COMPOUNDS AND METHODS FOR DIAGNOSIS OF LEISHMANIASIS

Abstract: Compounds and methods are provided for diagnosing Leishmania infection. Disclosed compounds include polypeptides that contain at least an epitope of the Leishmania chagasi acidic ribosomal antigen LcP0, or a variant thereof. Such compounds are useful in a variety of immunoassays for detecting Leishmania infection and for identifying individuals with asymptomatic infections that are likely to progress to acute visceral leishmaniasis. The polypeptide compounds are further useful in vaccines and pharmaceutical compositions for preventing leishmaniasis.

Description: Description COMPOUNDS AND METHODS FOR DIAGNOSIS OF LEISHMANIASIS Technical Field The present invention relates generally to the serodiagnosis of Leishmania infection. The invention is more particularly directed to the use of one or more Leishmania polypeptides in methods and diagnostic kits to screen individuals and blood supplies for Leishmania, and to identify those asymptomatic individuals that are likely to progress to acute visceral leishmaniasis. The invention is also directed to vaccines and pharmaceutical compositions for immunizing an individual against leishmaniasis. Background of the Invention Leishmania organisms are intracellular protozoan parasites of macrophages that cause a wide range of clinical diseases in humans and other animals. In some infections, the parasite may lie dormant, and an infected host may be asymptomatic for many years. In other cases, particularly in immunocompromised individuals, the host may develop one of a variety of forms of leishmaniasis. This disease may be subclinical visceral leishmaniasis (VL) or asymptomatic in nature. Patients with subclinical or asymptomatic disease usually have low antibody titers which fall into the gray zone in immunological tests using whole parasites or parasite lysates. Isolation of parasites from these patients is also extremely difficult. Subclinical patients will in some cases progress to acute disease, but often will self-heal. They exhibit mild symptoms of malaise, diarrhea and intermittent hepatomegaly. Asymptomatic patients, in addition to low antibody titers, also display strong, positive delayed hypersensitivity to leishmanial antigens. Alternatively, leishmaniasis may be manifested as a cutaneous disease, which is a severe medical problem but is generally self-limiting, or as a highly destructive mucosal disease. Finally, and most seriously, the disease may be manifested as an acute visceral infection involving the spleen, liver, and lymph nodes, which is generally a fatal disease. Symptoms of acute visceral leishmaniasis include hepatosplenomegaly, fever, leukopenia, anemia and hypergammaglobulinemia. Leishmaniasis is a serious problem in much of the world, including Brazil, China, East Africa, India and areas of the Middle East. The disease is also endemic in the Mediterranean region, including southern France, Italy, Greece, Spain, Portugal and North Africa. The number of cases of leishmaniasis has increased dramatically in the last 20 years, and millions of cases of this disease now exist worldwide. About 2 million new cases are diagnosed each year, 25% of which are visceral leishmaniasis (VL). There are 20 species of Leishmania that infect humans. Of these species, VL is generally caused by L. donovani in Africa, China, the Middle East and India, L. infantium in southern Europe and North Africa, or L. chagasi in Latin America. In general, Leishmania species are transmitted to humans and other mammals, primarily the dog, by the bite of a phlebotomine sand fly. Early diagnosis of leishmaniasis is crucial for successful treatment, but is difficult to achieve with existing techniques. There are no distinctive signs or symptoms of the disease. Parasite detection methods have been used, but such methods are not sensitive or practical. Current serological tests (using, for example, ELISA or immunofluorescence techniques) typically use whole or lysed parasites, and are generally insensitive and prone to cross-reaction with a variety of other diseases. Such methods often fail to detect the potentially fatal disease early enough to allow effective treatment, since they rely on the detection of antibodies that are present during the acute phase of the disease. Accordingly, there is a need in the art for more sensitive and specific methods for detecting Leishmania infection, and for identifying those asymptomatic Leishmania infections that are likely to progress to acute visceral infections. The present invention fulfills these needs and further provides other related advantages. Summary of the Invention Briefly stated, this invention provides compounds and methods for detecting and protecting against leishmaniasis in individuals and in blood supplies. In one aspect, the present invention provides methods for detecting asymptomatic or sub-clinical Leishmania infection in a biological sample, comprising: (a) contacting a biological sample with a polypeptide comprising an epitope of LcPO, or a variant thereof that differs only in conservative substitutions and/or modifications; and (b) detecting in the biological sample the presence of antibodies that bind to the polypeptide, thereby detecting asymptomatic or sub¬ clinical Leishmania infection in the biological sample. In a related aspect, the present invention provides methods for detecting Leishmania infection in a biological sample, comprising: (a) contacting a biological sample with a first ammo acid sequence comprising an epitope of LcPO, or a variant thereof that differs only in conservative substitutions and/or modifications; (b) contacting the biological sample with a second amino acid sequence comprising Leu Glu Gin Gin Leu Arg Xaa Ser Glu Xaa Arg Ala Ala Glu Leu Ala Ser Gin Leu Glu Xaa Thr Xaa Ala Ala Lys Xaa Ser Ala Glu Gin Asp Arg Glu Xaa Thr Arg Ala Xaa, wherein Xaa at position 7 is Asp or Glu, at position 10 is Glu or Ala, at position 21 is Ala or Ser, at position 23 is Ala or Thr, at position 27 is Met or Ser, at position 35 is Asn or Ser, and at position 39 is Thr or Ala, or a variant thereof that differs only in conservative substitutions and/or modifications; and (c) detecting in the sample the presence of antibodies that bind to one or both of the amino acid sequences, thereby detecting Leishmania infection in the biological sample. In yet another related aspect of this invention, methods are provided for identifying a patient afflicted with asymptomatic or subclinical leishmaniasis that is likely to develop acute visceral leishmaniasis. In one embodiment, the method comprises: (a) contacting a biological sample obtained from a patient afflicted with asymptomatic or subclinical leishmaniasis with a polypeptide comprising the amino acid sequence Leu Glu Gin Gin Leu Arg Xaa Ser Glu Xaa Arg Ala Ala Glu Leu Ala Ser Gin Leu Glu Xaa Thr Xaa Ala Ala Lys Xaa Ser Ala Glu Gin Asp Arg Glu Xaa Thr Arg Ala Xaa, wherein Xaa at position 7 is Asp or Glu, at position 10 is Glu or Ala, at position 21 is Ala or Ser, at position 23 is Ala or Thr, at position 27 is Met or Ser, at position 35 is Asn or Ser, and at position 39 is Thr or Ala, or a variant thereof that differs only in conservative substitutions and/or modifications; and (b) detecting in the sample the presence of antibodies that bind to the polypeptide, thereby identifying a patient afflicted with asymptomatic or subclinical leishmaniasis that is likely to develop acute visceral leishmaniasis. In another embodiment, the method comprises: (a) contacting a biological sample obtained from a patient afflicted with asymptomatic or subclinical leishmaniasis with a first polypeptide comprising an epitope of LcPO, or a variant thereof that differs only in conservative substitutions and/or modifications; (b) independently contacting the biological sample with a second polypeptide comprising the amino acid sequence Leu Glu Gin Gin Leu Arg Xaa Ser Glu Xaa Arg Ala Ala Glu Leu Ala Ser Gin Leu Glu Xaa Thr Xaa Ala Ala Lys Xaa Ser Ala Glu Gin Asp Arg Glu Xaa Thr Arg Ala Xaa, wherein Xaa at position 7 is Asp or Glu, at position 10 is Glu or Ala, at position 21 is Ala or Ser, at position 23 is Ala or Thr, at position 27 is Met or Ser, at position 35 is Asn or Ser, and at position 39 is Thr or Ala, or a variant thereof that differs only in conservative substitutions and/or modifications; and (c) detecting in the sample the presence of antibodies that bind to the first and/or second polypeptides, thereby identifying a patient afflicted with asymptomatic or subclinical leishmaniasis that is likely to develop acute visceral leishmaniasis. In another aspect of this invention, polypeptides are provided comprising amino acids 306-322 of SEQ ID NO:2. Within related aspects, diagnostic kits for diagnosing leishmaniasis are provided. In one embodiment, this invention provides kits for detecting asymptomatic or sub¬ clinical leishmaniasis in a biological sample, comprising: (a) a polypeptide comprising an epitope of LcPO, or a variant thereof that differs only in conservative substitutions and/or modifications; and (b) a detection reagent. In another embodiment, diagnostic kits are provided for detecting Leishmania infection in a biological sample, comprising: (a) a first amino acid sequence comprising an epitope of LcPO, or a variant thereof that differs only in conservative substitutions and/or modifications; (b) a second amino acid sequence comprising the amino acid sequence Leu Glu Gin Gin Leu Arg Xaa Ser Glu Xaa Arg Ala Ala Glu Leu Ala Ser Gin Leu Glu Xaa Thr Xaa Ala Ala Lys Xaa Ser Ala Glu Gin Asp Arg Glu Xaa Thr Arg Ala Xaa, wherein Xaa at position 7 is Asp or Glu, at position 10 is Glu or Ala, at position 21 is Ala or Ser, at position 23 is Ala or Thr, at position 27 is Met or Ser, at position 35 is Asn or Ser, and at position 39 is Thr or Ala, or a variant thereof that differs only in conservative substitutions and/or modifications; and (c) a detection reagent. In still another embodiment, diagnostic kits are provided for identifying a patient afflicted with asymptomatic or subclinical leishmaniasis that is likely to develop acute visceral leishmaniasis, comprising: (a) a polypeptide comprising the amino acid sequence Leu Glu Gin Gin Leu Arg Xaa Ser Glu Xaa Arg Ala Ala Glu Leu Ala Ser Gin Leu Glu Xaa Thr Xaa Ala Ala Lys Xaa Ser Ala Glu Gin Asp Arg Glu Xaa Thr Arg Ala Xaa, wherein Xaa at position 7 is Asp or Glu, at position 10 is Glu or Ala, at position 21 is Ala or Ser, at position 23 is Ala or Thr, at position 27 is Met or Ser, at position 35 is Asn or Ser, and at position 39 is Thr or Ala, or a variant thereof that differs only in conservative substitutions and/or modifications; and (b) a detection reagent. In yet another related embodiment, the present invention provides diagnostic kits for identifying a patient afflicted with asymptomatic or subclinical leishmaniasis that is likely to develop acute visceral leishmaniasis, comprising: (a) a first polypeptide comprising an epitope of LcPO, or a variant thereof that differs only in conservative substitutions and/or modifications; (b) a second polypeptide comprising the amino acid sequence Leu Glu Gin Gin Leu Arg Xaa Ser Glu Xaa Arg Ala Ala Glu Leu Ala Ser Gin Leu Glu Xaa Thr Xaa Ala Ala Lys Xaa Ser Ala Glu Gin Asp Arg Glu Xaa Thr Arg Ala Xaa, wherein Xaa at position 7 is Asp or Glu, at position 10 is Glu or Ala, at position 21 is Ala or Ser, at position 23 is Ala or Thr, at position 27 is Met or Ser, at position 35 is Asn or Ser, and at position 39 is Thr or Ala, or a variant thereof that differs only in conservative substitutions and/or modifications; and (c) a detection reagent. Within other aspects, this invention provides pharmaceutical compositions comprising a polypeptide containing an epitope of LcPO, or a variant thereof that differs only in conservative substitutions and/or modifications, and a physiologically acceptable carrier; and vaccines comprising a