since their administration can produce an undesirable immune response (autoinm cross unit, for example), induce nephrotoxicity, serum sickness and, in severe cases, shock. anaphylactic. Additionally, the hyperimmune anti-scorpion serum contains other proteins, lipids and carbohydrates, which can potentially provoke an immune response, but the greatest danger is that these components can harbor pathogens, such as the agent that causes Bovine Spongiform Encephalopathy or others that may cause zoonoses. Also, endotoxins, molecules capable of producing pyrogenic, potentially fatal responses, may be present. Other drawbacks in the case of the use of monoclonal antibodies may be the presence of contaminants in the culture media, which contain the antibodies expressed by a hybridoma of interest, such as cells or nucleic acids. As well as the aggregates of antibodies can also act as immunogens and cause an undesirable immune response in the body under therapy. In addition to the drawbacks of current vaccines and until the most appropriate and safe peptides for vaccination are not determined, the most viable alternative of greater purity, at least in the short term, for the protection of scorpion stings, is the use of anti-scorpion antisera. On the other hand, regardless of whether adequate vaccines are obtained for the prevention of scorpion venom poisoning, there will be a constant need for an effective reagent (anti-scorpion antiserum or purified anti-scorpion antibodies) for administration in unvaccinated individuals. or intoxicated, that is available for immediate use in the field, since the time in which the poison has its toxic effect, even causing death in the affected organism is very short (0.33 hrs in mice) 19. For this reason, there is interest in obtaining biological reagents, such as anti-scorpion antisera or purified anti-scorpion antibodies suitable for immediate administration in order to neutralize the toxic activity of scorpion venom in affected individuals. Until before the present invention, monoclonal antibodies and their corresponding Fab fragments were not known in the literature to show protection in vivo, not only against the toxic activity of scorpion-specific toxins, but also against the toxic activity of total scorpion venom. Antibodies of the immunoglobulin type, particularly those of the G type, are constituted by four peptide chains, two heavy and two light, joined together by bridges of sulfur. The immunoglobulins G can be fragmented by the action of the enzymes papain, pepsin in 2 or 3 active molecules: the fragment called Fe that has a function associated with the introduction of the immunoglobulin to the placenta and the cellular lysis of the organism or invader; the other two fragments may be the so-called Fab fragments, or the so-called F (ab ') 2 fragment which are variable polypeptide chains and which, even after they have been bound to an antigen, do not precipitate.

BRIEF DESCRIPTION OF THE DRAWINGS. Figure 1. Neutralization experiments with the monoclonal antibody BCF2 and its Fab fragment. This graphic representation shows the DP50 values (medium protective dose) defined as the amount of monoclonal antibody needed or to protect 50% of the mice exposed to the indicated doses of toxin or complete venom. For each of the points of the neutralization curves, 6 female mice (20 g of weight) were used. The solid lines refer to experimental results, while the segmented lines show the linear regression calculated for each curve. 5 Panel A. Increasing amounts of the total venom of C. noxius Hoffmann and the monoclonal antibody BCF2, which were mixed to determine the DP50 of each point. Panel B. Increasing amounts of the total venom of C. noxius Hoffmann and the Fab fragment of the monoclonal antibody BCF2, which were mixed to determine the corresponding DP of each point.

Panel C. Overlap of panels A and B.

DETAILED DESCRIPTION OF THE INVENTION.

