e158 Abstracts of the 23 rd National Congress of Digestive Diseases / Digestive and Liver Disease 49S2 (2017) e73–e223 Conclusions: We found a reduced HCMV-specific immunity in active IBD patients with respect to patients in remission and IBS subjects. The ELISPOT assay represents a novel approach for quantifying and monitoring virus-specific T-cell immunity in IBD. P.05.6 EPSTEIN-BARR VIRUS INFECTION IN ULCERATIVE COLITIS AND IN CONTROLS S. Sferrazza ∗ , A. Rizzo, E. Gallo, L. Montalbano, A. Orlando, S. Renna, M. Cottone Ospedali Riuniti Villa Sofia-Cervello, Palermo, Italy Background and aim: Epstein-Barr virus (EBV) infection has been shown to be associated with Inflammatory Bowel disease in few series and its role is not clear. Aim: To evaluate the frequency of EBV infection in colonic speci- mens of patients with active Ulcerative Colitis (UC) and in controls. Material and methods: Between 2013 and 2016 an heterogeneous population of 28 patients (14 males and 14 females) with active UC (4 new cases, 3 mild colitis, 14 steroid dependent UC who successively responded to immunosuppressors or to anti-TNFα,5 non responders to anti-TNFα, 2 pouchitis) and 28 controls (patients who made colonoscopy for irritable bowel diseases or for colon cancer screening) were followed-up in our center. The presence of EBV virus was searched for in the specimens of colon by PCR with primer SLI and SL3 specific for EBNA gene and successively ampli- fied and analyzed on gel. The rates of frequency were compared and, if needed, X2 was calculated. Results: The EBV virus was present in 20 patients (69%) with UC and absent in all the controls. The virus was present in 3 of 4 new cases not treated, in 1 case of those treated with mesalazine and in 16 cases of steroid dependent or steroid resistant patients. Conclusions: EBV infection is very frequent in UC. The meaning of this finding is not clear. Prospective studies are needed in order to clarify if the virus is a by stander or if it has a role in steroid resistance and in the flares of the disease. P.05.7 LOOKING FOR THE MOST USEFUL TAXA AS MICROBIAL BIOMARKERS TO DECIPHER IBD MICROBIOTA: A PILOT STUDY S. Cocca ∗,2 , A. Altomare 1 , L. Putignani 2 , M.P. Guarino 1 , F. Del Chierico 2 , S. Emerenziani 1 , B. Dalla Piccola 2 , M. Cicala 1 1 Campus Bio-Medico, Roma, Italy; 2 Parasitology and Metagenomics Unit, Bambino Gesù Children’s Hospital and Research Institute, Roma, Italy Background and aim: The existing literature on human intestinal microbiota in IBD does not reveal uniform alterations in microbiota composition among all patients and most of studies have been conducted on fecal microbiota. The aim of the present study was to evaluate the mucosal and fecal microbiota composition in healthy controls (CTRLs) and IBD patients, in a case-control study exploited by 16S rRNA targeted metagenomics-based approach. Material and methods: Fecal specimens were collected from 20 IBD patients [12 Crohn’s disease (CD), 8 ulcerative colitis (UC)], and from 15 healthy subjects, undergone colonoscopy for screen- ing. Mucosal specimens were obtained during colonoscopy from the terminal ileum, and descending colon. All patients were in wash-out from antibiotics, probiotics and corticosteroids. PH was assessed by pyrosequencing as follows: Genomic DNA was isolated from the entire set of samples. The V1-V3 region of 16S rRNA locus was amplified on a 454-Junior Genome Sequencer. Reads were ana- lyzed by Quantitative Insights into Microbial Ecology, grouped into operational taxonomic units (OTUs) at a sequence similarity level of 97% for taxonomic assignment, and aligned for OTUs matching against Greengenes database. Results: In adult IBD patients colonic biopsies showed a statisti- cally significant increase of Proteobacteria and decrease of butyrate producing bacteria (Roseburia, Faecalibacterium prausnitzii, Ru- minococcus) compared to CTRLs. The microbiota analysis of stool samples showed only a predominant presence of Enterobacte- riaceae in IBD compared to CTRLs (P<0.05). Stratifying patients findings, according to intestinal sampling site, only in colon biopsies a significant reduction of butyrate producing bacteria was observed. At phylum level, a significant decrease of Proteobacteria and Fir- micutes togheter with a reduced abundance of Bacteroidetes was evident in IBD biopsies compared to fecal samples. Finally, in active disease status, a decrease of Ruminococcus, Peptostreptococcus and Paraprevotella and an increase in Enterococcus was found (P<0.05). Conclusions: In IBD patients there is a reduction of butyrate- producing bacteria, more pronounced in mucosal- than in faecal- associated microbiota. It appears that microbiota adhering to the gut mucosa better discriminates patients from controls especially at family/species level. Our data suggest to go into the direction of diagnostic pipeline to improve microbiota profiling with special ref- erence to mucosal biosystem: disease bacterial biomarker searching and characterization. P.05.8 CLAUSII IN COLITIS: ROLE AND MECHANISMS OF ACTION OF BACILLUS CLAUSII IN EXPERIMENTAL COLITIS F. Scaldaferri ∗,1 , C. Graziani 1 , V. Petito 1 , L. Lopetuso 1 , G. Quaranta 2 , M. Sanguinetti 2 , L. Masucci 2 , F. Franceschi 1 , A. Poscia 3 , V. Arena 4 , D. Scannone 4 , G. Ianiro 1 , G. Cammarota 1 , A. Sgambato 4 , A. Gasbarrini 1 1 Gastroenterological and Endocrino-Metabolical Sciences Department Fondazione Policlinico Universitario Gemelli, Rome, Italy; 2 Department of Microbiology, Fondazione Policlinico Universitario A. Gemelli, Rome, Italy; 3 Institute of Hygiene, Rome, Italy; 4 Institute of General Pathology, Università Cattolica del Sacro Cuore, Rome, Italy Background and aim: Bacillus clausii is a gram-positive bacteria, used as in spore form as a probiotic. It is wide used in acute diarrhea, little is known about its ability to modify intestinal microbiota. Aim of this study is to investigate the effect of B.clausii on mice acute DSS colitis, experimental condition mimicking human IBD and we evaluated gut microbiota modulation in this animal models. Material and methods: Mice were exposed to 2.5% of DSS for 5 days, with or without concomitant administration of B.clausii by oral gavage at two different doses. Stool samples were cultured for microbiological analysis before starting the experiments (day 0) at the end of the DSS treatment: 5 days and 14 days. Every other day, disease activity index was calculated based on body weight monitoring, fecal occult blood and type of feces. At sacrifice, histology was analyzed. The direct microbial properties of B.clausii were also evaluated in vitro using aerobic and anaerobic selective culture media. Results: Higher dose of B.clausii (80 millions of spores) significantly ameliorated mild DSS colitis in mice, according to DAI. No major changes were found on body weight in treated and untreated mice. Histology showed a lower inflammatory score for mice treated with B.clausii lower dose and a reduction of inflammatory total score. B.clausii modulates gut microbiota composition in mild DSS murine colitis in stool samples in colitic mice: colitic mice displayed lower counts of aerobic bacteria and higher anaerobes in fecal samples