Diagnostic evaluation of a recombinant chimeric Sporothrix brasiliensis protein-based ELISA for serological detection of feline sporotrichosis.

Abstract

Sporotrichosis is a zoonotic infection caused by fungi of the Sporothrix schenkii complex, with S. brasiliensis being the most prevalent etiological agent in animals, particularly cats. Felines are highly susceptible to infection and may develop severe clinical forms characterized by extensive cutaneous lesions and systemic dissemination. In addition, infected cats play a major role in zoonotic transmission, as Sporothrix spp. can be transmitted to humans through bites and scratches. The gold standard for sporotrichosis diagnosis remains the isolation and identification of Sporothrix species from clinical samples, a process that requires prolonged culture prior to identification. However, the increasing number of cases highlights the need for a reliable, rapid, and cost-effective diagnostic method. This study aimed to develop an indirect enzyme-linked immunosorbent assay (ELISA) for the serodiagnosis of feline sporotrichosis using a recombinant chimeric S. brasiliensis protein. The antigen was designed from immunogenic fragments of two S. brasiliensis proteins, SsEno and Gp70, and expressed in a prokaryotic system. A total of 201 feline serum samples were analyzed, including 66 from cats diagnosed with sporotrichosis, 73 from healthy animals, and 62 from cats with other medical conditions. The assay demonstrated 97.0% sensitivity (95% CI: 89.4-99.6%) and 94.1% specificity (95% CI: 88.6%-97.4%). The recombinant chimeric antigen showed strong reactivity with sera from infected cats and no cross-reactivity with controls samples. These results indicate that this recombinant antigen-based ELISA is a simple, accurate, and low-cost diagnostic alternative with promising potential for validation and routine application in the diagnosis of feline sporotrichosis.