The present invention is directed to sequence Fab fragments of the variable fraction SEQ ID No. 1 and SEQ ID No. 2 or equivalent fragments thereof capable of neutralizing the total venom and Cn2 toxin of the scorpion venom Centruroides noxius Hoffmann. The term "equivalent fragment thereof" as used in the context of or this description, means that a particular molecule may vary, with respect to the reference molecule (Fab fragment), such that it retains the neutralizing activity of the Fab fragment. against the total poison or against toxins of the scorpion venom Centruroides noxius Hoffmann. This also means that within the contemplated variations, one or more substitutions, omissions or additions may be included in the structure or amino acid sequence of the Fab fragment, whose immediate effect is to retain the neutralizing activity of the Fab fragment. The Fab fragment (fragment of antigen binding or Fragment antigen binding) is a protein fragment of an antibody that has the characteristic of retaining or antigen binding activity, since said fragment comprises the variable domains of each pair of light chain and that form the antigen binding site, inherent property of the complete antibody. However, the fragment completely loses the activity associated with the constant fraction or Fe, responsible for fixing the Fe receptors of cells and also activating the complement. By enzymatic treatment of the complete antibody of interest with enzymes such as papain, trypsin or pepsin, antibody fragments are generated, which include the Fab and F (ab ') 2 fragments correspondingly. Like the Fab fragment, the F (ab ') 2 fragment retains the antigen binding activity. The treatment of antibodies capable of neutralizing the total venom or toxins of the scorpion venom Centruroides noxius Hoffmann, generates the fragments of the present invention. Such fragments are especially useful in the therapeutic applications of this invention. Those skilled in the art will note that the antigen-binding region of the neutralizing antibody fragments is the key feature of the invention. Hybridoma cells producing neutralizing monoclonal antibodies serve as a preferred source of DNA of SEQ ID No. 3 and SEQ ID No. 4 encoding the antigen binding regions of the invention. This DNA by recombinant DNA technology, can be linked to a DNA encoding any desired sequence of amino acid residues to form a new hybrid or chimeric DNA sequence, which encodes a chimeric or hybrid protein, which in turn retains the neutralizing capacity . Accordingly, a Fab fragment or equivalent fragment thereof of the present invention can be derived from a neutralizing monoclonal antibody obtained from a murine hybridoma., rat and / or human, wherein the amino acid sequences of the heavy and light chains of the antigen binding site are homologous with those antibody sequences produced by the lymphocyte species in vivo or in vitro through hybridomas. However, this invention also comprises any chimeric molecule that contains a region of binding to the total venom or against toxins of the scorpion venom Centruroides noxius Hoffmann and with neutralizing capacity. Preferably the Fab fragment of this invention is an altered fragment as a hybrid fragment in which the heavy and light chains of the antigen binding site are homologous to a natural antibody but are combined so that they do not occur naturally. The Fab fragment can be a chimeric Fab fragment having variable regions of one antibody and constant regions of another. In this way, the chimeric Fab fragments can be a chimera species / species or a chimera class / class. The chimeric Fab fragments may have one or more modifications to improve the ability to bind the antigen or to alter the toxic functioning of the scorpion venom. Another form of altered Fab fragment is a humanized fragment in which the CDRs of the BCF2 antibody are grafted onto a human amino acid sequence frame. Additional amino acids can be altered to the structure or constant regions of such fragments. Thus, any neutralizing Fab fragment of the scorpion venom in which the amino acid sequence does not exist or one that exists anywhere is included in the scope of the present invention. Additional amino acids can be altered to the structure or constant regions of such fragments. Thus, any neutralizing Fab fragment of the scorpion venom in which the amino acid sequence does not exist or one that exists anywhere is included in the scope of the present invention. The characteristics of one of the Fab fragments (from the monoclonal antibody BCF2 and the hybridoma cell line BCF219) of the invention, include the general characteristic of the fragments of the invention, which is the ability to neutralize the toxic action of the venom total or toxins from the scorpion venom Centruroides noxius Hoffmann. The specific characteristics of the neutralizing Fab fragment, derived from the monoclonal antibody BCF2 and the hybridoma cell line BCF219, include: a) Approximate molecular weight of 50,000. b) Sub-class IgG-, for the heavy chain and kappa (K) for the light chain (commercial assay ELISA-BioRad). c) Ability to recognize and neutralize the pure Cn2 toxin of C. noxius Hoffmann. d) Able to neutralize in vivo dose of 43 DL ^, of the total soluble poison of C. noxius Hoffmann with 1 milligram of Fab in the CD1 mouse strain (1 milligram of the monoclonal antibody BCF2 neutralizes in vivo dose of 28 LD50 of the total venom soluble of C. noxius Hoffmann). e) 124 micromoles of Fab neutralize in vivo 1 milligram of the total soluble poison of C. noxius Hoffmann. f) The amount of Fab required to neutralize several DLgos of the total soluble poison of C. noxius Hoffmann is 9 times less than the amount of commercial hyperimmune serum needed to neutralize the same DL8. The therapeutic utility of the neutralizing Fab fragment, derived from the monoclonal antibody BCF2 and the hybridoma cell line BCF219, has been established in the in vivo neutralization assays of Example no. 6 where details of the trial are shown. Those skilled in the art will note that the ability to neutralize the toxic action of the total venom or toxins of the scorpion venom Centruroides noxius Hoffmann is a general characteristic of the Fab fragments or equivalent fragments thereof of this invention and that neutralizing Fab fragments. , 0 different from those produced by the BCF219 hybridoma cell line will also work by neutralizing the toxic activity of the aforementioned poison. In this sense, within the scope of the present invention, include the affinity variations of the Fab fragments of the invention that neutralize the total venom or toxins of the scorpion venom Centruroides noxius 5 Hoffmann since in general, the greater the affinity of the antibody, More effective will be to neutralize the toxic effect. In relation to the above, given that the therapeutic and / or pharmacological success of infinity of antibodies lies in the affinity of these towards their binding site, it is possible to determine the areas of the Fab fragment of the present invention involved in said affinity by means of or modifications in such zones, which may include regions that determine the complementarity of the antibody binding sites (CDR's) 16,17,18 changes in the heavy chains of the variable domains of the antigen binding site, 19 or others. With this, the affinity of the Fab fragments of the present invention can be increased, thereby obtaining increased pharmacological effects, such as a greater neutralization of the toxic effect, of the total scorpion venom. The Fab fragments of this invention have the advantage of being able to be used, in medical therapy in amounts approximately 10 times lower than those required by commercial sera, to neutralize the toxic effect of the scorpion venom.; Likewise, the total amount of protein administered to the affected individual will be lower (in the same proportion), which reduces the potentially adverse effects of commercial sera (cross-autoimmunity, high risk of intoxication, etc.). Also included in the present invention is a purified preparation of Fab fragments or equivalent fragments thereof. Said preparation is substantially free of contaminants of host cells, of proteins of said cells, nucleic acids and endotoxins. Endotoxin levels can be measured using the LAL (Limulus Amoebocyte Lysate) method 20. As stated above, the elimination of undesirable substances in said preparations reduces the possibility of adverse effects in individuals after their administration. Also included in the present invention are formulations or compositions containing Fab fragments or equivalent fragments. These compositions include, preferably in addition to Fab fragments (substantially purified and / or free of contaminants): a physiologically acceptable diluent or carrier, in admixture with other agents such as antibodies and / or antibiotics. Some of the carriers that may be suitable include, but are not limited to: physiological saline, buffered saline phosphate, glucose in phosphate buffered saline and / or buffered saline. Alternatively, the Fab fragment or the aforementioned combinations can be lyophilized (freeze-dried) and reconstituted for use when required, by the addition of an aqueous buffered solution or simply water. The routes of administration of such compositions are routinely parenteral, including injection or intravenous, intramuscular, subcutaneous and intraperitoneal release. The term "purified", as used in the context of this description to define the purity of the Fab fragments, means that the protein or preparation of the protein is substantially free of other proteins of natural or endogenous origin. However, said compositions may contain other added proteins such as stabilizers, carriers, excipients and co-therapeutics.

