“A single-nuclei atlas of whole Pacific oysters in response to OsHV-1 infection (7107)”

A single-nuclei atlas of whole Pacific oysters in response to OsHV-1 infection

The Pacific oyster (Magallana or Crassostrea gigas) is a globally important species in aquaculture, yet its production remains threatened by recurring outbreaks of Ostreid herpesvirus 1 microvariant (OsHV-1 µVar), which can cause mass mortalities in juvenile oysters. Despite the scale of this problem and significant economic losses, our understanding of precise host cellular responses to the virus at different stages of the infection remains limited. Here, we present the first single-nucleus RNA sequencing (snRNA-seq) analysis of whole oysters to capture the dynamic landscape of host response to OsHV-1 µVar infection over a 72-hour infection cycle. We were able to capture transcriptomic changes at single-nucleus resolution encompassing early, mid, and late stages of the infection.

Using Parse Biosciences Evercode chemistry, we sequenced ~3.2 billion reads and profiled over 23,000 nuclei from OsHV-1 µVar bath-challenged and control oysters, leading to the identification of 18 distinct transcriptional clusters, including five discrete haemocyte immune cell types. These clusters represent cells from key oyster tissues, namely gill, mantle, adductor muscle, digestive gland, hepatopancreas, and immune cell types, providing a detailed atlas of oyster cell diversity. Temporal analysis revealed stage-specific changes in gene expression, with marked transcriptional shifts in haemocytes and gill tissues across infection stages. Differential gene expression analysis revealed subset-specific activation of antiviral and apoptotic regulatory networks within haemocytes and gill subtypes, and most notably in hepatopancreas.

In addition to characterizing infection-associated transcriptomic changes, we provide a curated list of cell-type-specific marker genes for key oyster tissues and immune cells, creating a valuable resource for the bivalve research community. Our analyses also underscore the current limitations of genome annotation in M. gigas, which remains a major bottleneck for functional interpretation and pathway mapping in non-model marine invertebrates

1. DEWARI, POORAN, UNIVERSITY OF EDINBURGH, Presenter
2. Chapuis, Ambre, UNIVERSITY OF EDINBURGH, Author
3. Florea, Alexandra, UNIVERSITY OF EDINBURGH, Author
4. Furniss, James, UNIVERSITY OF EDINBURGH, Author
5. Regan, Tim, UNIVERSITY OF EDINBURGH, Author
6. Bean, Tim, UNIVERSITY OF EDINBURGH, Author