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.

Multiple outbreaks of Norwalk-like virus gastro-enteritis associated with a Mediterranean-style restaurant

The role of diverse infectious agents, particularly Norwalk-like viruses (NLV), in three successive gastro-enteritis outbreaks in one setting (a restaurant) was evaluated. Methods included standard bacteriological tests, specific tests for Escherichia coli, tests for verocytotoxins, electron microscopy (EM) for viruses and reverse transcription-PCR (RT-PCR) methodology for NLV. No pathogenic bacteria were detected. Verocytotoxin genes, although detected by PCR in the first outbreak, could not be confirmed in the E. coli isolated, so they did not appear to be of significance. NLV was the main agent detected in each of the three outbreaks. DNA sequencing and phylogenetic analysis of the amplified products obtained from the RT-PCR positive specimens indicated that only one NLV strain was involved in each outbreak, but the NLV strains responsible for the three outbreaks were different from each other. PCR technology for detection of NLV proved highly sensitive, but failed to detect one specimen which was positive by EM. The restaurant associated with the outbreaks is a Mediterranean-style restaurant where food from a common platter is typically eaten with fingers. The findings indicate that NLV was introduced by guests or staff and was not due to a long-term reservoir within the setting.