Immunology of Reptiles

Abstract

Reptiles tend to have a broad innate immune response followed by a more moderate adaptive response, and as an ectotherm, their immune response is strongly affected by temperature. The innate immune responses in reptiles encompass a diverse group of molecules and cells that includes non‐specific leukocytes, lysozymes, antimicrobial peptides, the complement pathway and fever. The adaptive response involves both T and B cells; however, reptile humoral responses are much less robust than mammalian responses. Thus, reptiles may rely more heavily on a natural antibody response. The slower adaptive response may be because reptiles lack lymph nodes and do not form germinal centres. Phagocytic B cells have also been identified in reptiles. Studies of the reptilian immune system may contribute to our understanding of the evolution of the immune system as well as to the fields of conservation biology, ecological immunology and human medicine. Key Concepts Reptiles have a broad innate immune response able to encompass a variety of pathogens followed by a specific adaptive response. Because reptiles are ectothermic, temperature has a strong effect on immune responses. Seasonal variation in structure and function of the immune system in reptiles is common. As the only ectothermic amniotes, reptiles provide vital information on the evolution of the immune systems.

Relationships between parasitic infection and natural antibodies, age, and sex in a long‐lived vertebrate

“…NAbs have been proposed as one component that fights pathogens as part of a broad innate immune response. While characteristics of NAbs in reptiles have not been yet determined, NAbs in mammals are known to be polyreactive and secreted without antigenic stimulation (Rios & Zimmerman, ). In order to learn more about NAbs in reptiles, this study explored the presence and potential role of NAbs in T. scripta .…”

Immunocompetence in a long‐lived ectothermic vertebrate is temperature dependent but shows no decline in older adults

“…Beyond genetics, immune function can be impacted by a multitude of factors, including nutrition, sex, age and stress (Dhabhar 2009;Shanley et al 2009;Restif & Amos 2010;Calder 2013). Although all jawed vertebrates have both innate and adaptive immunity, terrestrial and semi-terrestrial ectotherms face the additional challenge of maintaining effective responses over a wide range of temperatures, and many species have impressive life spans (Rios & Zimmerman 2015). While the interaction of age and temperature may have a significant impact on immunity, there have been few studies that directly examine such an interaction in natural populations.…”

Complex immune responses and molecular reactions to pathogens and disease in a desert reptile (Gopherus agassizii)

“…Reptiles, like most ectotherms, invest in, and rely on broad innate responses such as nonspecific leukocytes, lysozymes, antimicrobial peptides, the complement pathway, and behaviorally induced fever as their primary lines of defense against pathogens (Rios & Zimmerman, ; Zimmerman, Paitz, et al, ). These responses are germline encoded and are relatively rapid and nonspecific.…”

“…Antibody production by selected plasma cells also requires high rates of metabolism (Alberts et al, ) and is energetically expensive (Sandmeier & Tracy, ). Consequently, ectothermic reptiles with reduced metabolic activity and limited resources likely rely more on innate immunity, selected cells such as phagocytic B cells, or natural antibody responses for their protection from pathogens and infectious disease (Hunter, Dupre, Sharp, Sandmeier, & Tracy, ; Rios & Zimmerman, ; Zimmerman, Paitz, et al, ; Zimmerman, Vogel, Edwards, & Bowden, ). Immune responses in reptiles may also vary depending on the type of pathogen (bacteria, virus, multicellular parasite, etc.)…”

“…sources likely rely more on innate immunity, selected cells such as phagocytic B cells, or natural antibody responses for their protection from pathogens and infectious disease (Hunter, Dupre, Sharp, Sandmeier, & Tracy, 2008;Rios & Zimmerman, 2015;Zimmerman, Paitz, et al, 2010;Zimmerman, Vogel, Edwards, & Bowden, 2009).…”