Emerging infectious diseases necessitate the rapid development of novel nucleic acid amplification tests (NAATs) for accurate diagnosis, as was the case with the coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). NAATs involve three critical processes: nucleic acid extraction, amplification, and detection. Ensuring the efficient and accurate performance of these sequential steps is vital for reliable test outcomes. Therefore, the validation and evaluation of NAATs require full-process control materials that closely mimic the characteristics of the target pathogen, such as single-stranded RNA encapsulated in virus particles.

Clinical laboratory tests, including NAATs, are conducted under international standards and own standard operating procedure developed referring to quality control documents [1,2]. For instance, NAAT for human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV) are internationally standardized and report value with international units (IU) [3]. However, many SARS-CoV-2 NAATs currently used worldwide have not yet achieved full international standardization. Although numerous SARS-CoV-2 NAATs were rapidly developed, distributed, and implemented during the initial stages of the COVID-19 pandemic, the production and availability of full-process control materials lagged. Under the situation, recombinant alphavirus containing SARS-CoV-2 NAAT target sequences and inactivated SARS-CoV-2 have since become commercially available as full-process control materials. Regrettably, the internal quality control (IQC) of NAAT is not effectively implemented in Japan. This is almost certainly because clinical laboratories avoid purchasing expensive quality control materials, as they want to avoid incurring additional expenses not covered by laboratory revenues.

Standardization of NAAT is essential to ensure consistent and comparable test results across different laboratories. This standardization can be achieved using internationally recognized standard materials. For SARS-CoV-2 NAATs, the World Health Organization (WHO) and the National Institute for Biological Standards and Control (NIBSC, Potters Bar, UK) released the first WHO international standard material (NIBSC code: 20/146) as an inactivated whole virus in November 2020 [4,5]. Due to limited supplies of the first standard, a second WHO international standard material (NIBSC code: 22/252) has been prepared [5]. If we had a method for producing sequence-customized, full-process control material, we could obtain a traceable international standard material at an early stage using the first WHO international material. Rather than directly using the WHO international standard material for individual test standardization, it is more practical to use it to produce traceable downstream standards materials. To better prepare for future emerging infectious diseases, it is crucial to develop protocols that allow for the production of sequence-customized and traceable full-process control materials.

In this study, we proposed a protocol for generating recombinant lentiviral materials that incorporate sequence-customized and are traceable to international standards, using SARS-CoV-2 NAAT as a model. Additionally, we validated the stability of these lentiviral materials and demonstrated their utility through a pilot external quality assessment (EQA).