Liu Z, Zhang C, Shen H, Sun J, Zhang J. Duplex fluorescence melting curve analysis as a new tool for rapid detection and differentiation of genotype I, II and Bartha-K61 vaccine strains of pseudorabies virus.
BMC Vet Res 2018;
14:372. [PMID:
30486818 PMCID:
PMC6264625 DOI:
10.1186/s12917-018-1697-4]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 11/13/2018] [Indexed: 12/21/2022] Open
Abstract
Background
Recently, pseudorabies (PR) outbreaks have been reported in a large number of swine herds vaccinated with the Bartha-K61 vaccine in China, the current pseudorabies virus (PRV) belonging to Genotype II is differential genetically from Bartha-K61 vaccine belonging to Genotype I. Furthermore, it has been proved that the Bartha-K61 vaccine cannot provide sufficient protection against the current PRVs in China. Therefore, the accurate and rapid identification of PRVs is essential. The objective of this study is to develop a duplex fluorescence melting curve analysis (FMCA) capable of rapid, simple, high-throughput differentiation of Chinese, European/American and Bartha-K61 vaccine strains of PRV.
Results
Primers 6F/6R and probes P1/P2, combined with three recombinant plasmids p-B (Bartha-K61), p-N (Genotype I), and p-H (Genotype II), were used to establish the Bicolor FMCA. FAM Tm values (probe P1) and HEX (probe P2) channels of p-B were used as reference values. Tm differences (ΔTm) between detected samples and reference plasmid p-B were calculated in each channel. Bartha-K61 vaccine samples had ΔTm values of ±1 °C in both FAM and HEX channels, Genotype I samples had ΔTm values of ±1 °C in the FAM channel and 4.38 ± 1 °C in the HEX channel, and Genotype II samples had ΔTm values of 6.52 ± 1 °C in the FAM channel and 4.38 ± 1 °C in the HEX channel. The minimum detection limit of the duplex FMCA was approximately 1 × 100 copies per reaction for p-B, p-N, and p-H. The duplex FMCA technique was used to detect and different 198 suspected clinical samples, of which 18 (9%) were positive for Genotype II strains and eight (4%) were positive for Bartha-K61 vaccine strains, and the results were compared with sequencing and phylogenetic analyses, which confirmed that the Bicolor FMCA worked correctly for all samples.
Conclusions
In this study, we developed a duplex FMCA of dual-labeled, self-quenched probes that was performed for rapid detection and differentiation of Genotype I, II and Bartha-K61 vaccine strains of PRV. The duplex FMCA was rapid, simple, and high-throughput, and will likely prove useful for molecular epidemiological investigations and pathogen surveillance of PRV.
Electronic supplementary material
The online version of this article (10.1186/s12917-018-1697-4) contains supplementary material, which is available to authorized users.
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