# Reclassification and Recombination Analysis of Porcine Epidemic Diarrhea Virus Strains in South Korea Based on Spike Gene Analysis

## TL;DR

This study reclassifies recent Korean PEDV strains based on spike gene analysis, revealing a new subgroup and potential recombination.

## Contribution

The study identifies a reclassification of Korean PEDV isolates and potential recombination between subgroups.

## Key findings

- Korean PEDV isolates from 2021-2022 were reclassified from G2b to G2e subgroup.
- G2e strains are potential recombinants from G2a and G1d subgroups.
- Phylogenetic analysis suggests a need for updated classification of Korean PEDV strains.

## Abstract

Porcine epidemic diarrhea (PED) is a severe, contagious viral disease, causing significant damage to the global swine industry. The PED virus (PEDV) relies on its spike (S) protein for host entry and virulence. However, the S gene undergoes frequent mutations, necessitating updated phylogenetic classifications to track viral evolution accurately. In this study, we analyzed the S genes of 162 sequences, comprising 161 PEDV strains (58 Korean isolates and 103 global references) and one TGEV strain used as an outgroup. The strains were categorized into two major groups (G1 and G2) and nine distinct subgroups (G1a–G1d and G2a–G2e). A critical finding revealed that Korean isolates from 2021 to 2022, previously identified as G2b, actually belong to the G2e subgroup. Evidence suggests these G2e strains are potential recombinants derived from the G2a and G1d subgroups. These results indicate a need to reclassify Korean PEDV isolates to reflect recent genetic shifts and ensure accurate epidemiological monitoring.

Porcine epidemic diarrhea (PED) is a severe and highly contagious enteric disease of pigs caused by porcine epidemic diarrhea virus (PEDV). The spike (S) protein of PEDV is the main driving force for viral entry into host cells, influencing the pathogenicity and virulence of the virus subgroup. Currently, the S gene of PEDV exhibits a wide array of variations, with numerous mutations reported. Consequently, recent studies on the phylogenetic classification of PEDV have categorized these variants into clusters or lineages. In this study, 161 PEDV subgroups, including 58 Korean isolates and 103 global PEDV reference subgroups, were classified into two groups, G1 and G2, with nine subgroups (G1a, G1b, G1c, G1d, G2a, G2b, G2c, G2d, and G2e) based on the complete S gene. Phylogenetic analysis revealed that the subgroups isolated in Korea between 2021 and 2022, which were previously reported as G2b subgroups, were G2e subgroups, derived as potential recombinants from the G2a and G1d subgroups. These results indicate that PEDV subgroups isolated from Korea may require reclassification based on recently reported subgroups.