Biology subjects

Cross, S. T.

Publications and source records attributed to Cross, S. T..

6 recordsLinked to original sources

bioRxiv2026

BaitBench: a comprehensive tool for building, as-sessing, and predicting outcomes for hybrid capture enrichment probes

The effectiveness of hybridization capture sequencing, a powerful lab technique to isolate and characterize low-abundance samples from complex nucleic acid mixtures, relies heavily on creating a robust probe set. There are a variety of tools that design, evaluate, or simulate capture probes, however, these tools are often siloed and frequently difficult to use. To our knowledge there is no tool that connects all steps of the hybridization capture probe development and analysis process. Here we introduce BaitBench, a comprehensive tool to aid in the design, assessment, and simulation of target capture probes. BaitBench wraps or reimplements in Rust several current tools, and implements a thermodynamic model for simulating capture. Integrating steps allows us to track simulated reads through the whole process enabling us to report sources of false positives and reasons for false negatives. Easy to read output files and the ability to run via command line or GUI interfaces increases usability. We validated BaitBench against publicly available data and achieved a high correlation ({rho} = 0.916), demonstrating its accuracy and translation to real-world settings. Code is available at github.com/niel-infante/BaitBench, with installers for Mac and Windows available at github.com/niel-infante/BaitBench/releases.

bioinformatics↗

bioRxiv2021

Spatiotemporal transcriptomics reveals pathogenesis of viral myocarditis

A significant fraction of sudden death in children and young adults is due to myocarditis, an inflammatory disease of the heart, most often caused by viral infection. Here we used integrated single-cell and spatial transcriptomics to create a high-resolution, spatially resolved map of reovirus-induced myocarditis in neonatal murine hearts. We assayed hearts collected at three timepoints after reovirus infection and studied the temporal, spatial, and cellular heterogeneity of host-virus interactions. We further assayed the intestine, the primary site of reovirus infection to establish a full chronology of molecular events that ultimately lead to myocarditis. We implemented targeted enrichment of viral transcripts to establish the cellular targets of the virus in the intestine and the heart. Our data give insight into the cell-type specificity of innate immune responses, and into the transcriptional states of inflamed cardiac cells in reovirus-infected heart. We find that inflamed endothelial cells recruit cytotoxic T cells and undergo pyroptosis in the myocarditic tissue. Analyses of spatially restricted gene expression in myocarditic regions and the border zone around those regions identified immune-mediated cell-type specific injury and stress responses. Overall, we observe a dynamic and complex network of cellular phenotypes and cell-cell interactions associated with viral myocarditis.

genomics↗

bioRxiv2021

Galbut virus infection minimally influences Drosophila melanogaster fitness traits in a strain and sex-dependent manner

Galbut virus (family Partitiviridae) infects Drosophila melanogaster and can be transmitted vertically from infected mothers or infected fathers with near perfect efficiency. This form of super-Mendelian inheritance should drive infection to 100% prevalence, and indeed galbut virus is ubiquitous in wild D. melanogaster populations. But on average only about 60% of individual flies are infected. One possible explanation for this apparent paradox is that a subset of flies are resistant to infection. Although galbut virus infected flies seem healthy, infection may be sufficiently costly to drive selection for resistant hosts, thereby decreasing overall prevalence. To test this hypothesis, we quantified a variety of fitness-related traits in galbut virus infected flies from two lines from the Drosophila Genetic Reference Panel (DGRP). Galbut virus infected flies had slightly decreased average lifespan and total offspring production, but these decreases were mostly not statistically significant. Galbut virus DGRP-517 flies pupated and eclosed slightly faster than their uninfected counterparts. Some galbut virus infected flies exhibited altered sensitivity to viral, bacterial, and fungal pathogens. Galbut virus infection produced minimal changes to host mRNA levels as measured by RNA sequencing, consistent with minimal phenotypic changes. The microbiome composition of flies was not measurably perturbed by galbut virus infection. Differences in phenotype attributable to galbut virus infection varied as a function of fly sex and DGRP strain and were generally dwarfed by larger differences attributable to strain and sex. Thus, galbut virus infection does produce measurable phenotypic changes, with changes being minor, offsetting, and possibly net negative. ImportanceVirology has largely focused on viruses that cause unmistakable phenotypic changes. But metagenomic surveys are revealing that persistent virus infections are extremely common, even in apparently healthy organisms. The extent to which these persistent viruses impact host fitness and evolution remains largely unclear. Here we study fitness impacts of a partitivirus named galbut virus that is ubiquitous in wild D. melanogaster populations. Despite efficient biparental vertical transmission, galbut virus is present in only just over half of wild flies. We quantified various fitness-related traits in galbut virus infected and uninfected fly lines and found that infection produced small but measurable changes in host phenotype that in aggregate may reduce fly fitness. Further studies that take advantage of this virus that naturally infects a premier model organism that is easy to study in the wild will shed further light on the persistent virus-host dynamics that may actually represent most viral infections.

microbiology↗

bioRxiv2021

The multi-functional reovirus σ3 protein is a virulence factor that suppresses stress granule formation to allow viral replication and myocardial injury