This invention is also directed to a method of obtaining Fab fragments or equivalent fragments thereof of the present invention. Hybridoma cell lines producing monoclonal antibodies neutralizing the toxic activity of the total venom or toxins of the scorpion venom Centruroides noxius Hoffmann, can be prepared using as immunogenic material toxins thereof, such as purified Cn219, for the activation of immunologically relevant spleen cells of the immunized animal. In order to improve the animal's immune response, the toxin can be linked to a macromolecule that functions as a peptide carrier. For example, the peptide can be conjugated to a protein such as porcine thyroglobulin. Other carriers can be used within the scope of the present invention, including those known in the state of the art, such as human and bovine serum albumin, myoglobin, β-galactosidase, penicillinase and bacterial toxoids. The carriers can also be synthetic molecules such as multi-poly-DL-alanyl-poly-L-lysine and poly-L-lysine. The immunogen can be administered either alone or conjugated. The peptide can be administered by conventional methods such as subcutaneous injection, intramuscular injection and intravenous flow; as well as transdermal or oral administration. It is particularly preferable to use a poso logical regimen in which an initial administration of the peptide is followed by one or more booster administrations of the same peptide at regular intervals of time. Subsequent steps for the preparation of the neutralizing monoclonal antibodies include: removing the spleen of the animals immunized with the Cn2 toxin of Centruroides noxius Hoffmann, preparing lymphocyte suspensions, fusing these lymphocytes to mouse myeloma cells, culturing the cells and collecting the supernatants of the surviving hybridomas for the search for antibodies by ELISA. Those hybridomas that produce the desired antibodies (such as the BCF2 hybridoma) are subsequently subcloned and injected into mice to produce ascites fluid. The monoclonal antibodies are then purified by collecting the ascites fluid from the peritoneal cavity of the mice and the immunoglobulin (Ig), which is purified either by precipitation with ammonium sulfate, with (diethyl-amino-ethyl) -cellulose in chromatography of ion exchange or preferably by a protein A affinity column in the presence of a high ionic strength. Protein A (synthesized by some strains of Staphylococcus aureus) is a group-specific binder that binds to the Fe region of most IgG. An alternative method is to use the complete bacterium from a bacterial strain that has large amounts of protein on the cell surface. An alternative to protein A is protein G. The immunoglobulin samples thus purified contain the desired monoclonal antibodies, which can be identified by an ELISA. 0 The ability of the antibodies to neutralize the Cn2 toxin is assayed by incubation for 30 minutes of 650 micrograms of each antibody with 12 LD50 (3 micrograms) of the Cn2 toxin and subsequently injected into groups of five mice and monitored. survival time. In the case of the monoclonal antibody called BCF2, it was found that there is a 5 increase in survival from 0.33 to 60 hrs. with these doses. Additionally, the monoclonal antibodies thus obtained are used to evaluate, through tests, their capacity to neutralize the soluble fraction of the total scorpion venom Centruroides noxius Hoffmann. For this, the LD50 was determined de novo, both of the soluble fraction of the total poison of the scorpion C. noxius or Hoffmann, and of the Cn2 toxin isolated from it, as indicated in the methodology, being 3.8 micrograms and 250 nanograms per each 20 grams of mouse weight, respectively. The LD50 (11.4 micrograms) of the soluble fraction of the total scorpion venom is incubated 3 times with the antibodies in a 1:10 molar ratio, for 30 minutes in a total volume of 200 microliters of a PBS solution by injecting a group of mice and monitoring their survival time. Subsequently, the Fab fragments and equivalent fragments thereof of the present invention are generated by the enzymatic treatment of the BCF2 antibodies, either with trypsin to obtain the F (ab ') 2 fragments or with or papain to obtain, after a purification , through a protein A column, the corresponding Fab fragments, whose activity to neutralize the Cn2 toxin is demonstrated by an ELISA. The Fab fragments thus obtained are tested for their ability to neutralize the soluble fraction of the total scorpion venom Centruroides noxius Hoffmann in the same way as the complete antibodies were tested, replacing them in the assay with the corresponding Fab fragments. In order to eliminate some undesirable contaminants present in the preparation of final Fab fragments, additional steps can be added to the purification procedure set forth above. Ultraf iltration can be used to reduce viral and nucleic acid contamination of cells. This can be done using ultraf iltration units that allow retaining the Fab fragment of interest. There are commercially available filtration units (Millipore). An alternative method to reduce virus contamination is microfiltration using a Nylon membrane in the form of a cartridge, for example, Nylon 66 membrane with 0.04 molar PALL. A purification step can also be introduced to remove the contaminating DNA, for example, by washing the Protein A column using NaCl in the range of 1-3 molar in the buffer with neutral pH, preferably PBS with pH 7.2. Glycine may be added to the NaCl preferably at 1.5 molar in the pH range of 8.8-9.0. This invention also relates to the use of the above-mentioned Fab fragments or equivalent fragments thereof, for the manufacture of a medicament for neutralizing the effect of the scorpion sting Centruroides noxius Hoffmann in the organism of an affected mammal. The Fab fragments of this invention are especially useful for neutralizing the toxic activity of the total venom or toxins of the scorpion venom Centruroides noxius Hoffmann, allowing to administer relatively small amounts of said fragments compared to the amount that would be required of commercial horse hyperimmune sera. The amount of total protein (Fab fragments) to be administered in an organism intoxicated with scorpion venom could be approximately 10 times less than the amount required for commercial hyperimmune sera. Also, the invention provides a method for the treatment of a human affected by the scorpion sting Centruroides noxius Hoffmann, which comprises the administration of a therapeutically effective amount of Fab fragments or equivalents thereof of the present invention. The following examples are included for the purpose of illustrating the present invention, without this limiting the scope thereof.

