FDA Grants Emergency Use Authorization to Seegene's Allplex Multiplex PCR Assay for Simultaneous Detection of Four Viral Pathogens
Key Insights
FDA has granted Emergency Use Authorization to Seegene USA (search)'s Allplex assay, the first multiplex PCR test authorized in the U.S. to simultaneously detect and differentiate HSV-1 (search), HSV-2 (search), VZV, and monkeypox virus (search) in a single reaction.
The four pathogens produce clinically indistinguishable vesicular or pustular lesions, and prior clinical evaluation showed multiplex testing uncovered 54 missed infections among 966 samples that had tested negative with single-pathogen methods.
The assay was developed using Seegene's proprietary high-multiplex PCR technologies and builds on the company's earlier FDA 510(k) clearance for its two-target Anyplex II HSV-1 (search)/2 Assay.
The FDA has granted Emergency Use Authorization (EUA) to Seegene USA (search)'s Allplex HSV-1&2/VZV/MPXV Assay (search), marking the first multiplex real-time PCR test authorized in the United States capable of simultaneously detecting and differentiating four viral pathogens—herpes simplex virus type 1 (HSV-1 (search)), herpes simplex virus type 2 (HSV-2 (search)), varicella-zoster virus (search) (VZV), and monkeypox virus (search) (MPXV)—in a single reaction.
The authorization represents a significant advancement in syndromic testing for ulcerative skin lesions, where clinical presentation alone is often insufficient to distinguish between these four pathogens. HSV-1 (search), HSV-2 (search), VZV, and MPXV frequently produce vesicular or pustular lesions that are clinically indistinguishable by appearance alone, creating a diagnostic challenge that single-pathogen testing has historically failed to fully address.
The Diagnostic Gap and Clinical Impact
The clinical significance of multiplex testing was underscored by data presented at the 2024 Clinical Virology Symposium. When researchers applied a multiplex PCR assay to 966 samples that had previously returned negative results using single-pathogen methods, the multiplex test identified HSV, VZV, or MPXV clade I or II in 54 of those samples—cases that single-target testing had missed entirely. This finding highlights the real-world consequences of sequential or single-pathogen testing strategies, where infections caused by untested viruses can go undiagnosed.
"When clinicians test for only one pathogen at a time, infections caused by untested viruses can go undiagnosed, a meaningful gap with real patient consequences," the company noted in its announcement.
Technology Platform
The Allplex assay was developed end-to-end at Seegene USA (search) using the company's proprietary high-multiplex PCR technologies: Dual Priming Oligonucleotide (DPO), Tagging Oligonucleotide Cleavage and Extension (TOCE), and Multiple Detection Temperatures (MuDT), along with its automated product development platform. These technologies enable comprehensive target coverage within a single reaction while maintaining the sensitivity and specificity required for reliable multiplex diagnostic testing.
Regulatory Foundation and Prior Performance
The EUA builds on Seegene's established regulatory footprint in the U.S. molecular diagnostics market. The company previously received its first FDA clearance—a 510(k)—for the Anyplex II HSV-1 (search)/2 Assay, a two-target real-time PCR test for the qualitative detection and differentiation of HSV-1 and HSV-2 (search) from female anogenital lesions. In a multi-center clinical evaluation of 656 prospective specimens across three U.S. sites, that assay demonstrated sensitivity of 98.9% and specificity of 93.7% for HSV-1, and sensitivity of 97.2% and specificity of 93.6% for HSV-2.
Jong-Yoon Chun, PhD, founder, CTO, and CEO of Seegene, described the initial FDA clearance as "an important milestone in support of our planned entry into the United States, the largest molecular diagnostic market in the world," adding that "through FDA approval, Seegene now intends to actively enhance its leadership in the multiplex real-time PCR diagnostic testing market."
The new Allplex assay significantly expands on that cleared platform by adding VZV and MPXV detection in a single reaction, addressing diagnostic gaps that a two-pathogen assay cannot resolve when lesion presentations clinically overlap.
Strategic Implications
With the EUA secured, Seegene USA (search) is positioned to expand its portfolio of locally developed multiplex PCR assays for the U.S. market, moving beyond its initial HSV-focused clearance into broader syndromic testing. The authorization strengthens the company's competitive position in the largest molecular diagnostics market globally and addresses an unmet need in the differential diagnosis of clinically overlapping ulcerative skin lesions.