title: Emergence of HBV resistance to lamivudine (3TC) in HIV/HBV co-infected patients in The Gambia, West Africa.
abstract: BACKGROUND
  Lamivudine (3TC) is a potent inhibitor of both Hepatitis B virus (HBV) and Human Immunodeficiency Virus (HIV) replication and is part of first-line highly active antiretroviral therapy (HAART) in the Gambia. Unfortunately, the effectiveness of 3TC against HBV is limited by the emergence of resistant strains.
  
  
  OBJECTIVE
  The aim of this retrospective study was to characterise 3TC-resistant mutations in HBV from co-infected patients receiving HAART, by generating HBV polymerase sequence data and viral loads from HBV genotype E infected patients, both at initiation and during a course of 3TC therapy.
  
  
  METHODS
  Samples from 21 HBV chronic carriers co-infected with HIV-1 (n = 18), HIV-2 (n = 2) and HIV-dual (n = 1) receiving HAART for a period of 6-52 months were analysed for the emergence of 3TC-resistance mutations.
  
  
  RESULTS
  Sixteen out of 21 HBV/HIV co-infected patients responded well to HAART treatment maintaining suppression of HBV viraemia to low (≤ 104 copies/mL) (n = 5) or undetectable levels (< 260 copies/ml) (n = 11). Out of the 5 non-responders, 3 had developed 3TC-resistant HBV strains showing mutations in the YMDD motif at position 204 of the RT domain of the HBV polymerase. One patient showed the M204V+ L180M+ V173L+ triple mutation associated with a vaccine escape phenotype, which could be of public health concern in a country with a national HBV vaccination programme. All except one patient was infected with HBV genotype E.
  
  
  CONCLUSIONS
  Our findings confirm the risk of 3TC mutations in HAART patients following monotherapy. This is a novel study on 3TC resistance in HBV genotype E patients and encourage the use of tenofovir (in association with 3TC), which has not shown unequivocally documented HBV resistance to date, as part of first-line therapy in HIV/HBV co-infected patients in West Africa.HBV- hepatitis B infection; HIV- human immunodeficiency virus; HAART- antiretroviral therapy.
authors.affiliation: Medical Research Council, Fajara, P O Box 273, Banjul, The Gambia, West Africa. maimunamendy@hotmail.com.
authors.forename: Balint
authors.initials: B
authors.lastname: Stewart
authors.forename: Modou L
authors.initials: ML
authors.lastname: Jobarteh
authors.forename: Ramu
authors.initials: R
authors.lastname: Sarge-Njie
authors.forename: Abraham
authors.initials: A
authors.lastname: Alabi
authors.forename: Thushan
authors.initials: T
authors.lastname: de Silva
authors.forename: Kevin
authors.initials: K
authors.lastname: Peterson
authors.forename: Ingrid
authors.initials: I
authors.lastname: Peterson
authors.forename: Hilton
authors.initials: H
authors.lastname: Whittle
authors.forename: Sarah
authors.initials: S
authors.lastname: Rowland-Jones
authors.forename: Assan
authors.initials: A
authors.lastname: Jaye
authors.forename: Matthew
authors.initials: M
authors.lastname: Cotten
authors.forename: Maimuna
authors.initials: M
authors.lastname: Mendy