Characterization of serum complement activity in serum of the Komodo dragon (<i>Varanus komodoensis</i>)

Abstract

Incubation of different volumes of serum from the Komodo dragon (<i>Varanus komodoensis</i>) with sheep red blood cells (SRBCs) resulted in volume-dependent hemolysis, as measured spectrophotometrically at 540 nm. The hemolysis occurred rapidly, with almost 90% of the hemolytic activity occurring within 20 min of incubation. A thermal profile showed that Komodo dragon serum exhibited low activity from 5- 20℃, but exerted maximum activity at 35℃, which was substantially reduced at 40℃. The maximum activity was observed near optimal temperatures to which Komodo dragons thermoregulate. Mild heat treatment of Komodo dragon serum (56℃, 30 min) depleted the ability to hemolyze SRBCs. In addition, preincubation of Komodo dragon serum with only 5 mM EDTA or phosphate, both chelators of divalent metal ions, reduced the hemolytic activity sharply. These results indicate that the hemolytic activity was due to the presence of a potent serum complement system. Incubation of Komodo dragon serum with 5 mM EDTA and 15 mM Ca<sup>2+</sup> or Mg<sup>2+</sup>, but not Ba<sup>2+</sup>, Zn<sup>2+</sup>, or Fe<sup>2+</sup>, completely restored activity. These results indicate that Komodo dragon serum complement activity requires the presence of Mg<sup>2+</sup> or Ca<sup>2+</sup>. This is the first assessment of innate immune activity of a Varanid

Characterization of Phospholipase A2 Enzyme Activity in Serum of the Komodo Dragon (Varanus komodoensis)Soluble phospholipase A2 (sPLA2) is an enzyme found in the peripheral circulation of vertebrates which has significant immunological activity. This en

“…The curve appeared to be asymptotic in nature, approaching a maximum product formation of approximately 85-90 nmol. This strong activity is not surprising considering the potent and broad-acting antibacterial activity of the Komodo dragon serum [11], and also the effective serum complement activity [12] previously described for these animals. These animals are known to have a broad spectrum of both gram positive and negative bacterial species in their saliva [22].…”

“…[23] showed that the preferred body temperature of Komodo dragons is 34.0-35.6 o C, and thus these animals have a relatively high PLA2 activity (111.1 -114.3 nmol/30 min) in this temperature range. The PLA2 thermal profile presented in Figure 3 exhibits different characteristics than the temperature dependent serum complement activity reported by Merchant et al [12], but was almost identical to the dipeptidyl peptidase IV activity [13]. These data would seem to indicate that an innate immune response in Komodo dragons would be optimal at 35-40 o C. It would be reasonable to expect that these animals would need optimal immune activity during warmer weather when they are more active, and might be more likely to engage in territorial disputes.…”

“…Several recent studies have characterized antibacterial activity [11], serum complement [12], and dipeptidyl peptidase [13] activities of serum from the Komodo dragon. In addition, these animals have been reported to express antimicrobial peptides [14].…”

Characterization of Dipeptidyl Peptidase IV Enzyme Activity in Serum of the Komodo Dragon (Varanus komodoensis)

“…Blood was collected from the tail caudal veins of three adults (20 -81.5 kg) and five juveniles (1.5 -6.2 kg), transferred to Vaccutainer™ tubes, and allowed to clot for at least five hr before serum was collected by centrifugation. The serum was pooled so that the average DPPIV activities for this species could be generated [16].…”

“…In 2011, Merchant et al showed that the serum of Komodo dragons exhibited potent antibacterial activities [15]. Another study from this group demonstrated that these animals have a very effective serum complement innate immunity [16]. This study was undertaken to identify and characterize soluble DPPIV activity in the serum of these ancient vertebrates.…”