title: Development of γδ T cell subset responses in gnotobiotic pigs infected with human rotaviruses and colonized with probiotic lactobacilli.
abstract: γδ T cell responses are induced by various viral and bacterial infections. Different γδ T cells contribute to activation and regulation of the inflammatory response and to epithelial repair. How γδ T cells respond to rotavirus infection and how the colonization of probiotics influences the γδ T cell response were unknown. In this study, we evaluated by multicolor flow cytometry the frequencies and distribution of total γδ T cells and three major subsets (CD2-CD8-, CD2+CD8- and CD2+CD8+) in ileum, spleen and blood of gnotobiotic (Gn) pigs at early (3-5 days) and late phases (28 days) after rotavirus infection. The Gn pigs were inoculated with the virulent human rotavirus Wa strain and colonized with a mixture of two strains of probiotics Lactobacillus acidophilus and Lactobacillus reuteri. In naïve pigs, the highest frequency of total γδ T cells was found in blood, followed by spleen and ileum at the early age (8-10 days old) whereas in older pigs (32 days of age) the highest frequency of total γδ T cells was found in ileum and spleen followed by blood. Rotavirus infection significantly increased frequencies of intestinal total γδ T cells and the putatively regulatory CD2+CD8+ γδ T cell subset and decreased frequencies of the putatively proinflammatory CD8- subsets in ileum, spleen and blood at post-infection days (PID) 3 or 5. The three γδ T cell subsets distributed and responded differently after rotavirus infection and/or lactobacilli colonization. The CD2+CD8+ subset contributed the most to the expansion of total γδ T cells after rotavirus infection in ileum because more than 77% of the total γδ T cells there were CD2+CD8+ cells. There was an additive effect between lactobacilli and rotavirus in inducing total γδ T cell expansion in ileum at PID 5. The overall effect of lactobacilli colonization versus rotavirus infection on frequencies of the CD2+CD8+ γδ T cell subset in ileum was similar; however, rotavirus-infected pigs maintained significantly higher frequencies of CD8- subsets in ileum than lactobacilli-colonized pigs. The dynamic γδ T cell responses suggest that γδ T cell subsets may play important roles in different stages of immune responses after rotavirus infection and probiotic colonization. The knowledge on the kinetics and distribution patterns of γδ T cell subsets in naïve pigs and after rotavirus infection or lactobacilli colonization provides the foundation for further mechanistic studies of their functions.
authors.affiliation: Department of Biomedical Sciences and Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Integrated Life Science Building (0913), 1981 Kraft Dr, Blacksburg, VA 24061, USA.
authors.forename: Ke
authors.initials: K
authors.lastname: Wen
authors.forename: Guohua
authors.initials: G
authors.lastname: Li
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Marli S P
authors.initials: MS
authors.lastname: Azevedo
authors.forename: Linda J
authors.initials: LJ
authors.lastname: Saif
authors.forename: Fangning
authors.initials: F
authors.lastname: Liu
authors.forename: Tammy
authors.initials: T
authors.lastname: Bui
authors.forename: Ahmed
authors.initials: A
authors.lastname: Yousef
authors.forename: Lijuan
authors.initials: L
authors.lastname: Yuan
mesh_terms: D000818:Animals; D005856:Germ-Free Life; D007082:Ileum / Q000166:cytology; D007778:Lactobacillus / Q000502:physiology*; D016131:Lymphocyte Subsets / Q000502:physiology*; D019936:Probiotics / Q000627:therapeutic use*; D012400:Rotavirus Infections / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary* / Q000821:virology; D013154:Spleen / Q000166:cytology; D013552:Swine; D013553:Swine Diseases / Q000276:immunology* / Q000382:microbiology / Q000517:prevention & control / Q000821:virology; D013997:Time Factors