Prolonged use of tenofovir in HIV/hepatitis B virus (HBV)-coinfected individuals does not lead to HBV polymerase mutations and is associated with persistence of lamivudine HBV polymerase mutations.

OBJECTIVES: The aim of the study was to identify and characterize hepatitis B virus (HBV) polymerase gene mutations associated with ongoing HBV replication in HIV/HBV-coinfected individuals receiving tenofovir (TDF). METHODS: This retrospective cross-sectional study identified 28 HIV/HBV-coinfected individuals who had received TDF for at least 3 months. All patients had samples available while receiving TDF (on-TDF), and 24 also had samples available prior to treatment (pre-TDF). Case records were reviewed to obtain clinical and virological data at the times of sampling (+/-3 months). The HBV DNA of all samples was amplified using polymerase chain reaction (PCR), and the polymerase region of PCR-positive samples was sequenced and compared with reference HBV data. RESULTS: Of the pre-TDF samples, 15 of 24 (63%) were HBV PCR positive. Of the on-TDF samples, four of 28 (14%) were HBV PCR positive (mean time on TDF 13.5 months; range 3-23 months). Lamivudine (3TC)-resistance mutations were detected in three of four (75%) of these viraemic samples. The previously identified putative TDF-resistance mutations, rtA194T+rtL180M+rtM204V, were not detected in any individual. CONCLUSIONS: Unique mutations in the HBV polymerase gene associated with TDF resistance are rare in HIV/HBV coinfection. 3TC-resistance mutations persist and a significant proportion of patients are HBV PCR positive despite the addition of TDF.

The growth of attenuated influenza vaccine donor strains in continuous cell lines.

The growth of the Russian live attenuated influenza vaccine donor strains A/Leningrad/134/17/57, A/Leningrad/134/47/57 and B/USSR/60/69 was studied in cells of the VERO and Madin-Darby canine kidney (MDCK) lines as six-well cultures and cell factories infected at different multiplicities of infection. Yields for A/Leningrad/134/17/57 and A/Leningrad/134/47/57 were comparable in either cell line over a range of multiplicities but were about 10-fold lower than in the allantoic fluids of infected chicken embryos. For both A/Leningrad/134/47/57 and B/USSR/60/69, yields from the MDCK line were about 10-fold higher than for the VERO line. For B/USSR/60/69, yields in eggs were approximately 100-fold higher than those obtained in the MDCK line. A feature of the growth of B/USSR/60/69 was its reduced capacity to produce infectious progeny in either cell line at multiplicities of infection of 2.0 or 1.0 pfu/cell. Inhibition was due probably due to the presence of defective-interfering particles and was not detected with A/Leningrad/134/17/57 or A/Leningrad/134/47/57 in cultures of either line infected at the same multiplicities. Yields for both A/Leningrad/134/47/57 and B/USSR/60/69 in cells of the MDCK line were comparable when grown in six-well cultures or cell factories.

The role of cell culture vaccines in the control of the next influenza pandemic.

Pandemic influenza A viruses of avian origin are of particular concern and have crossed the species barrier several times in recent years, giving rise to illness and occasionally death in humans. This situation could become dramatically worse if the infectivity of avian viruses for humans were increased by reassortment between the genes of human and avian viruses. Co-infection of humans or an intermediate host with an avian strain and an existing human strain could produce new viruses of unknown pathogenicity to which the entire population would be susceptible. Inactivated vaccines against influenza have been prepared for many years using viruses grown in embryonated chicken eggs. However, the use of eggs presents difficulties when vaccine supplies need to be expanded at short notice. It seems likely that future vaccines will be prepared in high-yielding cell cultures from continuous lines that are preferably anchorage-independent. At present, only certain preparations of the Vero and Madin-Darby canine kidney cell lines, grown and maintained in serum-free medium, are acceptable to all regulatory authorities. However, this situation is likely to change with increasing need for non-pandemic and pandemic vaccines.

Management ... working day of a health services manager.

The private sector is not immune from financial pressures; some of the effects of these directly affect staff. As manager of a small independent hospital, John Audsley, Director, Benenden Hospital, finds that his proximity to staff--and patients--is always a factor in decision making.