Mycobacterium avium is an opportunistic bacterium associated with pathogenic behavior in both humans and animals. M. avium has evolved as a pathogen by having an environmental component in its life style. Prophages ar...Mycobacterium avium is an opportunistic bacterium associated with pathogenic behavior in both humans and animals. M. avium has evolved as a pathogen by having an environmental component in its life style. Prophages are the integrated viral forms in bacterium genome. They constitute about 10% - 20% of genome of many bacteria and they contribute to pathogenicity of microbes. We investigated whether the M. avium 104 genome contained prophages and evaluated the genes/proteins for putative functions. Three prophage genes were identified in the M. avium 104 database, and sequences were analyzed for specific motifs. The prophage sequences were then cloned in Mycobacterium smegmatis and the bacterial phenotype was evaluated in gain of function assays for environmental stresses, such as tolerance to extreme temperatures, UV light, biofilm formation and resistance to acid as well as macrophage survival. The results indicate that two of the prophage genes, MAV_0696 and MAV_2265, confer M. smegmatis with enhanced ability to produce biofilm. Using a Real-Time PCR, it was determined that MAV_0696 and MAV_2265 transcripts were upregulated upon biofilm formation by M. avium. The expression of MAV_2265 gene was significantly higher at all selected time points. In addition, the expression of MAV_2265 in M. smegmatis also led to significantly greater survival rate at pH 5.0 compared to the wild-type control. None of the other physical abilities were altered by overexpressing the prophage genes in M. smegmatis. In summary, we identified three prophage sequences in M. avium 104, from which two of them were found to be associated with biofilm formation and one with resistance to the acidic environment. Future studies will identify the mechanisms involved in the prophages function.展开更多
Background: Urinary tract infection caused by Escherichia coli is a frequently observed condition both in humans and animals. Uropathogenic E. coli (UPEC) has been shown to have a pathogenicity island that enables the...Background: Urinary tract infection caused by Escherichia coli is a frequently observed condition both in humans and animals. Uropathogenic E. coli (UPEC) has been shown to have a pathogenicity island that enables them to infect the urinary tract. Because there is little information about the presence of UPEC-associated virulent genes in animal isolates this work was carried out with the intent to enhance the understanding about the strains of E.coli that cause infections in animals. Results: We screened 21 E. coli strains isolated causing urinary tract infection in domestic animals. Primers were designed to amplify urinary infection-associated genes. Nine genes, papA, tcpC, fyuA, tpbA, Lma, hylA, picU, tonB, and flicC were then amplified and sequenced. Different from the human isolate CFT073, all the animals E. coli lack some of the pathogenesis-associated genes. Genes encoding for proteins used to scavenge iron appear not to be so necessary during animal infections as they are in human infection. In further investigation of phenotypic properties, it was observed that animal UPECs have significantly more impaired ability to form biofilms than human UPEC strain. Conclusions: This study identified significant differences between human and animal UPECs. This may have its roots in the fact that it is difficult to determine if an animal has symptoms. Future studies will focus on some of the observations.展开更多
文摘Mycobacterium avium is an opportunistic bacterium associated with pathogenic behavior in both humans and animals. M. avium has evolved as a pathogen by having an environmental component in its life style. Prophages are the integrated viral forms in bacterium genome. They constitute about 10% - 20% of genome of many bacteria and they contribute to pathogenicity of microbes. We investigated whether the M. avium 104 genome contained prophages and evaluated the genes/proteins for putative functions. Three prophage genes were identified in the M. avium 104 database, and sequences were analyzed for specific motifs. The prophage sequences were then cloned in Mycobacterium smegmatis and the bacterial phenotype was evaluated in gain of function assays for environmental stresses, such as tolerance to extreme temperatures, UV light, biofilm formation and resistance to acid as well as macrophage survival. The results indicate that two of the prophage genes, MAV_0696 and MAV_2265, confer M. smegmatis with enhanced ability to produce biofilm. Using a Real-Time PCR, it was determined that MAV_0696 and MAV_2265 transcripts were upregulated upon biofilm formation by M. avium. The expression of MAV_2265 gene was significantly higher at all selected time points. In addition, the expression of MAV_2265 in M. smegmatis also led to significantly greater survival rate at pH 5.0 compared to the wild-type control. None of the other physical abilities were altered by overexpressing the prophage genes in M. smegmatis. In summary, we identified three prophage sequences in M. avium 104, from which two of them were found to be associated with biofilm formation and one with resistance to the acidic environment. Future studies will identify the mechanisms involved in the prophages function.
文摘Background: Urinary tract infection caused by Escherichia coli is a frequently observed condition both in humans and animals. Uropathogenic E. coli (UPEC) has been shown to have a pathogenicity island that enables them to infect the urinary tract. Because there is little information about the presence of UPEC-associated virulent genes in animal isolates this work was carried out with the intent to enhance the understanding about the strains of E.coli that cause infections in animals. Results: We screened 21 E. coli strains isolated causing urinary tract infection in domestic animals. Primers were designed to amplify urinary infection-associated genes. Nine genes, papA, tcpC, fyuA, tpbA, Lma, hylA, picU, tonB, and flicC were then amplified and sequenced. Different from the human isolate CFT073, all the animals E. coli lack some of the pathogenesis-associated genes. Genes encoding for proteins used to scavenge iron appear not to be so necessary during animal infections as they are in human infection. In further investigation of phenotypic properties, it was observed that animal UPECs have significantly more impaired ability to form biofilms than human UPEC strain. Conclusions: This study identified significant differences between human and animal UPECs. This may have its roots in the fact that it is difficult to determine if an animal has symptoms. Future studies will focus on some of the observations.