The mammalian orthoreovirus double-stranded (ds) RNA binding protein {sigma}3 is a multifunctional protein that promotes viral protein synthesis and facilitates viral entry and assembly. The dsRNA-binding capacity of {sigma}3 correlates with its capacity to prevent dsRNA-mediated activation of protein kinase R (PKR). However, the effect of {sigma}3 binding to dsRNA during viral infection remains largely unknown. To identify functions of {sigma}3 dsRNA-binding activity during reovirus infection, we engineered a panel of 13 {sigma}3 mutants and screened them for the capacity to bind dsRNA. Six mutants were defective in dsRNA binding, and mutations in these constructs cluster in a putative dsRNA-binding region on the surface of {sigma}3. Two recombinant viruses expressing these {sigma}3 dsRNA-binding mutants, K287T and R296T, display strikingly different phenotypes. In a cell-type dependent manner, K287T, but not R296T, replicates less efficiently than wild-type (WT) virus. In cells in which K287T virus demonstrates a replication deficit, PKR activation occurs and abundant stress granules (SGs) are produced at late times post-infection. In contrast, the R296T virus retains the capacity to suppress activation of PKR and does not form SGs at late times post-infection. These findings indicate that {sigma}3 inhibits PKR independently of its capacity to bind dsRNA. In infected mice, K287T produces lower viral titers in the spleen, liver, lungs, and heart relative to WT or R296T. Moreover, mice inoculated with WT or R296T viruses develop myocarditis, whereas those inoculated with K287T do not. Overall, our results indicate that {sigma}3 functions to suppress PKR activation and subsequent SG formation during viral infection and that these functions correlate with virulence in mice.

microbiology↗

bioRxiv2020

A Whole Virion Vaccine for COVID-19 Produced Via a Novel Inactivation Method: Results from Animal Challenge Model Studies

The COVID-19 pandemic has generated intense interest in the rapid development and evaluation of vaccine candidates for this disease and other emerging diseases. Several novel methods for preparing vaccine candidates are currently undergoing clinical evaluation in response to the urgent need to prevent the spread of COVID-19. In many cases, these methods rely on new approaches for vaccine production and immune stimulation. We report on the use of a novel method (SolaVAX) for production of an inactivated vaccine candidate and the testing of that candidate in a hamster animal model for its ability to prevent infection upon challenge with SARS-CoV-2 virus. The studies employed in this work included an evaluation of the levels of neutralizing antibody produced post-vaccination, levels of specific antibody sub-types to RBD and spike protein that were generated, evaluation of viral shedding post-challenge, flow cytometric and single cell sequencing data on cellular fractions and histopathological evaluation of tissues post-challenge. The results from this study provide insight into the immunological responses occurring as a result of vaccination with the proposed vaccine candidate and the impact that adjuvant formulations, specifically developed to promote Th1 type immune responses, have on vaccine efficacy and protection against infection following challenge with live SARS-CoV-2. This data may have utility in the development of effective vaccine candidates broadly. Furthermore, the results suggest that preparation of a whole virion vaccine for COVID-19 using this specific photochemical method may have utility in the preparation of one such vaccine candidate. Author SummaryWe have developed a vaccine for COVID-19 which is prepared by a novel method for inactivation of a whole virion particle and tested it in a hamster animal model for its ability to protect against SARS-CoV-2 infection.

immunology↗

bioRxiv2020

Partitiviruses infecting Drosophila melanogaster and Aedes aegypti exhibit efficient biparental vertical transmission

Partitiviruses are segmented, multipartite dsRNA viruses that until recently were only known to infect fungi, plants, and protozoans. Metagenomic surveys have revealed that partitivirus-like sequences are also commonly associated with arthropods. One arthropod-associated partitivirus, galbut virus, is extraordinarily common in wild populations of Drosophila melanogaster fruit flies. To begin to understand the processes that underlie this viruss high global prevalence, we established colonies of wild-caught infected flies. Infection remained at stably high levels over three years, with between 63-100% of individual flies infected. Galbut virus infects fly cells and replicates in tissues throughout infected adults, including reproductive tissues and the gut epithelium. We detected no evidence of horizontal transmission via ingestion but vertical transmission from either infected females or infected males was ~100% efficient. Vertical transmission of a related partitivirus, verdadero virus, that we discovered in a laboratory colony of Aedes aegypti mosquitoes was similarly efficient. This suggests that efficient biparental vertical transmission may be a feature of at least a subset of insect-infecting partitiviruses. To study the impact of galbut virus infection free from the confounding effect of other viruses, we generated an inbred line of flies with galbut virus as the only detectable virus infection. We were able to transmit infection experimentally via microinjection of homogenate from these galbut-only flies. This sets the stage for experiments to understand the biological impact and possible utility of partitiviruses infecting important model organisms and disease vectors. ImportanceGalbut virus is a recently discovered partitivirus that is extraordinarly common in wild populations of the model organism Drosophila melanogaster. Like most viruses discovered through metagenomics, most of the basic biological questions about this virus remain unanswered. We found that galbut virus, along with a closely related partitivirus found in Aedes aegypti mosquitoes, is transmitted from infected females or males to offspring with ~100% efficiency and can be maintained in laboratory colonies over years. This represents one of the most efficient means of virus transmission described, and likely underlies the successful spread of these viruses through insect populations. We created Drosophila lines that contained galbut virus as the only virus infection and showed that these flies can be used as a source for experimental infections. This provides insight into how arthropod-infecting partitiviruses may be maintained in nature and sets the stage for exploration of their biology and potential utility.

microbiology↗