Selective expression of a “correct cloud” of Dscam in crayfish survivors after second exposure to the same pathogen

• Published in: Fish & shellfish immunology 2019-09, Vol.92, p.430-437
• Main Authors: Ng, Tze Hann, Kumar, Ramya, Apitanyasai, Kantamas, He, Shu-Ting, Chiu, Shen-Po, Wang, Han-Ching
• Format: Article
• Language: English
• Subjects: Crayfish; Dscam; Immune priming; WSSV
• ISSN: 1050-4648; 1095-9947
• DOI: 10.1016/j.fsi.2019.06.023

Arthropod hypervariable Dscam (Down syndrome cell adhesion molecule) may be involved in adaptive-like immune characteristics, namely immune priming, enabling the host to “learn” and “remember” pathogens previously encountered in arthropods. However, expression of Dscam in immune-primed arthropods after a second challenge has apparently not been confirmed. Herein, working with Dscam of Australian freshwater crayfish (Cherax quadricarinatus, i.e. CqDscam), we further investigated whether immune priming is mediated by “clouds” of appropriate (or “correct”) CqDscam isoforms. In crayfish that survived a first WSSV challenge (immune priming), long-lasting CqDscam expression remained higher after a second WSSV challenge. Selective CqDscam isoforms were also induced after both challenges. Based on pathogen binding assays, these WSSV-induced CqDscam isoforms had a higher WSSV binding ability, perhaps mainly mediated by Ig3-spliced variants. We therefore hypothesized that in these crayfish survivors, an unknown selection process was generating a “correct cloud” of CqDscam against a previously encountered pathogen. •In crayfish that survived a 1st WSSV challenge, long-lasting CqDscam expression remained higher after a 2nd WSSV challenge.•Selective CqDscam isoforms were also induced after both challenges.•WSSV-induced CqDscam isoforms had higher WSSV binding ability.•Ig3 variants may be involved in pathogen-binding specificity.