Example 1. Production of the BCF2 antibody. As a preliminary step, the Cn2 toxin was isolated from the total scorpion venom Centruroides noxius Hoffmann as referred to in reference no. 19. However, a different isolation and purification strategy can be used to obtain the Cn2 toxin, with which the hybridomas are generated. In order to obtain the required amount of the monoclonal antibody BCF2, it was necessary to cultivate in large quantities the hybridoma producing it (BCF219). These cells were grown in 25 milliliters of half RPM I supplemented with fetal bovine serum in a proportion of 10% and with L-glutamine. Once the initial cells were grown, they underwent several growth cycles, passing the cells to new containers with fresh medium in each cycle. Subsequently, the cellular package was injected intraperitoneally in BALB / c mice so that the production of ascites fluid was started and in this way a high concentration of the antibody was obtained. After the necessary time, the ascites fluid was removed from the mice and stored at a temperature of -25-20 ° C.

Example 2. Purification of the BCF2 antibody. The purification of the antibodies was carried out by means of a protein A affinity column in the presence of a high ionic strength (3 molar NaCl). The procedure used was as follows: a) The column was equilibrated with a buffer of 100 millimolar borates, pH 8.9 and 3 molar sodium chloride. b) An aliquot of 1 milliliter of ascites was taken and diluted in 4 milliliters of the same equilibrium buffer. c) This solution was passed 3 times through the affinity column, d) Two washes were performed, one with a borate absorber 50 millimolar pH 8.9 with 3 molar NaCl and the other washing with a borate buffer 10 millimolar pH 8.9 with NaCl 3 molar. On both occasions, 10 column volumes were passed (the column volume was 5 milliliters). e) Once the washings have been carried out, the antibody is released with a column volume of glycine 100 millimolar pH 3 and the fractions were recovered in 50 microliters of Tris buffer pH 7.5.

Example 3. Determination of the DL .. 5 Dent et. to the. 198021 reports a DL ^ for the Centruroides noxius Hoffmann venom of 5 micrograms per 20 grams of mouse weight. In the present invention, the LD50 was determined de novo both for the soluble fraction of the complete venom and for the Cn2 toxin. For this trial, eight female mice of the CD1 strain, four weeks old, were used. They were weighed to or adjust the doses to be used, both Cn2 toxin and total poison.

It was started with a dose of 100 nanograms per 20 grams of mouse weight for the Cn2 toxin and 2.5 micrograms per 20 grams of weight for the complete venom. The dose was increased until half of the mice used died and the other half survived; this dose is the so-called LD50. Example 4. Determination of the ability of the BCF2 antibody to neutralize total C. noxius venom. This test was carried out in order to demonstrate that the BCF2 antibody, capable of neutralizing the Cn2 toxin, is also capable of neutralizing the complete venom of the Centruroides noxius Hoffmann scorpion.

For this test, six female mice were used, to which three complete venom DLgos were applied in the presence of the BCF2 antibody, the molar ratio of the venom-antibody used was 1: 10. Before applying the complex, the venom and antibody are mixed without agitation at 37 ° C for 30 minutes. The total volume 5 applied is 200 microliters, the venom and the antibody are dissolved in a PBS solution. The poison mixture was applied in the peritoneal cavity and all the mice were observed to survive the test (Fig. 1 A). There was another control group to which the same dose of poison without antibody was applied, of this group all or mice died. This result shows how the antibody has the ability to neutralize the complete scorpion venom Centruroides noxius Hoffmann.

Example 5. Activity assay of the Fab fragment against the Cn2 toxin of Centruroides noxius Hoffmann. This example shows how the Fab fragment, product of the digestion of the monoclonal antibody BCF2, retains the ability to recognize and neutralize the Cn2 toxin. Ten micrograms of the antibody BCF2, purified as indicated in Example 0 2, were reacted in the presence of the enzyme papain for a time of 8 hours. After this time, the reaction with 20 millimolar iodoacetamide was inactivated.

