Development of a Scrub Typhus Diagnostic Platform Incorporating Cell-Surface Display Technology

Area of Science:

• Biotechnology
• Medical Diagnostics
• Infectious Diseases

Background:

• Scrub typhus (ST), caused by Orientia tsutsugamushi, is a significant epidemic in the Asia-Pacific, causing a million infections annually.
• Accurate diagnosis of ST is challenging due to non-specific symptoms and the need for specialized detection methods.
• Current diagnostic limitations pose a global health threat, necessitating improved, accessible tools.

Purpose of the Study:

• To develop a novel, accurate, convenient, and low-cost diagnostic method for scrub typhus.
• To utilize baculovirus surface-display technology for expressing Orientia tsutsugamushi antigens.
• To establish a cell-based ELISA for serological detection of ST.

Main Methods:

• Employed baculovirus surface-display technology to express TSA56 variants and ScaC-PD on insect Sf21 cell surfaces.
• Developed a cell-based enzyme-linked immunosorbent assay (ELISA) using these antigen-displaying cells.
• Validated the assay using monoclonal antibodies and serum samples from ST-positive rats and a pilot study with human sera.

Main Results:

• Successfully expressed and displayed recombinant TSA56 and ScaC-PD antigens on Sf21 cell surfaces.
• The cell-based ELISA demonstrated high diagnostic performance: 96.3% accuracy, 98.6% sensitivity, and 84.6% specificity in rat sera.
• Pilot studies with human sera showed high consistency with immunofluorescence analyses.

Conclusions:

• The developed cell-based ELISA circumvents complex antigen purification and reduces the need for specialized equipment and personnel.
• This approach offers a promising, simplified, and potentially widely applicable serological platform for diagnosing scrub typhus.
• The method addresses the critical need for accessible and reliable ST diagnostic tools, mitigating a global health concern.