Browsing by Author "Liu, Fangning"

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    A neonatal gnotobiotic pig model of human enterovirus 71 infection and associated immune responses
    Yang, Xingdong; Li, Guohua; Wen, Ke; Bui, Tammy; Liu, Fangning; Kocher, Jacob; Jortner, Bernard S.; Vonck, Marlice; Pelzer, Kevin D.; Deng, Jie; Zhu, Runan; Li, Yuyun; Qian, Yuan; Yuan, Lijuan (Nature Publishing Group, 2014-05-21)
    Vaccine development and pathogenesis studies for human enterovirus 71 are limited by a lack of suitable animal models. Here, we report the development of a novel neonatal gnotobiotic pig model using the non-pig-adapted neurovirulent human enterovirus 71 strain BJ110, which has a C4 genotype. Porcine small intestinal epithelial cells, peripheral blood mononuclear cells and neural cells were infected in vitro. Oral and combined oral–nasal infection of 5-day-old neonatal gnotobiotic pigs with 53108 fluorescence forming units (FFU) resulted in shedding up to 18 days post-infection, with viral titers in rectal swab samples peaking at 2.223108 viral RNA copies/mL. Viral capsid proteins were detected in enterocytes within the small intestines on post-infection days (PIDs) 7 and 14. Additionally, viral RNA was detected in intestinal and extra-intestinal tissues, including the central nervous system, the lung and cardiac muscle. The infected neonatal gnotobiotic pigs developed fever, forelimb weakness, rapid breathing and some hand, foot and mouth disease symptoms. Flow cytometry analysis revealed increased frequencies of both CD41 and CD81 IFN-c-producing T cells in the brain and the blood on PID 14, but reduced frequencies were observed in the lung. Furthermore, high titers of serum virus-neutralizing antibodies were generated in both orally and combined oral–nasally infected pigs on PIDs 7, 14, 21 and 28. Together, these results demonstrate that neonatal gnotobiotic pigs represent a novel animal model for evaluating vaccines for human enterovirus 71 and for understanding the pathogenesis of this virus and the associated immune responses.
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    Probiotic as Adjuvant Significantly Improves Protection of the Lanzhou Trivalent Rotavirus Vaccine against Heterologous Challenge in a Gnotobiotic Pig Model of Human Rotavirus Infection and Disease
    Parreno, Viviana; Bai, Muqun; Liu, Fangning; Jing, Jiqiang; Olney, Erika; Li, Guohua; Wen, Ke; Yang, Xingdong; Castellucc, Tammy Bui; Kocher, Jacob F.; Zhou, Xu; Yuan, Lijuan (MDPI, 2022-09-14)
    This preclinical study in the gnotobiotic (Gn) pig model of human rotavirus (HRV) infection and disease evaluates the effect of probiotic Lactobacillus rhamnosus GG (LGG) as a mucosal adjuvant on the immunogenicity and cross-protective efficacy of the Lanzhou live oral trivalent (G2, G3, G4) vaccine (TLV, aka LLR3). Gn pigs were immunized with three doses of TLV with or without concurrent administration of nine doses of LGG around the time of the first dose of the TLV vaccination, and were challenged orally with the virulent heterotypic Wa G1P[8] HRV. Three doses of TLV were highly immunogenic and conferred partial protection against the heterotypic HRV infection. LGG significantly enhanced the intestinal and systemic immune responses and improved the effectiveness of protection against the heterotypic HRV challenge-induced diarrhea and virus shedding. In conclusion, we demonstrated the immune-stimulating effects of probiotic LGG as a vaccine adjuvant and generated detailed knowledge regarding the cross-reactive and type-specific antibody and effector B and T cell immune responses induced by the TLV. Due to the low cost, ease of distribution and administration, and favorable safety profiles, LGG as an adjuvant has the potential to play a critical role in improving rotavirus vaccine efficacy and making the vaccines more cost-effective.
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    Probiotic Lactobacillus rhamnosus GG mono-association suppresses human rotavirus-induced autophagy in the gnotobiotic piglet intestine
    Wu, Shaoping; Yuan, Lijuan; Zhang, Yongguo; Liu, Fangning; Li, Guohua; Wen, Ke; Kocher, Jacob; Yang, Xingdong; Sun, Jun (2013-08-07)
    Background Human rotavirus (HRV) is the most important cause of severe diarrhea in infants and young children. Probiotic Lactobacillus rhamnosus GG (LGG) reduces rotavirus infection and diarrhea. However, the molecular mechanisms of LGG-mediated protection from rotavirus infection are poorly understood. Autophagy plays an essential role in responses to microbial pathogens. However, the role of autophagy in HRV infection and LGG treatment is unknown. We hypothesize that rotavirus gastroenteritis activates autophagy and that LGG suppresses virus-induced autophagy and prevents intestinal damage in infected piglets. Methods We used LGG feeding to combat viral gastroenteritis in the gnotobiotic pig model of virulent HRV infection. Results We found that LGG feeding did not increase autophagy, whereas virus infection induced autophagy in the piglet intestine. Virus infection increased the protein levels of the autophagy markers ATG16L1 and Beclin-1 and the autophagy regulator mTOR. LGG treatment during viral gastroenteritis reduced autophagy marker expression to normal levels, induced apoptosis and partially prevented virus-induced tissue damage. Conclusion Our study provides new insights into virus-induced autophagy and LGG suppression of uncontrolled autophagy and intestinal injury. A better understanding of the antiviral activity of LGG will lead to novel therapeutic strategies for infant infectious diseases.