Regulatory T cells (T_regs) are a subset of T cells that are responsible for maintaining peripheral immune tolerance and homeostasis. The hallmark of T_regs is the expression of the forkhead box P3 (FoxP3) transcription factor. Natural regulatory T cells (nT_regs) are a distinct population of T cells that express CD4 and FoxP3. nTregs develop in the thymus and function in maintaining peripheral immune tolerance. Other CD4⁺, CD4^-CD8^-, and CD8⁺CD28^- T cells can be induced to acquire regulatory function by antigenic stimulation, depending on the cytokine milieu. Inducible (or adaptive) T_regs frequently express high levels of the interleukin 2 receptor (CD25). Atypical T_regs express FoxP3 and CD4 but have no surface expression of CD25. Type 1 regulatory T cells (Tr1 cells) produce IL-10, while T helper 3 cells (Th3) produce TGF-β. The function of inducible T_regs is presumably to maintain immune homeostasis, especially in the context of chronic inflammation or infection. Induction of T_regs in coronaviral infections protects against the more severe forms of the disease attributable to the host response. However, arteriviruses have exploited these T cell subsets as a means to dampen the immune response allowing for viral persistence. T_reg induction or activation in the pathogenesis of disease has been described in both porcine reproductive and respiratory syndrome virus, lactate dehydrogenase elevating virus, and mouse hepatitis virus. This review discusses the development and biology of regulatory T cells in the context of arteriviral and coronaviral infection.

Fusobacterium spp. are Gram-negative, oral bacteria that are increasingly associated with human pathologies as diverse as periodontitis, preterm birth, and colorectal cancer. While a recent surge in F. nucleatum research has increased our understanding of this human pathogen, a lack of complete genomes has hindered the identification and characterization of associated host-pathogen virulence factors. Here we report the first eight complete Fusobacterium genomes sequenced using an Oxford Nanopore MinION and Illumina sequencing pipeline and assembled using the open-source program Unicycler. These genomes are highly accurate, and seven of the genomes represent the first complete sequences for each strain. In summary, the FusoPortal resource provides a publicly available resource that will guide future genetic, bioinformatic, and biochemical experiments to characterize this genus of emerging human pathogens.

Theileria orientalis, genotype Ikeda, was recently detected in North America. Determining the emerging distribution of this pathogen is critical for understanding spread and developing management strategies. Whole blood samples were collected from cattle at Virginia livestock markets from September 2018 through December 2020. Animals were tested for T. orientalis using a universal and then genotype specific real-time PCR based on the MPSP gene. Prevalence for each genotype was analyzed for temporal trends and mapped by county. Spatial patterns were compared between genotypes and assessed for associations with habitat features, cattle movements through cattle markets and county proximity. Overall, 212 of 1980 samples tested positive for T. orientalis with an overall prevalence of 8.7% (172/1980) for genotype Ikeda, 1.8% (36/1980) for genotype Chitose, 0.2% (3/1980) for genotype Buffeli. The Ikeda genotype increased over time in northern and southwestern Virginia markets. The Ikeda and Chitose genotypes occurred in different regions, with little overlap, but for each genotype, spatial distribution was associated with a combination of cattle movements and environmental factors. Genotype specific qPCR testing and surveillance of cattle from across a wide area of Virginia are providing information on temporal, spatial, and other patterns for this emerging disease.

We report the complete genome sequence of a clinical isolate of Providencia stuartii strain CMC-4104, isolated from a splenic abscess. Oxford Nanopore Technologies (ONT) and Illumina sequencing reads were assembled using Geneious to generate a 4,504,925-bp circular chromosome containing multiple copies of the NDM-1 and PER-1 genes in a genomic resistance island.