polypeptide as described above and an adjuvant. In related aspects, DNA sequences encoding the above polypeptides, expression vectors comprising these DNA sequences and host cells transformed or transfected with such expression vectors are also provided. These and other aspects of the present invention will become apparent upon reference to the following detailed description and attached drawings. All references disclosed herein are hereby incoφorated by reference in their entirety as if each was incoφorated individually. Brief Description of the Drawings Figures 1(a) and (b) show the sequence of a representative cDNA molecule encoding LcPO, along with the amino acid sequence encoded by the cDNA. Figures 2(a), (b), and (c) depict the sequence of the full length K39 polypeptide. Figures 3(a) and (b) present the DNA sequence of a representative cDNA encoding the full length K39 polypeptide. Figure 4 illustrates the reactivity of LcPO. Figure 4(a) shows the reactivity with sera from normal individuals, Figure 4(b) shows the reactivity with asymptomatic patient sera and Figure 4(c) depicts the reactivity with sera from patients with acute visceral leishmaniasis. Figure 5 illustrates the reactivity of a polypeptide containing the 17 C-terminal amino acids of LcPO as compared to that of recombinant LcPO. Figure 5(a) shows the reactivity with sera from normal individuals, Figure 5(b) shows the reactivity with asymptomatic patient sera and Figure 5(c) depicts the reactivity with sera from patients with acute visceral leishmaniasis. Figure 6 shows the reactivity of the 17 amino acid polypeptide evaluated in Figure 5. Figure 6(a) shows the reactivity with sera from normal individuals, Figure 6(b) shows the reactivity with sera from patients with acute visceral leishmaniasis and Figure 6(c) depicts the reactivity with asymptomatic patient sera. Figure 7 illustrates the reactivity of the recombinant K39 polypeptide. Figure 7(a) shows the reactivity with sera from normal individuals, Figure 7(b) shows the reactivity with asymptomatic patient sera and Figure 7(c) depicts the reactivity with sera from patients with acute visceral leishmaniasis. Figure 8 shows the reactivity of LcPO together with K39, as compared to that of Leishmania lysate, with sera from normal, asymptomatic and visceral leishmaniasis patients. Detailed Description of the Invention As noted above, the present invention is generally directed to compounds and methods useful for detecting and protecting against Leishmania infection. The compounds of this invention generally comprise one or more antigenic epitopes of Leishmania proteins. In particular, polypeptides comprising an epitope of a Leishmania chagasi homolog of the eukaryotic acidic ribosomal P-protein family (referred to herein as LcPO) are disclosed. As used herein, the term "polypeptide" encompasses amino acid chains of any length, including full length proteins, wherein the amino acid residues are linked by covalent peptide bonds. The use of such LcPO polypeptides for specifically detecting asymptomatic or subclinical leishmaniasis is also disclosed. In addition, the present invention discloses the use of epitopes from other Leishmania proteins, in combination with an epitope of LcPO, to diagnose Leishmania infection and to monitor the development of acute visceral leishmaniasis. The compounds and methods of this invention also encompass variants of the recited polypeptides. As used herein, a "variant" is a polypeptide that differs from the recited polypeptide only in conservative substitutions and/or modifications, such that it retains the antigenic properties of the recited polypeptide. Such variants may generally be identified by modifying the polypeptide sequence as described below and evaluating the antigenic properties of the modified polypeptide using, for example, one or more of the assays described herein. A "conservative substitution" in the context of this invention is one in which an amino acid is substituted for another amino acid that has similar properties, such that one skilled in the art of peptide chemistry would expect the secondary structure and hydropathic nature of the polypeptide to be substantially unchanged. In general, the following groups of amino acids represent conservative changes: (1) ala, pro, gly, glu, asp, gin, asn, ser, thr; (2) cys, ser, tyr, thr; (3) val, ile, leu, met, ala, phe; (4) lys, arg, his; and (5) phe, tyr, tφ, his. Preferred substitutions include changes between asp and glu, ala and glu, ala and ser, ala and thr, met and ser, and asn and ser. Variants may also, or alternatively, contain other modifications, including the deletion or addition of amino acids, that have minimal influence on the antigenic properties, secondary structure and hydropathic nature of the polypeptide. For example, the polypeptide may be conjugated to a linker or other sequence for ease of synthesis or to enhance binding of the polypeptide to a solid support. In one aspect of the invention, polypeptides are provided comprising an epitope of the Leishmania chagasi acidic ribosomal antigen LcPO. A genomic DNA sequence encoding LcPO is shown in Figures 1(a) and (b). A DNA molecule encoding LcPO may be isolated by screening a Leishmania chagasi genomic expression library for clones that express antigens which react with pooled sera from T. cπ rz-infected patients. This screen may be generally performed using methods known to those of ordinary skill in the art, such as methods described in Sambrook et al., Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratories, Cold Spring Harbor, N.Y. 1989, which is incorporated herein by reference. Briefly, a bacteriophage expression library may be plated and transferred to filters. The filters may then be incubated with serum and a detection reagent. In the context of this invention, a "detection reagent" is any compound capable of binding to the antibody-antigen complex, which may then be detected by any of a variety of means known to those of ordinary skill in the art. Typical detection reagents contain a "binding agent," such as Protein A, Protein G, IgG or a lectin, coupled to a reporter group. Preferred reporter groups include, but are not limited to, enzymes, substrates, cofactors, inhibitors, dyes, radionuclides, luminescent groups, fluorescent groups and biotin. More preferably, the reporter group is horseradish peroxidase, which may be detected by incubation with a substrate such as tetramethylbenzidine or 2,2'-azino-di-3-ethylbenzthiazoline sulfonic acid. Plaques containing genomic DNA sequences that express a protein which binds to an antibody in the serum may be isolated and purified by techniques known to those of ordinary skill in the art. Appropriate methods may be found, for example, in Sambrook et al., Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratories, Cold Spring Harbor, NY. Epitopes of LcPO may generally be determined by generating polypeptides containing portions of the LcPO sequence and evaluating the reactivity of the polypeptides with sera from Leishmania-infected individuals using, for example, an enzyme linked immunosorbent assay (ELISA). Suitable assays for evaluating reactivity of a polypeptide with Leishmania-infected sera are described in more detail below. Within such representative assays, portions of the LcPO sequence that generate a signal that differentiates between positive and negative sera in a manner substantially similar to that of the full length LcPO are considered to contain an epitope. In other words, a portion of LcPO that contains an epitope will generate a signal indicating Leishmania infection in substantially all (i.e., at least about 80%, and preferably at least about 90%) of the biological samples for which such infection would be indicated using the full length LcPO and will generate a signal indicating the absence of Leishmania infection in substantially all of those samples that would be negative with the full length polypeptide. Portions of LcPO containing at least the 17 C-terminal amino acids shown in Figures 1 (i.e., residues 306-322) have generally been found to generate a signal in an ELISA that is substantially equivalent to that generated by the full length LcPO. Accordingly, polypeptides comprising at least the 17 C-terminal amino acids of LcPO contain an epitope of LcPO, and such polypeptides (and variants thereof) are within the scope of this invention. In a related aspect, combination polypeptides comprising epitopes of multiple Leishmania polypeptides are disclosed. A "combination polypeptide" is a polypeptide in which epitopes of different Leishmania peptides, or variants thereof, are joined though a peptide linkage into a single amino acid chain. The epitopes may be joined directly (i.e., with no intervening amino acids) or may be joined by way of a linker sequence (e.g., Gly-Cys-Gly) that does not significantly alter the antigenic properties of the epitopes. In preferred embodiments, the combination polypeptide comprises an LcPO epitope along with an epitope derived from the Leishmania K39 antigen (see Figures 2(a), (b) and (c) and U.S. Patent No. 5,411,865). More preferably, the K39 epitope is a K39 repeat unit antigen, having the amino acid sequence Leu Glu Gin Gin Leu Arg Xaa Ser Glu Xaa Arg Ala Ala Glu Leu Ala Ser Gin Leu Glu Xaa Thr Xaa Ala Ala Lys Xaa Ser Ala Glu Gin Asp Arg Glu Xaa Thr Arg Ala Xaa, wherein Xaa at position 7 is Asp or Glu, at position 10 is Glu or Ala, at position 21 is Ala or Ser, at position 23 is Ala or Thr, at position 27 is Met or Ser, at position 35 is Asn or Ser, and at position 39 is Thr or Ala, or a variant thereof that differs only in conservative substitutions and/or modifications. The polypeptides of this invention may be generated using techniques well known to those of ordinary skill in the art. Polypeptides having fewer than about 100 amino acids, and generally fewer than about 50 amino acids, can be synthesized using, for example, the Merrifield solid-phase synthesis method, where amino acids are sequentially added to a growing amino acid chain. See Merrifield, J. Am. Chem. Soc. 55:2149-2146, 1963. Equipment for automated synthesis of polypeptides is commercially available from suppliers such as Applied Biosystems, Inc., Foster City, CA. Thus, for example, the K39 repeat unit antigen, or portions thereof, may be synthesized by this method. Similarly, polypeptides comprising epitopes of LcPO, such as residues 306-322 of SEQ. ED NO:2, may be prepared using an automated synthesizer. Alternatively, the polypeptides of this invention may be prepared by expression of recombinant DNA encoding the polypeptide in cultured host cells. Preferably, the host cells are E. coli, yeast, an insect cell line (such as Spodoptera or Trichoplusiά) or a mammalian cell line, including (but not limited to) CHO, COS and NS-1. The DNA sequences expressed in this manner may encode naturally occurring proteins, such as LcPO and K39, portions of naturally occurring proteins, or other variants of such proteins. Expressed polypeptides of this invention are generally isolated in substantially pure form. Preferably, the polypeptides are isolated to a purity of at least 80% by weight, more preferably, to a purity of at least 95% by weight, and most preferably to a purity of at least 99% by weight. In general, such purification may be achieved using, for example, the standard techniques of ammonium sulfate fractionation, SDS-PAGE electrophoresis, and affinity chromatography. In another aspect of this invention, methods are disclosed for detecting and monitoring Leishmania infection, as well as for distinguishing among types of Leishmania infections, in individuals and blood supplies. In general, Leishmania infection may be detected in any biological sample that contains antibodies. Preferably, the sample is blood, serum, plasma, saliva, cerebrospinal fluid or urine. More preferably, the sample is a blood or serum sample obtained from a patient or a blood