Biology subjects

Myles, K. M.

Publications and source records attributed to Myles, K. M..

6 recordsLinked to original sources

bioRxiv2025

The Sindbis virus nsP3 opal codon protects viral RNA and fitness by maintaining replication spherule integrity

Most alphaviruses maintain an in-frame opal stop codon that interrupts their non-structural polyprotein (nsP) ORF between nsP3 and nsP4 in both vertebrate and insect hosts. We show that the nsP3 opal stop codon confers a replicative advantage to Sindbis virus (SINV) in RNAi-competent mosquito cells and in Aedes aegypti mosquitoes, but not in cells or mosquitoes lacking RNAi. Mutation of the opal stop codon delays processing of the viral nsP polyprotein, disrupts viral replication spherule integrity, and renders viral RNA susceptible to Dicer 2 cleavage, resulting in higher antiviral siRNA responses against SINV. Similarly, these defects caused by opal codon mutations lead to increased viral RNA detection and enhanced immune signaling in vertebrate cells. Thus, a single stop codon in alphaviruses mediates a multipotent viral strategy to evade innate immune defenses across diverse hosts. TeaserA conserved ORF-interrupting stop codon helps alphaviruses avoid triggering innate antiviral immunity across diverse hosts.

microbiology↗

bioRxiv2025

Enhancing Tissue-Specific Antiviral Immunity to Disrupt Arbovirus Transmission by Mosquitoes

Arboviruses, including dengue virus (DENV), Zika virus (ZIKV), and chikungunya virus (CHIKV), pose a significant global health and economic burden, with Aedes aegypti serving as their primary vector. Arbovirus infection in Ae. aegypti progresses sequentially through the midgut (MG), carcass (CA), and salivary glands (SG), with each tissue exhibiting distinct antiviral responses. Here, we investigate tissue-specific antiviral mechanisms, focusing on the small interfering RNA (siRNA) pathway in SGs. Our results reveal that SGs possess weaker antiviral defense and are more susceptible to arboviral infection compared to MGs and CAs. Notably, overexpression of Dicer2 (Dcr2), a key component of the siRNA pathway, in SGs leads to a significant decrease in arboviral replication. Conversely, Dcr2 overexpression in fat bodies, the primary tissue in CAs, only moderately suppresses DENV2 infection and has no notable effect on Mayaro virus (MAYV) infection. Remarkably, the simultaneous overexpression of Dcr2 in both MGs and SGs enhances antiviral activity, effectively blocking the transmission of multiple arboviruses. These findings reveal the tissue-specific dynamics of mosquito antiviral immunity and underscore the potential for targeting SG-specific immunity to disrupt arbovirus transmission, providing a promising approach for controlling mosquito-borne diseases.

microbiology↗

bioRxiv2025

Exploiting attP landing sites and gypsy retrovirus insulators to identify and study viral suppressors of RNA silencing

RNA interference (RNAi) pathways are crucial for regulating viral infections in both animals and plants, acting as defense mechanisms that limit pathogen replication. This has led to the evolution of viral suppressors of RNA silencing (VSRs) across various plant and insect viruses, with potential analogs in arthropod-borne human pathogens. However, while functionally similar, VSRs often lack genetic conservation due to convergent evolution. Research on VSRs typically involves analyzing individual proteins expressed in host cells with secondary reporter constructs, but the lack of a standardized system can lead to inconsistent findings. Our study examined how genomic insertion sites affect VSR activity using a transgenic Drosophila melanogaster reporter system. We integrated the VSR protein DCV-1A into three different attP sites and assessed silencing. The results showed significant variation in VSR activity across loci due to position effects. However, by flanking the transgenes with gypsy retrovirus insulators, we achieved consistent high-level silencing across all sites. These findings suggest the potential for establishing a standardized reporter system in Drosophila, facilitating the identification, study and comparison of VSR proteins. However, our results also highlight the limitations of using isolated proteins in reporter systems, emphasizing the need for a comprehensive holistic approach to definitively determine VSR functions.

microbiology↗

bioRxiv2024

The Rac1 homolog CED-10 is a component of the MES-1/SRC-1 pathway for asymmetric division of the C. elegans EMS blastomere

