Infection chains and evolution rates of hepatitis B virus in cardiac transplant recipients infected nosocomially

Following an outbreak of hepatitis B virus (HBV) infection amongst immunosu ppressed transplant recipients, the complete sequences of the HBV-DNA isola ted from nine of the affected patients were determined. The DNA sequences w ere found to differ from each other by a maximum of three nucleotides and b elonged to the same serotype (ayw3). By contrast, the sequences differed by 18 nucleotides from the most similar HBV-DNA sequence published, indicatin g a common source of infection. The infection chains that have been constru cted according to the base differences between the DNAs agreed well with th ose previously established on the basis of epidemiological data [Drescher e t at. (1994) Journal of Hospital Infection 26:81-92]. At least two HBV popu lations, differing by one or two nucleotides, were detected in four patient s, and coexisted for differing periods of time. Mutations of the core and X -peptide were not found. The data were used to calculate evolution rates of HBV DNA, both for HBV persisting within a patient and for infection chains . The rates obtained were of the same order as described previously for imm unocompetent patients, indicating that the immunosuppressive medication did not influence the evolution rate. However, the evolution rate was found to decrease with increasing evolution time. J. Med. Virol. 58:1-10, 1999. (C) 1999 Wiley-Liss, Inc.