Evaluation of inactivated snakehead rhabdovirus as an internal positive control for RT-qPCR diagnosis of viral hemorrhagic septicemia virus in fish

Abstract

Viral hemorrhagic septicemia virus (VHSV) is a significant pathogen causing mass mortalities in marine and freshwater fish worldwide. Accurate diagnosis through quantitative reverse transcription PCR (RT-qPCR) is essential to prevent its spread, but false negatives can compromise results. In this study, we evaluate the use of heat-inactivated snakehead rhabdovirus (SHRV) as an internal positive control (IPC) for VHSV diagnosis. SHRV's similarity to VHSV in viral structure and genome makes it an ideal IPC. The introduction of SHRV IPC into the RT-qPCR workflow can improve the reliability of diagnostic results by enabling the detection of technical failures during the RNA extraction or amplification process. Our results show that heat-inactivated SHRV preserved RNA integrity for IPC use, and SHRV IPC can provide a useful tool for detecting and interpreting false negatives without affecting assay sensitivity.