HIV type-1 drug resistance testing on dried blood spots is feasible and reliable in patients who fail antiretroviral therapy in rural Tanzania.
BACKGROUND
HIV type-1 (HIV-1) drug resistance testing is rarely available in resource-limited settings because of high costs and stringent requirements for storage and transport of plasma. Dried blood spots (DBS) can be a convenient alternative to plasma, but the use of DBS needs validation under field conditions. We assessed the performance of DBS in genotypic resistance testing of patients who failed first-line antiretroviral therapy (ART) in rural Tanzania.


METHODS
A total of 36 ART-experienced patients with viral loads >1,000 copies/ml (median 15,180 copies/ml [range 1,350-3,683,000]) and with various HIV-1 subtypes were selected for resistance testing. DBS were stored with desiccant at ambient temperature for a median of 29 days (range 8-89). Samples were amplified using an in-house reverse transcriptase-nested PCR method and sequenced using the ViroSeq™ assay (Abbott Molecular, Des Plaines, IL, USA). DBS-derived genotypes were compared with genotypes from plasma.


RESULTS
Overall, 34 of 36 (94%) DBS specimens were successfully genotyped. In the protease region, of 142 polymorphisms found in plasma, 132 (93%) were also detected in DBS. In the reverse transcriptase region, of 57 clinically relevant mutations present in plasma, 51 (89%) were also detected in DBS. A total of 30 of 34 (88%) patients had identical resistance profiles to antiretroviral drugs in plasma and DBS.


CONCLUSIONS
Genotyping was successful in the vast majority of DBS specimens stored at ambient temperature for up to 3 months, and there was high concordance between mutations found in DBS and plasma. Our study suggests that DBS can be a feasible and reliable tool to monitor HIV-1 drug resistance in patients on ART in resource-limited settings.
Department of Infectious Diseases, Oslo University Hospital, Ullevål, Oslo, Norway. asgeir.johannessen@medisin.uio.no
Asgeir
A
Johannessen
Mona
M
Holberg-Petersen
Gunilla
G
Lövgaarden
Ezra
E
Naman
Vidar
V
Ormaasen
Mecky I
MI
Matee
Svein G
SG
Gundersen
Johan N
JN
Bruun
D000293:Adolescent; D000328:Adult; D000368:Aged; D023241:Antiretroviral Therapy, Highly Active; D001769:Blood / Q000821:virology*; D002648:Child; D002675:Child, Preschool; D024921:Drug Resistance, Multiple, Viral; D005240:Feasibility Studies; D005260:Female; D005838:Genotype; D015658:HIV Infections / Q000097:blood; D015497:HIV-1 / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D010949:Plasma / Q000821:virology*; D016133:Polymerase Chain Reaction; D012424:Rural Population; D013048:Specimen Handling / Q000379:methods; D013636:Tanzania; D019562:Viral Load; D055815:Young Adult