Meeting Abstract
Being able to accurately measure the immunocompetence of free living, non-model animals would be of great value; making it possible to make comparisons across species, niche, sex, and life-history stage. However, currently it is very difficult to measure even just one aspect of immunocompetence. The methods currently used for determining innate immune capacity (phytohemagglutinin assay (PHA) and bacteria killing assays (BKA)) are problematic and often don’t work for non-model species (Martin et. al., 2004). We have developed a variation on a more traditional BKA technique that can accurately and efficiently assess immune capabilities of birds by exposing static bacteria to the antibodies and complement contained in blood plasma and then observing bacterial growth using a spectrophotometer. Previous BKA techniques either did not factor in bacterial growth rate or life stages, leading to an increase in overall variance of results or utilized to great a quantity of plasma to be of use in small vertabrates. Our assay overcomes this problem by ensuring all bacteria are at the same point in growth at the time of inoculation with plasma as well as not allowing for microbial growth while plasma mediated killing is occurring. In principle, the greater the cell death caused by plasma, the longer it will take to observe log growth in the E. coli population following exposure to complement in bird plasma. This variation on the BKA takes a relatively short amount of time to conduct, is cost effective, and utilizes a minimal amount of plasma making it useful for small vertebrates and potentially even invertebrates. Here we present results utilizing this technique to determine complement mediated killing in various passerine groups, in comparison with heterophil:lymphocyte ratio. The use of the heterophil:lymphocyte ratio technique was used to validate the data observed in the use of our novel BKA.