supply. Briefly, Leishmania infection may be detected using one or more polypeptides containing one or more of the epitopes discussed above, or variants thereof. If multiple epitopes are employed, these epitopes may be present on one or more polypeptides. The polypeptide or polypeptides are then used to determine the presence or absence of antibodies to the polypeptide or polypeptides in the sample, relative to a predetermined cut-off value. There are a variety of assay formats known to those of ordinary skill in the art for using a polypeptide to detect antibodies in a sample. See, e.g., Harlow and Lane, Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory, 1988, which is incoφorated herein by reference. In a preferred embodiment, the assay involves the use of polypeptide immobilized on a solid support to bind to and remove the antibody from the sample. The bound antibody may then be detected using a detection reagent that binds to the antibody/peptide complex and contains a detectable reporter group. Suitable detection reagents include antibodies that bind to the antibody/polypeptide complex and free polypeptide labeled with a reporter group (e.g., in a semi-competitive assay). Alternatively, a competitive assay may be utilized, in which an antibody that binds to the polypeptide is labeled with a reporter group and allowed to bind to the immobilized polypeptide after incubation of the polypeptide with the sample. The extent to which components of the sample inhibit the binding of the labeled antibody to the polypeptide is indicative of the reactivity of the sample with the immobilized polypeptide. The solid support may be any material known to those of ordinary skill in the art to which the polypeptide may be attached. For example, the support may be a test well in a microtiter plate or a nitrocellulose or other suitable membrane. Alternatively, the support may be a bead or disc, such as glass, fiberglass, latex or a plastic material such as polystyrene or polyvinylchloride. The support may also be a magnetic particle or a fiber optic sensor, such as those disclosed, for example, in U.S. Patent No. 5,359,681. The polypeptide may be bound to the solid support using a variety of techniques known to those in the art, which are amply described in the patent and scientific literature. In the context of the present invention, the term "bound" refers to both noncovalent association, such as adsoφtion, and covalent attachment (which may be a direct linkage between the antigen and functional groups on the support or may be a linkage by way of a cross-linking agent). Binding by adsoφtion to a well in a microtiter plate or to a membrane is preferred. In such cases, adsoφtion may be achieved by contacting the polypeptide, in a suitable buffer, with the solid support for a suitable amount of time. The contact time varies with temperature, but is typically between about 1 hour and 1 day. In general, contacting a well of a plastic microtiter plate (such as polystyrene or polyvinylchloride) with an amount of polypeptide ranging from about 10 ng to about 1 μg, and preferably about 100 ng, is sufficient to bind an adequate amount of antigen. Nitrocellulose will bind approximately 100 μg of protein per cm-*. Covalent attachment of polypeptide to a solid support may generally be achieved by first reacting the support with a bifunctional reagent that will react with both the support and a functional group, such as a hydroxyl or amino group, on the polypeptide. For example, the polypeptide may be bound to a support having an appropriate polymer coating using benzoquinone or by condensation of an aldehyde group on the support with an amine and an active hydrogen on the polypeptide (see, e.g., Pierce Immunotechnology Catalog and Handbook (1991) at A12-A13). In certain embodiments, the assay is an enzyme linked immunosorbent assay (ELISA). This assay may be performed by first contacting a polypeptide antigen that has been immobilized on a solid support, commonly the well of a microtiter plate, with the sample, such that antibodies to the polypeptide within the sample are allowed to bind to the immobilized polypeptide. Unbound sample is then removed from the immobilized polypeptide and a detection reagent capable of binding to the immobilized antibody-polypeptide complex is added. The amount of detection reagent that remains bound to the solid support is then determined using a method appropriate for the specific detection reagent. Once the polypeptide is immobilized on the support, the remaining protein binding sites on the support are typically blocked. Any suitable blocking agent known to those of ordinary skill in the art, such as bovine serum albumin (BSA) or Tween 20™ (Sigma Chemical Co., St. Louis, MO) may be employed. The immobilized polypeptide is then incubated with the sample, and antibody (if present in the sample) is allowed to bind to the antigen. The sample may be diluted with a suitable diluent, such as phosphate-buffered saline (PBS) prior to incubation. In general, an appropriate contact time (i.e., incubation time) is that period of time that is sufficient to permit detect the presence of antibody within a Leishmania-itifected sample. Preferably, the contact time is sufficient to achieve a level of binding that is at least 95% of that achieved at equilibrium between bound and unbound antibody. Those of ordinary skill in the art will recognize that the time necessary to achieve equilibrium may be readily determined by assaying the level of binding that occurs over a period of time. At room temperature, an incubation time of about 30 minutes is generally sufficient. Unbound sample may then be removed by washing the solid support with an appropriate buffer, such as PBS containing 0.1% Tween 20™. Detection reagent may then be added to the solid support. An appropriate detection reagent is any compound that binds to the immobilized antibody-polypeptide complex and that can be detected by any of a variety of means known to those in the art. Preferably, the detection reagent contains a binding agent (such as, for example, Protein A, Protein G, immunoglobulin, lectin or free antigen) conjugated to a reporter group. Preferred reporter groups include enzymes (such as horseradish peroxidase), substrates, cofactors, inhibitors, dyes, radionuclides, luminescent groups, fluorescent groups and biotin. The conjugation of binding agent to reporter group may be achieved using standard methods known to those of ordinary skill in the art. Common binding agents may also be purchased conjugated to a variety of reporter groups from many sources (e.g., Zymed Laboratories, San Francisco, CA and Pierce, Rockford, D ). The detection reagent is then incubated with the immobilized antibody- polypeptide complex for an amount of time sufficient to detect the bound antibody. An appropriate amount of time may generally be determined from the manufacturer's instructions or by assaying the level of binding that occurs over a period of time. Unbound detection reagent is then removed and bound detection reagent is detected using the reporter group. The method employed for detecting the reporter group depends upon the nature of the reporter group. For radioactive groups, scintillation counting or autoradiographic methods are generally appropriate. Spectroscopic methods may be used to detect dyes, luminescent groups and fluorescent groups. Biotin may be detected using avidin, coupled to a different reporter group (commonly a radioactive or fluorescent group or an enzyme). Enzyme reporter groups may generally be detected by the addition of substrate (generally for a specific period of time), followed by spectroscopic or other analysis of the reaction products. To determine the presence or absence of an -Leishmania antibodies in the sample, the signal detected from the reporter group that remains bound to the solid support is generally compared to a signal that corresponds to a predetermined cut-off value. In one preferred embodiment, the cut-off value is preferably the average mean signal obtained when the immobilized polypeptide is incubated with samples from an uninfected patient. In general, a sample generating a signal that is three standard deviations above the predetermined cut-off value is considered positive (i.e., reactive with the polypeptide). In an alternate preferred embodiment, the cut-off value is determined using a Receiver Operator Curve, according to the method of Sackett et al., Clinical Epidemiology: A Basic Science for Clinical Medicine, p. 106-7 (Little Brown and Co., 1985). Briefly, in this embodiment, the cut-off value may be determined from a plot of pairs of true positive rates (i.e., sensitivity) and false positive rates (100%-specificity) that correspond to each possible cut-off value for the diagnostic test result. The cut-off value on the plot that is the closest to the upper left-hand corner (i.e., the value that encloses the largest area) is the most accurate cut-off value, and a sample generating a signal that is higher than the cut-off value determined by this method may be considered positive. Alternatively, the cut-off value may be shifted to the left along the plot, to minimize the false positive rate, or to the right, to minimize the false negative rate. In a related embodiment, the assay is performed in a flow-through or strip test format, wherein the antigen is immobilized on a membrane such as nitrocellulose. In the flow- through test, antibodies within the sample bind to the immobilized polypeptide as the sample passes through the membrane. A detection reagent (e.g., protein A-colloidal gold) then binds to the antibody-polypeptide complex as the solution containing the detection reagent flows through the membrane. The detection of bound detection reagent may then be performed as described above. In the strip test format, one end of the membrane to which polypeptide is bound is immersed in a solution containing the sample. The sample migrates along the membrane through a region containing detection reagent and to the area of immobilized polypeptide. Concentration of detection reagent at the polypeptide indicates the presence of Leishmania antibodies in the sample. Typically, the concentration of detection reagent at that site generates a pattern, such as a line, that can be read visually. The absence of such a pattern indicates a negative result. In general, the amount of polypeptide immobilized on the membrane is selected to generate a visually discernible pattern when the biological sample contains a level of antibodies that would be sufficient to generate a positive signal in an ELISA, as discussed above. Preferably, the amount of polypeptide immobilized on the membrane ranges from about 25 ng to about lμg, and more preferably from about 50 ng to about 500 ng. Such tests can typically be performed with a very small amount (e.g., one drop) of patient serum or blood. Of course, numerous other assay protocols exist that are suitable for use with the polypeptides of the present invention. The above descriptions are intended to be exemplary only. In one aspect of the invention, the assays discussed above may be used to specifically detect asymptomatic or sub-clinical leishmaniasis. In this aspect, antibodies in the sample may be detected using a polypeptide comprising LcPO or an epitope thereof. Preferably, the polypeptide comprises amino acids 306-322 of SEQ ID NO:2. It has been found in the present invention that polypeptides comprising at least this C-terminal portion of LcPO generate a positive result with sera from less than 35% of patients with acute visceral leishmaniasis, but generate a positive result with sera from more than 95% patients having asymptomatic or sub-clinical leishmaniasis. Accordingly, LcPO, and antigenic portions thereof, may be used to specifically identify patients with asymptomatic or sub-clinical leishmaniasis. In another aspect, both asymptomatic/sub-clinical and acute visceral