Development of an ELISA test prototype for serodiagnosis of human sporotrichosis caused by Sporothrix spp.

Abstract

Since 1998, the human and feline sporotrichosis epidemic caused by the new pathogen, S. brasiliensis, discovered in 2007, has spread in Brazil without any perspective of epidemiological control. Already considered a hyperepidemia in some states, the disease reaches the entire South-Southeast region, expanding to the Northeast. Current epidemiological bulletins and reports record from hundreds to thousands of human cases, in exponential growth curve in number of patients per year. The creation of BioInsumos e Diagnóstico (BiDi) company meets the urgent need to develop a diagnostic test for sporotrichosis caused by S. brasiliensis. The old well known species, Sporothrix schenckii has low pathogenicity but S. brasiliensis is highly virulent, causing severe clinical manifestations previously considered rare, such as mucosal infection, endocarditis and meningitis. In view of the increasingly alarming number of cases, sporotrichosis is a priority for inclusion in the list of neglected fungal diseases, an agenda of the World Health Organization (WHO). One of the challenges pointed out by the WHO is the lack of an effective laboratory test for the prompt diagnosis of human sporotrichosis, which can distinguish it from other infections with similar clinical features, especially cutaneous leishmaniasis, also endemic in Brazil. Another challenge raised is the diagnosis reaching out to patients living in remote regions. Serological tests such as the ELISA test, proposed in this project, solve this problem because human serum is a clinical material that is easy to collect, does not require a complex infrastructure or highly specialized professionals. Another advantage is the fact that human serum, after being collected, can be easily preserved and sent to a reference center or to a diagnostic laboratory. A last important aspect to be considered in the development of new methods for diagnosing infectious diseases is the fact that a late or unrealized diagnosis means a poor prognosis for the patient and/or a high cost to the health system. The proponent has described a species-specific antigen (SsCBF) for the serological diagnosis of human sporotrichosis caused by S. schenckii. From the characterization of this antigen, a validated ELISA test was developed, sensitive and specific to diagnose all clinical forms of S. schenckii infection. The PIPE project aims to innovate and develop a new test to diagnose human sporotrichosis caused by S. brasiliensis. The proof of concept will be to validate the ELISA test using the two antigens, SsCBF and SbCBF, to verify the degree of sensitivity and specificity testing serum samples of patients with confirmed sporotrichosis by S. brasiliensis. In addition, we aimed to test the potential of the test to be applied in the differential diagnosis between sporotrichosis and tegumentary leishmaniasis. The project has a low risk, due to our extensive domain of the processes and is supported by some unpublished preliminary data showing that our product is prominsig for the differential diagnosis of these two pathologies. We emphasize that there is no similar product on the market or described, so far, and for this reason, SsCBF-ELISA is the only laboratory test ever developed that has been recommended in the specialized medical literature. A new test with the S. brasiliensis antigen will supply a national demand due to the recent clinical-epidemiological pannel. A method is needed to provide rapid and accurate diagnosis of the disease caused by Sporothrix spp. Our market would also reach cutaneous leishmaniasis, since if the test is efficient for the differential diagnosis of the two diseases it can be applied to rule out a possible suspicion of sporotrichosis or co-infection, in this group. The proposal is promising and we aim for the expansion of BIDi to serve not only the domestic market (PIPE Phase 2) but an expanding world market (Phase 3). (AU)