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  • 1. Craig, Kelsey A Novel Lactic Acid Bacteria (LAB)-based Vaccine Candidate for Human Norovirus

    Master of Science, The Ohio State University, 2018, Comparative and Veterinary Medicine

    Human noroviruses (HuNoVs) are responsible for more than 95% of the non-bacterial acute gastroenteritis epidemics in the world. The CDC estimates that every year 21 million individuals suffer from HuNoV-induced gastroenteritis in the U.S. Currently, there is no FDA-approved vaccine for HuNoVs. Development of an effective vaccine has been seriously hampered by the lack of an efficient cell culture system for HuNoVs and a suitable small animal model. The goal of this study is to develop lactic acid bacteria (LAB) as a vector to deliver HuNoV antigen. To do this, a LAB bacteria strain (Lactococcus lactis) carrying VP1 gene of a HuNoV GII.4 virus (LAB-VP1) was constructed. It was found that HuNoV VP1 protein was highly expressed by LAB vector. Subsequently, a novel microencapsulation technology was developed to enhance the stability of LABs in low and high pH environments. To test whether LAB-based HuNoV vaccine is immunogenic, 4-day-old gnotobiotic piglets were orally inoculated with various doses of LAB-VP1 either with or without microencapsulation. It was found that LABs were persistent in the small intestine of piglets and shed in pig feces for at least 25 days post inoculation. Live LABs or LAB DNA were found in mesenteric lymph nodes and spleen tissue in LAB-VP1 inoculated groups. HuNoV-specific IgG and IgA were detectable in serum and feces at day 13 post-inoculation, respectively, and further increased at late time points. After challenge with HuNoV GII.4 strain, a large amount of HuNoV antigens were observed in the duodenum, jejunum, and ileum sections of the intestine in the LAB control group. In contrast, significantly less or no HuNoV antigens were detected in the LAB-VP1 immunized groups. Collectively, these results demonstrate that LAB-based HuNoV vaccine induces protective immunity in gnotobiotic piglets.

    Committee: Jianrong Li (Advisor); Prosper Boyaka (Committee Member); Melvin Pascall (Committee Member) Subjects: Microbiology; Virology