leishmaniasis may be detected. In this aspect, an LcPO epitope is combined with a second Leishmania epitope that detects the presence of acute visceral leishmaniasis. Preferably, the second epitope comprises at least one repeat unit of the K39 antigen, the sequence of which is provided in Figures 2(a), (b) and (c) and SEQ ID NO:3. In one such embodiment, the K39 antigen comprises the repeat unit antigen having the amino acid sequence Leu Glu Gin Gin Leu Arg Xaa Ser Glu Xaa Arg Ala Glu Leu Ala Ser Gin Leu Glu Xaa Thr Xaa Ala Ala Lys Xaa Ser Ala Glu Gin Asp Arg Glu Xaa Thr Arg Ala Xaa, wherein Xaa at position 7 is Asp or Glu, at position 10 is Glu or Ala, at position 21 is Ala or Ser, at position 23 is Ala or Thr, at position 27 is Met or Ser, at position 35 is Asn or Ser, and at position 39 is Thr or Ala. In another such prefered embodiment, the K39 epitope is present within a recombinant K39 polypeptide, which comprises amino acids 1-955 of SEQ ID NO:3. The use of variants of the above sequences, that differ only in conservative substitutions and/or modifications, is also preferred. Preferably, the LcPO and K39 antigens are immobilized by adsoφtion to a solid support such as a well of a microtiter plate or a membrane, as described above, in roughly similar amounts such that the total amount of polypeptide in contact with the support ranges from about 10 ng to about 100 μg. The remainder of the steps in the assay may generally be performed as described above. It will be readily apparent to those of ordinary skill in the art that, by combining LcPO and K39 polypeptides with other polypeptides that can detect cutaneous and mucosal leishmaniasis, the polypeptides disclosed herein may be used in methods that detect all types of leishmaniasis. In another aspect of the invention, patients with asymptomatic or subclinical VL whose disease is likely to progress to acute visceral leishmaniasis may be distinguished from infected patients whose disease is not likely to progress. Such progression may occur within a year (and typically within 5-12 months) for subclinical disease, or within many years in the case of asymptomatic patients. This determination may be made using any of several approaches. In one embodiment, the assay is performed using a polypeptide that comprises at least one repeat unit of the K39 antigen, without the use of an LcPO epitope. Preferably, the polypeptide comprises the K39 repeat unit antigen described above. While the K39 repeat unit antigen generates a positive result (relative to the predetermined cut-off value) when reacted with sera from more than 97% of patients with acute visceral leishmaniasis, only a relatively small percentage (around one third) of patients with asymptomatic leishmaniasis react with this antigen. Those sera that do react are likely to indicate infections that are in the process of progression, or are likely to progress, to acute visceral leishmaniasis (or infections that are in remission or responding to treatment, which may be distinguished based on patient history). In another embodiment, the assay is separately performed with LcPO, or an epitope thereof, and with a polypeptide that comprises at least one repeat unit of the K39 antigen. In this embodiment, the optical density (OD) obtained in the assay using the LcPO epitope is compared to the value obtained using the K39 polypeptide. A relatively high OD in the assay using the LcPO epitope, along with a relatively low OD in the assay using the K39 polypeptide indicates an asymptomatic or subclinical infection that is not likely to progress to acute visceral leishmaniasis. On the other hand, a relatively high OD in the assay using the K39 polypeptide, along with a relatively low OD in the assay using the LcPO epitope indicates an asymptomatic or subclinical infection that is likely to progress to acute visceral leishmaniasis (or in remission or responding to treatment). Those asymptomatic or subclinical patients for whom both values are relatively high are likely to be in the process of developing acute visceral leishmaniasis (or in the process of recovering from infection). In each case, the direction of the disease (i.e., progression or remission) may be determined using the patient's history. In another embodiment, asymptomatic or subclinical patients that are likely to develop acute visceral leishmaniasis may be identified using separate LcPO and K39 assays (as described above) that are performed over a period of time. For example, the assays may be performed every 1-6 months for a period of months or years. Asymptomatic or subclinical patients that are likely to remain asymptomatic or subclinical will generally have sera that shows a high reactivity with LcPO and a low reactivity with the K39 polypeptide, as discussed above, at each time point. However, patients that are progressing toward acute visceral leishmaniasis will show an increase in the reactivity with the K39 polypeptide and a decrease in the reactivity with LcPO over the time period of the assays. By monitoring an individual patient in this manner, the development of acute visceral leishmaniasis may be identified before other symptoms become apparent. This early identification allows selective treatment of only those asymptomatic patients that are predisposed to develop a more serious form of the disease. In another aspect of this invention, immobilized LcPO polypeptides may be used to purify antibodies that bind to LcPO. Such antibodies may be prepared by any of a variety of techniques known to those of ordinary skill in the art. See, e.g., Harlow and Land, Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory, 1988. In one such technique, an immunogen comprising a LcPO polypeptide is initially injected into any of a wide variety of mammals (e.g., mice, rats, rabbits, sheep and goats). In this step, the polypeptide may serve as the immunogen without modification. Alternatively, particularly for relatively short polypeptides, a superior immune response may be elicited if the polypeptide is joined to a carrier protein, such as bovine serum albumin or keyhole limpet hemocyanin. The immunogen is injected into the animal host, preferably according to a predetermined schedule incorporating one or more booster immunizations, and the animals are bled periodically. Polyclonal antibodies specific for the polypeptide may then be purified from such antisera by, for example, affinity chromatography using the polypeptide coupled to a suitable solid support. Monoclonal antibodies specific for the antigenic polypeptide of interest may be prepared, for example, using the technique of Kohler and Milstein, Eur. J. Immunol. 6:511- 519, 1976, and improvements thereto. Briefly, these methods involve the preparation of immortal cell lines capable of producing antibodies having the desired specificity (i.e., reactivity with the polypeptide of interest). Such cell lines may be produced, for example, from spleen cells obtained from an animal immunized as described above. The spleen cells are then immortalized by, for example, fusion with a myeloma cell fusion partner, preferably one that is syngeneic with the immunized animal. A variety of fusion techniques may be employed. For example, the spleen cells and myeloma cells may be combined with a nonionic detergent for a few minutes and then plated at low density on a selective medium that supports the growth of hybrid cells, but not myeloma cells. A preferred selection technique uses HAT (hypoxanthine, aminopterin, thymidine) selection. After a sufficient time, usually about 1 to 2 weeks, colonies of hybrids are observed. Single colonies are selected and tested for binding activity against the polypeptide. Hybridomas having high reactivity and specificity are preferred. Monoclonal antibodies may be isolated from the supernatants of growing hybridoma colonies. In this process, various techniques may be employed to enhance the yield, such as injection of the hybridoma cell line into the peritoneal cavity of a suitable vertebrate host, such as a mouse. Monoclonal antibodies may then be harvested from the ascites fluid or the blood. Contaminants may be removed from the antibodies by conventional techniques, such as chromatography, gel filtration, precipitation, and extraction. One or more LcPO polypeptides may be used in the purification process in, for example, an affinity chromatography step. Monospecific antibodies that bind to an LcPO polypeptide may be used, for example, to detect Leishmania infection in a biological sample using one of a variety of immunoassays, which may be direct or competitive. Briefly, in one direct assay format, a monospecific antibody may be immobilized on a solid support (as described above) and contacted with the sample to be tested. After removal of the unbound sample, a second monospecific antibody, which has been labeled with a reporter group, may be added and used to detect bound antigen. In an exemplary competitive assay, the sample may be combined with the monoclonal or polyclonal antibody, which has been labeled with a suitable reporter group. The mixture of sample and antibody may then be combined with polypeptide antigen immobilized on a suitable solid support. Antibody that has not bound to an antigen in the sample is allowed to bind to the immobilized antigen, and the remainder of the sample and antibody is removed. The level of antibody bound to the solid support is inversely related to the level of antigen in the sample. Thus, a lower level of antibody bound to the solid support indicates the presence of Leishmania in the sample. Other formats for using monospecific antibodies to detect Leishmania in a sample will be apparent to those of ordinary skill in the art, and the above formats are provided solely for exemplary puφoses. In another aspect of this invention, vaccines and pharmaceutical compositions are provided for the prevention of Leishmania infection, and complications thereof, in a mammal, preferably a human or dog. Pharmaceutical compositions generally comprise one or more polypeptides, containing one or more epitopes of Leishmania proteins, and a physiologically acceptable carrier. The vaccines comprise one or more of the above polypeptides and an adjuvant, for enhancement of the immune response. Routes and frequency of administration and polypeptide doses will vary from individual to individual and may parallel those currently being used in immunization against other protozoan infections. In general, the pharmaceutical compositions and vaccines may be administered by injection (e.g., intramuscular, intravenous or subcutaneous), intranasally (e.g., by aspiration) or orally. Between 1 and 4 doses may be administered for a 2-6 week period. Preferably, two doses are administered, with the second dose 2-4 weeks later than the first. A suitable dose is an amount of polypeptide that is effective to raise antibodies in a treated mammal that are sufficient to protect the mammal from Leishmania infection for a period of time. In general, the amount of polypeptide present in a dose ranges from about 1 pg to about 100 mg per kg of host, typically from about 10 pg to about 1 mg, and preferably from about 100 pg to about 1 μg. Suitable dose sizes will vary with the size of the animal, but will typically range from about 0.01 mL to about 5 mL for 10-60 kg animal. While any suitable carrier known to those of ordinary skill in the art may be employed in the pharmaceutical compositions of this invention, the type of carrier will vary depending on the mode of administration. For parenteral administration, such as subcutaneous injection, the carrier preferably comprises water, saline, alcohol, a fat, a wax or a buffer. For oral administration, any of the above carriers or a solid carrier, such as mannitol, lactose, starch, magnesium stearate, sodium saccharine, talcum, cellulose, glucose, sucrose, and magnesium carbonate, may be employed. Biodegradable microspheres (e.g., polylactic