Previous Article | Next Article 
Journal of Clinical Microbiology, October 2005, p. 5301-5304, Vol. 43, No. 10
0095-1137/05/$08.00+0 doi:10.1128/JCM.43.10.5301-5304.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
Oligonucleotide Ligation Assay for Detection of Mutations Associated with Reverse Transcriptase and Protease Inhibitor Resistance in Non-B Subtypes and Recombinant Forms of Human Immunodeficiency Virus Type 1
Yolanda Vega,
Lucía Pérez-Alvárez,
Elena Delgado,
Mercedes Muñoz,
Gema Casado,
Rocío Carmona,
María Sierra,
Elena Vázquez de Parga,
Milagros Pinilla,
Valentina García,
Leandro Medrano,
Gerardo Contreras,
Miguel Thomson, and
Rafael Nájera*
Área de Patogenia Viral, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda, Madrid, Spain
Received 12 January 2005/
Returned for modification 22 April 2005/
Accepted 20 July 2005

ABSTRACT
The oligonucleotide ligation assay is a genotypic assay for
the detection of resistance-associated mutations to reverse
transcriptase and protease inhibitors in human immunodeficiency
virus type 1 subtype B. This assay has been modified and developed
for non-B subtypes and recombinant strains and has been evaluated
with sequencing, resulting in a more sensitive assay than sequencing
for non-B subtypes.

TEXT
Methods to identify resistance mutations in the human immunodeficiency
virus type 1 (HIV-1)
pol gene are needed since the use of protease
(PR) and/or reverse transcriptase (RT) inhibitors may increase
the prevalence of resistance mutations (
9,
11). DNA sequencing
is the most commonly used method to evaluate the presence of
drug resistance mutations, but its high cost and equipment requirements
make it unsuitable when economic resources are limited (
1,
8).
The oligonucleotide ligation assay (OLA) is a genotypic assay which has been used to identify point mutations in DNA for a variety of diseases (3, 5) and to detect drug resistance-associated mutations in HIV-1 subtype B (1, 7, 8, 15). This is the most prevalent subtype in developed countries, although non-B subtypes and recombinant forms (RFs) are dramatically increasing in developing countries, where antiretroviral therapy is starting to be accessible (13), as well as in several areas of the developed world (9, 13).
In this work, we describe the development of OLA for the detection of point mutations associated with high-level resistance to PR and RT inhibitors in HIV-1 non-B subtypes and RFs, and we evaluate OLA and sequencing methods for resistance-associated mutation detection in non-B and subtype B strains.
RNAs extracted from plasmas of 66 HIV-1 specimens (22 non-B subtypes and 44 subtype B strains) were selected. The distribution of the 22 non-B subtypes, according to their pol genes, was as follows: (i) three subtype G strains and one each of subtypes A1, C, and F1; (ii) 10 circulating recombinant forms (CRFs) (nine CRF02_AG and one CRF14_BG strain); and (iii) two GKU strains and one each of subtypes AG, UA2, and UAJ (U, unknown fragment). Five non-B strains included in this study were characterized in our laboratory by full-length genome sequencing (4).
To carry out RT-PCR, 5 to 15 µl of RNA extracted from plasma was reverse transcribed following purification and sequencing with an automated fluorescence sequencer (Applied Biosystems). Reaction conditions, oligonucleotides, and the thermocycling profile were described previously (14).
The OLA is based on the covalent joining of two adjacent oligonucleotides by a DNA ligase when they are hybridized to a cDNA target. A set of three oligonucleotides was designed for the detection of the following mutations: K103N, Q151M, Y181C, M184V, and T215Y in RT and D30N, V82A, and L90M in PR. Table 1 shows the drugs to which these mutations appear to confer resistance, the amino acid substitutions detected, and the oligonucleotide sequences. The 5' end of the common oligonucleotide is phosphorylated and designed to anneal to the complementary region of the pol gene adjacent to the 3' end of the wild-type/mutant oligonucleotide. Ligation between wild-type/mutant and common oligonucleotides occurs when both are annealed to the complementary strand of the PCR product. The procedure and reaction conditions were described by Villahermosa et al. (15), with the following modifications: the ligation reaction included 2 µl of the PCR product, 10 µl of distilled H2O containing 0.1% Triton X-100, and 10 µl of a reaction mixture of 20% 10x ligase buffer with 200 nmol Tris, pH 8, 100 mM NAD (Sigma), 2.5% 1 M KCl (Sigma), 57.5% distilled H2O containing 0.1% Triton X-100, 3 U of thermostable ligase (Epicenter Technologies), and 5 pmol of each ligation oligonucleotide. The McNemar test (RSIGMA; Babel statistical computer program) was used to assess significant differences between percentages.
