Minority HIV mutation detection in dried blood spots indicates high specimen integrity and reveals hidden archived drug resistance.
BACKGROUND
Dried blood spots (DBS) could serve as an attractive, cost-effective alternative to plasma for HIV drug resistance testing.


OBJECTIVE
To assess the utility and potential gain in genotypic information with sensitive testing of DBS compared to conventional bulk plasma genotyping, and examine the correlation of majority and minority-level resistance mutations in DBS with treatment history.


METHODS
Evaluate nucleic acids from the DBS of 33 antiretroviral-experienced subtype B-infected subjects for minority M41L, K65R, K70R, K103N, Y181C, M184V, and T215Y/F mutations by real-time PCR. Compare minority resistance mutations in DBS with bulk genotypes from the same DBS cards and available plasma specimens.


RESULTS
All but one (50/51, 98%) mutation from the original plasma bulk sequencing were still detectable in the DBS after three years of storage. The one mutation not identified in DBS was also no longer detectable by bulk sequencing. Furthermore, sensitive testing found 12 additional drug resistance mutations at minority levels in the DBS of 11 (33%) patients. Six minority mutations were in the RNA compartment and six were detected only in the DNA compartment. Resistance was detected in the DBS RNA compartment only in cases where the associated drug was in use within one year of sample collection.


CONCLUSIONS
Our ability to identify majority and additional minority-level resistance mutations demonstrated that DBS, if stored properly, is a high-integrity specimen type for conventional and sensitive drug resistance testing. Our data further support the global utility of DBS for drug resistance surveillance and clinical monitoring.
Laboratory Branch, Division of HIV/AIDS Prevention, National Centers for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, 1600 Clifton Rd., NE, MS G45 Atlanta, GA 30333, USA.
Xierong
X
Wei
Ae S
AS
Youngpairoj
Carolina
C
Garrido
Natalia
N
Zahonero
Angelica
A
Corral
Carmen
C
de Mendoza
Walid
W
Heneine
Jeffrey A
JA
Johnson
J Gerardo
JG
Garcia-Lerma
D019380:Anti-HIV Agents / Q000494:pharmacology*; D023241:Antiretroviral Therapy, Highly Active; D001769:Blood / Q000821:virology*; D001800:Blood Specimen Collection; D004279:DNA, Viral / Q000235:genetics; D024882:Drug Resistance, Viral / Q000235:genetics*; D005838:Genotype; D015658:HIV Infections / Q000188:drug therapy / Q000821:virology*; D015497:HIV-1 / Q000187:drug effects* / Q000235:genetics*; D006801:Humans; D009154:Mutation; D021141:Nucleic Acid Amplification Techniques; D016133:Polymerase Chain Reaction
D019380:Anti-HIV Agents; D004279:DNA, Viral