galactide) may also be employed as carriers for the pharmaceutical compositions of this invention. Any of a variety of adjuvants may be employed in the vaccines of this invention to nonspecifically enhance the immune response. Most adjuvants contain a substance designed to protect the antigen from rapid catabolism, such as aluminum hydroxide or mineral oil, and a nonspecific stimulator of immune response, such as lipid A, Bordello pertussis or Mycobacterium tuberculosis. Such adjuvants are commercially available as, for example, Freund's Incomplete Adjuvant and Complete Adjuvant (Difco Laboratories, Detroit, MI) and Merck Adjuvant 65 (Merck and Company, Inc., Rahway, NJ). The following Examples are offered by way of illustration and not by way of limitation. EXAMPLES Example 1 Preparation of LcPO This Example illustrates the isolation of a genomic DNA sequence encoding LcPO and the preparation of LcPO. A genomic expression library was constructed with sheared DNA of L. chagasi (MHOM BR/82/BA-2,Cl) in bacteriophage λZAPII (Stratagene, La Jolla, California). The library was screened and pBSK(-) phagemid sequences were excised according to the manufacturer's protocols. For this screen, serum samples from 5 T. crwz/-infected individuals were pooled and anti-E. coli reactivity was removed by adsoφtion. One clone, containing an approximately 3 kb insert, was isolated (pLcPO). Expression of pLcPO produced a recombinant fusion protein of approximately 42 kD, of which about 4 kD represented a plasmid fusion sequence. The DNA sequence (shown in Figures 1(a) and (b)) contained a single open reading frame (nucleotides 1-966) encoding 322 amino acids with a predicted molecular weight of 34,600. Rabbit anti-serum against purified recombinant LcPO was used to probe immunoblots of L. chagasi promastigote lysate. The anti-serum reacted specifically to a 37 kD antigen present in the promastigotes. These results suggest that the recombinant DNA sequence contained the entire coding region of LcPO. To further verify that the LcPO genomic clone contained the full-length protein sequence, a cDNA library was screened with the LcPO clone. Briefly, poly(A) + RNA was purified from total L. chagasi (MHOM/BR 84/Jonas) promastigote RNA, using standard protocols. A cDNA expression library was constructed with the poly(A) + RNA, using the ZAP-cDNA unidirectional cloning kit (Stratagene, La Jolla, California). This library was screened as described above for the genomic DNA library, and a 1.2 kb cDNA clone was isolated. Partial sequence analysis of the 5' and 3' portions revealed that it encoded a full- length LcPO insert. The sequence contained the last 8 nucleotides of the traws-spliced leader sequence found on the 5* end of all trypanosome nuclearly-encoded transcripts, followed by a short (29 nucleotide) 5' untranslated leader sequence. Partial sequencing of the 3' portion of the cDNA revealed an open reading frame and a stop codon (TAA) followed by a 203 nucleotide 3 '-untranslated portion terminating in a stretch of poly(A) residues. The 5' and 3' ends of the cDNA were present in the genomic clone. Accordingly, the genomic LcPO clone encodes the complete LcPO protein. Full-length LcPO was produced and purified from E. coli transformed with an expression vector containing the genomic clone pLcPO. Purification to homogeneity was accomplished by preparative SDS-PAGE, followed by excision and electroelution of the recombinant antigen. The SDS-PAGE was performed by loading expressed protein onto a 12% polyacrylamide gel in sample buffer (50 mM Tris-HCl, 1% SDS, 10% glycerol, 2% 2- mercaptoethanol, 0.01% bromphenol blue) and running according to standard procedure. A section of the gel was transferred to nitrocellulose for immunoblotting with patient serum for band identification. Bands of interest were excised and gel slices were diced into 2-3 mm cubes and soaked overnight at 4°C in 2% SDS, 0.4 M NH4HCO3 and 0.1% dithiothreitol. The gel pieces and soaking buffer were then placed into an electro-eluter (Bio-Rad Laboratories, Richmond, CA). Elution occurred for 6-7 hours at 10 mA per tube in 0.5 M NH4HCO3, 0.1% SDS. The eluted fractions were dialyzed against 0.01 M NH4HCO3, 0.02% SDS for 24 hours, followed by dialysis against a minimum of 100 volumes of PBS, pH 7.4 for 3-5 days with two buffer changes per 24 hours. All dialysis was done at 4 °C. Eluted samples were assayed for protein content using the Pierce assay (Pierce Chemical Co., Rockford, IL) and checked for purity on SDS-PAGE minigels with silver staining (Bio-Rad Laboratories, Richmond, CA). Example 2 Detection of Asymptomatic Leishmania using LcPO This Example illustrates the detection of Leishmania infection using LcPO, prepared as described in Example 1, in an ELISA format. The ELISA assays were performed as follows. Plastic 96-well plates (Probind, Falcon Plastics, Cockeysville, MD) were coated with 250 ng of LcPO, diluted to 50 μl with 0.05 M carbonate buffer (pH 9.6), and incubated overnight. Sensitized wells were washed with 0.01 M phosphate buffered saline (pH 7.2) containing 0.3% Tween 20™ (PBS/T). Positive control, negative control, and unknown serum samples were diluted 1:50 in PBS/T, and 50 μl was added to each well. After 30 minutes of incubation at room temperature, wells were washed six times with PBS/T. Fifty μl of protein-A peroxidase (Zymed Laboratories, San Francisco, CA), diluted in PBS/T was added and the plates were incubated as described above. Wells were washed eight times with PBS/T and 100 μl of 2,2'-azino-di-3- ethylbenzethiazoline sulfonic acid (ABTS) substrate solution (50 μl of 50 X ABTS, 50 μl of 1.5% H 2 O 2 , 2.5 ml of 0.1 M citrate buffer (pH 4.1), Zymed Laboratories, San Francisco, CA) was added. After 15 minutes at room temperature, the enzymatic reaction was stopped by adding 100 μl of 10% sodium dodecylsulfate. A405 values were determined with an ELISA reader (Titertek Multiskan, Flow Laboratories, McLean, VA). The cut-off value was determined for each test by calculating the mean of negative sera plus three standard deviations. Individuals in Brazil with asymptomatic leishmaniasis (AL) or acute visceral leishmaniasis (AVL) were identified based on serology (e.g., IF AT or IHA immunofluorescence or hemaglutination), clinical symptoms (e.g., malaise, diarrhea, splenomegaly and hepatomegaly) and whole lysate ELISA. Of 21 serum samples from patients with AL, all (i.e., 100%) tested positive using the above assay. However, of 31 serum samples from patients with AVL, only 9 (i.e., 29%) were positive. In addition, 44 normal serum samples (from unexposed individuals in Seattle, WA) were assayed. All 44 (i.e., 100%) of the normal samples were negative. When the assay was performed using crude lysate, all 44 normal samples were negative, all 21 AL samples were positive, and 28 out of 31 AVL samples were positive. These results are depicted in Figure 4. Figure 4(a) shows the distribution of absorbance values at 405 nm for the normal sera assayed with LcPO. In Figure 4(b), the distribution for sera from individuals with AL is presented and, in Figure 4(c), the distribution for sera from individuals with AVL is shown. These results demonstrate that LcPO may be used to detect asymptomatic leishmaniasis, with a very low incidence of false positive results in normal individuals. Example 3 Detection of Asymptomatic Leishmania using the C-terminal Epitope of LcPO This Example illustrates the detection of Leishmania infection using a polypeptide containing the 17 C-terminal amino acids of LcPO (i.e., residues 306-322) in an ELISA format. The polypeptide was synthesized on an ABI 430 A peptide synthesizer using FMOC chemistry with HPTU (O-Benzotriazole-N,N,N',N , -tetramethyluronium hexafluorophosphate) activation. Cleavage of the polypeptide from the solid support was carried out using the following cleavage mixture: trifluoroacetic acid:ethanedithiol:thioanisole:water:phenol (40:1 :2:2:3). After cleaving for 2 hours, the polypeptide was precipitated in cold methyl-t-butyl-ether. The pellet was then dissolved in water containing 0.1% trifluoroacetic acid (TFA) and lyophilized prior to purification by C18 reverse phase HPLC. A gradient of 0%-60% acetonitrile (containing 0.1% TFA) in water (containing 0.1% TFA) was used to elute the peptides. Following lyophilization of the pure fractions, the polypeptide was characterized using electrospray mass spectrometry and by amino acid analysis. The synthesized C-terminal polypeptide had the sequence Glu-Glu-Pro- Glu-Glu-Ser-Asp-Glu-Asp-Asp-Phe-Gly-Met-Gly-Gly-Leu-Phe (i.e., residues 306-322 of the amino acid sequence of Figures 2(a), (b) and (c) and SEQ ID NO:3). The ELISA assays were performed as described in Example 2, using either 250 ng of LcPO or 1 μg of the above C-terminal polypeptide. AL, AVL and normal serum samples were assayed. Of 20 serum samples from patients with AL, all tested positive in the assay using full length LcPO, and 19 (i.e., 95%) tested positive with the C-terminal polypeptide. Of 28 serum samples from patients with AVL, 20 (i.e., 28%) were positive. In addition, all 45 (i.e., 100%) of the normal samples were negative. These results are depicted in Figure 5. Figure 5(a) shows the distribution of absorbance values at 405 nm for the normal sera assayed with LcPO and the C-terminal polypeptide. In Figure 5(b), the distribution for sera from individuals with AL is presented and, in Figure 5(c), the distribution for sera from individuals with AVL is shown. These results demonstrate that a polypeptide containing the 17 C-terminal amino acids of LcPO contains a major epitope and may be used to detect asymptomatic leishmaniasis, with a very low incidence of false positive results in normal individuals. Example 4 Detection of Leishmania Infection in Serum with K39 This Example demonstrates the detection of Leishmania infection using a recombinant K39 polypeptide. In one experiment, the assays were performed in an ELISA format, as described in Example 2, except that the wells were coated with 100 ng of recombinant K39 polypeptide having the amino acid sequence shown in Figures 2(a), (b) and (c). In this experiment, the AL, AVL and normal serum samples described in Example 2 were assayed. Of 21 serum samples from patients with AL, 17 (i.e., 33%) tested positive in the assay. However, of 31 serum samples from patients with AVL, 30 (i.e., 97%) were positive. In addition, all 44 (i.e., 100%) of the normal samples were negative. These results are depicted in Figure 6. Figure 6(a) shows the distribution of absorbance values at 405 nm for the normal sera assayed with K39. In Figure 6(b), the distribution for sera from individuals with AVL is presented and, in Figure 6(c), the distribution for sera from individuals with AL is shown. These results demonstrate that K39 detects acute visceral leishmaniasis, with a very low incidence of false positive results in normal individuals, but that K39 is not sensitive for detecting asymptomatic leishmaniasis. In addition, Figures 4-6, and the results described in Example 2 and this Example, indicate that nearly all patients with AVL or AL (i.e., 60 out of 61) tested positive with at least one of LcPO and K39. This indicates that the two antigens, used in combination, would detect both types of leishmaniasis. To further illustrate this point, Table 1, below, shows the absorbance values for the 21 AL samples and the 31 AVL samples tested with LcPO and K39. Table ! Reactivity of Serum Samples with LcPO and K39 Antigens Absorbance (405 nm) Serum K39 LcPO AL 01SP 0.07 1.47 02SP 0.04 0.64 04SP 0.1 >3.0 05SP 0.08 2.07 06SP 0.06 1.95 07SP 0.33 2.18 08SP 0.08 2.02 09SP 0.10 >3.0 10SP 0.62 2.49 11SP 0.08 >3.0 12SP 0.88 1.77 130L 0.10 2.07 140L 0.07 2.65 150L 0.03 2.19 160L 0.12 1.35 170L >3.0 0.78 190L 0.11 1.41 210L 0.29 1.84 220L 2.42 >3.0 25aPK 0.11 0.35 27PK 0.92 0.98 AVL K8 2.31 0.12 K22 1.47 0.08 K36 2.52 0.16 K39 2.60 0.39 K49 2.50 1.94 K52 >3.0 0.25 K2 >3.0 2.48 K7 >3.0 