Foreign gene expression attenuates a virulent Newcastle disease virus in chickens

In this study, a recombinant NDV based on a velogenic strain carrying the orange fluorescent protein (OFP) gene between the phosphoprotein (P) and matrix (M) genes was generated using reverse genetics. Biological characteristics, including virus replication, virulence, and OFP expression, and the pathogenicity in chickens were evaluated. The recombinant NDV showed comparable replication capacity in eggs and cells as the parental virus, whereas OFP insertion resulted in a mild impairment of virulence, evidenced by longer mean death time in embryos. High OFP expression was detected in the cells inoculated with the recombinant NDV. In addition, the recombinant NDV induced delayed onset of disease, lower severity of clinical signs, and lower mortality in chickens compared to the parental virus. Moreover, high titers of the parental virus were detected in the spleen, lung, and intestinal tract, while no recombinant NDV was recovered from these tissues. Our findings suggest that in vitro characteristics related to the insertion of the OFP gene in a virulent NDV do not correlate to alteration of the pathogenicity in chickens. Our results provided new information regarding assessment of the impact of foreign gene expression on the pathogenicity of NDV.

Source: Virus Genes - June 25, 2022 Category: Genetics & Stem Cells Source Type: research