Porcine Epidemic Diarrhea Virus (PEDV) was introduced in the United States (U.S.) in 2013, spreading rapidly and leading to economic losses. Two strains, S-INDEL and non-S-INDEL, are present in the U.S. We analyzed 313 genomes and 556 Spike protein sequences generated since its introduction. PEDV case numbers were highest during the first two years after its introduction (epidemic phase), then declined and stabilized in the following years (endemic phase). Sequence surveillance was higher during the initial epidemic phase. Our results suggest the non-S-INDEL strain is the predominant strain in U.S. The non-S-INDEL sequences exhibit pairwise nucleotide identity percentages above 97.6%. Most non-S-INDEL sequences sampled after 2017 clustered into two sub-clades. No descendants derived from other clades present in the epidemic period were detected in the contemporary data, suggesting that these clades are no longer circulating in the U.S. The two clades currently circulating are restricted to two respective geographic regions and our results suggest limited inter-regional spread. This insight helps determine the risk of re-introduction of PEDV if it were regionally eliminated. Ongoing molecular surveillance is essential to confirming that some older clades no longer circulate anymore in the U.S., mapping the distribution and spread of recent clades, and understanding PEDV’s evolutionary diversification.

Porcine Reproductive and Respiratory Syndrome Virus 2 (PRRSV-2) represents one of the greatest threats to global pork production. Increased incidence of a genetic variant of Porcine Reproductive and Respiratory Syndrome Virus (variant 1H.18) was recently reported in the Midwestern USA Sequence comparisons in the ORF5 region indicate that 1H.18 was closely related to both sub-lineages L1H and L1C. To expand our understanding and attempt to elucidate the origin of the 1H.18, we sequenced a near-complete genome, covering all coding regions, and investigated the occurrence of recombination events that may have contributed to the emergence of the new variant. At least six distinct recombination events were identified across the coding portion of the genome. Evidence of recombination in the ORF5 region between variants 1H.31 and 1C.3 was detected. Our results suggest a likely origin of 1H.18 driven by recombination.

PRRSV-2 represents a major threat to the swine industry. Canada is one of the world’s leading pork producers and a major trading partner of live pigs with the United States, yet PRRSV-2 evolutionary dynamics in these two countries are often studied independently, partly due to limited publicly available sequence data from Canada. We analyzed more than 3000 PRRSV-2 ORF5 sequences collected between 2000 and 2024 from five Canadian provinces. Thirteen previously described sub-lineages were detected in Canada, while approximately one-third of the sequences could not be assigned to any known sub-lineage. Phylogenetic analyses incorporating global reference sequences revealed that most unclassified sequences clustered into four distinct monophyletic clades, exhibiting genetic distances greater than 9.5% from recognized sub-lineages. We propose two new sub-lineages, 1K and 1L, corresponding to clades that were prevalent and persistent over time, whereas the remaining two clades were rare and last detected in 2021. We reconstructed cross-border transmission histories and found that sub-lineages 1C, 1H, 1I, 1K, and 1L originated in Canada, whereas 1A, 1B, 1E, and 1F originated in the United States. Transmission patterns varied across sub-lineages, ranging from unidirectional to bidirectional movement. Our findings refine PRRSV-2 classification and provide insights to inform targeted surveillance, particularly at national borders.

Begomoviruses pose a major threat to food security, particularly in developing countries. These small ssDNA viruses exhibit substitution rates comparable to those of RNA viruses. The temporal dynamics of begomoviruses in non-agricultural environments have been largely overlooked, and little is known about how these viruses evolve in the absence of anthropogenic influence. In this study, we investigated the temporal dynamics of begomoviruses in a small fragment of regenerating Atlantic Forest area in the state of Minas Gerais, Brazil. Samples of Sida acuta , a wild plant native from South America, were collected at the same location over a 12-year period (2011-2022). Five distinct begomoviruses were detected infecting this host: OxYVV, SiYLCV, SimMV, MaYVV, and SiMV. OxYVV and SimMV were subdivided into multiple variants, revealing their potential as reservoirs of viral biodiversity. Several shifts in species and variant composition were observed in the viral community over time, with the most drastic change occurring in 2016, when SiYLCV outnumbered OxYVV. The reasons behind this turnover remain uncertain, but the most compelling clues point to a population expansion of SiYLCV. We detected a strong temporal signal in two of the most abundant viruses (OxYVV and SiYLCV), which allowed us to calibrate molecular clocks and estimate substitution rates for both of them. Our results indicate that, even in the natural environment, begomoviruses can evolve at rates similar to those reported in agricultural systems.

PRRSV-2 represents a major threat to the swine industry. Canada is one of the world’s leading pork producers and a major trading partner of live pigs with the United States, yet PRRSV-2 evolutionary dynamics in these two countries are often studied independently, partly due to limited publicly available Canadian data. We analyzed more than 3,000 PRRSV-2 ORF5 sequences collected between 2000 and 2024 from five Canadian provinces. Thirteen distinct sub-lineages were detected in Canada, while approximately one-third of the sequences could not be assigned to any known sub-lineage. Phylogenetic analyses incorporating global reference sequences revealed that most unclassified sequences clustered into four distinct monophyletic clades, exhibiting genetic distances greater than 9.5% from recognized sub-lineages. We propose two new sub-lineages, 1K and 1L, cor-responding to clades that were prevalent and persistent over time, whereas the remaining two clades were rare and last detected in 2021. We reconstructed cross-border transmission histories and found that sub-lineages 1C, 1H, 1I, 1K, and 1L originated in Canada, whereas 1A, 1B, 1E, and 1F originated in the United States. Transmission patterns varied across sub-lineages, ranging from unidirectional to bidirectional movement. Our findings refine PRRSV-2 classification and provide insights to inform targeted surveillance, par-ticularly at national borders.