<b>Isolation and characterization of a recombinant porcine epidemic diarrhea virus S-INDEL strain in China</b>

Porcine epidemic diarrhea virus (PEDV) is a contagious enteric coronavirus that causes severe diarrhea and dehydration in pigs, with mortality rates reaching up to 100% in piglets. In 2024, the novel S-INDEL PEDV strain (PEDV_CHJSHA2024) was isolated from the intestines of piglets on a pig farm in China. The recombination analysis indicated that the S gene of this strain underwent recombination, resulting from the integration of sequences from the Ch/HNLH/2015 strain and the SQ2014 strain. Compared with strain OH851, this strain exhibited amino acid substitutions and insertions in the S1 region, along with a loss of the N-glycosylation site at amino acid position 114. The pathogenicity of the S-INDEL strain remains controversial. The PEDV_CHJSHA2024 strain was evaluated in pigs of different ages and antibody levels, revealing 100% mortality in 1-day-old neonatal piglets, 50% mortality in 3-day-old piglets without maternal antibodies, and no mortality in 3-day-old piglets with maternal antibodies, with differences in clinical signs of infection. It induces severe diarrhea and reduced feeding in 4-week-old piglets and gilts but is not fatal. High levels of serum IgA antibodies were observed for at least two months post-infection. These findings provide valuable insights into coronavirus recombination and evolution, supporting further investigations into the molecular pathogenesis of S-INDEL strains.