The digestion product was passed through an affinity column with protein A to separate the Fab fragment from the Fe fragment and the undigested antibody. Once the purified Fab was obtained, we proceeded to determine if it was still active. This assay was performed by means of an ELISA, in which the Cn2 toxin was applied to the plate in a concentration of 3 microgram / milliliter. After the plate was saturated with bovine albumin, the purified Fab was applied and left to incubate for one hour at 37 ° C. Washes were performed and a second goat anti-mouse antibody was added and it was revealed after leaving an hour or at 37 ° C the second antibody.

As the result was positive, he indicated that the antibody does not need the Fe portion to recognize its antigen, that is to say that the Fab fragment does indeed retain the ability to recognize the Cn2 toxin.

Example 6. Activity of the Fab fragment with total scorpion venom Centruroides noxius Hoffmann. This example is intended to show that the Fab fragment retains the neutralizing capacity not only against the Cn2 toxin of Centruroides noxius Hoffmann, but against the total poison of Centruroides noxius Hoffmann. The procedure was the same as in Example 4, with the difference that the Fab fragment and not the BCF2 antibody was the one that reacted with the scorpion venom. The result obtained was the same as in the case of the complete BCF2 antibody, that is to say that while the individuals of the control group died, those of the group tested survived (see Figure 1 B). This confirms that the fragment Fab of the present invention effectively exhibits an in vivo neutralizing capacity against the total scorpion venom C. noxius Hoffmann.

Example 7. Comparison of the efficiency of the Fab fragment. A comparison was made between the Fab fragment of the monoclonal antibody BCF2 and the commercial anti-scorpion serum of the National Institute of Health (Lot SA046-9), in order to determine if the Fab fragment of the present invention could be commercially competitive. Neutralization tests were carried out with the commercial anti-scorpion serum to determine its neutralizing capacity: the tests were carried out as described in reference no. 23. Comparing the results, it was observed that the Fab fragment is ten times more potent than the commercial antiserum to neutralize the Centruroides noxius Hoffmann venom, at the test conditions used.

