Biology subjects

McCune, B. T.

Publications and source records attributed to McCune, B. T..

7 recordsLinked to original sources

bioRxiv2026

Circadian Clock Programming of Anticipatory Antiviral Immunity Gates Enteric Virus Infection Susceptibility

Susceptibility to viral infection varies widely but is not fully explained by genetics, immune status, or exposure level. We show that time of day strongly influences infection outcome, with up to 100-fold differences in enteric viral burden depending on infection timing. This temporal gating is abolished in mice lacking a functional circadian clock. We identify the antiviral transcription factor IRF1 as a direct target of the circadian transcription factor BMAL1, resulting in rhythmic expression of a basal antiviral gene program prior to infection. Loss of IRF1 eliminates this program and abrogates time-of-day-dependent differences in viral replication. This circuit operates within intestinal myeloid cells, establishing a preexisting antiviral state. These findings indicate that the circadian clock programs host susceptibility in the intestine, before infection occurs.

immunology↗

bioRxiv2024

Interferons and tuft cell numbers are bottlenecks for persistent murine norovirus infection

Noroviruses (NoVs) are a leading cause of viral gastroenteritis. Despite global clinical relevance, our understanding of how host factors, such as antiviral cytokines interferons (IFNs), modulate NoV population dynamics is limited. Murine NoV (MNoV) is a tractable in vivo model for the study of host regulation of NoV. A persistent strain of MNoV, CR6, establishes a reservoir in intestinal tuft cells for chronic viral shedding in stool. However, the influence of host innate immunity and permissive cell numbers on viral population dynamics is an open question. We generated a pool of 20 different barcoded viruses (CR6BC) by inserting 6-nucleotide barcodes at the 3 position of the NS4 gene and used this pool as our viral inoculum for in vivo infections of different mouse lines. We found that over the course of persistent CR6 infection, shed virus was predominantly colon-derived, and viral barcode richness decreased over time irrespective of host immune status, suggesting that persistent infection involves a series of reinfection events. In mice lacking the IFN-{lambda} receptor, intestinal barcode richness was enhanced, correlating with increased viral intestinal replication. IL-4 treatment, which increases tuft cell numbers, also increased barcode richness, indicating the abundance of permissive tuft cells to be a bottleneck during CR6 infection. In mice lacking type I IFN signaling (Ifnar1-/-) or all IFN signaling (Stat1-/-), barcode diversity at extraintestinal sites was dramatically increased, implicating different IFNs as critical bottlenecks at specific tissue sites. Of interest, extraintestinal barcodes were overlapping but distinct from intestinal barcodes, indicating that disseminated virus represents a distinct viral population than that replicating in the intestine. Barcoded viruses are a valuable tool to explore the influence of host factors on viral diversity in the context of establishment and maintenance of infection as well as dissemination and have provided important insights into how NoV infection proceeds in immunocompetent and immunocompromised hosts.

microbiology↗

bioRxiv2020

A single intranasal dose of chimpanzee adenovirus-vectored vaccine confers sterilizing immunity against SARS-CoV-2 infection

The Coronavirus Disease 2019 pandemic has made deployment of an effective vaccine a global health priority. We evaluated the protective activity of a chimpanzee adenovirus-vectored vaccine encoding a pre-fusion stabilized spike protein (ChAd-SARS-CoV-2-S) in challenge studies with Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and mice expressing the human angiotensin-converting enzyme 2 receptor. Intramuscular dosing of ChAd-SARS-CoV-2-S induces robust systemic humoral and cell-mediated immune responses and protects against lung infection, inflammation, and pathology but does not confer sterilizing immunity, as evidenced by detection of viral RNA and induction of anti-nucleoprotein antibodies after SARS-CoV-2 challenge. In contrast, a single intranasal dose of ChAd-SARS-CoV-2-S induces high levels of systemic and mucosal IgA and T cell responses, completely prevents SARS-CoV-2 infection in the upper and lower respiratory tracts, and likely confers sterilizing immunity in most animals. Intranasal administration of ChAd-SARS-CoV-2-S is a candidate for preventing SARS-CoV-2 infection and transmission, and curtailing pandemic spread.

microbiology↗

bioRxiv2020

TMPRSS2 and TMPRSS4 mediate SARS-CoV-2 infection of human small intestinal enterocytes

Both gastrointestinal symptoms and fecal shedding of SARS-CoV-2 RNA have been frequently observed in COVID-19 patients. However, whether SARS-CoV-2 replicate in the human intestine and its clinical relevance to potential fecal-oral transmission remain unclear. Here, we demonstrate productive infection of SARS-CoV-2 in ACE2+ mature enterocytes in human small intestinal enteroids. In addition to TMPRSS2, another mucosa-specific serine protease, TMPRSS4, also enhanced SARS-CoV-2 spike fusogenic activity and mediated viral entry into host cells. However, newly synthesized viruses released into the intestinal lumen were rapidly inactivated by human colonic fluids and no infectious virus was recovered from the stool specimens of COVID-19 patients. Our results highlight the intestine as a potential site of SARS-CoV-2 replication, which may contribute to local and systemic illness and overall disease progression.

