Precursors of Sea Star Wasting: Immune and microbial disruption during initial disease outbreak in Southeast Alaska

Sea Star Wasting Disease (SSW) has devastated sea star populations along
the North American Pacific coast since 2013, yet the mechanisms of disease
progression, particularly in natural environments, remain unclear. Here we
integrate transcriptomic and microbial data from wild Pycnopodia
helianthoides sampled across sites affected and unaffected by SSW in
Southeast Alaska during the initial outbreak recorded in the region in
2016. Individuals exposed to SSW but lacking visible symptoms showed
elevated expression of complement system components, pathogen recognition
genes, immune regulatory and cell death pathways. Alongside signs of
immune activation, genes involved in maintaining extracellular matrix
composition, tissue remodeling, and cell adhesion were differentially
expressed, indicating early disruption of tissue homeostasis preceding
visible wasting symptoms. Gene ontology analysis revealed enrichment of
immune response, cell-cell adhesion, response to oxygen levels and nervous
system regulatory pathways. Furthermore, network analyses revealed
differentially abundant microbes in Exposed individuals—notably Vibrio
spp.—were highly correlated with immune response, tissue integrity, stress
and detoxification genes in network modules. Together, our findings offer
insight into early host-pathogen dynamics in wild populations,
underscoring putative links between immune activation and microbial
community shifts with the onset of SSW disease.