Project description:We performed whole genome single nucleotide polymorphism (SNP) based analysis of all available Venezuelan equine encephalitis (VEE) virus antigenic complex genomes and developed a high resolution genome-wide SNP microarray. We used the SNP microarray to analyze a broad panel of VEEV isolates, found excellent concordance between array and sequence based genotypes for previously sequenced strains, and genotyped unsequenced strains.
Project description:No vaccines or antivirals are approved against Venezuelan equine encephalitis virus (VEEV) infection in humans. To improve our understanding of VEEV-host interactions, we simultaneously profiled host transcriptome and viral RNA (vRNA) in thousands of single cells during infection of human astrocytes. Host transcription was suppressed, and “superproducer cells” with extreme vRNA abundance and altered transcriptome emerged during the first viral life cycle. Cells with increased structural-to-nonstructural transcript ratio demonstrated upregulation of trafficking genes at later time points. Loss- and gain-of-function experiments confirmed pro- and antiviral host factors. Single-cell deep sequencing analysis identified a viral E3 protein mutation altering host gene expression. Lastly, comparison with data from other viruses highlighted common and unique pathways perturbed by infection across evolutionary scales. This study provides a high-resolution characterization of the cellular response to VEEV infection, identifies candidate targets for antivirals, and establishes a comparative single-cell approach to study the evolution of virus-host interactions.
Project description:Differing from other experimental models, intranasal infection with vaccine strain of Venezuelan equine encephalitis virus, VEEV, (TC83) caused high titer infection in the brain and 90–100% mortality in the C3H/HeN murine model. Intranasal infection with VEEV (TC83) caused persistent viral infection in the brains of mice without functional αβ T-cells (αβ-TCR -/-). While wild-type C57BL/6 mice clear infectious virus in the brain by 13 dpi, αβ-TCR -/- maintain infectious virus in the brain to 92 dpi. To better characterize the susceptibility to disease development in different strains of mice, we have analyzed the gene transcriptomes in the brains of infected mice.
Project description:The high mutation rate of RNA viruses provides viral populations with the ability to adapt to new environments but also makes them vulnerable to extinction due to the deleterious effects of mutations, which is the conceptual basis for the antiviral activity of RNA mutagens. However, there are still gaps in the quantitative understanding of the dynamics between the mutations induced by an RNA mutagen and its effects on viral fitness. To address this, we used Venezuelan Equine Encephalitis Virus (VEEV) and the potent RNA mutagen β-d-N4-hydroxycytidine (NHC) as a model to analyze virus replication competency and mutation frequency following treatment in the total and replication-competent viral populations separately. We found that NHC induced transition mutations in a concentration dependent manner in the total population, while the replication-competent population maintained itself within an increased, yet narrow, mutation spectrum. The incorporation of NHC mainly happened during the positive sense RNA synthesis of VEEV. A growth kinetic analysis of VEEV population treated with NHC pointed to a lower but more diverse distribution in mutational fitness, demonstrating that NHC-induced mutations negatively and broadly affect the fitness of the virus. Together, our study provides mechanistic insight into how RNA mutagens affect viral population landscape and the potential of RNA mutagens as an antiviral strategy for alphaviruses.