Molecular Detection of Drug Resistant Mutants<<Return to Laboratory
Molecular detection of nucleoside/nucleotide analogue resistance by sequence analysis.
- Hepatitis B
Serum or plasma sample. Minimum volume required for serum or plasma – 1.0 mL.
Collect blood in serum separator tubes (SST) or EDTA tubes.
Store samples frozen until shipped for testing. Ship frozen on dry ice.
Shipping of specimens shall be done by a TDG certified individual in accordance with TDG regulations. For additional information regarding classification of specimens for the purposes of shipping, consult either Part 2 Appendix 3 of the TDG Regulations or section 3.6.2 of the IATA Dangerous Goods Regulations as applicable.
Patient on previous or current antiviral therapy for Hepatitis B infection. For patients on current treatment, HBV DNA viral load levels suggest antiviral failure (breakthrough) or nonresponse (i.e., confirmed rise on 2 occasions at least 1 month apart in HBV DNA by > 1 log10 IU/ml from treatment initiation, or HBV DNA reduction < 1 log10 IU/ml, respectively). Previous antiviral treatment warrants drug resistance testing to determine subsequent therapies. HBV DNA results must be positive (i.e., must have detectable viral load).
Completed Viral Hepatitis and Bloodborne Pathogens requisition including sender name, address and telephone number. Patient name or identifier (referring specimen lab #), date of birth, suspected exposure, test(s) requested. Type of specimen and date collected. If possible, include the clinical history and lab results that have already been done at local or provincial laboratories.
Conventional PCR followed by sequence alignment and analysis in comparison to HBV reference sequences. Detection of recognized resistance or compensatory amino acid mutations indicates possible resistance or intermediate sensitivity to certain antiviral therapies dependent on the mutation site (Lamivudine resistance: rtL80V/I, rtV/G173L, rtL180M, rtA181T/V, rtM204V/I/S; Adefovir resistance: rtA181T/V, rtN236T; Entecavir resistance: rtL180M, rtT184S/C/G/A/I/L/F/M, rtS202G/C/I, rtM204I/V, rtM250V/I/L; Tenofovir resistance or reduced susceptibility: rtA181T/V, rtA194T, rtN236T).
19 calendar days.
- Kim JH, Park YK, et al. Molecular diagnosis and treatment of drug-resistant hepatitis B virus. World J Gastroenterol 2014 20:5708-5720.