Date of Graduation

5-2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Poultry Science (PhD)

Degree Level

Graduate

Department

Poultry Science

Advisor/Mentor

Erf, Gisela F.

Committee Member

Bottje, Walter G.

Second Committee Member

Heyes, Colin D.

Keywords

Chicken; Feather; Immunization; Nanotechnology; Quantum Dots; Vaccine

Abstract

Due to their unique physicochemical and enhanced immunostimulatory properties, quantum dot (QD) nanoparticles have shown increasing promise in biomedical research applications including bioimaging, drug delivery, and as vaccine adjuvants. Toxicity, however, remains a concern for the use of QD in these applications and thus, there is an increased demand for effective in vitro and in vivo systems to measure the bioactivity of QD. In this study in vitro and in vivo chicken models were used to investigate the effects of QD on innate and adaptive immunity. Chicken macrophage cultures were treated in vitro with QD to measure macrophage activation and the effect of QD on cell viability. The chicken growing feather (GF) injection model was used as the cutaneous test-site to monitor leukocyte infiltration in response to intradermal injection of QD without and with conjugation to a protein antigen. Additionally, the humoral and cellular adaptive immune responses to protein antigen conjugated to QD were examined in chickens. In vitro results showed negligible macrophage activation in response to QD treatment; however, cell viability was negatively affected by QD in a dose-dependent manner. Leukocyte infiltration results of in vivo GF injections with QD revealed immunostimulatory activity of QD, independent of whether or not QD were conjugated to protein antigen. When used as a vaccine platform, immunization with QD conjugated with protein antigen generated a higher primary and secondary antibody response compared to antigen mixed with alum adjuvant. The adaptive cellular responses to protein antigen examined in GF of immunized chickens also support an important role of B cells in the local effector phases of the responses, while T cells appear to primarily help in B cell activation and differentiation, including antibody isotype switching from IgM to IgG. These results provide additional evidence that QD possess promising vaccine adjuvant properties while demonstrating the viability and utility of the minimally invasive chicken GF cutaneous test-site to study the immunostimulatory effects of nanoparticles initiated in vivo. Further investigation of nanoparticles using the chicken GF injection model should provide additional valuable knowledge of the relative risks and rewards of using QD in biological applications.

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