0.17 Kl l 1.58 0.07 K18 >3.0 0.28 K24 >3.0 0.17 K26 2.60 0.08 K33 2.22 0.11 K41 >3.0 0.24 K46 >3.0 0.23 K50 2.31 0.01 K54 2.70 0.22 K61 >3.0 1.14 K68 >3.0 0.12 K70 >3.0 0.08 K71 >3.0 0.30 74 >3.0 0.17 K2 >3.0 0.61 K50 1.27 0.02 K68 >3.0 0.60 139177 0.09 0.13 139178 0.38 0.13 139180 0.28 0.31 139181 >3.0 0.93 139182 0.66 0.62 139183 1.97 1.44 As shown in the above table, most samples with very low absorbance values when assayed with one antigen had high absorbances when assayed with the other antigen. Accordingly, LcPO and K39 are complementary and, together, form a sensitive assay for monitoring disease progression from asymptomatic subciinical disease to acute visceral disease, or vice versa. Example 5 Detection of Leishmania Infection in Serum with LcPO in Combination with K39 This Example demonstrates the detection of Leishmania infection using LcPO in combination with a recombinant K3 polypeptide. Assays were performed as described in Example 2 except that, in addition to the LcPO, wells were coated with 100 ng of recombinant K39. In a parallel experiment, the assays were performed using Leishmania lysate as the antigen The same AL. AVL and normal serum samples described in Example 2 were assayed. Of the 21 serum samples from patients with AL, 21 (i.e., 100%) tested positive in the assay. Of 31 samples from patients with AVL, 30 (i.e., 97%) were positive. All (i.e., 100%) of the normal samples were negative. The absorbance values for representative assays using LcP0/K39 or Leishmania lysate are shown in Table 2 below. Table 2 Reactivity of Serum Samples With Leishmania Lysate and K39/LcP0 Antigens SAMPLE ID Lc LYSATE K39+LCP0 STATUS 01-SP 1.545 1.148 ASYMPTOMATIC 02-SP 1.174 0.34 ASYMPTOMATIC 03-SP 1.263 0.168 ASYMPTOMATIC 04-SP 2.533 2.521 ASYMPTOMATIC 06-SP 1.478 1.556 ASYMPTOMATIC 07-SP 1.365 1.701 ASYMPTOMATIC 08-SP 1.192 1.369 ASYMPTOMATIC 220L 1.669 3 ASYMPTOMATIC 10SP 1.651 1.951 ASYMPTOMATIC 140L 1.192 2.061 ASYMPTOMATIC 150L 0.863 1.461 ASYMPTOMATIC 160L 2.104 1.067 ASYMPTOMATIC 170L 3 3 ASYMPTOMATIC 180L 2.032 1.264 ASYMPTOMATIC 190L 1.586 0.908 ASYMPTOMATIC 210L 1.52 1.572 ASYMPTOMATIC 139189 0.348 0.431 AVL 139197 0.481 2.455 AVL 139199 1.235 2.601 AVL 139200 2.022 0.792 AVL 139202 1.182 0.263 AVL 139204 1.375 0.964 AVL 139205 3 3 AVL 139206 2.209 3 AVL K18 0.95 3 AVL K26 1.298 3 AVL K41 3 3 AVL K52 3 3 AVL K54 3 3 AVL K74 2.509 3 AVL K71 3 3 AVL K75 2.118 3 AVL 4/15/93-2 0.003 0.004 NORMAL 4/15/93-3 0.001 0.007 NORMAL 4/15/93-4 0.001 0.004 NORMAL 6/15/93-3 0 0.002 NORMAL 6/15/93-2 0.001 0.004 NORMAL 2/9/94-4 0.003 0.003 NORMAL 2 9/94-3 0.003 0.001 NORMAL 2 9/94-2 0.005 0.006 NORMAL 9/9/93-2 0.17 0.046 NORMAL 7/22/94-4 0.034 0.049 NORMAL 7/22/94-3 0.055 0.055 NORMAL 7 22/94-2 0.034 0.066 NORMAL 7/22/94-1 0.029 0.051 NORMAL 3 25 94-4 0.035 0.023 NORMAL 3/25/94-3 0.02 0.021 NORMAL The absorbance values provided above are depicted in Figure 7, which shows the distribution of absorbance values at 405 nm for assays performed using representative sera from normal AL and AVL patients. The results of this experiment demonstrate that LcPO, in combination with K39, detects asymptomatic and acute visceral leishmaniasis, with a very low incidence of false positive results in normal individuals. Example 6 Non-reactivitv of LcPO and K39 with Sera from Patients with Mucosal or Cutaneous Leishmaniasis This Example shows that LcPO and K39 are specific for asymptomatic subclinical and visceral leishmaniasis, respectively. Assays were generally performed as described in Examples 4 and 5, except that the sera assayed was from patients with mucosal or cutaneous leishmaniasis, as diagnosed by clinical symptoms. Fourteen samples from patients with each form of the disease were assayed with LcPO, K39 and a combination of LcPO and K39, as well as with Leishmania lysate. With each set of 14 samples, a positive control (i.e., a sample obtained from a patient infected with Leishmania) and a blank with no antibodies were assayed, in addition to eight samples from normal individuals. The absorbance values are shown below in Table 3. Table 3 Non-reactivity of LcPO and K39 With Sera From Patients With Mucosal and Cutaneous Leishmaniasis Serum Lc lysate K39+LcP0 K39 LcPO MUCOSAL Ml 0.312 0.033 0.03 0.011 M2 0.11 0.036 0.015 0.029 M3 0.37 0.054 0.003 0.055 M4 0.109 0.039 0.036 0.007 M5 0.586 0.02 0.009 0.016 M6 0.116 0.038 0.025 0.017 M7 0.245 0.156 0.099 0.067 M8 0.09 0.078 0.05 0.047 M9 0.046 0.026 0.026 0.003 M10 0.343 0.042 0.013 0.033 Mil 0.327 0.34 0.009 0.346 M12 0.035 0.014 0.003 0.008 Ml 3 0.131 0.031 0.026 0.007 M14 0.282 0.014 0.006 0.006 positive control 0.444 0.543 0.545 0.114 No Ab 0.001 0.002 -0.002 -0.001 CUTANEOUS CI 0.06225 0.01255 0.00725 0.0033 C2 0.1602 0.01225 0.00325 0.0083 C3 0.1402 0.03925 0.02625 0.0143 C4 0.1932 0.01725 0.01325 0.0053 C5 0.1672 0.04825 0.01725 0.0283 C6 0.1672 0.02825 0.01925 0.0213 C7 0.09025 0.07425 0.07225 0.0103 C8 0.05425 0.01725 0.00725 0.0103 C9 0.0803 0.05525 0.05425 0.007 CIO 0.2702 0.04825 0.03225 0.019 Cl l 0.4882 0.3782 0.1992 0.297 C12 0.5632 0.5352 0.5312 -0.002 C13 0.0263 0.01425 0.00425 0.005 C14 0.0293 0.01525 0.01525 0.003 positive control 0.4132 0.5732 0.5362 0.096 No Ab 0.0043 0.00025 -0.00275 -0.002 NORMAL 6/8/93-1 0.018 0.01 0.005 0.005 6/8/93-2 0.03 0.01 0.005 0.006 6/8/93-3 0.016 0.02 0.012 0.003 8/31/93-3 0.018 0.014 0.002 0.01 8/31/93-4 0.003 0.005 -4E-09 0.005 9/10/93-2 0.006 0.004 -4E-09 0.002 9/10/93-3 0.005 -3.7E-09 -0.001 -4E-09 4/15/93-2 0.014 0.043 0.037 0.009 1/12/93 0.0023 0.00725 0.0013 0.0003 3/2/94-4 0.0013 0.00025 -0.0028 0.0003 3/2/94-3 -0.002 -0.00275 -0.0048 -0.006 3/2 94-2 0.0003 0.00025 -0.0008 -0.008 3/2/94-1 0.0043 0.00225 -0.0048 0.0033 4/28/94-3 -0.002 -0.00375 -0.0058 -0.012 4/28/94-2 0.0083 0.00225 •O.0028 0.0003 4/15/93-2 0.0123 0.04325 0.0333 0.0023 Of the normal serum samples assayed, no positive results were obtained using either LcPO or K39, or a combination of the two. Of the 14 mucosal samples, one tested positive with LcPO and LcP0/K39, and none were positive with K39 alone. When the 14 cutaneous samples were assayed, one tested positive with each of LcPO and K39, and two were positive with the LcP0/K39 combination. These results demonstrate that assays performed using LcPO and or K39 detect only a small percentage of mucosal and cutaneous manifestations of leishmaniasis. From the foregoing, it will be appreciated that, although specific embodiments of the invention have been described herein for the puφose of illustration, various modifications may be made without deviating from the spirit and scope of the invention. SEQUENCE LISTING (1) GENERAL INFORMATION: (i) APPLICANT: Reed, Steven G. (ii) TITLE OF INVENTION: COMPOUNDS AND METHODS FOR DIAGNOSIS OF LEISHMANIASIS (iii) NUMBER OF SEQUENCES: 5 (iv) CORRESPONDENCE ADDRESS: (A) ADDRESSEE: SEED and BERRY (B) STREET: 6300 Columbia Center, 701 Fifth Avenue (C) CITY: Seattle (D) STATE: Washington (E) COUNTRY: USA (F) ZIP: 98104-7092 (v) COMPUTER READABLE FORM: (A) MEDIUM TYPE: Floppy disk (B) COMPUTER: IBM PC compatible (C) OPERATING SYSTEM: PC-DOS/MS-DOS (D) SOFTWARE: Patentln Release #1.0, Version #1.30 (vi) CURRENT APPLICATION DATA: (A) APPLICATION NUMBER: US (B) FILING DATE: 21-DEC-1995 (C) CLASSIFICATION: (viii) ATTORNEY/AGENT INFORMATION: (A) NAME: Kadlecek, Ann T. (B) REGISTRATION NUMBER: P-39,244 (C) REFERENCE/DOCKET NUMBER: 210121.407 (ix) TELECOMMUNICATION INFORMATION: (A) TELEPHONE: (206) 622-4900 (B) TELEFAX: (206) 682-6031 (C) TELEX: 3723836 SEEDANDBERRY (2) INFORMATION FOR SEQ ID NO:l: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 1202 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ix) FEATURE: (A) NAME/KEY: CDS (B) LOCATION: 30..998 (xi) SEQUENCE DESCRIPTION: SEQ ID NO:l. ATAGCCAAGG CTATTGCAAG TCTCACAAG ATG CCG TCT ATC ACC ACT GCC AAG 53 Met Pro Ser He Thr Thr Ala Lys CGC GAG TAC GAG GAG CGC CTC GTC GAC TGC CTG ACC AAG TAC AGC TGC 101 Arg Glu Tyr Glu Glu Arg Leu Val Asp Cys Leu Thr Lys Tyr Ser Cys 10 15 20 GTG CTG TTC GTG GGC ATG GAC AAC GTC CGC TCG CAG CAG GTG CAC GAT 149 Val Leu Phe Val Gly Met Asp Asn Val Arg Ser Gin Gin Val His Asp 25 30 35 40 GTG CGC CGT GGC TGT CGC GGC AAG GCC GAG TTC ATT ATG GGC AAG AAG 197 Val Arg Arg Gly Cys Arg Gly Lys Ala Glu Phe He Met Gly Lys Lys 45 50 55 ACG CTG CAG GCG AAG ATC GTG GAG AAG CGC GCG CAA GCC AAG GAC GCG 245 Thr Leu Gin Ala Lys He Val Glu Lys Arg Ala Gin Ala Lys Asp Ala 60 65 70 AGC CCC GAG GCG AAG CCT TTC AAC GAT CAG TGT GAG GAG TAC AAC CTG 293 Ser Pro Glu Ala Lys Pro Phe Asn Asp Gin Cys Glu Glu Tyr Asn Leu 75 80 85 CTG AGC GGC AAC ACC GGC CTC ATC TTC ACT AAC AAC GCT GTC CAG GAG 341 Leu Ser Gly Asn Thr Gly Leu He Phe Thr Asn Asn Ala Val Gin Glu 90 95 100 ATC ACC TCT GTG CTT GAC GGC CAC CGC GTG AAG GCC CCG GCG CGT GTC 389 He Thr Ser Val Leu Asp Gly His Arg Val Lys Ala Pro Ala Arg Val 105 110 115 120 GGA GCG ATT CCG TGC GAC GTG GTT GTG CCT GCT GGC AGC ACC GGC ATG 437 Gly Ala He Pro Cys Asp Val Val Val Pro Ala Gly Ser Thr Gly Met 125 130 135 GAG CCG ACC CAG ACG TCC TTC TTC CAG GCG CTG AAC ATT GCG ACG AAG 485 Glu Pro Thr Gin Thr Ser Phe Phe Gin Ala Leu Asn He Ala Thr Lys 140 145 150 ATT GCC AAG GGT ATG GTG GAG ATC GTG ACG GAG AAG AAG GTG CTG AGC 533 He Ala Lys Gly Met Val Glu He Val Thr Glu Lys Lys Val Leu Ser 155 160 165 GTC GGC GAC AAG GTG GAC AAC TCG ACG GCG ACG CTG CTG CAA AAG CTG 581 Val Gly Asp Lys Val Asp Asn Ser Thr Ala Thr Leu Leu Gin Lys Leu 170 175 180 AAC ATC AGC CCG TTC TAC TAC CAG GTG AAT GTG CTG TCC GTG TGG GAC 629 Asn He Ser Pro Phe Tyr Tyr Gin Val Asn Val Leu Ser Val Trp Asp 185 190 195 200 CGC GGT GTG CTG TTC ACC CGC GAG GAC CTC ATG ATG ACG GAG GAC ATG 677 Arg Gly Val Leu Phe Thr Arg Glu Asp Leu Met Met Thr Glu Asp Met 205 210 215 GTG GAG AAG ATG CTG ATG GAA GGC CTG AGC AAC GTT GCG GCG ATG GCG 725 Val Glu Lys Met Leu Met Glu Gly Leu Ser Asn Val Ala Ala Met Ala 220 225 230 CTG GGT GCT GGC ATC CCG ACG TCT TCG ACG ATT GGC CCG ATG CTG GTG 773 Leu Gly Ala Gly He Pro Thr Ser Ser Thr He Gly Pro Met Leu Val 235 240 245 GAC GCC TTC AAG AAC CTG CTG GCT GTC TCC GTG GCG ACC TCG TAC GAG 821 Asp Ala Phe Lys Asn Leu Leu Ala Val Ser Val Ala Thr Ser Tyr Glu 250 255 260 TTC GAG GAG CAC AAC GGC AAG GAG CTG CGC GAG GCC GCG ATC AAC GGC 869 Phe Glu Glu His Asn Gly Lys Glu Leu Arg Glu Ala Ala He Asn Gly 265 270 275 280 CTG CTG GCC GGC TCT GGC TCG GCT GCT GCG GAG CCC GCC GCT GCC GCG 917 Leu Leu Ala Gly Ser Gly Ser Ala Ala Ala Glu Pro Ala Ala Ala Ala 285 290 295 CCG GCC GCC CCT AGC GCT GCT GCC AAG GAG GAG CCG GAG GAG AGC GAC 965 Pro Ala Ala Pro Ser Ala Ala Ala Lys Glu Glu Pro Glu Glu Ser Asp 300 305 310 GAG GAC GAC TTC GGC ATG GGC GGT CTC TTC TAA GCGACTCGCT ATCCGCCACC 1018 Glu Asp Asp Phe Gly Met Gly Gly Leu Phe * 315 320 CAGCACCGTC GAGTGTTCGT GCGTTCGCAT GGTGGACAGT GGCGAGCGTG TGATGCCCTT 1078 GGATCATCAG GAAGCAACTC TCTCCCTTTC TCTGGGTGTT CTTCGTTTCT TCTTTCATTT 1138 GTTTTTGATC GCCGTGGCGC TGCGGCGATC GCTCAGTTCT TATTTTCGAT CAACCAACAA 1198 CGAA 1202 (2) INFORMATION FOR SEQ ID NO:2: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 322 amino acids (B) TYPE: amino acid (D) TOPOLOGY: linear (ii) MOLECULE TYPE: protein (xi) SEQUENCE DESCRIPTION: SEQ ID NO:2: Met Pro Ser He Thr Thr Ala Lys Arg Glu Tyr Glu Glu Arg Leu Val 1 5 10 15 Asp Cys Leu Thr Lys Tyr Ser Cys Val Leu Phe Val Gly Met Asp Asn 20 25 30 Val Arg Ser Gin Gin Val His Asp Val Arg Arg Gly Cys Arg Gly Lys 35 40 45 Ala Glu Phe He Met Gly Lys Lys Thr Leu Gin Ala Lys He Val Glu 50 55 60 Lys Arg Ala Gin Ala Lys Asp Ala Ser Pro Glu Ala Lys Pro Phe Asn 65 70 75 80 Asp Gin Cys Glu Glu Tyr Asn Leu Leu Ser Gly Asn Thr Gly Leu He 85 90 95 Phe Thr Asn Asn Ala Val Gin Glu He Thr Ser Val Leu Asp Gly His 100 105 110 Arg Val Lys Ala Pro Ala Arg Val Gly Ala He Pro Cys Asp Val Val 115 120 125 Val Pro Ala Gly Ser Thr Gly Met Glu Pro Thr Gin Thr Ser Phe Phe 130 135 140 Gin Ala Leu Asn He Ala Thr Lys He Ala Lys Gly Met Val Glu He 145 150 155 160 Val Thr Glu Lys Lys Val Leu Ser Val Gly Asp Lys Val Asp Asn Ser 165 170 175 Thr Ala Thr Leu Leu Gin Lys Leu Asn He Ser Pro Phe Tyr Tyr Gin 180 185 