title: Detection of lamivudine-resistant variants and mutations related to reduced antigenicity of HBsAg in individuals from the cities of Santos and São Paulo, Brazil.
abstract: BACKGROUND
  Continuous long-term treatment is recommended to reduce the hepatitis B virus (HBV) viral load. However, as a consequence, resistance mutations can emerge and be transmitted to other individuals. The polymerase (POL) gene overlaps the surface (S) gene. Thus, during treatment, mutations in the POL gene may lead to changes in hepatitis B surface antigen (HBsAg). The purpose of this study was to evaluate the frequency of lamivudine and vaccine escape mutations in HBsAg-positive blood donors from the city of Santos and in untreated HBV mono-infected patients from the city of São Paulo, Brazil.
  
  
  METHODS
  HBV DNA was extracted from 80 serum samples, of which 61 were from volunteer blood donors and 19 were from untreated HBV patients. A fragment of the POL/S genes containing 593 base pairs was amplified using nested PCR. Thirty four were PCR-positive and sequencing was performed using an ABI Prism 3130 Genetic Analyzer. Alignments and mutation mapping were performed using BioEdit software.
  
  
  RESULTS
  HBV DNA from 21 blood donors and 13 untreated patient samples were characterized using nucleotide sequencing PCR products from the POL/S genes. We were able to detect one sample with the resistance mutation to lamivudine rtM204V + rtL180M (2.94%), which was found in a volunteer blood donor that has never used antiviral drugs. The other samples showed only compensatory mutations, such as rtL80F (5.88%), rtL80V (2.94%), rtL82V + rtV207L (2.94%), rtT128P (5.88%), rtT128N/S (2.94%) and rtS219A (5.88%). We found modifications in the S gene in 14 of the 34 samples (41.16%). The mutations detected were as follows: sM133L + sI195T (2.94%), sI195M (2.94%), sP120T (2.94%), sY100S/F (2.94%), sY100C (17.64%), sI/T126P + sQ129P (2.94%), sM198I + sF183C (2.94%) and sS210R (5.88%).
  
  
  CONCLUSIONS
  Our results suggest the transmission of lamivudine-resistant forms. Thus, the evaluation of HBV-infected subjects for lamivudine resistance would improve treatment regime. Moreover, the mutations in the S gene may impair HBsAg antigenicity and contribute to HBsAg failure detection and vaccine escape.
authors.forename: Nathalia
authors.initials: N
authors.lastname: Mantovani
authors.forename: Maira
authors.initials: M
authors.lastname: Cicero
authors.forename: Luiz Claudio
authors.initials: LC
authors.lastname: Santana
authors.forename: Carla
authors.initials: C
authors.lastname: Silveira
authors.forename: Eliane Pereira
authors.initials: EP
authors.lastname: do Carmo
authors.forename: Paulo Roberto Ferreira
authors.initials: PR
authors.lastname: Abrão
authors.forename: Ricardo Sobhie
authors.initials: RS
authors.lastname: Diaz
authors.forename: Marcos Montani
authors.initials: MM
authors.lastname: Caseiro
authors.affiliation: Retrovirology Laboratory, Infectious Diseases Division, Federal University of São Paulo, R, Pedro de Toledo, n, 781, 16° andar, São Paulo, SP Cep 04039-032, Brazil. skomninakis@yahoo.com.br.
authors.forename: Shirley Vasconcelos
authors.initials: SV
authors.lastname: Komninakis
mesh_terms: D000328:Adult; D000998:Antiviral Agents / Q000494:pharmacology*; D001938:Brazil; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D003951:Diagnostic Errors; D024882:Drug Resistance, Viral; D005188:False Negative Reactions; D005260:Female; D006514:Hepatitis B Surface Antigens / Q000097:blood / Q000276:immunology*; D017325:Hepatitis B Vaccines / Q000276:immunology; D006515:Hepatitis B virus / Q000187:drug effects* / Q000235:genetics*; D019694:Hepatitis B, Chronic / Q000175:diagnosis / Q000188:drug therapy / Q000821:virology*; D006801:Humans; D057131:Immune Evasion; D019259:Lamivudine / Q000494:pharmacology*; D008297:Male; D020125:Mutation, Missense; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D000998:Antiviral Agents; D004279:DNA, Viral; D006514:Hepatitis B Surface Antigens; D017325:Hepatitis B Vaccines; D019259:Lamivudine