View this table:
[in this window]
[in a new window]
|
TABLE 1. Oligonucleotides used in OLA to detect mutations in HIV-1 pol associated with resistance to RT and PR inhibitors
|
To perform OLA with non-B strains, we performed sequence alignment
and analysis and designed specific oligonucleotides for positions
181 and 184 of RT and for codon 90 of PR, obtaining a significant
improvement over the use of standard subtype B oligonucleotides
(data not shown).
Four hundred seventy-seven codons of the HIV-1 pol gene were analyzed, including 156 codons from non-B and RF samples and 321 from subtype B samples. Four hundred four (84.7%) of the 477 codons analyzed were coincident by OLA and sequencing (Table 2). The greater sensitivity of the OLA method than of sequencing for the detection of minor HIV-1 species was demonstrated by our experiments. OLA detected mutant viral sequences in 39 samples (8.2%) that had been genotyped as wild type by sequencing (Table 2). Of these, 37 had mixtures of mutant and wild-type sequences, with 32 having mutations in the RT region and 5 having mutations in the PR sequence. The potential detection of minor mutant populations before they become predominant could be a useful tool for the management and preliminary orientation of antiretroviral therapy, showing a clear advantage over sequencing (1, 8, 16) and representing the first time that a genotypic assay other than the sequencing method was successfully performed for the detection of resistance-associated mutations to nucleoside and nonnucleoside RT and PR inhibitors in non-B subtypes. In fact, a nitrocellulose strip hybridization-based assay, the LiPA (Innogenetics), has been performed for the detection of resistance-associated mutations to PR and RT inhibitors, with evident limitations due to the sequence variability between non-B and B subtypes (6). The OLA, in contrast to the LiPA assay, allows the design and incorporation of new oligonucleotides into the reaction, which adapt well to the sequence variability present in non-B subtypes.
View this table:
[in this window]
[in a new window]
|
TABLE 2. Summary of genotype results for 477 codons associated with resistance to RT and PR inhibitors by OLA and sequencing of HIV-1 samples
|
The OLA detected 32 (6.7%) indeterminate results from the 477
codons analyzed (Table
2): 19/156 (12.2%) were from non-B subtypes
and RFs and 13/321 (4%) were from subtype B (
P < 0.01). The
presence of alternative mutations (T215F/C, V82I/F/S, and K103H)
no longer complementary to the oligonucleotides used in the
assay was the most common cause of indeterminate results. Most
of these indeterminate reactions were due to mutations located
within three bases of the ligation site or to the presence of
two or more base changes in the region complementary to one
of the ligation oligonucleotides (
1,
7,
15). This is not surprising
considering that polymorphisms and accessory mutations in regions
of RT and also in PR are common, particularly in non-B subtypes
(
2). In fact, the L89M mutation of PR was present in 18 of the
22 HIV-1 non-B strains.
In conclusion, OLA is a rapid and sensitive method for identifying mutations associated with antiretroviral resistance to RT inhibitors and PR inhibitors in either HIV-1 non-B strains, RFs, or subtype B strains. In contrast to the LiPA assay, the OLA is highly adaptable since it allows the design of novel and specific oligonucleotides to detect new resistance-associated mutations as they are identified or to detect resistance-associated mutations in non-B subtype samples, where multiple genetic polymorphisms and accessory mutations are commonly found (1, 7, 16). This assay could also be used for the efficient determination and discrimination of different genetic subtypes through the design of specific oligonucleotides, as previously described for a similar genotyping approach (10, 12). Moreover, the OLA has the ability to detect drug-resistant subpopulations present in a relatively small proportion (8), which represents a big advantage compared to sequencing because this makes OLA useful for the election of initial therapeutic regimens or changes in therapy in order to prevent the accumulation of additional mutations. Finally, OLA is available from the National Institutes of Health AIDS Reagent Program for the detection of resistance-associated mutations to nucleoside RT inhibitors and nonnucleoside RT inhibitors (7), in which preparation our laboratory has actively participated (15), and to protease inhibitors (1), making this method easy and cheap to perform and offering a real and practical alternative to DNA sequencing, especially in places with limited economic resources.

