Time-resolved mapping in calves reveals bovine herpesvirus 1 shift from mucosal replication to trigeminal ganglion neuroinvasion with promyelocytic leukemia protein-centered host-virus antagonism.

Abstract

Although bovine herpesvirus 1 (BoHV-1) causes massive losses of cattle, the transition from mucosal replication to neuroinvasion remains poorly understood. Using a controlled calf model, we integrated quantitative virology and transcriptomics to map its pathogenesis and define the role of promyelocytic leukemia protein (PML). Calves inoculated intranasally and ocularly (1.4 × 106 plaque-forming units/head) were sampled daily (1-14 days post-infection, dpi) for glycoprotein B (gB) qPCR. Tissues were analyzed at 4 and 14 dpi to measure viral DNA via gB-specific qPCR, and for mRNA-seq of trigeminal ganglia (TG). Shedding peaked at 3-6 dpi, being highest in nasal samples, lower in ocular samples, and substantially lower in rectal samples, and declined by 10-14 dpi. At 4 dpi, among the tissues sampled, the tonsils exhibited the highest viral burden. TG exhibited low viral levels at 4 dpi, although they remained detectable at 14 dpi, indicating neuroinvasion. The TG program shifted from early proteostasis priming (4 dpi) to immune/extracellular matrix activation with synaptic repression (14 dpi). In MDBK/Vero cells, IFN-α resulted in higher bovine PML (bPML) levels and enlarged PML nuclear bodies (PML-NBs), reducing very early viral DNA levels, whereas BoHV-1 disrupted PML-NB integrity. The different bPML isoforms exerted different effects on viral infection. STRING analysis revealed a conserved PML-SUMO1-UBE2I-DAXX-SP100 core. These findings delineate the mucosal-to-neuronal trajectory, establish PML as both an effector and viral target in complementary in vitro systems, and identify SUMO/ubiquitin-linked proteostasis as a tractable target for antiviral intervention.IMPORTANCEAlthough bovine herpesvirus 1 (BoHV-1) remains a major challenge to cattle health, the early transition from mucosal replication to trigeminal neuroinvasion has not been clearly mapped in natural-host calves. By integrating daily shedding kinetics, tissue viral DNA profiling, and time-resolved trigeminal ganglion transcriptomics, we delineate when and how BoHV-1 reaches the sensory neurons. Promyelocytic leukemia protein (PML) is identified as a key intrinsic antiviral factor that is upregulated by IFN-α and restricts very early viral genome accumulation, while viral BoHV-1-encoded infected cell protein 0 actively dismantles PML nuclear bodies. The discovery of opposing isoform-specific PML functions and a conserved PML-SUMO proteostasis hub provides mechanistic insight into BoHV-1 immune evasion. These findings refine our understanding of the mucosal-to-neuronal trajectory of infection and highlight proteostasis-linked antiviral pathways as promising targets for intervention.