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The dynamics of an influenza epidemic are difficult to determine because they vary for each circulating influenza subtype. We evaluated the epidemiology of influenza A subtypes at Oshima Medical Center [...]

The hemolysin-determining plasmid pAD1 is a member of a widely disseminated family of highly conjugative elements commonly present in clinical isolates of Enterococcus faecalis. The determinants repA, repB, and repC, as well as adjacent iteron sequences, are believed to play important roles in pADI replication and maintenance. The repA gene encodes an initiator protein, whereas repB and repC encode proteins related to stability and copy number. The present study focuses specifically on repA and identifies a replication origin (oriV) within a central region of the repA determinant. A small segment of repA carrying oriV was able to support replication in cis of a plasmid vector otherwise unable to replicate, if an intact RepA was supplied in trans. We demonstrate that under conditions in which RepA is expressed from an artificial promoter, a segment of DNA carrying only repA is sufficient for stable replication in E. faecalis. We also show that RepA binds specifically to oriV DNA at several sites containing inverted repeat sequences (i.e., IR-1) and nonspecifically to single-stranded DNA, and related genetic analyses confirm that these sequences play an important role in replication. Finally, we reveal a relationship between the internal structure of RepA and its ability to recognize oriV. An in-frame deletion within repA resulting in loss of 105 nucleotides, including at least part of oriV, did not eliminate the ability of the altered RepA protein to initiate replication using an intact origin provided in trans. The relationship of RepA to other known initiator proteins is also discussed.

Researchers describe an E. coli-Enterococcus faecalis shuttle vector that can express cloned genes in E. faecalis without a promoter. E. faecalis is human pathogen that may become resistant to antibiotics that are normally used to treat enterococcal infections.

Research was conducted to study the cloning and genetic and sequence analyses of the bacteriocin 21 determinant encoded on the Enterococcus faecalis pheromone-responsive conjugative plasmid pPD1. The alkali lysis method was utilized to isolate plasmid DNA while the locations of the insertions were determined by nucleotide sequencing with synthetic primers. Results showed that deletions of the genes in the distal half of the determinant led in reduced bacteriocin expression.

Research was conducted to study DNA damage-inducible genes encoded on the Enterococcus faecalis pheromone-responsive conjugative plasmid pAD1. Plasmid DNA was isolated by the alkaline lysis method while the nucleotide sequence of the uvr gene of pAD1 was determined rom a series of nested deletion mutants. Results showed that the potential promoter sequences were in the upstream of the start codons of uvrA, uvrB and uvrC. They also indicated that Uv resistance determinants also enhance the UV resistance of wild-type E. faecalis FA2-2.

Isolation and characterization of the Enterococcus faecalis pheromone-responsive conjugative bacteriocin plasmids encoding a new bacteriocin determinant type 3 have identified two classes of genes: the bacteriocin bacA gene; and an immunity gene bacB. Sequence analysis showed that bacA is located between 3.37kb and 3.57 kb, and bacB between 3.59kb and 3.87 kb. The bacA gene encodes 67 amino acids and bacB encodes 94 amino acids.

The bacteriocin plasmid pPD1 involved in pheromone response in Enterococcus faecalis has been physically mapped and found to contain the following gene sequence: repB- repA-traC-traB-traA-ipd-traE-traF-orfY-sea-1. Researchers determined the nucleotide sequence of DNA that conferred constitutive clumping on bacteria. traC and traB correspond to prgY and prgZ on the plasmid pCF10 and to traC and traB on the plasmid pAD1.