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↗

bioRxiv2019

Related enteric viruses have different requirements for host microbiota in mice

Accumulating evidence suggests that intestinal bacteria promote enteric virus infection in mice. For example, previous work demonstrated that antibiotic treatment of mice prior to oral infection with poliovirus reduced viral replication and pathogenesis. Here we examined the effect of antibiotic treatment on infection with coxsackievirus B3 (CVB3), a picornavirus closely related to poliovirus. We treated mice with a mixture of five antibiotics to deplete host microbiota and examined CVB3 replication and pathogenesis following oral inoculation. We found that, like poliovirus, CVB3 shedding and pathogenesis were reduced in antibiotic-treated mice. While treatment with just two antibiotics, vancomycin and ampicillin, was sufficient to reduce CVB3 replication and pathogenesis, this treatment had no effect on poliovirus. Quantity and composition of bacterial communities were altered by treatment with the five antibiotic cocktail and by treatment with vancomycin and ampicillin. To determine whether more subtle changes in bacterial populations impact viral replication, we examined viral infection in mice treated with milder antibiotic regimens. Mice treated with one-tenth the concentration of the normal antibiotic cocktail supported replication of poliovirus but not CVB3. Importantly, a single dose of one antibiotic, streptomycin, was sufficient to reduce CVB3 shedding and pathogenesis, while having no effect on poliovirus shedding and pathogenesis. Overall, replication and pathogenesis of CVB3 is more sensitive to antibiotic treatment than poliovirus, indicating that closely related viruses may differ in their reliance on microbiota.\n\nImportanceRecent data indicate that intestinal bacteria promote intestinal infection of several enteric viruses. Here we show that coxsackievirus, an enteric virus in the picornavirus family, also relies on microbiota for intestinal replication and pathogenesis. Relatively minor depletion of the microbiota was sufficient to decrease coxsackievirus infection, while poliovirus infection was unaffected. Surprisingly, a single dose of one antibiotic was sufficient to reduce coxsackievirus infection. Therefore, these data indicate that microbiota can influence enteric virus infection through distinct mechanisms, even for closely related viruses.

microbiology↗

bioRxiv2018

Caspase-mediated cleavage of Murine Norovirus NS1/2 potentiates apoptosis and is required for persistent infection

Human norovirus (HuNoV) is the leading cause of acute gastroenteritis and is spread by fecal shedding that can often persist for weeks to months after infection. Murine norovirus (MNV) is also shed persistently in the feces and provides a tractable model to study molecular mechanisms of enteric persistence. Previous studies have identified non-structural protein 1 (NS1) from the persistent MNV strain CR6 as critical for persistent infection in intestinal epithelial cells (IECs), but its mechanism of action remains unclear. We now find that the function of NS1 in promoting persistence is regulated by apoptosis. Following induction of apoptosis in infected cells, a minority of NS1 is cleaved from the precursor NS1/2 protein, and this cleavage is prevented by mutation of caspase target motifs. MNV strain CR6 with these mutations (CR6{triangleup}casp) is profoundly compromised in infection of IECs and persistence in the intestine. Conversely, replication in tissues outside of the intestine, or in a cultured macrophage cell line, is unchanged, indicating that the requirement of NS1/2 cleavage is intestine-specific. Intriguingly, we also find that cleavage of CR6 NS1/2 potentiates apoptosis, suggesting that regulation of cell death is a novel function of this viral protein. Together, these data indicate that the ability of NS1 to promote MNV persistence in IECs is regulated by host caspases, and suggest that potentiation of apoptosis plays a role in viral tropism in the intestine.\n\nAuthor SummaryHuman Norovirus infection is highly contagious and the most common cause of acute gastroenteritis. Norovirus can persist and be shed for months after infection, leading to continued outbreaks. There are many unanswered questions as to host and viral components of norovirus pathogenesis that can be addressed within the murine norovirus (MNV) model system. We previously identified a critical role for a viral protein, NS1, for intestinal persistence. Herein we describe how the regulation of NS1 is critical for persistent infection in intestinal epithelial cells, but is not required for acute infection of non-epithelial cells, or infection of tissues outside of the gut. Additionally, we demonstrate that NS1 is both regulated by the host cell death machinery, and also reciprocally regulates that machinery to promote cell death during MNV infection, and found that this is specific to persistent strain of MNV. Altogether these data identify a role for how NS1 in a new pathway involved in establishing a persistent norovirus infection in the intestine.

microbiology↗