Asymmetric cell division is essential for the creation of cell types with different identities and functions. The EMS blastomere of the four-cell Caenorhabditis elegans embryo undergoes an asymmetric division in response to partially redundant signaling pathways. One pathway involves a Wnt signal emanating from the neighboring P2 cell, while the other pathway is defined by the receptor-like MES-1 protein localized at the EMS/P2 cell contact, and the cytoplasmic kinase SRC-1. In response to these pathways, the EMS nuclear-centrosome complex rotates so that the spindle forms on the anterior-posterior axis; after division, the daughter cell contacting P2 becomes the endodermal precursor cell. Here we identify the Rac1 homolog, CED-10, as a new component of the MES-1/SRC-1 pathway. Loss of CED-10 affects both spindle positioning and endoderm specification. Although MES-1 is still present at the EMS/P2 contact in ced-10 embryos, SRC-1 dependent phosphorylation is reduced. These and other results suggest that CED-10 acts downstream of MES-1 and upstream of, or at the level of, SRC-1 activity. In addition, we find that the branched actin regulator ARX-2 is enriched at the EMS/P2 cell contact site, in a CED-10 dependent manner. Loss of ARX-2 results in spindle positioning defects, suggesting that CED-10 acts through branched actin to promote the asymmetric division of the EMS cell.

developmental biology↗

bioRxiv2024

Exposure to cooler temperatures during pupal development increases Aedes aegypti vector competence and the R0 for Zika virus

Temperature profoundly affects various aspects of ectotherm biology. Notably, in mosquito species that spread viral diseases, temperature influences not only vector biology, but also the dynamics of pathogen-vector interactions. However, research attempting to address the role of the thermal environment in disease transmission often employs constant temperatures, which do not reflect the natural diurnal fluctuations these organisms experience. Additionally, most studies focus on adult mosquitoes in the period following virus infection. Much less attention has been paid to evidence indicating that temperatures experienced during earlier developmental stages may also affect the ability of disease vectors to be infected with and transmit viruses. Here, we show that Aedes aegypti exposed to temperatures below 25{degrees}C, specifically during the pupal stage of development, exhibit heightened susceptibility to Zika virus (ZIKV), which increases transmission efficiency. Modeling suggests that exposing mosquitoes to cooler fluctuating diurnal temperature ranges only during the relatively short pupal stage increases the R0 or reproductive number of ZIKV. Data loggers placed near Harris County Mosquito Control trap sites consistently recorded temperatures below 25{degrees}C, indicating natural exposure to such conditions. These results highlight the significance of thermal heterogeneity in the microhabitats where container-breeding mosquitoes undergo development. Such heterogeneity may play a more important role in the transmission of mosquito-borne diseases than previously recognized. Author SummaryA paucity of information regarding how natural heterogeneity in thermal environments influences the spread of viral pathogens by mosquito species hinders our ability to decipher current and future patterns of disease transmission under changing climatic conditions. Here, we show that Ae. aegypti pupae exposed to cooler fluctuating diurnal temperature ranges, mimicking realistic field conditions, increases vector competence for ZIKV. Modeling cooler temperatures during immature life stages predicts slower development and increased mortality, counterbalancing increases in disease transmission. However, exposing mosquitoes to lower temperatures only during the relatively short pupal stage was predicted to increase the R0 value of ZIKV. These results suggest that environmental temperatures specifically experienced during the pupal stage may have an important role in disease transmission.

microbiology↗

bioRxiv2018

Predicting Aquatic Development and Mortality Rates of Aedes Aegypti

Mosquito-borne pathogens continue to be a significant burden within human populations, with Aedes aegypti continuing to spread dengue, chikungunya, and Zika virus throughout the world. Using data from a previously conducted study, a linear regression model was constructed to predict the aquatic development rates based on the average temperature, temperature fluctuation range, and larval density. Additional experiments were conducted with different parameters of average temperature and larval density to validate the model. Using a paired t-test, the model predictions were compared to experimental data and showed that the prediction models were not significantly different for average pupation rate, adult emergence rate, and juvenile mortality rate. The models developed will be useful for modeling and estimating the number of Aedes aegypti in the environment under different temperature, diurnal temperature variations, and larval densities.\n\nAuthor SummaryUsing experimental data from experiments conducted on Aedes aegypti, we formulated regression models to predict pupation, adult emergence, and juvenile mortality rates based on average temperature, temperature fluctuation range, and larval density. The prediction models produced were shown to account for high levels of variation within the data. Validation was performed by comparing omitted data sets to the predictions generated by our models. Our results show that the models produce results that are not significantly different from the experimental results and are capable of predicting aquatic development rates of Ae. aegypti.

ecology↗