Biology subjects

Evans, A. B.

Publications and source records attributed to Evans, A. B..

4 recordsLinked to original sources

bioRxiv2026

Energy Flux Regulates Cell Death Induced by California Serogroup Orthobunyaviruses

The California serogroup (CSG) of orthobunyaviruses includes neuroinvasive viruses with varying pathogenicity. La Crosse virus (LACV) is a leading cause of pediatric arboviral encephalitis in the USA, while Inkoo virus (INKV) is widespread in Northern Europe but rarely causes disease. The reassortment potential of CSG viruses raises concerns about emerging virulent strains and highlights the need to develop therapies that are broadly effective against multiple CSG viruses. To identify host factors mediating viral neurotoxicity, we performed genome-wide CRISPR-Cas9 knockout screens in human neuroblastoma cells infected with LACV or INKV. Analysis revealed largely overlapping host dependency factors for both viruses. Unexpectedly, the screens identified mitochondrial energy production as a major pathway required for both LACV- and INKV-induced cell death. Reducing host cell energy production with mild hypothermia or sugar source substitution prolonged cell survival during viral infection with additive effects mediated by different mechanisms. Both manipulations also protected neuroblastoma cells from the Bunyamwera virus (BUNV), a non-CSG orthobunyavirus; and mild hypothermia protected mature human neurons from LACV. These results highlight host energy metabolism as a key modulator of CSG virus cytotoxicity and suggest novel avenues for general non-invasive therapeutic intervention against current and future strains of these and other orthobunyaviruses.

microbiology↗

bioRxiv2025

Orthobunyavirus neurovirulence is a complex trait involving all three genome segments

La Crosse orthobunyavirus (LACV) is a tri-segmented negative sense RNA virus and is the leading cause of pediatric arboviral encephalitis in the USA. The viral factors that mediate LACVs ability to replicate and cause damage and disease in the brain (neurovirulence) are not fully understood. We previously characterized the neurovirulence of LACV and closely related Inkoo virus (INKV) and discovered they have opposing neurovirulence phenotypes in mice and human neuronal cells: LACV has high neurovirulence and INKV has low neurovirulence. We therefore generated reassortant viruses between LACV and INKV to map the genome segments that mediate LACVs high neurovirulence phenotype. We recovered all six possible reassortant viruses of the L, M, and S genome segments using coinfection and reverse genetics approaches. We evaluated the neurovirulence of these reassortant viruses in mice in vivo and in human neuronal cells in vitro. Our results show that no single LACV genome segment alone was sufficient to cause wildtype LACV-like neurological disease in mice, and in fact all six reassortant viruses were attenuated from wildtype LACV. We found that the LACV M and S segments together were the primary drivers of neurological disease in mice, whereas the LACV L segment played a minor role. Our in vitro results indicate that the LACV M segment is crucial for efficient replication in neurons, but the LACV L segment appears to mediate slightly more efficient neuronal replication than the INKV L segment. The LACV M and S segments together induced wildtype LACV-like levels of neuronal death, indicating the LACV M and S are the primary mediators of neuronal death, and the L segment is not required. Together, these results indicate that LACV neurovirulence is a complex trait mediated by viral proteins on all three genome segments.

microbiology↗

bioRxiv2024

A mix-and-match reverse genetics system for evaluating genetic determinants of orthobunyavirus neurological disease

The encephalitic orthobunyaviruses have tri-segmented, negative sense RNA genomes and can cause severe neurological disease in humans, including La Crosse virus (LACV), which is the leading cause of pediatric arboviral encephalitis in the United States. However, little is known about the genetic factors that drive neuropathogenesis. Reverse genetics (RG) systems are valuable tools for studying viral genetics and pathogenesis. Plasmid-based cDNA RG systems are available for LACV, however the plasmid backbones are medium-copy number and have a propensity for recombination. We therefore generated a plasmid-based cDNA RG system for LACV utilizing a more stable and high-copy number plasmid backbone. Additionally, we created the first full RG systems for two closely related orthobunyaviruses, Jamestown Canyon virus (JCV), and Inkoo virus (INKV), which have differing reported disease incidences in humans and differing neuropathogenic phenotypes in mice compared to LACV. We compared wild type (wt) viruses with RG-derived viruses in human neuronal cells and in mice, and found that RG-derived viruses maintained the replication and neuropathogenic phenotypes of their wt counterpart. Additionally, we demonstrated that reverse genetics plasmids from different parental viruses can be readily mix-and-matched to generate reassortant viruses. This system provides a valuable genetic tool utilizing viruses with differing neuropathogenic phenotypes to investigate the genetic determinants of orthobunyavirus neuropathogenesis.

microbiology↗

bioRxiv2023

N4-Hydroxycytidine/Molnupiravir Inhibits RNA-Virus Induced Encephalitis by Producing Mutated Viruses with Reduced Fitness

A diverse group of RNA viruses including Rabies, Polio, La Crosse, West Nile, Zika, Nipah, Eastern and Western equine encephalitis, Venezuelan equine encephalitis, Japanese encephalitis, and tick-borne encephalitis viruses have the ability to gain access to and replicate in the central nervous system (CNS), causing severe neurological disease. Current treatment for these patients is generally limited to supportive care. To address the need for a generalizable antiviral, we utilized a strategy of mutagenesis to limit virus replication. We evaluated ribavirin (RBV), favipiravir (FAV) and N4-hydroxycytidine (NHC) against La Crosse virus (LACV) which is the primary cause of pediatric arboviral encephalitis cases in North America. NHC was more potent than RBV or FAV in neuronal cells. Oral administration of molnupiravir (MOV), the 5-isobutyryl prodrug of NHC, decreased neurological disease development by 32% following intraperitoneal (IP) infection of LACV. MOV also reduced disease by 23% when virus was administered intranasally (IN). NHC and MOV produced less fit viruses by incorporating predominantly G-to-A or C-to-U mutations. Furthermore, NHC also inhibited two other orthobunyaviruses, Jamestown Canyon virus and Cache Valley virus. Collectively, these studies indicate that NHC/MOV has therapeutic potential to inhibit virus replication and subsequent neurological disease caused by this neurotropic RNA virus.

microbiology↗