Biology subjects

Geary, S. J.

Publications and source records attributed to Geary, S. J..

5 recordsLinked to original sources

bioRxiv2026

Host transcriptional programs underlying lesion development in contagious bovine pleuropneumonia

Contagious bovine pleuropneumonia (CBPP), caused by Mycoplasma mycoides subsp. mycoides (Mmm), remains a major burden to cattle health and the agricultural industry. Mmm is an atypical bacterial pathogen that appears to lack classical virulence factors that cause direct tissue injury (i.e. toxins), and little is known about the mechanisms driving its pathogenicity. The host immune response is believed to be implicated in CBPP pathology, though the molecular mechanisms underlying lesion initiation, progression and chronicity are poorly defined. Classical pathology describes a continuum of lung lesions starting from early inflammation to more mature necrotic lesions and formation of fibrotic sequestra. However, the host transcriptional response driving this potentially immunopathological progression during Mmm infection has never been resolved in vivo. Here, we performed lesion-stage-resolved transcriptomic profiling of pathological lung tissue collected from experimentally infected animals and compared to healthy lung tissue collected from unchallenged controls. Differential gene expression and functional enrichment analyses were used to identify biological pathways relevant to Mmm infection and pathological lesion formation. Early infection was dominated by interferon-stimulated genes and cytokine-responsive pathways, creating a primarily antiviral-like response environment despite the bacterial etiology. Red hepatization showed strong induction of neutrophil chemoattractants, epithelial remodeling markers, and early matrix-remodeling enzymes. Consolidation, spanning red and grey stages, was enriched for innate immune activation, leukocyte adhesion, extracellular matrix organization, and persistent interferon signaling. Grey hepatization reflected late-stage consolidation with heightened neutrophil effector activity, oxidative and proteolytic injury, and macrophage and fibroblast-linked collagen processing. Necrosis/Sequestra lesions showed reduced inflammatory signaling, robust extracellular matrix organization, adhesion, and morphogenetic pathways consistent with encapsulation and sequestrum formation. Our data indicate that the dynamic continuum of CBPP lung pathology is initiated by interferon-primed myeloid recruitment and amplified by neutrophil-driven injury and macrophage- and fibroblast-mediated matrix remodeling. These data further substantiate the role of dysregulated immunity in the development of disease during Mmm infection.

immunology↗

bioRxiv2026

A 14-Color Blue-Violet Laser Restricted Full Spectrum Flow Cytometry Panel for Comprehensive Immunophenotyping of Pulmonary Inflammation in Mouse Bronchoalveolar Lavage Fluid

Here we describe a 16-parameter, 14-color surface staining panel optimized for murine bronchoalveolar lavage cells that enables reproducible identification of major innate and adaptive immune populations relevant to pulmonary infections or other inflammatory conditions of the airways. The panel enables confident identification of neutrophils, eosinophils, B cells, T cells and subtypes, NK cells, and distinguishes between tissue resident and monocyte-derived macrophages populations. The panel was carefully designed for BAL samples that vary in cell number, are rich in debris, and often autofluorescent. Antibody concentrations are optimized to provide reproducible results regardless of sample-variable cell numbers allowing for the preparation of a single antibody cocktail master mix and rapid sample staining time, thereby cutting down on sample preparation and optimizing cell viability of analyzed samples. The panel facilitates robust cross-sectional and longitudinal comparison of airway inflammation across different airway inflammatory conditions, infections by different respiratory pathogens, impact of vaccination or therapeutics on the inflammatory landscape, and more. It facilitates hypothesis generation by revealing recruitment kinetics and remodeling of myeloid compartments, supports downstream sorting for transcriptomic or functional assays, and provides a standardized baseline for labs to adopt or extend for activation or intracellular cytokine analyses. We have successfully utilized this panel to identify differential host responses to different respiratory Mycoplasma pathogens as well as to longitudinally track the progression of inflammatory response to Mycoplasma pneumoniae over a 21-day time course study. This panel provides an economic immunophenotyping option by utilizing only 14 markers and a two laser (Blue and Violet) full spectrum cytometer to provide comprehensive immunophenotyping power of both myeloid and lymphoid cells. Furthered by lacking the requirement for advanced unmixing for sample analysis, the panel can be easily adopted by the community, enabling comparative meta-analyses of host responses across murine respiratory infection models.

