Molecular ecological structure of intestinal fungal flora in patients with chronic hepatitis B infection
Objective To investigate the ecological structure of intestinal fungal flora of patients with chronic hepatitis B infection. Methods HBV-liver cirrhosis patients, chronic hepatitis B patients, HBV carriers, and healthy volunteers were selected as research subjects to extract the total DNA from stool of each subject, 18S rRNA genes of intestinal fungi was cloned and sequence was analyzed for the construction of 18S rDNA clone libraries and phylogenetic tree, diversity and structural characteristics of intestinal fungal flora in each group was then analyzed. Results A total of 29 operational taxonomic units (OTUs) of intestinal fungal flora in all research subjects was acquired. All positive clones belonged to three fungal taxa: Zygomycetes (3.4%) , Ascomycetes (82. 8%) and Basidiomycetes (13. 8%) . The dominant fungal community was Candida spp. , uncultured fungus and Saccharomyces spp. , which accounted for 29. 2% , 15. 9%, 15.0% respectively. The OTUs which belonged to HBV-liver cirrhosis patients, chronic hepatitis B patients, HBV carriers, and healthy volunteers was 20,16,12,14 respectively. Conclusion There is an abundant fungal flora in the human intestine. Ecological structure of intestinal fungal flora appears to be various in patients with chronic hepatitis B infection, which indicate the close relationship between the alteration of ecological structure of fungal flora and the stage of chronic hepatitis B infection. 
 
Key words: 
Intestinal fungi;  Ecological structure;  HBV infection