Global Evolutionary and Transmission Dynamics of Transmissible Gastroenteritis Virus, 1952–20231

TGEV comprises three genotypes with distinct geographic distribution patterns. Adaptive evolution of TGEV is shaped by recombination and the host–virus arms race. China serves as the major hub for global transmission of TGEV. Transmissible gastroenteritis virus (TGEV) is an enteric coronavirus that poses a significant threat to the swine industry. However, the ecology, evolutionary history, and transmission dynamics of TGEV remain poorly understood. In this study, we analyzed 67 complete TGEV genomes collected globally between 1952 and 2023, employing comparative genomics to uncover the evolutionary dynamics and spatial dissemination of TGEV. Our findings reveal that TGEV can be classified into three major genotypes: the admixed GIa lineage with intercontinental distribution, the Europe-specific GIb lineage, and the U.S.-restricted GII lineage. Recombination events were identified in the ORF1a and S gene regions of GIa strains, suggesting that these genetic changes may have contributed to the evolutionary diversification of TGEV. Notably, the S gene is under strong positive selection, with five key codons under selection pressure, suggesting that the potential host–virus evolutionary arms race accelerates TGEV adaptation and diversification. Haplotype network analysis revealed that U.S. strains exhibit the highest genetic diversity, while Chinese strains are characterized by two dominant haplotypes surrounded by multiple closely related minor haplotypes. Bayesian phylogeographic analysis further confirmed that China has played an important role in the global dissemination of TGEV and clarified its transmission routes to regions such as the United States and Vietnam. Overall, this study advances our understanding of the evolution and spread of TGEV, and may contribute to the development of more effective strategies for its prevention and control.