Optimizing selection of large animals for antibody production by screening immune response to standard vaccines

Abstract

Antibodies made in large animals are integral to many biomedical research endeavors. Domesticated herd animals like goats, sheep, donkeys, horses and camelids all offer distinct advantages in antibody production. However, their cost of use is often prohibitive, especially where poor antigen response is commonplace; choosing a non-responsive animal can set a research program back or even prevent experiments from moving forward entirely. Over the course of production of antibodies from llamas, we found that some animals consistently produced a higher humoral antibody response than others, even to highly divergent antigens, as well as to their standard vaccines. Based on our initial data, we propose that these "high level responders" could be pre-selected by checking antibody titers against common vaccines given to domestic farm animals. Thus, time and money can be saved by reducing the chances of getting poor responding animals and minimizing the use of superfluous animals.

Keywords: Antibody generation; Antigen; Camelid antibody; Immunization; Vaccine.

Figure 1

Rabies vaccine or GFP responses by ELISA. Representative ELISA curves from three llamas concurrently immunized with GFP (5094, 5095, and 5096) are shown for serum activity against rabies vaccine (left) or GFP (right). A sigmoidal 4-parameter logistic curve was fit to each serum titration. An intermediate cutoff (fourth out of five tested) was selected to calculate titers (grey dashed line). A zoomed-in view of the low-response range for each plot is shown inset.

Figure 2

Correlation of llama or alpaca vaccine and antigen titers. Those animals of the same species and injected with identical antigens are shown in the same color (see Table 2). Species and antigen types are indicated. All animals’ antigen titers were measured with a GFP ELISA, except for 4761 and 4762, which were titered with an mCherry ELISA. The combined vaccine titer was obtained by averaging each animal’s response to the rabies and CDT vaccines. All titers were calculated based on an intermediate cutoff (fourth highest out of five calculated). Experiments were performed in triplicate, and error bars reflect s.e.m. values. A linear regression was performed (dashed grey line), which had an R² value of 0.75 (p = 0.003).