ACKNOWLEDGMENTS
We thank G. M. Inclán Iribar, Departamento de Sanidad
del Gobierno Vasco, J. I. Garay Ibáñez de Elejalde,
Osakidetza Servicio Vasco de Salud, Departamento de Sanidad
del Gobierno Vasco, and D. Zulaica, Plan de Prevención
y Control del SIDA, Osakidetza Servicio Vasco de Salud, Departamento
de Sanidad del Gobierno Vasco, for their support in the development
of the study. We also thank José Manuel González
Alvárez, Conselleiro de Sanidade e Servicios Sociais,
Manuel Barral, Director Xeral de Saúde Pública,
and José Antonio Taboada, Consellería de Sanidade
e Servicios Sociais, Xunta de Galicia, for their support in
the development of the study in Galicia.
This work was funded by contracts SLVI/1431-01 and SLVI/1068-03 from Plan Nacional del SIDA, Ministerio de Sanidad y Consumo, Spain, and by scientific agreements with the Government of Galicia, Xunta de Galicia, and Basque Country, Spain.

FOOTNOTES
* Corresponding author. Mailing address: Viral Pathogenesis Department, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda, Madrid, Spain. Phone: 34 91 8223910. Fax: 34 91 5097014. E-mail:
rafael.najera{at}isciii.es.


REFERENCES
1 - Beck, I. A., M. Mahalanabis, G. Pepper, A. Wright, S. Hamilton, E. Langston, and L. M. Frenkel. 2002. Rapid and sensitive oligonucleotide ligation assay for detection of mutations in human immunodeficiency virus type 1 associated with high-level resistance to protease inhibitors. J. Clin. Microbiol. 40:1413-1419.[Abstract/Free Full Text]
2 - Bossi, P., M. Mouroux, A. Yvon, F. Bricaire, H. Agut, J. M. Huraux, C. Katlama, and V. Calvez. 1999. Polymorphism of the human immunodeficiency virus type 1 (HIV-1) protease gene and response of HIV-1-infected patients to a protease inhibitor. J. Clin. Microbiol. 37:2910-2912.[Abstract/Free Full Text]
3 - Bui, M. H., G. G. Stone, A. M. Nilius, L. Almer, and R. K. Flamm. 2003. PCR-oligonucleotide ligation assay for detection of point mutations associated with quinolone resistance in Streptococcus pneumoniae. Antimicrob. Agents Chemother. 47:1456-1459.[Abstract/Free Full Text]
4 - Delgado, E., M. M. Thomson, M. L. Villahermosa, M. Sierra, A. Ocampo, C. Miralles, R. Rodríguez-Pérez, J. Diz-Aren, R. Ojea-de Castro, E. Losada, M. T. Cuevas, E. Vázquez-de Parga, R. Carmona, L. Pérez-Álvarez, L. Medrano, L. Cuevas, J. A. Taboada, and R. Najera. 2002. Identification of a newly characterized HIV-1 BG intersubtype circulating recombinant form in Galicia, Spain, which exhibits a pseudotype-like virion structure. J. Acquir. Immune Defic. Syndr. 29:536-543.