190 Val Asn Val Leu Ser Val Trp Asp Arg Gly Val Leu Phe Thr Arg Glu 195 200 205 Asp Leu Met Met Thr Glu Asp Met Val Glu Lys Met Leu Met Glu Gly 210 215 220 Leu Ser Asn Val Ala Ala Met Ala Leu Gly Ala Gly He Pro Thr Ser 225 230 235 240 Ser Thr He Gly Pro Met Leu Val Asp Ala Phe Lys Asn Leu Leu Ala 245 250 255 Val Ser Val Ala Thr Ser Tyr Glu Phe Glu Glu His Asn Gly Lys Glu 260 265 270 Leu Arg Glu Ala Ala He Asn Gly Leu Leu Ala Gly Ser Gly Ser Ala 275 280 285 Ala Ala Glu Pro Ala Ala Ala Ala Pro Ala Ala Pro Ser Ala Ala Ala 290 295 300 Lys Glu Glu Pro Glu Glu Ser Asp Glu Asp Asp Phe Gly Met Gly Gly 305 310 315 320 Leu Phe (2) INFORMATION FOR SEQ ID NO:3: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 955 amino acids (B) TYPE: amino acid (C) STRANDEDNESS: (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:3: Met His Pro Ser Thr Val Arg Arg Glu Ala Glu Arg Val Lys Val Ser 1 5 10 15 Val Arg Val Arg Pro Leu Asn Glu Arg Glu Asn Asn Ala Pro Glu Gly 20 25 30 Thr Lys Val Thr Val Ala Ala Lys Gin Ala Ala Ala Val Val Thr Val 35 40 45 Lys Val Leu Gly Gly Ser Asn Asn Ser Gly Ala Ala Glu Ser Met Gly 50 55 60 Thr Ala Arg Arg Val Ala Gin Asp Phe Gin Phe Asp His Val Phe Trp 65 70 75 80 Ser Val Glu Thr Pro Asp Ala Cys Gly Ala Thr Pro Ala Thr Gin Ala 85 90 95 Asp Val Phe Arg Thr He Gly Tyr Pro Leu Val Gin His Ala Phe Asp 100 105 110 Gly Phe Asn Ser Cys Leu Phe Ala Tyr Gly Gin Thr Gly Ser Gly Lys 115 120 125 Thr Tyr Thr Met Met Gly Ala Asp Val Ser Ala Leu Ser Gly Glu Gly 130 135 140 Asn Gly Val Thr Pro Arg He Cys Leu Glu He Phe Ala Arg Lys Ala 145 150 155 160 Ser Val Glu Ala Gin Gly His Ser Arg Trp He Val Glu Leu Gly Tyr 165 170 175 Val Glu Val Tyr Asn Glu Arg Val Ser Asp Leu Leu Gly Lys Arg Lys 180 185 190 Lys Gly Val Lys Gly Gly Gly Glu Glu Val Tyr Val Asp Val Arg Glu 195 200 205 His Pro Ser Arg Gly Val Phe Leu Glu Gly Gin Arg Leu Val Glu Val 210 215 220 Gly Ser Leu Asp Asp Val Val Arg Leu He Glu He Gly Asn Gly Val 225 230 235 240 Arg His Thr Ala Ser Thr Lys Met Asn Asp Arg Ser Ser Arg Ser His 245 250 255 Ala He He Met Leu Leu Leu Arg Glu Glu Arg Thr Met Thr Thr Lys 260 265 270 Ser Gly Glu Thr He Arg Thr Ala Gly Lys Ser Ser Arg Met Asn Leu 275 280 285 Val Asp Leu Ala Gly Ser Glu Arg Val Ala Gin Ser Gin Val Glu Gly 290 295 300 Gin Gin Phe Lys Glu Ala Thr His He Asn Leu Ser Leu Thr Thr Leu 305 310 315 320 Gly Arg Val He Asp Val Leu Ala Asp Met Ala Thr Lys Gly Ala Lys 325 330 335 Ala Gin Tyr Ser Val Ala Pro Phe Arg Asp Ser Lys Leu Thr Phe He 340 345 350 Leu Lys Asp Ser Leu Gly Gly Asn Ser Lys Thr Phe Met He Ala Thr 355 360 365 Val Ser Pro Ser Ala Leu Asn Tyr Glu Glu Thr Leu Ser Thr Leu Arg 370 375 380 Tyr Ala Ser Arg Ala Arg Asp He Val Asn Val Ala Gin Val Asn Glu 385 390 395 400 Asp Pro Arg Ala Arg Arg He Arg Glu Leu Glu Glu Gin Met Glu Asp 405 410 415 Met Arg Gin Ala Met Ala Gly Gly Asp Pro Ala Tyr Val Ser Glu Leu 420 425 430 Lys Lys Lys Leu Ala Leu Leu Glu Ser Glu Ala Gin Lys Arg Ala Ala 435 440 445 Asp Leu Gin Ala Leu Glu Arg Glu Arg Glu His Asn Gin Val Gin Glu 450 455 460 Arg Leu Leu Arg Ala Thr Glu Ala Glu Lys Ser Glu Leu Glu Ser Arg 465 470 475 480 Ala Ala Ala Leu Gin Glu Glu Met Thr Ala Thr Arg Arg Gin Ala Asp 485 490 495 Lys Met Gin Ala Leu Asn Leu Arg Leu Lys Glu Glu Gin Ala Arg Lys 500 505 510 Glu Arg Glu Leu Leu Lys Glu Met Ala Lys Lys Asp Ala Ala Leu Ser 515 520 525 Lys Val Arg Arg Arg Leu Asp Ala Glu He Ala Ser Glu Arg Glu Lys 530 535 540 Leu Glu Ser Thr Val Ala Gin Leu Glu Arg Glu Gin Arg Glu Arg Glu 545 550 555 560 Val Ala Leu Asp Ala Leu Gin Thr His Gin Arg Lys Leu Gin Glu Ala 565 570 575 Leu Glu Ser Ser Glu Arg Thr Ala Ala Glu Arg Asp Gin Leu Leu Gin 580 585 590 Gin Leu Thr Glu Leu Gin Ser Glu Arg Thr Gin Leu Ser Gin Val Val 595 600 605 Thr Asp Arg Glu Arg Leu Thr Arg Asp Leu Gin Arg He Gin Tyr Glu 610 615 620 Tyr Gly Glu Thr Glu Leu Ala Arg Asp Val Ala Leu Cys Ala Ala Gin 625 630 635 640 Glu Met Glu Ala Arg Tyr His Ala Ala Val Phe His Leu Gin Thr Leu 645 650 655 Leu Glu Leu Ala Thr Glu Trp Glu Asp Ala Leu Arg Glu Arg Ala Leu 660 665 670 Ala Glu Arg Asp Glu Ala Ala Ala Ala Glu Leu Asp Ala Ala Ala Ser 675 680 685 Thr Ser Gin Asn Ala Arg Glu Ser Ala Cys Glu Arg Leu Thr Ser Leu 690 695 700 Glu Gin Gin Leu Arg Glu Ser Glu Glu Arg Ala Ala Glu Leu Ala Ser 705 710 715 720 Gin Leu Glu Ala Thr Ala Ala Ala Lys Ser Ser Ala Glu Gin Asp Arg 725 730 735 Glu Asn Thr Arg Ala Thr Leu Glu Gin Gin Leu Arg Glu Ser Glu Ala 740 745 750 Arg Ala Ala Glu Leu Ala Ser Gin Leu Glu Ala Thr Ala Ala Ala Lys 755 760 765 Met Ser Ala Glu Gin Asp Arg Glu Asn Thr Arg Ala Thr Leu Glu Gin 770 775 780 Gin Leu Arg Asp Ser Glu Glu Arg Ala Ala Glu Leu Ala Ser Gin Leu 785 790 795 800 Glu Ser Thr Thr Ala Ala Lys Met Ser Ala Glu Gin Asp Arg Glu Ser 805 810 815 Thr Arg Ala Thr Leu Glu Gin Gin Leu Arg Asp Ser Glu Glu Arg Ala 820 825 830 Ala Glu Leu Ala Ser Gin Leu Glu Ser Thr Thr Ala Ala Lys Met Ser 835 840 845 Ala Glu Gin Asp Arg Glu Ser Thr Arg Ala Thr Leu Glu Gin Gin Leu 850 855 860 Arg Glu Ser Glu Glu Arg Ala Ala Glu Leu Ala Ser Gin Leu Glu Ser 865 870 875 880 Thr Thr Ala Ala Lys Met Ser Ala Glu Gin Asp Arg Glu Ser Thr Arg 885 890 895 Ala Thr Leu Glu Gin Gin Leu Arg Asp Ser Glu Glu Arg Ala Ala Glu 900 905 910 Leu Ala Ser Gin Leu Glu Ala Thr Ala Ala Ala Lys Ser Ser Ala Glu 915 920 925 Gin Asp Arg Glu Asn Thr Arg Ala Ala Leu Glu Gin Gin Leu Arg Asp 930 935 940 Ser Glu Glu Arg Ala Ala Glu Leu Ala Ser Gin 945 950 955 (2) INFORMATION FOR SEQ ID NO: : (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 3319 base pairs (B) TYPE: nucleic acid (C) STRANDEDNESS: single (D) TOPOLOGY: linear (ii) MOLECULE TYPE: cDNA to mRNA (xi) SEQUENCE DESCRIPTION: SEQ ID NO: : GCTCCCACGG CGCTACCCCC TTTCCCGCAT GTGCGACAGT TTCACGCGTA CAAACGTCTT 60 TCTCTCTCCT TCGCGCGTGT CGCTATGGGC GGCGGCGCGT CGGTGTCTTT GATTGCACAG 120 CTCACCGCCT CGCCATATTT TCGTCGTGGC CACGCGACCC CCCGACCTTC CCCTCCTCCG 180 CCCCCAAAGA CAAGCCAGAC ATACCGACCA TGCCGTCTGC CCGCGTCTCT GCTTACCAAG 240 CGCGCCACGC ACCCCTTCCT CGGCCCTGAA TCTTTCGCGC GGCGCCATAC ATTGCATGCA 300 CGTCACTACG CCTGTACACC TTACACCTCC TCTTGCCCAC CCCTTTCCCC TTCTACACGC 360 CTAACTACAC ACACATATAT ATATATATAT ATAAAGCGCT CAACGCACAC ATACTGTGGC 420 CAGTATTACT GCACCAACGT CTGCCTCTTC CAGGATGCAC CCTTCCACTG TGCGGCGTGA 480 GGCGGAGCGG GTGAAGGTGT CGGTGCGCGT GCGCCCCCTA AACGAACGTG AAAACAATGC 540 CCCGGAAGGG ACGAAAGTGA CCGTTGCGGC GAAACAGGCG GCCGCCGTGG TGACGGTCAA 600 GGTCCTGGGA GGCAGCAACA ACAGCGGCGC CGCCGAGTCG ATGGGGACTG CAAGGCGGGT 660 AGCGCAGGAC TTTCAGTTCG ACCACGTGTT CTGGTCTGTG GAGACGCCGG ACGCGTGCGG 720 CGCGACCCCC GCGACGCAGG CAGACGTGTT CCGGACGATC GGGTACCCGC TGGTGCAGCA 780 CGCGTTCGAC GGGTTCAACT CGTGCTTGTT TGCGTACGGG CAGACAGGGA GCGGGAAGAC 840 GTACACGATG ATGGGCGCGG ACGTGAGCGC GCTTAGTGGT GAGGGCAACG GCGTGACGCC 900 GCGGATCTGC CTGGAGATCT TTGCGCGGAA GGCGAGCGTG GAGGCGCAGG GGCACTCGCG 960 GTGGATCGTG GAGCTGGGGT ACGTGGAGGT GTACAACGAG CGCGTGTCGG ACCTGCTTGG 1020 GAAGCGGAAG AAGGGTGTGA AGGGCGGCGG CGAGGAGGTG TACGTGGACG TGCGCGAGCA 1080 CCCGAGCCGC GGCGTGTTCC TGGAGGGGCA GCGGCTGGTG GAGGTTGGGA GCCTGGACGA 1140 TGTTGTGCGG CTGATCGAGA TCGGCAACGG CGTGCGGCAC ACCGCTTCGA CGAAGATGAA 1200 CGACCGGAGC AGCCGGAGCC ACGCGATCAT CATGCTGCTG CTGCGCGAGG AGCGGACGAT 1260 GACGACGAAG AGCGGGGAGA CGATCCGTAC TGCCGGCAAG AGCAGCCGCA TGAACCTTGT 1320 GGACCTTGCG GGGTCTGAGC GCGTGGCGCA GTCGCAGGTG GAGGGGCAGC AGTTCAAGGA 1380 GGCGACGCAC ATCAACCTGT CGCTGACGAC GCTCGGGCGC GTGATCGACG TGCTCGCGGA 1440 CATGGCGACG AAGGGTGCGA AGGCGCAGTA CAGCGTTGCG CCGTTCCGCG ACTCGAAGCT 1500 GACGTTCATC CTGAAGGACT CGCTTGGCGG GAACTCGAAG ACGTTCATGA TCGCGACTGT 1560 GAGCCCGAGC GCGCTGAACT ACGAGGAGAC GCTGAGCACG CTGCGGTACG CGTCGCGCGC 1620 GCGCGACATT GTGAATGTTG CGCAGGTGAA CGAGGACCCG CGCGCACGGC GGATCCGCGA 1680 GCTGGAGGAG CAGATGGAGG ACATGCGGCA GGCGATGGCT GGCGGCGACC CCGCGTACGT 1740 GTCTGAGCTG AAGAAGAAGC TTGCGCTGCT GGAGTCGGAG GCGCAGAAGC GTGCGGCGGA 1800 CCTGCAGGCG CTGGAGAGGG AGCGGGAGCA CAACCAGGTG CAGGAGCGGC TGCTGCGCGC 1860 GACGGAGGCG GAGAAGAGCG AGCTGGAGTC GCGTGCGGCT GCGCTGCAGG AGGAGATGAC 1920 CGCGACTCGA CGGCAGGCGG ACAAGATGCA GGCGCTGAAC CTGCGGCTGA AGGAAGAGCA 1980 GGCGCGCAAG GAGCGCGAGC TGCTGAAAGA GATGGCGAAG AAGGACGCCG CGCTCTCGAA 2040 GGTTCGGCGA CGCAAAGACG CCGAGATAGC AAGCGAGCGC GAGAAGCTGG AGTCGACCGT 2100 GGCGCAGCTG GAGCGTGAGC AGCGCGAGCG CGAGGTGGCT CTGGACGCAT TGCAGACGCA 2160 CCAGAGAAAG CTGCAGGAAG CGCTCGAGAG CTCTGAGCGG ACAGCCGCGG AAAGGGACCA 2220 GCTGCTGCAG CAGCTAACAG AGCTTCAGTC TGAGCGTACG CAGCTATCAC AGGTTGTGAC 2280 CGACCGCGAG CGGCTTACAC GCGACTTGCA GCGTATTCAG TACGAGTACG GGGAAACCGA 2340 GCTCGCGCGA GACGTGGCGC TGTGCGCCGC GCAGGAGATG GAGGCGCGCT ACCACGCTGC 2400 TGTGTTTCAC CTGCAAACGC TCCTGGAGCT CGCAACCGAG TGGGAGGACG CACTCCGCGA 2460 GCGTGCGCTT GCAGAGCGTG ACGAAGCCGC TGCAGCCGAA CTTGATGCCG CAGCCTCTAC 2520 TTCCCAAAAC GCACGTGAAA GCGCCTGCGA GCGGCTAACC AGCCTTGAGC AGCAGCTTCG 2580 CGAATCCGAG GAGCGCGCTG CGGAGCTGGC GAGCCAGCTG GAGGCCACTG CTGCTGCGAA 2640 GTCGTCGGCG GAGCAGGACC GCGAGAACAC GAGGGCCACG CTAGAGCAGC AGCTTCGCGA 2700 ATCCGAGGCG CGCGCTGCGG AGCTGGCGAG CCAGCTGGAG GCCACTGCTG CTGCGAAGAT 2760 GTCAGCGGAG CAGGACCGCG AGAACACGAG GGCCACGCTA GAGCAGCAGC TTCGTGACTC 2820 CGAGGAGCGC GCTGCGGAGC TGGCGAGCCA GCTGGAGTCC ACTACTGCTG CGAAGATGTC 2880 AGCGGAGCAG GACCGCGAGA GCACGAGGGC CACGCTAGAG CAGCAGCTTC GTGACTCCGA 2940 GGAGCGCGCT GCGGAGCTGG CGAGCCAGCT GGAGTCCACT ACTGCTGCGA AGATGTCAGC 3000 GGAGCAGGAC CGCGAGAGCA CGAGGGCCAC GCTAGAGCAG CAGCTTCGCG AATCCGAGGA 3060 GCGCGCTGCG GAGCTGGCGA GCCAGCTGGA GTCCACTACT GCTGCGAAGA TGTCAGCGGA 3120 GCAGGACCGC GAGAGCACGA GGGCCACGCT AGAGCAGCAG CTTCGTGACT CCGAGGAGCG 3180 CGCTGCGGAG CTGGCGAGCC AGCTGGAGGC CACTGCTGCT GCGAAGTCGT CGGCGGAGCA 3240 GGACCGCGAG AACACGAGGG CCGCGTTGGA GCAGCAGCTT CGTGACTCCG AGGAGCGCGC 3300 CGCGGAGCTG GCGAGCCAG 3319 (2) INFORMATION FOR SEQ ID NO:5: (i) SEQUENCE CHARACTERISTICS: (A) LENGTH: 39 amino acids (B) TYPE: amino acid (C) STRANDEDNESS: (D) TOPOLOGY: linear (xi) SEQUENCE DESCRIPTION: SEQ ID NO:5: Leu Glu Gin Gin Leu Arg (Asp/Glu) Ser Glu (Glu/Ala) Arg Ala Ala 1 5 10 Glu Leu Ala Ser Gin Leu Glu (Ala/Ser) Thr (Ala/Thr) Ala Ala Lys 15 20 25 (Met/Ser) Ser Ala Glu Gin Asp Arg Glu (Asn/Ser) Thr Arg Ala 30 35 (Thr/Ala)

Claims: Claims 1. A method for detecting asymptomatic or sub-clinical Leishmania infection in a biological sample, comprising: (a) contacting a biological sample with a polypeptide comprising an epitope of LcPO, or a variant thereof that differs only in conservative substitutions and/or modifications; and (b) detecting in the biological sample the presence of antibodies that bind to the polypeptide, thereby detecting asymptomatic or sub-clinical Leishmania infection in the biological sample. 2. The method of claim 1 wherein the epitope of LcPO comprises amino acids 306-322 of SEQ ED NO:2, or a variant thereof that differs only in conservative substitutions and/or modifications. 3. The method of claim 1 wherein the polypeptide is bound to a solid support. 4. The method of claim 3 wherein the solid support comprises nitrocellulose, latex or a plastic material. 5. The method of claim 3 wherein the step of detecting comprises: (a) removing unbound sample from the solid support; (b) adding a detection reagent to the solid support; and (c) determining the level of detection reagent bound to the solid support, relative to a predetermined cutoff value, thereby detecting asymptomatic or sub¬ clinical Leishmania infection in the biological sample. 6. A method for detecting Leishmania infection in a biological sample, comprising: (a) contacting a biological sample with a first amino acid sequence comprising an epitope of LcPO, or a variant thereof that differs only in conservative substitutions and/or modifications; (b) contacting the biological sample with a second amino acid sequence comprising Leu Glu Gin Gin Leu Arg Xaa Ser Glu Xaa Arg Ala Ala Glu Leu Ala Ser Gin Leu Glu Xaa Thr Xaa Ala Ala Lys Xaa Ser Ala Glu Gin Asp Arg Glu Xaa Thr Arg Ala Xaa, wherein Xaa at position 7 is Asp or Glu, at position 10 is Glu or Ala, at position 21 is Ala or Ser, at position 23 is Ala or Thr, at position 27 is Met or Ser, at position 35 is Asn or Ser, and at position 39 is Thr or Ala, or a variant thereof that differs only in conservative substitutions and/or modifications; and (c) detecting in the sample the presence of antibodies that bind to one or both of the amino acid sequences, thereby detecting Leishmania infection in the biological sample. 