Biology subjects

Burnie, J.

Publications and source records attributed to Burnie, J..

4 recordsLinked to original sources

bioRxiv2026

Evaluating Spike Antigenicity across Endemic Human Coronavirus Models using Flow Virometry

While SARS-CoV-2 research has advanced rapidly since COVID-19, endemic human coronaviruses (HCoVs) remain comparatively understudied. Tools to phenotype spike (S), the primary antigenic target on coronaviruses, at the single-virion level could improve vaccine design by capturing variation in epitope availability and spike abundance. Here, we establish a calibrated flow virometry (FV) platform to quantify S antigenicity on native endemic (HCoV-229E, HCoV-OC43) and epidemic (SARS-CoV-2) coronaviruses directly in cell culture supernatants. FV revealed cell line-dependent differences in S antigenicity, including receptor-induced changes in epitope accessibility. Comparison of virion-associated S with recombinant stabilized S by ELISA and biolayer interferometry showed consistent binding for HCoV-OC43, MERS-CoV, and SARS-CoV-2, but differences for HCoV-229E, with FV resolving heterogeneity not captured by bulk assays. Finally, FV showed that HCoV-229E from patient-derived air-liquid interface cultures exhibited reduced antibody binding and distinct S antigenicity compared to cell line-derived virions. Together, these findings establish FV as a platform for single-virion analysis of HCoV antigenicity.

microbiology↗

bioRxiv2026

Evaluating the Utility of a Nanoscale Flow Cytometer for Detection of Surface Proteins on HIV and Extracellular Vesicles

BackgroundFlow virometry (FV) - the application of flow cytometry to viruses - has historically been hindered by the inability of cytometers to detect particles below [~]300 nm in size. However, advances in optics and fluidics have enabled cytometers primarily designed for cells to detect viruses and extracellular vesicles (EVs) through light scatter alone. In 2024, the CytoFLEX nano was released, marketed for the detection of particles as small as 40 nm; however, its performance has yet to be compared to a conventional instrument for FV. MethodsFV was utilized to evaluate performance of the CytoFLEX nano and a conventional flow cytometer (CytoFLEX S). Instrument scatter sensitivity was assessed using NIST beads (40-400 nm), and virus stocks [human immunodeficiency virus (HIV), human coronaviruses (HCoV)-229E and HCoV-OC43]. For fluorescence analysis, HIV virions were stained with PE- and BV421-conjugated antibodies targeting virion incorporated proteins (CD38, CD44), individually and in combination. Finally, HIV stocks were labeled with antibodies against the envelope (Env) glycoprotein and tetraspanins (CD9, CD81) to assess EVs within virus preparations. ResultsCompared to the CytoFLEX S, the CytoFLEX nano exhibited substantially greater scatter sensitivity, reflected by up to 50-fold higher signal-to-noise ratio across NIST-traceable beads and virus samples. This enabled clearer resolution of smaller populations, including bead populations < 70 nm that were undetectable on the CytoFLEX S, as well as improved resolution across all viruses. While both instruments reliably detected stained proteins on HIV virions, the CytoFLEX nano revealed a distinct population of tetraspanin-positive EVs within HIV stocks that was undetected on the CytoFLEX S. Using GFP-tagged HIV, we identified Env+ particles lacking GFP, indicating the presence of Env on EVs. ConclusionsThe CytoFLEX nano exhibited markedly improved scatter sensitivity compared to the CytoFLEX S, improving detection of viruses and enabling detection of EV populations that were undetectable on the conventional instrument. While both platforms performed similarly for surface protein labeling, additional consideration of spectral overlap was needed with the CytoFLEX nano in multicolor experiments. These findings highlight that the complementary strengths of each platform can be utilized to more comprehensively characterize virus and EV populations, providing new opportunities to investigate nanoparticle heterogeneity.

microbiology↗

bioRxiv2025

Gram-positive bacterial cell wall components inhibit herpes simplex virus infection.

The role of the mucosal microbiome in viral infections remains unclear. Genital herpes, caused by herpes simplex virus 1 and 2 (HSV-1 and HSV-2), is among the most prevalent sexually transmitted infections worldwide. Despite evidence linking vaginal Lactobacillus to protection against sexually transmitted viruses, the specific microbial components and mechanisms that mediate this defense are not well understood. Here, we show that multiple cell wall components from diverse gram-positive bacteria, including lactobacilli, inhibit HSV-1 and HSV-2 infection in cells and in a mouse model of genital herpes infection. Peptidoglycan (PG) and lipoteichoic acid (LTA), both major components of the gram-positive bacterial cell wall, significantly reduced HSV infectivity in vitro and improved survival and disease outcomes in mice. We further showed that Lactobacillus crispatus surface layer proteins SlpA and SlpB bind HSV-1 and inhibit infection. Antiviral effects of cell wall components were dose-dependent, relied on intact PG structure, and, in the case of PG and LTA, were independent of TLR2-mediated host signaling. Collectively, our findings identify a species-independent antiviral function for gram-positive bacterial cell wall components against HSV and suggest that the composition of the mucosal microbiome may play an underappreciated role in suppressing mucosal herpes infection in humans.

microbiology↗

bioRxiv2021

The P-selectin ligand PSGL-1 (CD162) is efficiently incorporated by primary HIV-1 isolates and can facilitate trans-infection

While P-selectin glycoprotein ligand-1 (PSGL-1/CD162) has been studied extensively for its role in mediating leukocyte rolling through interactions with its receptor, P-selectin, recently, it was identified as a novel HIV-1 host restriction factor. One key mechanism of HIV-1 restriction is the ability of PSGL-1 to be physically incorporated into the external viral envelope, which effectively reduces infectivity by blocking virus attachment through the steric hindrance caused by its large ectodomain. Importantly, a large portion of the literature demonstrating the antiviral activity of PSGL-1 has utilized viruses produced in transfected cells which express high levels of PSGL-1. However, herein we show that virion-incorporated PSGL-1 is far less abundant on the surface of viruses produced via infection of physiologically relevant models (T cell lines and primary cells) compared to transfection (overexpression) models. Unique to this study, we show that PSGL-1 is incorporated in a broad range of HIV-1 and SIV isolates, supporting the physiological relevance of this incorporation. We also report that high levels of virion-incorporated PSGL-1 are detectable in plasma from viremic HIV-1 infected individuals, further corroborating the clinical relevance of PSGL-1 in natural infection. Additionally, we show that PSGL-1 on viruses is functionally active and can bind its cognate receptor, P-selectin, and that virions captured via P-selectin can subsequently be transferred to HIV-permissive bystander cells in a model of trans-infection. Taken together, our data suggest that PSGL-1 may have diverse roles in the physiology of HIV-1 infection, not restricted to the current antiviral paradigm. IMPORTANCEPSGL-1 is an HIV-1 host restriction factor which reduces viral infectivity by physically incorporating into the envelope of virions. While the antiviral effects of PSGL-1 in viruses produced by transfection models is profound, HIV-1 continues to remain infectious when produced through natural infection, even when PSGL-1 is incorporated. To study this discordance, we compared the differences in infectivity and PSGL-1 abundance in viruses produced by transfection or infection. Viruses produced via transfection contained unnaturally high levels of incorporated PSGL-1 compared to viruses from primary cells, and were much less infectious. We also found PSGL-1 to be present on a broad range of HIV-1 isolates, including those found in plasma from HIV-infected patients. Remarkably, we show that virion-incorporated PSGL-1 facilitates virus capture and transfer to HIV-permissive host cells via binding to P-selectin. These findings suggest that PSGL-1 may also work to enhance infection in vivo.

microbiology↗