Project description:A Systematic Evaluation of High-Throughput Sequencing Approaches to Identify Low-Frequency Single Nucleotide Variants in Viral Populations
Project description:We describe the characterization of a foot-and-mouth disease (FMD) serotype A virus responsible for recent outbreaks of disease in Egypt. Phylogenetic analysis of VP1 nucleotide sequences demonstrated a close relationship to recent FMD virus isolates from East Africa, rather than to viruses currently circulating in the Middle East.
Project description:The current measures to control foot-and-mouth disease (FMD) include vaccination, movement control and slaughter of infected or susceptible animals. One of the difficulties in controlling FMD by vaccination arises due to the substantial diversity found among the seven serotypes of FMD virus (FMDV) and the strains within these serotypes. Therefore, vaccination using a single vaccine strain may not fully cross-protect against all strains within that serotype, and therefore selection of appropriate vaccines requires serological comparison of the field virus and potential vaccine viruses using relationship coefficients (r1 values). Limitations of this approach are that antigenic relationships among field viruses are not addressed, as comparisons are only with potential vaccine virus. Furthermore, inherent variation among vaccine sera may impair reproducibility of one-way relationship scores. Here, we used antigenic cartography to quantify and visualize the antigenic relationships among FMD serotype A viruses, aiming to improve the understanding of FMDV antigenic evolution and the scope and reliability of vaccine matching. Our results suggest that predicting antigenic difference using genetic sequence alone or by geographical location is not currently reliable. We found co-circulating lineages in one region that were genetically similar but antigenically distinct. Nevertheless, by comparing antigenic distances measured from the antigenic maps with the full capsid (P1) sequence, we identified a specific amino acid substitution associated with an antigenic mismatch among field viruses and a commonly used prototype vaccine strain, A22/IRQ/24/64.
Project description:A particular genetic lineage of foot-and-mouth disease virus (FMDV) serotype O, which we have named the PanAsia strain, was responsible for an explosive pandemic in Asia and extended to parts of Africa and Europe from 1998 to 2001. In 2000 and 2001, this virus strain caused outbreaks in the Republic of Korea, Japan, Russia, Mongolia, South Africa, the United Kingdom, Republic of Ireland, France, and the Netherlands, countries which last experienced FMD outbreaks decades before (ranging from 1934 for Korea to 1984 for the Netherlands). Although the virus has been controlled in all of these normally FMD-free or sporadically infected countries, it appears to be established throughout much of southern Asia, with geographically separated lineages evolving independently. A pandemic such as this is a rare phenomenon but demonstrates the ability of newly emerging FMDV strains to spread rapidly throughout a wide region and invade countries previously free from the disease.
Project description:Foot-and-mouth disease (FMD) is a highly contagious animal disease caused by an RNA virus subdivided into seven serotypes that are unevenly distributed in Asia, Africa, and South America. Despite the challenges of controlling FMD, since 1996 there have been only two outbreaks attributed to serotype C, in Brazil and in Kenya, in 2004. This article describes the historical distribution and origins of serotype C and its disappearance. The serotype was first described in Europe in the 1920s, where it mainly affected pigs and cattle but as a less common cause of outbreaks than serotypes O and A. No serotype C outbreaks have been reported in Europe since vaccination stopped in 1990. FMD virus is presumed to have been introduced into South America from Europe in the nineteenth century, although whether serotype C evolved there or in Europe is not known. As in Europe, this serotype was less widely distributed and caused fewer outbreaks than serotypes O and A. Since 1994, serotype C had not been reported from South America until four small outbreaks were detected in the Amazon region in 2004. Elsewhere, serotype C was introduced to Asia, in the 1950s to the 1970s, persisting and evolving for several decades in the Indian subcontinent and for eighteen years in the Philippines. Serotype C virus also circulated in East Africa between 1957 and 2004. Many serotype C viruses from European and Kenyan outbreaks were closely related to vaccine strains, including the most recently recovered Kenyan isolate from 2004. International surveillance has not confirmed any serotype C cases, worldwide, for over 15 years, despite more than 2,000 clinical submissions per year to reference laboratories. Serology provides limited evidence for absence of this serotype, as unequivocal interpretation is hampered by incomplete intra-serotype specificity of immunoassays and the continued use of this serotype in vaccines. It is recommended to continue strengthening surveillance in regions of FMD endemicity, to stop vaccination against serotype C and to reduce working with the virus in laboratories, since inadvertent escape of virus during such activities is now the biggest risk for its reappearance in the field.
Project description:Raw microarray derived data for evaluation of a feature and template-assisted assembler for the analysis of foot-and-mouth disease virus by sequence assembly
Project description:Systematic evaluation of the impact of genetic variants is critical for the study and treatment of human physiology and disease. While specific mutations can be introduced by genome engineering, we still lack scalable approaches that are applicable to the important setting of primary cells, such as blood and immune cells. Here, we describe the development of massively parallel base-editing screens in human hematopoietic stem and progenitor cells. Such approaches enable functional screens for variant effects across any hematopoietic differentiation state. Moreover, they allow rich phenotyping through single-cell RNA sequencing readouts, and separately, characterization of editing outcomes through pooled single-cell genotyping. We efficiently design improved leukemia immunotherapy approaches, comprehensively identify non-coding variants modulating fetal hemoglobin expression, define mechanisms regulating hematopoietic differentiation, and probe the pathogenicity of uncharacterized disease-associated variants. These strategies will advance effective and high-throughput variant-to-function mapping in human hematopoiesis to identify the causes of diverse diseases.
Project description:We compared genetic variations in the VP1 gene of foot-and-mouth disease viruses (FMDVs) isolated since 2000 from various region of the world. We analyzed relative synonymous codon usage (RSCU) and phylogenetic relationship between geographical regions, and calculated the genetic substitution patterns between Korean isolate and those from other countries. We calculated the ratios of synonymously substituted codons (SSC) to all observed substitutions and developed a new analytical parameter, EMC (the ratio of exact matching codons within each synonymous substitution group) to investigate more detailed substitution patterns within each synonymous codon group. We observed that FMDVs showed distinct RSCU patterns according to phylogenetic relationships in the same serotype (serotype O). Moreover, while the SSC and EMC values of FMDVs decreased according to phylogenetic distance, G + C composition at the third codon position was strictly conserved. Although there was little variation among the SSC values of 18 amino acids, more dynamic differences were observed in EMC values. The EMC values of 4- and 6-fold degenerate amino acids showed significantly lower values while most 2-fold degenerate amino acids showed no significant difference. Our findings suggest that different EMC patterns among the 18 amino acids might be an important factor in determining the direction of evolution in FMDV.
Project description:We report the genome sequence of a foot-and-mouth disease virus (FMDV) serotype A topotype Africa isolate collected from bovine vesicular epithelium from Kenya in 2016. This novel sequence updates the knowledge of FMDV diversity in eastern Africa and has important implications for FMDV epidemiology and molecular analyses.