Miranda R. Bertram

Foot‐and‐mouth disease virus (FMDV) persists endemically through carrier animals that maintain infection >21 days postdetection. We characterized within‐host FMDV evolution in persistently infected cattle ( n = 168) and buffalo ( n = 16) from northern Vietnam using longitudinal oropharyngeal sampling (3–4 month intervals) under non‐outbreak conditions. Animals remained rRT‐PCR positive without clinical FMD. Persistent infections were defined by 5% divergence between sequential samples. From 120 sequences across 38 persistently infected hosts (PIHs), 13.3% of apparent carriers (rRT‐PCR positive >21 days) were actually serially infected with distinct strains. This emphasizes the need for sequence confirmation alongside OPF positivity when estimating carrier prevalence in high‐diversity settings. True persistent infections ( n = 33 animals) showed rapid VP1 evolution (0.081 mutations/nt site/yr), with diversifying selection strongest in VP1 and VP3 capsid regions. Serotype O PIH exhibited higher VP3 mutation rates than serotype A. Interserotypic recombination was also detected, consistent with carrier animals serving as viral mixing vessels. These field data confirm high evolutionary rates and recombination within FMDV carriers under natural conditions, extending experimental superinfection findings to endemic systems. Results support targeted PIH detection and management to disrupt FMDV persistence and evolution in resource‐limited regions.

Two near full-length sequences of vesicular stomatitis Indiana virus (VSIV), representing endemic VSIV lineages circulating in cattle in Mexico, are reported. These sequences will allow us to gain more insight into the genetic relationship between endemic viruses in Mexico and the emergence of epizootic lineages in the United States.

For the first time, we describe phylogenomic signatures of an epidemic lineage of vesicular stomatitis Indiana virus (VSIV). We applied multiple evolutionary analyses to a dataset of 87 full-length genome sequences representing the circulation of an epidemic VSIV lineage in the US between 2019 and 2020. Based on phylogenetic analyses, we predicted the ancestral relationship of this lineage with a specific group of isolates circulating in the endemic zone of Chiapas, Mexico. Subsequently, our findings indicate that the lineage diversified into at least four different subpopulations during its circulation in the US. We identified single nucleotide polymorphisms (SNPs) that differentiate viral subpopulations and assessed their potential relevance using comparative phylogenetic methods, highlighting the preponderance of synonymous mutations during the differentiation of these populations. Purifying selection was the main evolutionary force favoring the conservation of this epidemic phenotype, with P and G genes as the main drivers of the evolution of this lineage. Our analyses identified multiple codon sites under positive selection and the association of these sites with specific functional domains at P, M, G, and L proteins. Based on ancestral reconstruction analyses, we showed the potential relevance of some of the sites identified under positive selection to the adaptation of the epidemic lineage at the population level. Finally, using a representative group of viruses from Colorado, we established a positive correlation between genetic and geographical distances, suggesting that positive selection on specific codon positions might have favored the adaptation of different subpopulations to circulation in specific geographical settings. Collectively, our study reveals the complex dynamics that accompany the evolution of an epidemic lineage of VSIV in nature. Our analytical framework provides a model for conducting future evolutionary analyses. The ultimate goal is to support the implementation of an early warning system for vesicular stomatitis virus in the US, enabling early detection of epidemic precursors from Mexico.