LIST OF SEQUENCES Number of sequences: 4 INFORMATION FOR SEQ ID NO: 1 I. CHARACTERISTICS OF THE SEQUENCES A) LENGTH: 117 amino acid residues B) TYPE: amino acids C) TOPOLOGY: linear II. TYPE OF MOLECULE: protein III. HYPOTHETICAL: yes IV. ANTICIPATE: no V. TYPE OF FRAGMENT: fragment N terminal VI. ORIGINAL SOURCE A) ORGANISM: mouse B) CEPA: Balb / C C) TISSUE TYPE: spleen D) TYPE OF CELL: lymphocyte E) CELLULAR LINE: hybridoma VII. IMMEDIATE SOURCE: A) LIBRARY: Library in phage lambda IX. CHARACTERISTICS: A) NAME / Key: B) LOCATION: C) IDENTIFICATION METHOD: Deduced D) OTHER INFORMATION: Amino acid sequence deduced from the variable region of the heavy chain of the neutralizing monoclonal antibody BCF2, directed against the toxin 2 of the scorpion C noxius Val Pro Trp Leu Gln Gln Ser Gli Pro Glu Leu Val Lis Pro Gli Ala 1 • 5 10 15 Ser Met Lis lie Ser Cis Lis Val Ser Gli Tir Ser Fen Tre Asp His 20 25 30 Tre Met Asn Trp Val Lis Gln Ser His Gli Gli Asn Leu Glu Leu lie 35 40 45 Gli Leu lie Asn Pro Fen Asn Gli Asp Ala Tre Tir Tir Lis Gln Lis Fen 50 55 60 Tre Gli Lis Ala Tre Lue Tre Val Asp Arg Ser Ser Ser Ala Ala Fen 65 70 75 80 Met Glu Leu Leu Ser Leu Tre Ser Glu Asp Ser Wing Val Tir Tir Cis 85 90 95 Wing Arg Tir Gli Asn Tir Wing Met Asp Tir Trp Gli Gln Gli Tre Ser 100 105 110 Val Tre Val Ser Ser 115 INFORMATION FOR SEQ ID NO: 2 I. CHARACTERISTICS OF THE SEQUENCES A) LENGTH: 111 amino acid residues B) TYPE: amino acids C) TOPOLOGY: linear II. TYPE OF MOLECULE: protein III. HYPOTHETICAL: yes IV. ANTICIPATE: no V. TYPE OF FRAGMENT: fragment N terminal VI. ORIGINAL SOURCE A) ORGANISM: mouse B) CEPA: Balb / C C) INDIVIDUAL / ISOLATED: D) TYPE OF TISSUE: spleen E) TYPE OF CELL: F lymphocyte) CELLULAR LINE: hybridoma VII. IMMEDIATE SOURCE: A) LIBRARY: Library in phage lambda IX. CHARACTERISTICS: A) NAME / KEY: B) LOCATION: C) IDENTIFICATION METHOD: deducted D) OTHER INFORMATION: Amino acid sequence deduced from the variable region of the light chain of the neutralizing monoclonal antibody BCF2, directed against the toxin 2 of the scorpion C noxius Asp lie Val Leu Tre Gln Ser Pro Val Ser Leu Ala Val Ser Val Gli 1 5 10 15 Gln Gli Wing Tre lie Be Cis Lis Wing Gln Ser Val Asp Fen Asp 20 25 30 Gli Glu Tre Tir Met Asn Trp Tir Gln Gln Lis Pro Gli Gln Pro Pro 35 40 45 Lis Leu Leu lie Tir Val Val Ser Asn Leu Glu Ser Gli lie Pro Wing 50 55 60 Arg Fen Ser Gli Ser Gli Ser Gli Tre Asp Fen Tre Leu Asn lie His 65 70 75 80 Pro Val Glu Glu Glu Asp Ala Ala Tre Tir Tir Cis Gln Gln Ser Asn 85 90 95 Glu Asp Pro Leu Tre Fen Gli Ala Gli Tre Asn Leu Glu Leu Lis 100 105 110 INFORMATION FOR SEQ ID NO: 3 I. CHARACTERISTICS OF SEQUENCES A) LENGTH: 333 base pairs B) TYPE: nucleotides C) TYPE OF CHAIN: double chain D) TOPOLOGY: linear II. TYPE OF MOLECULE: ANDc for mRNA III. HYPOTHETICAL: no IV. ANTICIPATE: no V. ORIGINAL SOURCE A) ORGANISM: mouse B) CEPA: Balb / c D) TYPE OF TISSUE: spleen E) TYPE OF CELL: F lymphocyte) CELLULAR LINE: hybridoma VII. IMMEDIATE SOURCE. A) LIBRARY: Library in phage lambda IX. CHARACTERISTICS: A) NAME / KEY: B) LOCATION: C) IDENTIFICATION METHOD: Experimental D) OTHER INFORMATION: Nucleotide sequence of the variable region of the light chain of the neutralizing monoclonal antibody BCF2, directed against the toxin 2 of the scorpion C. noxius GTA CCA TGG CTG CAA CAG TCT GGT CCT GAG CTG GTG AAG CCT GGA GCT 48 Val Pro Trp Leu Gln Gln Ser Gli Pro Glu Leu Val Lis Pro Gli Wing 1 5 10 15 TCA ATG AAG ATA TCC TGC AAG GTT TCT GGT TAC TCA TTC ACT GAC CAC 96 Ser Met Lis lie Ser Cis Lis Val Ser Gli Tir Ser Fen Tre Asp His 20 25 30 ACC ATG AAC GTG AAG CAG AGC CAT GGA AAG AAC CTT GAG TTG ATT 144 Tre Met Asn Trp Val Lis Gln Ser His Gli Gli Asn Leu Glu Leu lie 35 40 45 GGA CTT ATT AAT CCT TTC AAT GGT GAT GCT ACC TAC AAA CAG AAG TTC 192 Gli Leu lie Asn Pro Fen Asn Gli Asp Ala Tre Tir Lis Gln Lis Fen 50 55 60 ACG GGC AAG GCC ACTA TTA ACT GTA GAC AGG TCA TCC AGC ACA GCC TTC 240 Tre Gli Lis Ala Tre Lú Tre Val Asp Arg Ser Ser Ser Tre Ala Fen 65 70 75 80 ATG GAG CTC CTC AGT CTG ACT TCT GAG GAC TCT GCA GTC TAT TAC TGT 288 Met Glu Leu Leu Ser Leu Tre Ser Glu Asp Ser Wing Val Tir Tir Cis 85 90 95 GCA AGA TAT GGT AAC TAC GCT ATG GAC TAC TGG GGT CAÁ GGA ACC TCA 336 Wing Arg Tir Gli Asn Tir Wing Met Asp Tir Trp Gli Gln Gli Tre Ser 100 105 110 GTC ACC GTC TCC TCA 351 Val Tre Val Ser Ser 115 INFORMATION FOR SEQ ID NO: 4 I. CHARACTERISTICS OF THE SEQUENCES A) LENGTH : 351 base pairs B) TYPE: nucleotides C) CHAIN TYPE: double chain D) TOPOLOGY: linear II. TYPE OF MOLECULE: ANDc for mRNA III. HYPOTHETICAL: no IV. ANTICIPATED: no VI. ORIGINAL SOURCE A) ORGANISM: mouse B) CEPA: Balb / c C) TISSUE TYPE: spleen D) TYPE OF CELL: lymphocyte E) CELLULAR LINE: hybridoma VII. IMMEDIATE SOURCE: A) LIBRARY: Library in phage lambda IX. CHARACTERISTICS: A) NAME / KEY: B) LOCATION: C) METHOD OF IDENTIFICATION: Experimental D) OTHER INFORMATION: Nucleotide sequence of the variable region of the heavy chain of neutralizing monoclonal antibody BCF2, directed against toxin 2 of the scorpion C. noxius. GAC ATT GTG TTG ACC CAA TCT CGA GTT TCT TTG GCT GTG TCT GTA GGG 48 Asp lie Val Leu Tre Gln Ser Pro Val Ser Leu Wing Val Ser Val Gli 1 5 10 15 CAÁ GGG GCC ACC ATC TCC TGT AAG GCC AGC CAÁ AGT GTT GAT TTT GAT 96 Gln Gli Ala Tre lie Be Cis Lis Wing Gln Ser Val Asp Fen Asp 20 25 30 GGT GAA ACT TAT ATG AAC TGG TAC CA CA AAA CCA GGA CAG CCA CCC 144 Gli Glu Tre Tir Met Asn Trp Tir Gln Gln Lis Pro Gli Gln Pro Pro 35 40 45 AAA CTC CTC ATT TAT GTT GTA TCC AAT CTA GAA TCT GGG ATC CCA GCC 192 Lis Leu Leu lie Tir Val Val Ser Asn Leu Glu Ser Gli lie Pro Wing 50 55 60 AGG TTT AGT GGC AGT GGG TCT GGG ACA GAC TTC ACC CTC AAC ATC CAT 240 Arg Fen Ser Gli Ser Gli Ser Gli Tre Asp Fen Tre Leu Asn lie His 65 70 75 80 CCT GTG GAG GAG GAG GAT GCT GCA ACC TAT TAC TGT CAG CAG AGT AAT 288 Pro Val Glu Glu Glu Asp Ala Wing Tre Tir Tir Cis Gln Gln Ser Asn 85 90 95 GAG GAT CCG CTC ACG TTC GGT GCT GGG ACC AAC CTG GAG CTG AAA 333 Glu Asp Pro Leu Tre Fen Gli Ala Gli Tre Asn Leu Glu Leu Lis 100 105 110 REFERENCES. 1 Miranda, F., Kopeyan, C, Rochat, C. and Lissitzky, S. (1970). Eur. J. Biochem. 16: 514-523. 2 Zoltkin, E., Miranda, F. and Rochat, C. (1978) in Arthropod venoms (Bettini, S., de.) Vol. 48, pp. 317-369, Springer.Verlag, Berlin. 3 Possani, L.D. (1984) in Handbook of natural toxins (Tu, A. T., de.) Vol. 2, pp. 513-550, Marcel Dekker Inc., New York. 4 Vázquez, A., Tapia, J.V., Eliason, W.K., Martin, B.M., Lebreton, F., Delepierre. M., Possani, L.D. and Becerril, B. (1995). Cloning and characterization of the cDNA encoding Na + channel-specific toxins 1 and 2 of the scorpion Centruroides noxius Hoffmann. Toxicon 33: 1161-1170. 5 Couraud, F., Jover, E., Dubois, J.M. and Rochat, H. (1982). Toxicon 20: 9-16 6 Strichartz, G. Rando, T. and Wang, G.K. (1987). Annu. Rev. Neurosci 10: 237-267. 7 Calderón-Aranda, Hozbor, D. and Possani, L.D., (1993), Neutralizing capacity of murine will be induced by different aritigens of scorpion venom. Toxicon31: 327-337. 8 Caderon-Aranda, E.S., Olamendi-Portugal, T. and Possani, L.D. (nineteen ninety five). The use of synthetic peptides can be a mislead approach to generate vaccines against scorpion venom. Vaccine 13: 1198-1206. 9 Nonner, W. (1979). Adv. Cytopharmacol. 3: 345-351. 10 Strichartz, G., Rando, T. and Wang, G.K. (1987). Annu. Rev. Neurosci. 10: 237-267. 11 Fontecilla-Camps, J.C., Habersetzer-Rochat, C. and Rochat, H. (1988). Proc. Nati Acad. Sci. USA 85: 7443-7447. 12 Yatani, A., Kirsch, G.E., Possani, L.D. and Brown, A.M. (1988). Am. J. Physiol. 254: H443-H451. 13 Dent, M.A. R., Possani, L. D., Ramirez, G. A. and Fletcher, P. L. Jr. (1980). Purufucation and characterization of two mammalian toxins from the venom of the Mexican scorpion Centruroides noxius Hoffman. Toxicon 18: 343-350.

