Molecular characterization of porcine epidemic diarrhea virus in Sichuan from 2023 to 2024

Porcine Epidemic Diarrhea (PED) is an acute, highly contagious disease caused by Porcine Epidemic Diarrhea Virus (PEDV). It is characterized by symptoms such as diarrhea, vomiting, and dehydration in pigs of all ages, with particularly severe outcomes in neonatal pigs. In this study, a total of 254 samples were collected from Sichuan Province between 2023 and 2024 to investigate the prevalence and genetic characteristics of PEDV. The overall prevalence of PEDV was found to be 19.3 %, with regional prevalence rates of 26.5 % in the Guangyuan region and 14.3 % in the Suining region. Phylogenetic analysis revealed that the G2c genotype was the predominant circulating strain. Furthermore, sequence analysis demonstrated that the six isolates exhibited greater sequence similarity to the AJ1102 vaccine strain than to the CV7777 strain. Notably, consistent mutations were observed in the G2b and G2c genotypes, including the insertion of four amino acids (QGVN) at positions 59-62, as well as amino acid substitutions at positions 140 and 161 in the G2b and G2c strains, respectively. Moreover, the G1c (S-INDEL) strain displayed amino acid losses and gains at positions 140 and 160, respectively. Nglycosylation site analysis of the S proteins from both the isolates and the vaccine strains revealed the absence of an N-glycosylation site at position 510 in all isolates. Notably, the SC/GY/2022 isolate contained only six Nglycosylation sites throughout the S protein, which is significantly fewer than those found in the vaccine strains. These findings provide a comprehensive understanding of the epidemiology of PEDV in Sichuan Province and offer valuable insights for the development of more effective immunological prevention and control strategies against PEDV.