For the first time, we describe phylogenomic signatures of an epidemic lineage of vesicular stomatitis Indiana virus (VSIV). We applied multiple evolutionary analyses to a dataset of full-length genome sequences representing the circulation of an epidemic VSIV lineage in the US between 2019 and 2020. Based on phylogenetic analyses, we predicted the ancestral relationship of this lineage with a specific group of isolates circulating in the endemic zone of Chiapas, Mexico. Subsequently, our findings indicate that the lineage diversified into at least four different subpopulations during its circulation in the US. We identified single nucleotide polymorphisms (SNPs) that differentiate viral subpopulations and assessed their potential relevance using comparative phylogenetic methods, highlighting the preponderance of synonymous mutations during the differentiation of these populations. Purifying selection was the main evolutionary force favoring the conservation of this epidemic phenotype, with P and G genes as the main drivers of the evolution of this lineage. Our analyses identified multiple codon sites under positive selection and the association of these sites with specific functional domains at P, M, G, and L proteins. Based on ancestral reconstruction analyses, we showed the potential relevance of some of the sites identified under positive selection to the adaptation of the epidemic lineage at the population level. Finally, using a representative group of viruses from Colorado, we established a positive correlation between genetic and geographical distances, suggesting that positive selection on specific codon positions might have favored the adaptation of different subpopulations to circulation in specific geographical settings. Collectively, our study reveals the complex dynamics that accompany the evolution of an epidemic lineage of VSIV in nature. Our analytical framework provides a model for conducting future evolutionary analyses. The ultimate goal is to support the implementation of an early warning system for vesicular stomatitis virus in the US, enabling early detection of epidemic precursors from Mexico.

We conducted an integrative analysis to elucidate the spatial epidemiological patterns of the Vesicular Stomatitis New Jersey virus (VSNJV) during the 2014–15 epizootic cycle in the United States (US). Using georeferenced VSNJV genomics data, confirmed vesicular stomatitis (VS) disease cases from surveillance, and a suite of environmental factors, our study assessed environmental and phylogenetic similarity to compare VS cases reported in 2014 and 2015. Despite uncertainties from incomplete virus sampling and cross-scale spatial processes, patterns suggested multiple independent re-invasion events concurrent with potential viral overwintering between sequential seasons. Our findings pointed to a geographically defined southern virus pool at the US–Mexico interface as the source of VSNJV invasions and overwintering sites. Phylodynamic analysis demonstrated an increase in virus diversity before a rise in case numbers and a pronounced reduction in virus diversity during the winter season, indicative of a genetic bottleneck and a significant narrowing of virus variation between the summer outbreak seasons. Environment–vector interactions underscored the central role of meta-population dynamics in driving disease spread. These insights emphasize the necessity for location- and time-specific management practices, including rapid response, movement restrictions, vector control, and other targeted interventions.

Bayesian space–time regression models are helpful tools to describe and predict the distribution of infectious disease outbreaks and to delineate high-risk areas for disease control. In these models, structured and unstructured spatial and temporal effects account for various forms of non-independence amongst case counts across spatial units. Structured spatial effects capture correlations in case counts amongst neighboring provinces arising from shared risk factors or population connectivity. For highly mobile populations, spatial adjacency is an imperfect measure of connectivity due to long-distance movement, but we often lack data on host movements. Phylogeographic models inferring routes of viral dissemination across a region could serve as a proxy for patterns of population connectivity. The objective of this study was to investigate whether the effects of population connectivity in space–time regressions of case counts were better captured by spatial adjacency or by inferences from phylogeographic analyses. To compare these two approaches, we used foot-and-mouth disease virus (FMDV) outbreak data from across Vietnam as an example. We identified that accounting for virus movement through phylogeographic analysis serves as a better proxy for population connectivity than spatial adjacency in spatial–temporal risk models. This approach may contribute to design surveillance activities in countries lacking movement data.

Foot-and-mouth disease virus (FMDV) SAT2 sequences were acquired from Cape buffalo in Kenya in 2016, from either primary passage ( n = 38) or plaque purification of dually SAT1/SAT2-infected samples ( n = 61). All samples were derived from asymptomatic animals. These sequences contribute to our understanding of FMDV diversity in reservoirs and during subclinical FMDV infections.

Nearly complete genomes of 49 novel foot-and-mouth disease virus (FMDV) SAT1 strains acquired from oropharyngeal fluid samples from asymptomatic African Cape buffalo in Kenya in 2016 were determined. Sequences were from primary passage or plaque-purified dually SAT1/SAT2-infected samples. These sequences are important for elucidation of the molecular epidemiology of persistent and subclinical FMDV infections.

We report the near full genome sequences of 18 isolates of foot-and-mouth disease virus serotype O and 6 isolates of serotype A obtained from outbreaks in Pakistan between 2011 and 2012. The scarcity of full-length FMDV sequences from this region enhances the importance of these genomes for understanding regional molecular epidemiology.