Enhanced quantification of serum immunoglobulin G from a non-model wildlife species, the Steller sea lion (Eumetopias jubatus), using a protein A ELISA.

Immunoglobulins (Ig) are proteins that preserve immune homeostasis and are quantified to infer changes to the acquired humoral immune response in mammals. Measuring Ig in non-model wildlife for immune surveillance often requires ingenuity, and rigorous standardization of methodologies to provide reliable results especially when lacking species-specific reagents. We modified and optimized existing ELISA methodology utilizing the binding properties of Staphylococcus-derived Protein A (PrtA) to immunoglobulin G (IgG). We enhanced the assay for quantifying IgG in Steller sea lion (SSL) serum using critical quality control measures including dilution linearity, spike and percent recoveries, and internal controls. Of the modifications made, heat treatment of SSL serum enhanced accuracy and precision of IgG measurements by improving linearity and percent recovery in parallel dilutions and serum spikes. Purified canine IgG standard was not affected by heat inactivation. These results support that confounding serum proteins interfere with binding of PrtA with IgG demonstrating the need for heat treatment of serum to optimize IgG quantification using the PrtA-ELISA. Further, essential validation measures ensure proper assay performance. Consequently, the improved PrtA-ELISA provides species-independent IgG detection with validation criteria to enhance accuracy and precision for addressing future immunological questions in non-model wildlife in clinical, ecological, and conservation contexts.

Ecotoxicoparasitology: Understanding mercury concentrations in gut contents, intestinal helminths and host tissues of Alaskan gray wolves (Canis lupus).

Some gastrointestinal helminths acquire nutrients from the lumen contents in which they live; thus, they may be exposed to non-essential elements, such as mercury (Hg), during feeding. The objectives of this study were: 1) determine the total mercury concentrations ([THg]) in Gray wolves (Canis lupus) and their parasites, and 2) use stable isotopes to evaluate the trophic relationships within the host. [THg] and stable isotopes (C and N) were determined for helminths, host tissues, and lumen contents from 88 wolves. Sixty-three wolves contained grossly visible helminths (71.5%). The prevalence of taeniids and ascarids was 63.6% (56/88) and 20.5% (18/88), respectively. Nine of these 63 wolves contained both taeniids and ascarids (14.3%). All ascarids were determined to be Toxascaris leonina. Taenia species present included T. krabbei and T. hydatigena. Within the GI tract, [THg] in the lumen contents of the proximal small intestine were significantly lower than in the distal small intestine. There was a significant positive association between hepatic and taeniid [THg]. Bioaccumulation factors (BAF) ranged from <1 to 22.9 in taeniids, and 1.1 to 12.3 in T. leonina. Taeniid and ascarid BAF were significantly higher than 1, suggesting that both groups are capable of THg accumulation in their wolf host. δ13C in taeniids was significantly lower than in host liver and skeletal muscle. [THg] in helminths and host tissues, in conjunction with stable isotope (C and N) values, provides insight into food-web dynamics of the host GI tract, and aids in elucidating ecotoxicoparasitologic relationships. Variation of [THg] throughout the GI tract, and between parasitic groups, underscores the need to further evaluate the effect(s) of feeding niche, and the nutritional needs of parasites, as they relate to toxicant exposure and distribution within the host.