Pacific Oyster (Magallana gigas). Image credit: Ryan Hodnett via Wikimedia Commons (CC BY 4.0).
Pacific oysters are vital to the ecosystem. They are also a popular seafood and are increasingly used in life science research as a model to represent animals without a backbone (known as invertebrates). However, these oysters are prone to deadly infections caused by bacteria and viruses.
Like humans, oysters and other invertebrates need an immune system to fight infections. Immune cells called hemocytes – which travel through the oyster’s body in a blood-like fluid called hemolymph – help eliminate bacteria, viruses and other disease-causing microbes by absorbing them, releasing toxic molecules, and producing natural antibiotics called antimicrobial peptides. However, it is still unclear how many types of hemocytes Pacific oysters have or what each type does.
De La Forest Divonne et al. used single-cell RNA sequencing and other cell biology techniques to study the genetic activity and anatomy of immune cells in the Pacific oyster. The experiments confirmed that the oysters have at least seven distinct types of hemocytes, each with a specialized immune role, for example, some eat microbes while others produce antimicrobial peptides. The team also mapped how immature hemocytes develop into mature hemocytes with these specialist roles.
This work provides the first detailed atlas of oyster immune cells and reveals how their immune system is organized and operates. A deeper understanding of oyster immune cells may guide the development of new strategies to reduce disease outbreaks in farmed or wild oysters. Before these benefits can be realized, future studies must test how each type of hemocyte responds to actual infections and explore whether targeted treatments or breeding programs can enhance the immune systems of farmed oysters.
