Date of Graduation

1-2021

Document Type

Thesis

Degree Name

Master of Science in Poultry Science (MS)

Degree Level

Graduate

Department

Poultry Science

Advisor

Young Min Kwon

Committee Member

Billy M. Hargis

Second Committee Member

Palmy Jesudhasan

Third Committee Member

Adnan Ali Khalaf Alrubaye

Keywords

Aptamer, Rolling circle amplification, Salmonella

Abstract

Salmonella has been a major source of concern in public health and food industry. It is the cause of gastrointestinal illness and fever called salmonellosis. Severe cases of salmonellosis have resulted in hospitalization and even death around the world. Salmonella can be found in the intestinal tract of animals including chickens and can be transmitted to human through contaminated food. Hence, it is highly important to find ways of reducing the transmission of Salmonella from chickens to humans. This work is focused on the control of Salmonella in broiler chicken through the development of novel vaccine adjuvant. Two different aptamer rolling circle amplification (RCA) products were developed and combined to produce the vaccine complex: CD40-specific and Salmonella-specific RCA. CD40-specific RCA (termed aptamer RCA II), presenting two CD40-specific aptamers, has the ability to boost immune responses in broiler chickens through activation of the macrophage, and Salmonella-specific RCA (termed 3Sal-aptamer RCA) presents 3 Salmonella-specific aptamers, displaying strong binding affinity against various Salmonella serotypes, including S. Typhimurium, S. Enteritis and S. Kentucky. These two RCA products (aptamer RCA II and 3Sal-aptamer RCA) were designed to contain the spacer regions complementary to each other to facilitate the binding of the two RCA products through hybridization of the spacer regions. The vaccine complex was formed in the following steps: (1) 3Sal-aptamer RCA was incubated with S. Typhimurium cells, and unbound S. Typhimurium cells were removed by extensive washing. (2) The 3Sal-aptamer RCA-S. Typhimurium complex was then incubated with aptamer RCA II to form the final Salmonella vaccine complex. We determined that on average 2.15 ×10^6 CFUs of S. Typhimurium cells were loaded in 1 ml of RCA complex. These results showed that the final complex that consists of 3 components of Salmonella-specific RCA, Salmonella cells, and CD40-specific RCA can be a novel vaccine complex targeting CD40 for efficient control of Salmonella in broiler chickens.

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