Date of Graduation

5-2022

Document Type

Thesis

Degree Name

Bachelor of Science in Agricultural, Food and Life Sciences

Degree Level

Undergraduate

Department

Animal Science

Advisor/Mentor

Erf, Gisela

Committee Member/Reader

Alrubaye, Adnan

Committee Member/Second Reader

Powell, Jeremy G.

Abstract

Lipoteichoic acid (LTA) is component of the cell wall of Gram-positive bacteria that stimulates inflammation during bacterial infection. However, few studies have investigated the in vivo immune response to LTA, and none of the in vivo studies done have been performed in birds. For this project, the pulp (a skin-derivative) of growing feathers (GFs) of chickens were used as a test site to investigate the in vivo effects of intradermally injected LTA. In Study 1, the pulp of 12 GFs of 11-week-old Light-brown Leghorn (LBL) males were injected with 10 μL of differing concentrations of LTA (0.1, 1.0, 10, 100 or 250 μg LTA/mL; 3 chickens/dose). For each chicken, 2 GF were plucked before injection and at 6, 24, 48, and 72 h post-injection, flash frozen, and stored at -80°C. Frozen pulp sections were stained using immunohistochemistry for visual inspection of leukocyte infiltration in response to LTA. Based on this study, the 10 μg/mL LTA solution was found to be the optimal concentration to stimulate inflammation. In Study 2, GFs of 12, 15-week-old LBL males were then injected with either 10 μL of 10 μg/mL LTA (0.1 μg LTA/GF, 12 GF/bird, n = 8), or 10 μL of PBS (vehicle; n = 4). GFs were collected before injection (0 h) and at 6, 24, 48, and 72 h post-injection. At each time-point, pulp cell suspensions were prepared and immunofluorescently stained with a panel of chicken-leukocyte-specific monoclonal antibodies, and cell population analysis was carried out by flow cytometry. Analyses revealed elevated levels (% pulp cells) in total leukocytes, monocytes/macrophages, and class II MHC expressing cells in GFs injected with LTA when compared to the control. Infiltration of lymphocytes and heterophils was not different between treatment groups. This study suggests that the inflammatory response to LTA in chickens is characterized primarily by recruitment of monocytes/macrophages to the site of inflammation.

Keywords

leukocytes; chickens; lipoteichoic acid; innate immunity; inflammation

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