ORIGINAL RESEARCH article
Front. Amphib. Reptile Sci.
Sec. Physiology
This article is part of the Research TopicHerpetological Immunology: Structure, Function, and Disease ImplicationsView all articles
Innate Immune Function in the Diamondback Terrapin (Malaclemys terrapin)
Provisionally accepted
- McNeese State University, Lake Charles, United States
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The innate immune system serves as a critical first line of defense in reptiles, particularly under the energetic constraints of ectothermy. This study characterizes complement-mediated innate immune responses in the diamondback terrapin (Malaclemys terrapin), an estuarine turtle species facing increasing environmental and disease pressures. We evaluated the antibacterial capacity of terrapin plasma against Aeromonas hydrophila, Vibrio vulnificus, Staphylococcus aureus, and Streptococcus pyogenes, and assessed complement activity through sheep red blood cell (SRBC) hemolysis assays. Plasma showed strong, concentration-dependent antibacterial activity, with complete inhibition of S. aureus at 100% plasma and substantial inhibition of the other species at ≥25%. Hemolytic activity was rapid, occurring primarily within 10 minutes, and peaked at 25– 30°C. Complement activity was abolished by heat, protease, and EDTA treatments, and restored with divalent cations, indicating a heat-labile, protease-sensitive mechanism consistent with the alternative complement pathway. Mannan affinity chromatography and SDS-PAGE revealed two major lectins (~25.8 and ~33.4 kDa), consistent with known complement-associated lectins in other emydid turtles. These findings demonstrate that diamondback terrapins possess robust, complement-mediated innate immune responses, potentially shaped by evolutionary exposure to estuarine pathogens like Vibrio spp., and support their use in comparative eco-immunological research and conservation health assessments.
Keywords: Gulf Coast, innate immnity, Serum complement, Terrapin, turtle
Received: 20 Aug 2025; Accepted: 18 Dec 2025.
Copyright: © 2025 Baker, Delacerda and Merchant. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Sarah Baker
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