Development of reference material from Rift Valley fever virus RNA

Rift Valley fever virus (RVFV) has mainly been reported in African countries, and molecular diagnosis is performed using nucleic acid amplification tests. Nucleic acid reference materials (RMs) are necessary for the performance evaluation and quality assessment of molecular diagnosis of Rift Valley fever. However, metrological certified RMs for RVFV nucleic acids are currently unavailable.

In this study, RVFV RNA RMs (KRISS 111-10-537, 538, and 539) were developed from in vitro transcribed RNA containing a three-segment genome, including the L, M, and S segments. The RNA copy numbers of the L, M, and S segments of RMs were measured using reverse-transcription droplet digital PCR (RT-ddPCR), an advanced technology that enables the absolute quantification of viral genetic material.

In the homogeneity analysis, the copy number values were measured to be from 7.82 × 10⁴ to 2.51 × 10⁶ copies/µl, and the consistency between different bottles of these RMs showed variation of only 4.0-6.7%. These reference materials demonstrated excellent stability, remaining stable for up to 14 days at 4°C and at -80 °C for 12 months. This stability and consistency ensure that laboratories worldwide can rely on these materials for accurate testing.

RMs can help reduce false positives and negatives in RVFV molecular tests by providing accurate reference values for target viral gene copy numbers, ultimately contributing to better diagnosis and control of this viral disease.