Biology subjects

Lanahan, M. R.

Publications and source records attributed to Lanahan, M. R..

4 recordsLinked to original sources

bioRxiv2026

IFIT3 Associates with m⁶A-Modified RNA to Restrict Hepatitis C Virus Infection

Interferon-induced proteins with tetratricopeptide repeats (IFITs) are RNA-binding effectors that restrict infection by diverse RNA viruses. Among the IFIT family, how IFIT3 recognizes RNA remains the least understood. Here, we identify IFIT3 as preferentially associating with N6-methyladenosine (mA)-modified hepatitis C virus (HCV) genomic RNA and host transcripts to restrict HCV infection. IFIT3 cellular RNA binding sites and mA sites, mapped transcriptome-wide by HyperTRIBE-seq during HCV infection, showed significant overlap. This mA preference was further supported by findings that IFIT3 binding sites significantly overlapped those of established mA-binding proteins; that inhibiting mA installation reduced IFIT3 association with mA-modified HCV RNA and cellular transcripts; that IFIT3 co-purified more efficiently with mA-modified short RNA probes than with unmodified controls; and that mutating mA consensus motifs in the HCV genome reduced IFIT3 association with viral RNA. Structure-function analyses identified two regions required for RNA probe binding: tetratricopeptide repeat domains 1-2 (TPR1-2) and a previously uncharacterized predicted helical hairpin between TPRs 6 and 7. In infected cells, the helical hairpin was required for IFIT3 association with HCV RNA but dispensable for interactions with other IFIT proteins. Conversely, TPR1-2 was dispensable for HCV RNA binding but essential for IFIT2 interaction, establishing that these functions are structurally separable. Loss of either region diminished antiviral activity, as indicated by increased levels of HCV RNA in clarified supernatants. Consistent with models of mA-linked restriction of late stages of infection, extracellular HCV RNA showed reduced mA and decreased IFIT3 association relative to intracellular RNA. Together, these findings define an mA-linked mechanism by which IFIT3 engages viral RNA and reveal an unexpected role for mA in antiviral effector function. SIGNIFICANCERNA-binding proteins are critical effectors of antiviral defense, yet for many of these proteins the mechanisms of viral RNA recognition remain unclear. Here, we show that m6A modification on both host and viral RNA promotes recognition by the interferon stimulated gene, IFIT3. RNA recognition did not require interaction with IFIT1 or IFIT2, although IFIT3 antiviral function required both RNA binding and interaction with IFIT2. These findings identify m6A as a new regulator of IFIT protein function and broaden our understanding of how RNA modifications shape antiviral restriction.

immunology↗

bioRxiv2025

UFMylation promotes orthoflavivirus infectious particle production

Post-translational modifications play crucial roles in viral infections, yet many potential modifications remain unexplored in orthoflavivirus biology. Here we demonstrate that the UFMylation system, a post-translational modification system that catalyzes the transfer of UFM1 onto proteins, promotes infection by multiple orthoflaviviruses including dengue virus, Zika virus, West Nile virus, and yellow fever virus. We found that depletion of the UFMylation E3 ligase complex proteins UFL1 and UFBP1, as well as other UFMylation machinery components (UBA5, UFC1, and UFM1), significantly reduces infectious virion production for orthoflaviviruses but not the hepacivirus, hepatitis C. Mechanistically, UFMylation does not regulate viral RNA translation or RNA replication but instead affects a later stage of the viral lifecycle. We identified novel interactions between UFL1, and several viral proteins involved in orthoflavivirus virion assembly, including NS2A, NS2B-NS3, and Capsid. These findings establish UFMylation as a previously unrecognized post-translational modification system that promotes orthoflavivirus infection, likely through modulation of viral assembly. This work expands our understanding of the post-translational modifications that control orthoflavivirus infection and identifies new potential therapeutic targets. ImportanceOrthoflaviviruses depend on host-mediated post-translational modifications to successfully complete their lifecycle, yet many of these critical interactions remain undefined. Here, we describe a role for a post-translational modification pathway, UFMylation, in promoting infectious particle production of ZIKV and DENV. We show that UFMylation regulates these viruses at a lifecycle stage after initial RNA translation and RNA replication. Additionally, we find that regulation of infection by UFMylation extends to other orthoflaviviruses, including West Nile virus and yellow fever virus, but not to the broader Flaviviridae family. Finally, we demonstrate that UFMylation machinery directly interacts with specific DENV and ZIKV proteins during infection. These studies reveal a previously unrecognized role for UFMylation in regulating orthoflavivirus infection.

