Water-borne hepatitis E virus epidemic in Islamabad, Pakistan: a common source outbreak traced to the malfunction of a modern water treatment plant

Following the digestion of chromosomal DNA of Deinococcus radiodurans with a restriction enzyme a partial genomic library was constructed using lambda phage as a vector. A phage clone whose DNA can complement the deficiency in a radiation-sensitive mutant of D. radiodurans was isolated. Following the subcloning using phasmid vector, a hybrid plasmid containing 1.2 kb inserted DNA was obtained. After the determination of nucleotide sequence, the deduced amino acid sequence showed close homology to RuvB protein of Escherichia coli; approximately 81% of the amino acids (310 residues in total) was homologous (152 were identical and 100 amino acids were similar). The putative protein has a conserved ATP binding domain characteristic of DNA helicases. However, we could not find an SOS promoter and ORF for RuvA protein in the sequence upstream of ruvB in contrast to the E. coli homologue. The mutant was transformed with exogenous DNA at the same rate as the wild-type cells, but it was moderately sensitive to UV, gamma-rays and to interstrand cross-linking reagents.