276. Detection of Rhizopus oryzae-Specific Antigen (RSA) in Serum and Bronchial Alveolar Lavage Is a Potential Early Diagnostic Marker in Mucormycosis by R. oryzae

BACKGROUND: The diagnosis of mucormycosis was made by the identification of an organism in the histopathology with culture confirmation. However, culture often yields no growth, and histopathological identification of organism with typical of mucorales is sometimes difficult. Therefore, a reliable new diagnostic tool is expected. We reported a novel Rhisopus-specific antigen (23kDa, named protein RSA) by screening with a signal sequence trap was detected at significantly higher concentrations in serum and in lung homogenates in the infected mice on day 4. And the results were suggested RSA was a possible diagnostic marker of mucormycosis (Sato K, et al. Medical Mycology, 2017, 55,713–719). Here, we examined whether the RSA was detected on early stage in sera and bronchial alveolar lavage (BAL) of infected mice. METHODS: We developed the ELISA Kit using monoclonal antibody for RSA. The mice were injected with cortisone acetate and cyclophosphamide, and R. oryzae was infected intratracheally. Mice sera and BAL was obtained from infected mice on day 1, 2, 3, and 4. Then the concentration of RSA in sera and BAL was evaluated using the ELISA Kit for RSA. RESULTS: The RSA was detected in sera and BAL on day 1, 2, 3, and 4. The concentration of RSA in sera and BAL were significantly higher on day 1 as compared with uninfected mice. And the concentration of RSA in sera was the upward trend through day 1 to 4. However, the concentration of RSA in BAL was stable through day 1 to 4. CONCLUSION: The RSA is a potential early diagnostic marker in mucormycosis by R. oryzae. DISCLOSURES: All authors: No reported disclosures.