Clinical Evaluation of Rapid Diagnostic Test Kit for Scrub Typhus with Improved Performance

Diagnosis of scrub typhus is challenging due to its more than twenty serotypes and the similar clinical symptoms with other acute febrile illnesses including leptospirosis, murine typhus and hemorrhagic fever with renal syndrome. Accuracy and rapidity of a diagnostic test to Orientia tsutsugamushi is an important step to diagnose this disease. To discriminate scrub typhus from other diseases, the improved ImmuneMed Scrub Typhus Rapid Diagnostic Test (RDT) was evaluated in Korea and Sri Lanka. The sensitivity at the base of each IgM and IgG indirect immunofluorescent assay (IFA) in Korean patients was 98.6% and 97.1%, and the specificity was 98.2% and 97.7% respectively. The sensitivity and specificity for retrospective diagnosis at the base of IFA in Sri Lanka was 92.1% and 96.1%. ImmuneMed RDT was not reactive to any serum from seventeen diseases including hemorrhagic fever with renal syndrome (n = 48), leptospirosis (n = 23), and murine typhus (n = 48). ImmuneMed RDT shows superior sensitivity (98.6% and 97.1%) compared with SD Bioline RDT (84.4% at IgM and 83.3% at IgG) in Korea. The retrospective diagnosis of ImmuneMed RDT exhibits 94.0% identity with enzyme-linked Immunosorbent assay (ELISA) using South India patient serum samples. These results suggest that this RDT can replace other diagnostic tests and is applicable for global diagnosis of scrub typhus. This rapid and accurate diagnosis will be beneficial for diagnosing and managing scrub typhus.

Production and Characterization of Murine Monoclonal Antibodies ( MAbs ) which Specifically Recognize B-Subunit of Human Chorionic Gonadotropin ( HCG ) / 대한면역학회지

We have constructed several panels of MAbs which specifically recognize B-subunit of HCG (BHCG). Splenocytes from Balb/c mice immunized with B-subunit of HCG were fused with SP2/o-Ag14 myeloma cells by PEG method. Fifteen different hybridorna clones (individually named as mG10.127, mG10.61, mG9.5, mG9.18, rnG9.20, mG6.3, mG6.36, mG6.8, mG7.31, mG7.79, mG9.11, mG9.51.6, mG9.51.12, mH4.17, and mH4.4) were obtained by indirect ELISA screening and three to five successive cloning procedures. The distinct features of these MAbs were determined by specificity, western blot, isotyping, and isoelectrofocusing. All of the MAbs except mG9.20 and mG6.8 specifically bind to BHCG without cross- reaction with B-subunit of LH (BLH). In western blot analysis, all of the MAbs bind to non-denatured form of BHCG suggesting that the MAbs recognize conformation-dependent epitope of BHCG. This new panels of MAbs to BHCG should be useful for developing diagnostic reagent such as pregnancy, choriocarcinoma, Down's syndrome as well as for the fine quantitation of serum or urinary HCG.