7. The method of claim 6 wherein the epitope of LcPO comprises amino acids 306-322 of SEQ ID NO:2, or a variant thereof that differs only in conservative substitutions and/or modifications. 8. The method of claim 6 wherein the first and second amino acid sequences are bound to a solid support. 9. The method of claim 8 wherein the solid support comprises nitrocellulose, latex or a plastic material. 10. The method of claim 8 wherein the step of detecting comprises: (a) removing unbound sample from the solid support; (b) adding a detection reagent to the solid support; and (c) determining the level of detection reagent bound to the solid support, relative to a predetermined cutoff value, therefrom detecting Leishmania in the biological sample. 11. A method for identifying a patient afflicted with asymptomatic or subclinical leishmaniasis that is likely to develop acute visceral leishmaniasis, comprising: (a) contacting a biological sample obtained from a patient afflicted with asymptomatic or subclinical leishmaniasis with a polypeptide comprising the amino acid sequence Leu Glu Gin Gin Leu Arg Xaa Ser Glu Xaa Arg Ala Ala Glu Leu Ala Ser Gin Leu Glu Xaa Thr Xaa Ala Ala Lys Xaa Ser Ala Glu Gin Asp Arg Glu Xaa Thr Arg Ala Xaa, wherein Xaa at position 7 is Asp or Glu, at position 10 is Glu or Ala, at position 21 is Ala or Ser, at position 23 is Ala or Thr, at position 27 is Met or Ser, at position 35 is Asn or Ser, and at position 39 is Thr or Ala, or a variant thereof that differs only in conservative substitutions and/or modifications; and (b) detecting in the sample the presence of antibodies that bind to the polypeptide, thereby identifying a patient afflicted with asymptomatic or subclinical leishmaniasis that is likely to develop acute visceral leishmaniasis. 12. The method of claim 11 wherein the polypeptide is bound to a solid support. 13. The method of claim 12 wherein the solid support comprises nitrocellulose, latex or a plastic material. 14. The method of claim 12 wherein the step of detecting comprises: (a) removing unbound sample from the solid support; (b) adding a detection reagent to the solid support; and (c) determining the level of detection reagent bound to the solid support, relative to a predetermined cutoff value, therefrom identifying a patient afflicted with asymptomatic or subclinical leishmaniasis that is likely to develop acute visceral leishmaniasis. 15. A method for identifying a patient afflicted with asymptomatic or subclinical leishmaniasis that is likely to develop acute visceral leishmaniasis, comprising: (a) contacting a biological sample obtained from a patient afflicted with asymptomatic or subclinical leishmaniasis with a first polypeptide comprising an epitope of LcPO, or a variant thereof that differs only in conservative substitutions and/or modifications; (b) independently contacting the biological sample with a second polypeptide comprising the amino acid sequence Leu Glu Gin Gin Leu Arg Xaa Ser Glu Xaa Arg Ala Ala Glu Leu Ala Ser Gin Leu Glu Xaa Thr Xaa Ala Ala Lys Xaa Ser Ala Glu Gin Asp Arg Glu Xaa Thr Arg Ala Xaa, wherein Xaa at position 7 is Asp or Glu, at position 10 is Glu or Ala, at position 21 is Ala or Ser, at position 23 is Ala or Thr, at position 27 is Met or Ser, at position 35 is Asn or Ser, and at position 39 is Thr or Ala, or a variant thereof that differs only in conservative substitutions and/or modifications; and (c) detecting in the sample the presence of antibodies that bind to the first and/or second polypeptides, thereby identifying a patient afflicted with asymptomatic or subclinical leishmaniasis that is likely to develop acute visceral leishmaniasis. 16. The method of claim 15 wherein the epitope of LcPO comprises amino acids 306-322 of SEQ ID NO:2, or a variant thereof that differs only in conservative substitutions and/or modifications. 17. The method of claim 15 wherein the first and second polypeptides are each bound to a separate solid support. 18. The method of claim 17 wherein the solid supports comprise nitrocellulose, latex or a plastic material. 19. The method of claim 17 wherein the step of detecting comprises: (a) removing unbound sample from each solid support; (b) adding a detection reagent to each solid support; and (c) comparing the level of detection reagent bound to each solid support, relative to a predetermined cutoff value, therefrom identifying a patient afflicted with asymptomatic or subclinical leishmaniasis that is likely to develop acute visceral leishmaniasis. 20. The method of any of claims 1, 6, 11 or 15 wherein the biological sample is selected from the group consisting of blood, serum, plasma, saliva, cerebrospinal fluid and urine. 21. The method of claim 20 wherein the biological sample is whole blood or plasma. 22. The method of any of claims 5, 10, 14 or 19 wherein the detection reagent comprises a reporter group conjugated to a binding agent. 23. The method of claim 22 wherein the binding agent is selected from the group consisting of anti-immunoglobulin, Protein G, Protein A and lectins. 24. The method of claim 22 wherein the reporter group is selected from the group consisting of radioisotopes, fluorescent groups, luminescent groups, enzymes, biotin and dye particles. 25. A polypeptide comprising amino acids 306-322 of SEQ ID NO:2. 26. A diagnostic kit for detecting asymptomatic or sub-clinical leishmaniasis in a biological sample, comprising: (a) a polypeptide comprising an epitope of LcPO, or a variant thereof that differs only in conservative substitutions and/or modifications; and (b) a detection reagent. 27. A diagnostic kit for detecting Leishmania infection in a biological sample, comprising: (a) a first amino acid sequence comprising an epitope of LcPO, or a variant thereof that differs only in conservative substitutions and/or modifications; (b) a second amino acid sequence comprising the amino acid sequence Leu Glu Gin Gin Leu Arg Xaa Ser Glu Xaa Arg Ala Ala Glu Leu Ala Ser Gin Leu Glu Xaa Thr Xaa Ala Ala Lys Xaa Ser Ala Glu Gin Asp Arg Glu Xaa Thr Arg Ala Xaa, wherein Xaa at position 7 is Asp or Glu, at position 10 is Glu or Ala, at position 21 is Ala or Ser, at position 23 is Ala or Thr, at position 27 is Met or Ser, at position 35 is Asn or Ser, and at position 39 is Thr or Ala, or a variant thereof that differs only in conservative substitutions and/or modifications; and (c) a detection reagent. 28. A diagnostic kit for identifying a patient afflicted with asymptomatic or subclinical leishmaniasis that is likely to develop acute visceral leishmaniasis, comprising: (a) a polypeptide comprising the amino acid sequence Leu Glu Gin Gin Leu Arg Xaa Ser Glu Xaa Arg Ala Ala Glu Leu Ala Ser Gin Leu Glu Xaa Thr Xaa Ala Ala Lys Xaa Ser Ala Glu Gin Asp Arg Glu Xaa Thr Arg Ala Xaa, wherein Xaa at position 7 is Asp or Glu, at position 10 is Glu or Ala, at position 21 is Ala or Ser, at position 23 is Ala or Thr, at position 27 is Met or Ser, at position 35 is Asn or Ser, and at position 39 is Thr or Ala, or a variant thereof that differs only in conservative substitutions and/or modifications; and (b) a detection reagent. 29. A diagnostic kit for identifying a patient afflicted with asymptomatic or subclinical leishmaniasis that is likely to develop acute visceral leishmaniasis, comprising: (a) a first polypeptide comprising an epitope of LcPO, or a variant thereof that differs only in conservative substitutions and/or modifications; (b) a second polypeptide comprising the amino acid sequence Leu Glu Gin Gin Leu Arg Xaa Ser Glu Xaa Arg Ala Ala Glu Leu Ala Ser Gin Leu Glu Xaa Thr Xaa Ala Ala Lys Xaa Ser Ala Glu Gin Asp Arg Glu Xaa Thr Arg Ala Xaa, wherein Xaa at position 7 is Asp or Glu, at position 10 is Glu or Ala, at position 21 is Ala or Ser, at position 23 is Ala or Thr, at position 27 is Met or Ser, at position 35 is Asn or Ser, and at position 39 is Thr or Ala, or a variant thereof that differs only in conservative substitutions and/or modifications; and (c) a detection reagent. 30. The kit of any of claims 26-29 wherein the detection reagent comprises a reporter group conjugated to a binding agent. 31. The kit of claim 30 wherein the binding agent is selected from the group consisting of anti-immunoglobulin, Protein G, Protein A and lectins. 32. The kit of claim 30 wherein the reporter group is selected from the group consisting of radioisotopes, fluorescent groups, luminescent groups, enzymes, biotin and dye particles. 33. A pharmaceutical composition comprising: (a) a polypeptide comprising an epitope of LcPO, or a variant thereof that differs only in conservative substitutions and/or modifications; and (b) a physiologically acceptable carrier. 34. The pharmaceutical composition of claim 33, further comprising a second polypeptide comprising the amino acid sequence Leu Glu Gin Gin Leu Arg Xaa Ser Glu Xaa Arg Ala Ala Glu Leu Ala Ser Gin Leu Glu Xaa Thr Xaa Ala Ala Lys Xaa Ser Ala Glu Gin Asp Arg Glu Xaa Thr Arg Ala Xaa, wherein Xaa at position 7 is Asp or Glu, at position 10 is Glu or Ala, at position 21 is Ala or Ser, at position 23 is Ala or Thr, at position 27 is Met or Ser, at position 35 is Asn or Ser, and at position 39 is Thr or Ala, or a variant thereof that differs only in conservative substitutions and/or modifications. 35. The pharmaceutical composition of claim 33, wherein the polypeptide further comprises the amino acid sequence Leu Glu Gin Gin Leu Arg Xaa Ser Glu Xaa Arg Ala Ala Glu Leu Ala Ser Gin Leu Glu Xaa Thr Xaa Ala Ala Lys Xaa Ser Ala Glu Gin Asp Arg Glu Xaa Thr Arg Ala Xaa, wherein Xaa at position 7 is Asp or Glu, at position 10 is Glu or Ala, at position 21 is Ala or Ser, at position 23 is Ala or Thr, at position 27 is Met or Ser, at position 35 is Asn or Ser, and at position 39 is Thr or Ala, or a variant thereof that differs only in conservative substitutions and/or modifications. 36. A vaccine for stimulating the production of antibodies that bind to Leishmania, comprising: (a) a polypeptide comprising an epitope of LcPO, or a variant thereof that differs only in conservative substitutions and/or modifications; and (b) an adjuvant. 37. The vaccine of claim 36, further comprising a second polypeptide comprising the amino acid sequence Leu Glu Gin Gin Leu Arg Xaa Ser Glu Xaa Arg Ala Ala Glu Leu Ala Ser Gin Leu Glu Xaa Thr Xaa Ala Ala Lys Xaa Ser Ala Glu Gin Asp Arg Glu Xaa Thr Arg Ala Xaa, wherein Xaa at position 7 is Asp or Glu, at position 10 is Glu or Ala, at position 21 is Ala or Ser, at position 23 is Ala or Thr, at position 27 is Met or Ser, at position 35 is Asn or Ser, and at position 39 is Thr or Ala, or a variant thereof that differs .only in conservative substitutions and/or modifications. 38. The vaccine of claim 36, wherein the polypeptide further comprises the amino acid sequence Leu Glu Gin Gin Leu Arg Xaa Ser Glu Xaa Arg Ala Ala Glu Leu Ala Ser Gin Leu Glu Xaa Thr Xaa Ala Ala Lys Xaa Ser Ala Glu Gin Asp Arg Glu Xaa Thr Arg Ala Xaa, wherein Xaa at position 7 is Asp or Glu, at position 10 is Glu or Ala, at position 21 is Ala or Ser, at position 23 is Ala or Thr, at position 27 is Met or Ser, at position 35 is Asn or Ser, and at position 39 is Thr or Ala, or a variant thereof that differs only in conservative substitutions and/or modifications. 39. An isolated DNA sequence encoding the polypeptide of claim 25. 40. A recombinant expression vector comprising the isolated DNA sequence of claim 39. 41. A host cell transformed with the expression vector of claim 40. 42. The host cell of claim 41 wherein the host cell is selected from the group consisting of E. coli, yeast, insect cell lines and mammalian cell lines.

Inventors: REED STEVEN G, REED, STEVEN, G.
Applicants: CORIXA CORP, CORIXA CORPORATION
Application year: 1996
Main classification: G01N33
IPC codes: A61K38, A61K39, C07K14, G01N33