Revisiting porcine circovirus infections in Uruguay: first evidence of PCV3 circulation and PCV2d as the sole genotype detected.

Porcine circoviruses (PCVs) are widespread among pig populations, and porcine circovirus type 2 (PCV2) is a major pathogen affecting swine health and productivity worldwide. Although PCV2 genetic diversity was previously characterized in Uruguay, updated information has been lacking for more than a decade, and porcine circovirus type 3 (PCV3) has not been reported. This study aimed to characterize recent PCV2 clinical cases and retrospectively investigate PCV3 circulation in archived samples previously analysed for PCV2. Complete PCV2 genomes obtained from clinical cases detected between 2017 and 2020 belonged to PCV2d. PCV3 was detected in archived samples from 2010 to 2014, including domestic pigs and wild boars, providing the first evidence of PCV3 circulation in Uruguay. All characterized PCV3 strains clustered within PCV3a, and PCV2/PCV3 coinfection was observed in several PCV3-positive samples. These findings indicate that PCV2d predominated among the investigated clinical cases from non-vaccinated farms and confirm PCV3 circulation in Uruguay, making it the fifth South American country to report the virus. Continued molecular surveillance is warranted to monitor PCV2 and PCV3 diversity and better understand the epidemiology of PCVs in Uruguay and across South America.