Vibrio coralliilyticus: A temperature-driven coral pathogen-Genomic virulence, environmental interactions, and...

Vibrio coralliilyticus is a thermally regulated marine pathogen that causes devastating diseases in corals and bivalves globally. This review synthesizes current understanding of its biological features, pathogenic mechanisms, environmental interactions, and control strategies. The bacterium possesses a diverse virulence arsenal including metalloproteases, type III/VI secretion systems, and quorum sensing, with pathogenicity governed by multilayered regulatory networks. In many strains, temperature functions as a master switch: virulence gene expression, chemotaxis, competitive fitness, and host susceptibility typically increase above strain-specific thresholds (often near 27 °C for laboratory-adapted isolates such as YB1, but with notable variation across isolates), mechanistically linking ocean warming to disease emergence. Host metabolites guide chemotaxis toward stressed corals, while nutrient availability, oxygen gradients, and microbial interactions further modulate infection outcomes. By integrating perspectives from molecular microbiology, chemical ecology, and coral holobiont biology, this synthesis reveals a hierarchy of environmental checkpoints centered on temperature-driven virulence amplification and host-derived chemical signaling that determine infection outcome, providing a systems-level framework for predicting climate-driven disease risk. Detection methods now enable sensitive quantification via dnaJ-based quantitative PCR and VcpA immunoassays. Intervention strategies (phage therapy, antimicrobial peptides, and probiotics) show promise under controlled conditions but lack field validation. Critical knowledge gaps persist regarding thermosensing pathways, strain-specific host adaptation, keystone protective symbionts, and ecological safety of biocontrol agents. Addressing these priorities will be essential for predicting disease risk under climate change and developing effective reef conservation measures.