Generation and Biological Properties of a Recombinant Dodecahedron Containing the Short Fiber Protein of the Human Adenovirus 41

Objective: In order to gain further insight into the function of the enteric adenovirus short fiber (SF), we have constructed a recombinant dodecahedron containing the SF protein of HAdV-41 and the HAdV-3 penton base. Methods: Recombinant baculoviruses expressing the HAdV-41 SF protein and HAdV-3 penton base were cloned and amplified in Sf9 insect cells. Recombinant dodecahedra were expressed by coinfection of High Five (TM) cells with both baculoviruses, 72 h post-infection. Cell lysate was centrifuged on sucrose density gradient and the purified recombinant dodecahedra were recovered. Results: Analysis by negative staining electron microscopy demonstrated that chimeric dodecahedra made of the HAdV-3 penton base and decorated with the HAdV-41 SF were successfully generated. Next, recombinant dodecahedra were digested with pepsin and analyzed by Western blot. A 'site-specific' proteolysis of the HAdV-41 SF was observed, while the HAdV-3 penton base core was completely digested. Conclusion: These results show that, in vitro, the HAdV-41 SF likely undergoes proteolysis in the gastrointestinal tract, its natural environment, which may facilitate the recognition of receptors in intestinal cells. The results obtained in the present study may be the basis for the development of gene therapy vectors towards the intestinal epithelium, as well as orally administered vaccine vectors, but also for the HAdV-41 SF partner identification. Copyright (C) 2011 S. Karger AG, Basel

Fiber fermentability effects on energy and macronutrient digestibility, fecal traits, postprandial metabolite responses, and colon histology of overweight cats

Considering the different potential benefits of divergent fiber ingredients, the effect of 3 fiber sources on energy and macronutrient digestibility, fermentation product formation, postprandial metabolite responses, and colon histology of overweight cats (Felis catus) fed kibble diets was compared. Twenty-four healthy adult cats were assigned in a complete randomized block design to 2 groups of 12 animals, and 3 animals from each group were fed 1 of 4 of the following kibble diets: control (CO; 11.5% dietary fiber), beet pulp (BP; 26% dietary fiber), wheat bran (WB; 24% dietary fiber), and sugarcane fiber (SF; 28% dietary fiber). Digestibility was measured by the total collection of feces. After 16 d of diet adaptation and an overnight period without food, blood glucose, cholesterol, and triglyceride postprandial responses were evaluated for 16 h after continued exposure to food. On d 20, colon biopsies of the cats were collected under general anesthesia. Fiber addition reduced food energy and nutrient digestibility. Of all the fiber sources, SF had the least dietary fiber digestibility (P < 0.05), causing the largest reduction of dietary energy digestibility (P < 0.05). The greater fermentability of BP resulted in reduced fecal DM and pH, greater fecal production [g/(cat x d); as-is], and greater fecal concentration of acetate, propionate, and lactate (P < 0.05). For most fecal variables, WB was intermediate between BP and SF, and SF was similar to the control diet except for an increased fecal DM and firmer feces production for the SF diet (P < 0.05). Postprandial evaluations indicated reduced mean glucose concentration and area under the glucose curve in cats fed the SF diet (P < 0.05). Colon mucosa thickness, crypt area, lamina propria area, goblet cell area, crypt mean size, and crypt in bifurcation did not vary among the diets. According to the fiber solubility and fermentation rates, fiber sources can induce different physiological responses in cats, reduce energy digestibility, and favor glucose metabolism (SF), or improve gut health (BP).