Temporal Dynamics of Recombination in Field Isolates of Foot-and-Mouth Disease Virus.

Foot-and-mouth disease virus (FMDV) is a highly contagious pathogen of cloven-hoofed livestock. Recombination is one of the mechanisms that contribute to genetic diversity of FMDV and facilitate the generation of new viral lineages, or recombinant forms. While the general patterns of recombination in FMDV are well-known, the temporal dynamics of this process remain unexplored. This study systematically analyzed recombination across 1485 publicly available complete genome sequences of FMDV, collected from 1934 to 2024. In addition to the well-known general recombination pattern with hotspots on the borders of the genome region that encodes capsid proteins VP2-VP3-VP1, we identified serotype-specific recombination patterns. A significant temporal signal required to analyze temporal dynamics was found in serotypes A, Asia1, O, and SAT1 in the VP2-VP3-VP1 genome region. To assess the lifetimes of FMDV recombinant forms, we compared these time-scaled phylogenetic trees with phylogenies for other genomic regions exchanged by recombination events. The median lifetimes of FMDV recombinant forms ranged from 2 to 18 years, depending on the serotype and the nonstructural genomic region involved in recombination. These timescales are comparable to human (+)RNA viruses, such as enteroviruses and caliciviruses. In distinct serotypes, recombination could be more frequent on the 5' or 3' border of the capsid-encoding genome region, without a uniform pattern.