Dehesa-Dávila, M. and Possani, L.D. (1994). Scorpionism and serotherapy in Mexico. Toxicon 32: 1015-1018. Dehesa-Dávila, M., Alagon, A.C. and Possani, L.D. (nineteen ninety five). Cinical toxicology of scorpion stings. In: Handbook of Clinical Toxicology of Animal Venoms and Poisons, pp. 201-238 (Meier, J. and White, J. Eds.). New York, CRC Press. Zamudio, F., Saavedra, R., Martin, B.M., Gurrola-Briones, G., Herion, P. and Possani, L.D. (1992). Amino acid sequence and immunological characterization with monoclonal antobodies of two toxins from the venom of the scorpion Centruroides noxius Hoffmann. Eur. J. Biochem. 204: 281-292. Zamudio, F., Saavedra, R., Martin, B.M., Gurrola-Briones, G., Herion, P. and Possani, L.D. (1992). Amino acid sequence and immunological characterization with monoclonal antobodies of two toxins from the venom of the scorpion Centruroides noxius Hoffmann. Eur. J. Biochem. 204: 281-292. Zamudio, F., Saavedra, R., Martin, B.M., Gurrola-Briones, G., Herion, P. and Possani, L.D. (1992). Amino acid sequence and immunological characterization with monoclonal antobodies of two toxins from the venom of the scorpion Centruroides noxius Hoffmann. Eur. J. Biochem. 204: 281-292. Zamudio, F., Saavedra, R., Martin, B.M., Gurrola-Briones, G., Herion, P. and Possani, L.D. (1992). Amino acid sequence and immunological characterization with monoclonal antobodies of two toxins from the venom of the scorpion Centruroides noxius Hoffmann. Eur. J. Biochem. 204: 281-292. Zamudio, F., Saavedra, R., Martin, B.M., Gurrola-Briones, G., Herion, P. and Possani, L.D. (1992). Amino acid sequence and immunological characterization with monoclonal antobodies of two toxins from the venom of the scorpion Centruroides noxius Hoffmann. Eur. J. Biochem. 204: 281-292. Possani, L.D., Fernandez de Castro, J., and Julia, J.Z. (1981). In Antibodies. A Laboratory Manual, Chaps 7 and 8, pp. 245-318 (Harlow, E. and Lane D., Eds.). New York: Cold Spring Harbor. Calderon-Aranda, E.S., Olamendi-Portugal, T. and Possani, L.D. (nineteen ninety five). The use of synthetic peptides can be a mislead approach to generate vaccines against scorpion venom. Vaccine 13: 1198-1206. Calderon-Aranda, Hozbor, D. and Possani, L.D. (1993). Neutralizing capacity of the brain will be induced by different antigens of venom scorpion. Toxicon 31: 327-337.

