The aim of this study was to investigate the replication characteristics and pathogenicity of a cell-adapted strain derived from a prevalent PEDV isolate. The viral strain isolated from a large-scale pig farm was serially passaged in Vero cells to different generations. The biological characteristics of the virus were evaluated in vitro, and the 25th (F25) and 141st (F141) passages were inoculated into 3-day-old piglets to compare their pathogenic differences. The results showed that typical syncytial cytopathic effects (CPE) caused by PEDV were observed in Vero cells at the 4th blind passage of the clinical inoculum. By the 25th passage, both the CPE morphology and viral titers had stabilized. Upon reaching the 141st passage, the viral titer increased significantly and induced a more rapid cytopathic effect. Indirect immunofluorescence assay (IFA) specifically detected the expression of the PEDV N protein, and genomic sequence analysis identified the strain as genotype G2b. Pig challenge experiments demonstrated that, compared with the low-passage parental strain (YJH/2017/F25), the YJH/2017/F141-inoculated group showed no significant clinical symptoms or histopathological lesions, along with a significant reduction in viral shedding via anal swabs. All assessed parameters showed no significant difference from those of the DMEM control group, indicating reduced pathogenicity and favorable safety profile of the strain. These findings indicate that after serial in vitro passaging, the prevalent PEDV strain acquired enhanced cell adaptability while exhibiting decreased pathogenicity in neonates. This study provides a promising candidate strain for the development of an attenuated PEDV vaccine, and its complete genomic sequence and biological characteristics establish a foundation for further research on recombinant viruses.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |