# Rapid Differential Detection of Wild-Type Classical Swine Fever Virus and Hog Cholera Lapinized Virus Vaccines by TaqMan MGB-Based Dual One-Step Real-Time RT-PCR

## TL;DR

A new rapid test can distinguish between wild-type classical swine fever virus and vaccine strains, improving disease control in pigs.

## Contribution

A dual TaqMan-MGB RT-qPCR method was developed for specific and rapid differentiation of CSFV and HCLV.

## Key findings

- The method detected CSFV and HCLV with no cross-reactivity to other swine pathogens.
- The detection limit was 1.67 × 101 copies/μL for the NS3 gene of both CSFV and HCLV.
- The method showed high precision with a relative standard deviation of less than 2%.

## Abstract

Classical swine fever is a highly contagious disease that severely affects the swine industry worldwide. The clinical symptoms of infected pigs are unusually complex, making it difficult to distinguish between wild-type and vaccinated pigs. In this study, a dual TaqMan-MGB RT-qPCR method for the identification of wild-type CSFV and attenuated vaccine strains was established. This newly developed method could specifically detect CSFV and HCLV with no cross-reactivity with other swine pathogens. The detection limit for the NS3 gene of CSFV and HCLV was 1.67 × 101 copies/μL, respectively. For precision testing, the repeatability and reproducibility of the relative standard deviation was less than 2%. This method was successfully used for rapid detection of 193 real samples. This dual TaqMan-MGB RT-qPCR technology meets the needs for early and rapid detection of CSFV, and can provide an efficient and rapid detection method for the investigation and analysis of CSFV field strain infections and vaccine immune status, thereby laying the foundation for better prevention and control of the occurrence and spread of CSF.

To establish a rapid real-time RT-PCR method for differentiating wild-type classical swine fever virus (CSFV) strains from vaccine strains (HCLV), we designed a universal primer targeting the NS3 gene to detect wild-type CSFV strains and vaccine strains simultaneously, and two TaqMan-MGB probes were designed to differentiate between wild-type and vaccine strains. After optimizing the RT-qPCR conditions, a rapid dual TaqMan-MGB RT-qPCR method for the detection and identification of CSFV and HCLV was developed. The results showed that method could specifically detect CSFV and HCLV with no cross-reactivity with other swine pathogens. The analytic sensitivity for the NS3 gene of CSFV and HCLV were 1.67 × 101 copies/μL, respectively. For precision testing, the repeatability and reproducibility of the test was less than 2%. This method was successfully used for the rapid detection of 193 biological samples collected from CSFV-vaccinated pigs. This fast and accurate detection technology can be used for the detection of CSFV and is suitable for differentiating between wild-type CSFV strains and vaccine strains.