Duck plague virus (DPV) causes serious harm to the duck industry in China. Ducks latently infected with DPV display a clinically healthy state, which is one of the epidemiological characteristics of duck plague. In the present study, to rapidly distinguish vaccine-immunized ducks from wild virus-infected ducks during production, a PCR assay based on the newly identified LORF5 fragment was developed to effectively and accurately identify viral DNA in cotton swab samples and was used to assess artificial infection models and clinical samples. The results showed that the established PCR method had good specificity and that only the virulent and attenuated DNA of duck plague virus was specifically amplified. The amplified fragments of virulent and attenuated strains were 2,454 bp and 525 bp,respectively. The size of the PCR amplified bands can be compared to effectively and accurately identify the duck plague virus in cotton swabs. It makes up for the shortcomings of the national standard PCR which cannot identify of virulent and attenuated duck plague virus.
In conclusion, the PCR assay established in the present study can be used as a simple and effective method for the clinical screening of ducks that are latently infected with virulent strains of DPV and shedding virus, which can provide technical support for the elimination of duck plague from duck farms. The study was published as "Establishment and application of a PCR assay for the identification of virulent and attenuated duck plague virus DNA in cotton swabs " published in the journal Poultry Science. The thesis links: DOI: https://doi.org/10.1016/j.psj.2023.102555.
Figure 1. Discovery of the X fragment and its sequence alignment.
(A) Amplification of CHv and CVCC AV1222 using LORF5-F/R and sequence alignment of the X fragment. (B) Sequence alignment of the LORF5 5′UTR of 32 DPV strains after complementation of the X fragment. Blue arrow: newly designed primers for distinguishing the virulent strain from the attenuated strain after complementation of the X fragment. Orange arrow: LORF5-F/R. (C) Amplification of CHv and CVCC AV1222 using the newly designed identification-F/R primers.
