title: Third-generation recombinant immunoblot assay: comparison of reactivities according to hepatitis C virus genotype.
abstract: BACKGROUND
  Recombinant immunoblot assay (RIBA) is widely used as a supplemental test in hepatitis C virus (HCV) confirmatory algorithms. As this assay is based on HCV type 1, its performance was examined with the common European HCV genotypes (1, 2, and 3).
  
  
  METHODS
  A study was performed to retest in third-generation RIBA (RIBA-3) all 146 second-generation RIBA (RIBA-2)-positive polymerase chain reaction-positive samples detected by second-generation enzyme-linked immunosorbent assays and having known HCV genotypes (74 HCV type 1, 21 type 2, 51 type 3). RIBA band intensities were examined according to HCV genotype. An additional 90 RIBA-3-confirmed PCR-positive samples (47 HCV type 1, 5 type 2, 38 type 3) detected by third-generation enzyme-linked immunosorbent assays were also examined.
  
  
  RESULTS
  In the first group of 146 samples, the RIBA-3 NS4 (c100p) band showed a marked improvement in sensitivity for the detection of HCV types 2 and 3 over that of the c100 antigen of RIBA-2, but the mean band intensities of HCV types 2 and 3 remained significantly lower than those of type 1. Improved sensitivity of the NS3 band of RIBA-3 to HCV type 3 was also apparent, but, again, the mean band intensity measured was lower for type 3 than for either type 1 or type 2. The c22 band of RIBA-2 and RIBA-3 exhibited equal sensitivity for all HCV genotypes. These differences were also apparent when RIBA-3 was used in conjunction with third-generation enzyme-linked immunosorbent assays.
  
  
  CONCLUSIONS
  The current RIBA-3 lacks sensitivity to the NS4 antibody for HCV types 2 and 3. The incorporation of type-specific components to other genotypes for NS4 (and NS3) antigens should be considered by the manufacturers.
authors.affiliation: Scottish National Blood Transfusion Service Microbiology Reference Unit, Regional Virus Laboratory, Ruchill Hospital, Glasgow, United Kingdom.
authors.forename: B C
authors.initials: BC
authors.lastname: Dow
authors.forename: H
authors.initials: H
authors.lastname: Munro
authors.forename: I
authors.initials: I
authors.lastname: Buchanan
authors.forename: E A
authors.initials: EA
authors.lastname: Follett
authors.forename: F
authors.initials: F
authors.lastname: Davidson
authors.forename: P L
authors.initials: PL
authors.lastname: Yap
authors.forename: P
authors.initials: P
authors.lastname: Simmonds
mesh_terms: D001782:Blood Donors; D004797:Enzyme-Linked Immunosorbent Assay; D005814:Genes, Viral; D005838:Genotype; D016174:Hepacivirus / Q000145:classification / Q000235:genetics*; D006801:Humans; D015151:Immunoblotting / Q000379:methods* / Q000706:statistics & numerical data; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012680:Sensitivity and Specificity