Do “infectious” prey select for high levels of natural antibodies in tropical pythons?

Abstract

Natural antibodies (NAbs) constitute an important component in vertebrate immune system, but, in spite of this, have often been dismissed as ''non-specific background'' signals. We observed a significant positive relationship between water python (Liasis fuscus) body length/age and levels of antibodies reactive with two administered antigens (tetanus and diphtheria). However, no humoral immune response to the antigens was observed. The lack of elevated immune response, and the age-associated increase in antibody titres, strongly suggest that the antibodies consisted of polyreactive NAbs, and that absence of an elevated immune response was caused by such high levels of NAbs that they were able to mask the epitopes of the antigens. In our study area pythons feed mainly on rodents that frequently, before being killed, are able to inflict numerous bites to the snakes. The bites most likely transmit pathogens such as bacteria. As NAbs have been shown to act as a first line defence against bacterial infections, the high levels of NAbs in the pythons may be an adaptation to reduce pathogenic effects of bacteria transmitted by the prey when the snakes are feeding. Thus, the results from present study suggest that NAbs may have an important immunological function by reducing deleterious effects of pathogens in wild populations.

Complex Interplay of Body Condition, Life History, and Prevailing Environment Shapes Immune Defenses of Garter Snakes in the Wild

“…Meadow habitats have lower and less predictable food availability, lower ambient temperatures, and presence of a trematode parasite compared to lakeshore habitats (table 1). These environmental factors can have important impacts on immune function in vertebrates, including reptiles (Cooper et al 1985;Chandra and Chandra 1986;Ujvari and Madsen 2006;Madsen et al 2007), and could thus explain the lower innate immune levels in M-slow snakes compared to L-fast snakes in their natural environments (Sparkman and Palacios 2009). …”

State-dependent physiological maintenance in a long-lived ectotherm, the painted turtle (Chrysemys picta)

“…Physiological maintenance in a long-lived ectotherm Physiological maintenance has been widely studied in birds, mammals and invertebrate model systems, but much less is known about maintenance in ectothermic vertebrates [e.g. reptiles (Saad and El Ridi, 1988;Patnaik, 1994;Nelson and Demas, 1996;Zapata et al, 1992;Muñoz and de la Fuente, 2004;Madsen et al, 2007;Martin et al, 2008;Pitol et al, 2008;Les et al, 2009;Paitz et al, 2009;Sparkman and Palacios, 2009;Zimmerman et al, 2010)]. Ectothermic vertebrates have traits that suggest physiological maintenance patterns should deviate from those seen in previously studied endothermic vertebrates.…”

“…Ectothermic vertebrates have traits that suggest physiological maintenance patterns should deviate from those seen in previously studied endothermic vertebrates. For example, many reptiles are extremely long-lived and have increased reproductive output with age in adult females (as a result of indeterminate growth), suggesting that senescence should be minimal in these taxa and reduced in females compared with males (Patnaik, 1994;Congdon et al, 2003;Madsen et al, 2007;Bronikowski, 2008) (but see Congdon et al, 2001). Senescence in reproductive output appears to be nonexistent in long-lived reptiles (Congdon et al, 2001;Congdon et al, 2003;Sparkman et al, 2007).…”

Plasticity of immunity in response to eating

“…For example, only hemolysis was affected by sex (potentially due to the immunosuppressive effects of testosterone: Schuurs and Verheul, 1990;Folstad and Karter, 1992) (Fig. 1B), and eating affected only hemoagglutination (likely due to the high responsivity of NAbs to microbes: Madsen et al, 2007). Differences between hemoagglutination and hemolysis in response to treatments have also been detected in other experimental contexts, including temperature and reproductive status .…”

“…First, digesting animals up-regulate their immune systems during meal processing, presumably to combat the increased microbial load associated with ingested food (Madsen et al, 2007;Conway, 1997). Under this hypothesis, increased immune activation would contribute to the SDA response.…”