Fusion proteins and their use in the diagnosis and treatment of leishmaniasis
The present invention relates generally to a fusion protein made from a synthetic gene construct comprising of elements derived from the Leishmania antigens K26, K39, and K9. The fusion protein is particularly useful in the diagnosis of leishmaniasis, particularly visceral leishmaniasis in animals such as humans and dogs.
1. An isolated fusion polypeptide comprising: (i) the Leishmania K26 sequence set forth in SEQ ID NO: 5; (ii) the Leishmania K39 sequence set forth in SEQ ID NO: 6; and (iii) the Leishmania K9 sequence set forth in SEQ ID NO: 7.
2. The fusion polypeptide of claim 1 , wherein the fusion polypeptide comprises the amino acid sequence as set forth in amino acid residues 10-262 of SEQ ID NO: 8.
3. The fusion polypeptide of claim 1 , wherein the fusion polypeptide further comprises an N-terminal amino acid sequence of MHHHHHHTS (SEQ ID NO: 21).
4. A diagnostic kit for detecting asymptomatic or sub-clinical visceral leishmaniasis in a biological sample selected from the group consisting of sera, blood, and saliva, comprising:
(a) a fusion polypeptide of claim 1 ; and
(b) a detection reagent.
5. A diagnostic kit for identifying a patient afflicted with asymptomatic or sub-clinical visceral leishmaniasis that is likely to develop acute visceral leishmaniasis, comprising:
(a) a first polypeptide comprising a fusion polypeptide of claim 1 ;
(b) a second polypeptide comprising an amino acid sequence as set forth in SEQ ID NOs: 10 or 11; and
(c) a detection reagent.
6. The kit of any of claim 4 or 5 , wherein the detection reagent comprises a reporter group conjugated to a binding agent.
7. The kit of claim 6 , wherein the binding agent is selected from the group consisting of anti-immunoglobulin, Protein G, Protein A and lectins.
8. The kit of claim 6 , wherein the reporter group is selected from the group consisting of radioisotopes, fluorescent groups, luminescent groups, enzymes, biotin and dye particles.
9. An isolated fusion polypeptide which comprises the amino acid sequence set forth in 10-262 of SEQ ID NO: 8, or a sequence having at least 95% identity thereto along its entire length.
10. An isolated fusion polypeptide which comprises the amino acid sequence set forth SEQ ID NO: 8, or a sequence having at least 95% identity thereto along its entire length.