5 - Deng, J. Y., X. E. Zhang, Y. Mang, Z. P. Zhang, Y. F. Zhou, Q. Liu, H. B. Lu, and Z. J. Fu. 2004. Oligonucleotide ligation assay-based DNA chip for multiplex detection of single nucleotide polymorphism. Biosens. Bioelectron. 19:1277-1283.[CrossRef][Medline]
6 - Derdelinckx, I., K. Van Laethem, B. Maes, Y. Schrooten, K. De Schouwer, S. De Wit, K. Fransen, S. García Ribas, M. Moutschen, D. Vaira, G. Zissis, M. Van Ranst, E. Van Wijngaerden, and A.-M. Vandamme. 2003. Performance of the VERSANT HIV-1 resistance assays (LiPA) for detecting drug resistance in therapy-naïve patients infected with different HIV-1 subtypes. FEMS Immunol. Med. Microbiol. 39:119-124.[Medline]
7 - Edelstein, R. E., D. A. Nickerson, V. O. Tobe, L. A. Manns-Arcuino, and L. M. Frenkel. 1998. Oligonucleotide ligation assay for detecting mutations in the human immunodeficiency virus type 1 pol gene that are associated with resistance to zidovudine, didanosine, and lamivudine. J. Clin. Microbiol. 36:569-572.[Abstract/Free Full Text]
8 - Ellis, G. M., M. Mahalanabis, I. A. Beck, G. Pepper, A. Wright, S. Hamilton, S. Holte, W. E. Naugler, D. M. Pawluk, C.-C. Li, and L. M. Frenkel. 2004. Comparison of oligonucleotide ligation assay and consensus sequencing for detection of drug-resistant mutants of human immunodeficiency virus type 1 in peripheral blood mononuclear cells and plasma. J. Clin. Microbiol. 42:3670-3674.[Abstract/Free Full Text]
9 - Fauci, A. S. 2003. HIV and AIDS: 20 years of science. Nat. Med. 9:839-843.[CrossRef][Medline]
10 - Hoelscher, M., W. E. Dowling, E. Sanders-Buell, J. K. Carr, M. E. Harris, A. Thomschke, M. L. Robb, D. L. Birx, and F. E. McCutchan. 2002. Detection of HIV-1 subtypes, recombinants, and dual infections in east Africa by a multi-region hybridization assay. AIDS 16:2055-2064.[CrossRef][Medline]
11 - Johnson, V. A., F. Brun-Vezinet, B. Clotet, B. Conway, R. T. D'Aquila, L. M. Demeter, D. R. Kuritzkes, D. Pillay, J. M. Schapiro, A. Telenti, and D. D. Richman. 2004. Update of the drug resistance mutations in HIV-1: 2004. Top. HIV Med. 12:119-124.[Medline]
12 - Njai, H. F., G. Van der Auwera, C. A. Ngong, L. Heydricks, S. Sawadago, H. Whittle, P. Nyambi, R. Colebunders, G. Van der Groen, and W. Janssens. 2004. Development, evaluation and validation of an oligonucleotide probe hybridization assay to subtype human immunodeficiency virus type 1 circulating recombinant form CRF02_AG. J. Clin. Microbiol. 42:1428-1433.[Abstract/Free Full Text]
13 - Pérez-Álvarez, L., R. Carmona, M. Muñoz, E. Delgado, M. M. Thomson, G. Contreras, J. D. Pedreira, R. Rodríguez-Real, E. Vázquez de Parga, L. Medrano, J. A. Taboada, R. Nájera, and the Spanish Group for Antiretroviral Resistance Studies in Galicia. 2003. High incidence of non-B recombinant HIV-1 strains in newly diagnosed patients in Galicia, Spain: study of genotypic resistance. Antivir. Ther. 8:355-360.[Medline]
14 - Villahermosa, M. L., M. M. Thomson, E. Vázquez de Parga, M. T. Cuevas, G. Contreras, L. Pérez-Álvarez, E. Delgado, N. Manjón, L. Medrano, and R. Nájera. 2000. Improved conditions for extraction and amplification of HIV-1 RNA from plasma samples with low viral load. J. Hum. Virol. 3:27-34.[Medline]
15 - Villahermosa, M. L., I. Beck, L. Pérez-Álvarez, G. Contreras, L. M. Frenkel, S. Osmanov, E. Vázquez de Parga, E. Delgado, N. Manjón, M. T. Cuevas, L. Medrano, and R. Nájera. 2002. Detection and quantification of multiple drug resistance mutations in HIV-1 reverse transcription by an oligonucleotide ligation assay. J. Hum. Virol. 4:1-11.
16 - Wallis, C., I. Mahomed, L. Morris, T. Chidarikire, G. Stevens, N. Rekhviashvili, and W. Stevens. 2005. Evaluation of an oligonucleotide ligation assay for detection of mutations in HIV-1 subtype C individuals who have high level resistance to nucleoside reverse transcriptase inhibitors. J. Virol. Methods 125:99-109.[Medline]
Journal of Clinical Microbiology, October 2005, p. 5301-5304, Vol. 43, No. 10
0095-1137/05/$08.00+0 doi:10.1128/JCM.43.10.5301-5304.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
This article has been cited by other articles:
-
Jallow, S., Kaye, S., Schutten, M., Brandin, E., Albert, J., McConkey, S. J., Corrah, T., Whittle, H., Vanham, G., Rowland-Jones, S., Janssens, W.
(2007). Development and Evaluation of an Oligonucleotide Ligation Assay for Detection of Drug Resistance-Associated Mutations in the Human Immunodeficiency Virus Type 2 pol Gene. J. Clin. Microbiol.
45: 1565-1571
[Abstract]
[Full Text]