Construction of an infectious clone of novel duck picornavirus using the infectious subgenomic amplicon method

A picornavirus strain of Duck/FC22/China/2017 (FC22) with an unclear taxonomic status was isolated in our laboratory in 2017. To study the biological properties of the virus, an infectious clone of the FC22 strain was successfully rescued by the infectious subgenomic amplicon method. The FC22 gene was amplified in two segments and fused with CMV and HDR after the addition of marker sites. The fusion fragment was transfected into LMH cells and passaged, and the obtained virus was named rFC22 and identified by PCR, IFA and electron microscopy. The biological characteristics of strain rFC22 were studied by inoculation with LMH cells, and the results showed that the TCID₅₀ of rFC22 was essentially the same as that of its parent strain FC22 (1 × 10^6.6 TCID₅₀/mL) and that the growth curve of rFC22 was consistent with that of its parent strain FC22. The results indicated no significant difference in the biological characteristics between the rescued strain rFC22 and its parent strain FC22. In summary, our findings suggest that a duck-derived picornavirus was successfully rescued by ISA and the method was more convenient and more successful than alternative approaches.