microbiology↗

bioRxiv2021

Tradeoffs for a viral mutant with enhanced replication speed

RNA viruses exist as genetically heterogeneous populations due to high mutation rates and many of these mutations reduce fitness and/or replication speed. However, it is unknown whether mutations can increase replication speed of a virus already well adapted to replication in cultured cells. By sequentially passaging coxsackievirus B3 in cultured cells and collecting the very earliest progeny, we selected for increased replication speed. We found that a single mutation in a viral capsid protein, VP1-F106L, was sufficient for the fast-replication phenotype. Characterization of this mutant revealed quicker genome release during entry compared to wild-type virus, highlighting a previously unappreciated infection barrier. However, this mutation also reduced capsid stability in vitro and reduced replication and pathogenesis in mice. These results reveal a tradeoff between overall replication speed and fitness. Importantly, this approach-- selecting for the earliest viral progeny--could be applied to a variety of viral systems and has the potential to reveal unanticipated inefficiencies in viral replication cycles. SignificanceViruses have characteristic replication speeds within a given cell type. Many factors can slow the rate of viral replication, including attenuating mutations and host antiviral responses. However, it has been unclear whether it would be possible to "speed up" a virus that already replicates efficiently in a specific cell type. Here, we selected for a mutant coxsackievirus with enhanced replication speed by sequentially harvesting the very earliest progeny in multiple rounds of selection. A single mutation conferred the fast replication phenotype. While this mutant virus has enhanced replication in cultured cells due to faster genome uncoating, it was attenuated in mice. These results highlight selective pressures that shape viral populations in different environments.

microbiology↗

bioRxiv2019

Rapid dissemination and monopolization of viral populations in mice revealed using a panel of barcoded viruses

The gastrointestinal tract presents a formidable barrier for pathogens to initiate infection. Despite this barrier, enteroviruses, including coxsackievirus B3 (CVB3), successfully penetrate the intestine to initiate infection and spread systemically prior to shedding in stool. However, the effect of the gastrointestinal barrier on CVB3 population dynamics is relatively unexplored, nor are the selective pressures acting on CVB3 in the intestine well-characterized. To examine viral population dynamics in orally infected mice, we produced over one hundred CVB3 viruses harboring unique nine nucleotide \"barcodes.\" Using this collection of barcoded viruses, we found diverse viral populations throughout each mouse within the first day post-infection, but by 48 hours the viral populations were dominated by less than three barcoded viruses in intestinal and extra-intestinal tissues. Using light-sensitive viruses to track replication status, we found diverse viruses had replicated prior to loss of diversity. Sequencing whole viral genomes from samples later in infection did not reveal detectable viral adaptations. Surprisingly, orally inoculated CVB3 was detectable in pancreas and liver as soon as 20 minutes post inoculation, indicating rapid systemic dissemination. These results suggest rapid dissemination of diverse viral populations, followed by a major restriction in population diversity and monopolization in all examined tissues. These results underscore a complex dynamic between dissemination and clearance for an enteric virus.\n\nImportanceEnteric viruses initiate infection in the gastrointestinal tract but can disseminate to systemic sites. However, the dynamics of viral dissemination are unclear. In this study, we created a library of 135 barcoded coxsackieviruses to examine viral population diversity across time and space following oral inoculation of mice. Overall, we found that the broad population of viruses disseminates early, followed by monopolization of mouse tissues with three or fewer pool members at later time points. Interestingly, we detected virus in systemic tissues such as pancreas and liver just 20 minutes post-oral inoculation. These results suggest rapid dissemination of diverse viral populations, followed by a major restriction in population diversity and monopolization in all examined tissues.

microbiology↗