immunology↗

bioRxiv2025

Paying upfront: successful initial infections protect against severe future infections

Understanding the consistency with which individual hosts respond to repeated pathogen exposures is crucial for accurately modeling pathogen transmission and eco-evolutionary dynamics. When hosts face repeated pathogen exposures, immune memory is expected to reduce the probability and/or severity of subsequent infections, yet it remains unclear whether individuals remain consistent in their level of response relative to others. We investigated this question in house finches (Haemorhous mexicanus) from two populations varying in history of endemism of the bacterial pathogen Mycoplasma gallisepticum (MG). Individuals were confirmed to be MG-naive at capture and then experimentally inoculated twice with MG, allowing recovery between inoculations. We then asked if host responses to the second inoculation were predicted by responses to initial inoculation, sex, or population of origin. Our results suggest that individuals were not consistent in their relative response levels; rather, a successful initial infection provided protection against a severe second infection, increasing both tolerance and resistance. While we found no population differences in response to the second inoculation, males showed higher susceptibility to the second inoculation than females. Investigating and accounting for individual variation in response to subsequent exposures may improve the precision and accuracy of transmission models for wildlife pathogens.

ecology↗

bioRxiv2025

Host prior exposure augments heterogeneity in gene expression in both host and pathogen during in vivo infection

Variability in acquired protection, whether from prior pathogen exposure or vaccination, is increasingly recognized as a key determinant of host population-level variation in disease traits. It remains unclear whether this extends to the within-host physiological environment and what the consequences are for reinfecting pathogens. Here, we asked whether prior pathogen exposure of hosts induces gene expression heterogeneity in the host and/or pathogen during infection. We quantified gene expression in vivo following high-dose pathogen challenge of house finches (Haemorhous mexicanus) previously given controlled, varied exposure histories to a bacterial pathogen (Mycoplasma gallisepticum; MG). To measure gene expression heterogeneity, we collected transcriptomic data from two host tissues (conjunctiva and spleen), and, simultaneously, from pathogen infecting the primary site of infection (conjunctiva). In the conjunctiva, but not the spleen, prior pathogen exposure induced significant heterogeneity in host gene expression relative to pathogen-naive hosts. Further, hosts that received a lower prior exposure dose rather than a higher primary dose showed the greatest within-group heterogeneity in expression during re-challenge. Functional enrichment analyses for significantly variable host genes indicated an over-representation of terms involved in the immune systems response to pathogens, namely a diversified inflammatory response, in birds with prior pathogen exposure. The infecting pathogen from the conjunctiva followed similar patterns of heterogeneity in host gene expression, where pathogen infecting hosts with prior exposure had more heterogeneous expression than those infecting pathogen-naive hosts. While the exact mechanisms that underlie greater variation in gene expression cannot be resolved by this study, our results are consistent with the hypothesis that prior host exposure induces a within-host environment that promotes heterogeneous gene expression across both hosts and pathogens. This suggests that to understand the coevolutionary dynamics of infectious diseases we must consider not only the genetic sequence variation, but also gene expression variation in host and pathogen.

ecology↗

bioRxiv2024

Prior exposure to pathogens augments host heterogeneity in susceptibility and has key epidemiological consequences

Pathogen epidemics are key threats to human and wildlife health. Across systems, host protection from pathogens following initial exposure is often incomplete, resulting in recurrent epidemics through partially-immune hosts. Variation in population-level protection has important consequences for epidemic dynamics, but how acquired protection influences inter{-}individual heterogeneity in susceptibility and its epidemiological consequences remains understudied. We experimentally investigated whether prior exposure (none, low-dose, or high{-}dose) to a bacterial pathogen alters host heterogeneity in susceptibility among songbirds. Hosts with no prior pathogen exposure had little variation in protection, but heterogeneity in susceptibility was significantly augmented by prior pathogen exposure, with the highest variability detected in hosts given high-dose prior exposure. An epidemiological model parameterized with experimental data found that heterogeneity in susceptibility from prior exposure more than halved epidemic sizes compared with a homogeneous population with identical mean protection. However, because infection-induced mortality was also greatly reduced in hosts with prior pathogen exposure, reductions in epidemic size were smaller than expected in hosts with prior exposure. These results highlight the importance of variable protection from prior exposure and/or vaccination in driving population-level heterogeneity and epidemiological dynamics.

microbiology↗