Zamudio, F., Saavedra, R., Martin, B.M., Gurrola-Briones, G., Herion, P. and Possani, L.D. (1992). Amino acid sequence and immunological characterization with monoclonal antobodies of two toxins from the venom of the scorpion Centruroides noxius Hoffmann. Eur. J. Biochem. 204: 281-292. Patent application PCT / EP92 / 04800, mo. of publication WO / 92/15683. Zamudio, F., Saavedra, R., Martin, B.M., Gurrola-Briones, G., Herion, P. and Possani, L.D. (1992). Amino acid sequence and immunological characterization with monoclonal antobodies of two toxins from the venom of the scorpion Centruroides noxius Hoffmann. Eur. J. Biochem. 204: 281-292. Zamudio, F., Saavedra, R., Martin, B.M., Gurrola-Briones, G., Herion, P. and Possani, L.D. (1992). Amino acid sequence and immunological characterization with monoclonal antobodies of two toxins from the venom of the scorpion Centruroides noxius Hoffmann. Eur. J. Biochem. 204: 281-292.

Hale, et. to the. (1988). Lancet, ii: 1394.

Claims (22)

Having described the invention as above, property is claimed as contained in the following: CLAIMS.

1. A Fab fragment characterized by neutralizing the total scorpion venom and purified toxins from the scorpion venom.

2. The Fab fragment according to claim 1, characterized by having an amino acid sequence of the heavy chain SEQ ID No: 1 or a functionally equivalent sequence.

3. A Fab fragment according to claim 1, characterized in that the light chain is of the kappa subclass.

4. A Fab fragment according to claim 3, characterized in that it has an amino acid sequence of the light chain SEQ ID No. 2 or a functionally equivalent sequence.

5. A Fab fragment according to claims 2 to 4, characterized by neutralizing the total venom and purified toxins from the scorpion venom of the genus Centruroides.

6. A Fab fragment according to claim 5, characterized by neutralizing the total venom and purified toxins from the scorpion venom Centruroides noxius Hoffmann.

7. A Fab fragment according to claim 6, characterized in that it comes from the monoclonal antibody BCF2.

8. A Fab fragment according to claim 6, characterized in that it has an approximate molecular weight of 50,000.

9. A Fab fragment according to claim 6, characterized in that 124 micromoles of said fragment neutralize 1 milligram of the total scorpion venom.

10. A Fab fragment according to claim 6, characterized in that it neutralizes the Cn2 toxin.

11. A process for preparing the Fab fragment of claim 6, characterized by a) Obtaining a hybridoma producing a monoclonal antibody capable of neutralizing the toxic activity of the total scorpion venom. b) Purify the monoclonal antibody. c) Enzymatically hydrolyze said monoclonal antibody with the proteolytic enzyme papain. d) Purify the neutralizing fragment by means of an affinity column.

12. A pharmaceutical composition characterized in that it comprises a Fab fragment according to any of claims 1 or 6, and a pharmaceutically acceptable carrier.

The pharmaceutical composition of claim 12, characterized in that administered a therapeutically effective amount to a mammal affected by scorpion sting, neutralizes the toxic effect of the total scorpion venom.

14. The use of the pharmaceutical composition of claim 13, characterized in that its administration is intravenously, intramuscularly, subcutaneously, orally or topically.

15. A DNA segment, characterized by presenting a nucleotide sequence SEQ. ID. No: 3 or a functionally equivalent mutation encoding the heavy chain of the Fab fragment of the monoclonal antibody BCF2.

16. The DNA segment of claim 15, characterized in that it encodes the amino acid sequence of the heavy chain of the Fab fragment, SEQ. ID. NO: 1 or a functionally equivalent mutation.

17. A DNA segment, characterized by presenting a nucleotide sequence SEQ. ID. No: 4 or a functionally equivalent mutation encoding the light chain of the Fab fragment of the monoclonal antibody BCF2.

18. The DNA segment of claim 19, characterized in that it encodes the amino acid sequence of the light chain of the Fab fragment, SEQ. ID. NO: 2 or a functionally equivalent mutation.

19. The monoclonal antibody BCF2, characterized in that it contains the sequence SEQ in its variable fraction of the heavy chain. ID. NO: 1 and in the light chain a sequence SEQ. ID. DO NOT. 2.

20. The monoclonal antibody BCF2 according to claim 19, characterized by neutralizing the total scorpion venom.

21. The monoclonal antibody BCF2 according to claim 20, characterized by neutralizing the total scorpion venom Centruroides noxius Hoffmann.

22. A pharmaceutical composition characterized in that it comprises the monoclonal antibody BCF2 according to claim 21, and that when administered in a therapeutically effective amount to a mammal affected by scorpion sting it neutralizes the toxic effect of the total venom thereof.