Previous Article | Next Article 
Antimicrobial Agents and Chemotherapy, April 2009, p. 1670-1672, Vol. 53, No. 4
0066-4804/09/$08.00+0 doi:10.1128/AAC.01494-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
Detection of Human Immunodeficiency Virus (HIV) Type 1 M184V and K103N Minority Variants in Patients with Primary HIV Infection
Thomas A. Toni,1,2,3
Eugene L. Asahchop,1
Daniela Moisi,1
Michel Ntemgwa,1
Maureen Oliveira,1
Bernard Masquelier,4
Bluma G. Brenner,1 and
Mark A. Wainberg1,2*
McGill University AIDS Centre, Lady Davis Institute, Jewish General Hospital, Montreal, Quebec H3T 1E2,1
Department of Medicine, McGill University, Montreal, Quebec H3A 2T5, Canada,2
Programme PACCI-CIRBA, Abidjan, Côte d'Ivoire,3
EA2968, Université de Bordeaux 2, Bordeaux, France4
Received 7 November 2008/
Returned for modification 19 December 2008/
Accepted 16 January 2009

ABSTRACT
We used an allele-specific real-time PCR assay to explore the
presence of K103N and M184V minority species among primary human
immunodeficiency virus (HIV) infections and their potential
influence in HIV transmission. Thirty randomly chosen antiretroviral
drug-naive patients lacking both the K103N and the M184V mutations
as determined by conventional sequencing methods were studied,
and K103N and M184V viral minority species were found in three
(10%) and four (11%) patients, respectively.

INTRODUCTION
The activity of antiretroviral drugs (ARVs) can be impeded by
the selection and transmission of drug resistance-associated
mutations (
4,
6,
11). Yet, few studies of the potential impact
of such mutations on viral transmissibility have been carried
out (
13). Our group showed that mutations associated with protease
inhibitors (PIs), thymidine analogues (thymidine-associated
mutations), or nonnucleoside reverse transcriptase inhibitors
(NNRTIs) were present in approximately 10 to 20% of newly infected
patients but that the M184V mutation in reverse transcriptase
(RT), associated with resistance to lamivudine and emtricitabine,
was identified in only about 4% of such subjects (
12). Since
M184V is known to adversely affect viral replicative capacity
as well as efficiency of RT initiation and function (
3,
14),
we speculated that this mutation might also affect human immunodeficiency
virus (HIV) transmissibility.
The above-mentioned results were obtained using conventional sequencing methods that cannot detect minority variants that are present below a detection threshold of 20% of the total viral population. Therefore, it remained possible that viruses containing M184V might be transmitted as efficiently as other viruses but that the M184V mutation might revert to the wild type or be deselected in newly infected patients not receiving ARVs. As a consequence, M184V-containing viruses might be out-competed by wild-type viruses with higher replication capacity. To try to resolve this issue, we employed an allele-specific PCR assay (AS-PCR) to specifically detect the presence of minority species within the viral populations of newly infected individuals in the Montreal primary-HIV-infection (PHI) cohort.

Study population.
A random sampling of 30 untreated patients enrolled between
2005 and 2007 in the Montreal PHI cohort were included and had
been infected for less than 6 months, as described previously
(
12); none of these individuals possessed either the K103N or
the M184V resistance mutation, as determined by bulk sequencing.
All patients provided informed consent. Plasma HIV-1 RNA was
measured using the Quantiplex HIV-1 RNA and bDNA systems (threshold,
50 copies/ml; Bayer Diagnostics).

Drug resistance genotyping.
Viral RNA was extracted from plasma by using a QIAamp viral
extraction kit (Qiagen, Mississauga, Ontario, Canada). Genotyping
was performed by sequencing a 1,497-bp fragment of the HIV
pol region (positions 2253 to 3749) spanning the entire protease
(PR) and most of the RT region (codons 1 to 400), using Virco
primers (Virco, BVBA, Mechelen, Belgium) with a BigDye Terminator
cycle sequencing kit (version 1.1; Applied Biosystems, Foster
City, CA) and an automated sequencer (ABI Prism 3130 genetic
analyzer; Applied Biosystems).

Quantification of minority resistance species by AS-PCR.
Plasma viral samples obtained during PHI that lacked either
the M184V or the K103N mutation were evaluated by AS-PCR to
detect viral populations that possibly carried these mutations
(sensitivity,

1%); sensitivity and specificity were monitored
using positive and negative controls. Purified PCR products
of the genotyped samples were used as described previously (
7,
10) in an assay in which the 5' ends of forward primers were
subjected to an inosine modification. The primers used were
IN_K103N (5'-CCGCAGGGTTAAAAAAGAIC-3'; nucleotides [nt] 2839
to 2858) and Pol 3002 (5'-CTGTGGAAGCACATTGTACTG-3'; nt 2982
to 3002) for detection of K103N and IN_M184V (5'-CCAGACATAGTTATCTATCAATAIG-3';
nt 3075 to 3099) and N35 (5'-CCTACTAACTTCTGTATGTCATTGACAGTCCAGCT-3';
nt 3300 to 3333) for detection of M184V. Total viral populations
were also amplified with primers Pol 2801 (5'-TCAAGACTTCTGGGAAGTTCA-3';
nt 2801 to 2821) and Pol 3122 (5'-TGCTGCCCTATTTCTAAGTCA-3';
nt 3122 to 3134), spanning RT amino acids 103 to 184. Results
were expressed as proportions of mutant viruses in the total
population. Real-time PCR was performed using a Rotor-Gene 6000
apparatus (Corbett Life Sciences), with a third-generation dsDNA
intercalating dye termed SYTO9 (Invitrogen). DNA standards for
quantification were prepared by PCR amplification. Specific
K103N and M184V mutations were introduced by site-directed mutagenesis
(SDM) into HIV-1 subtype B pNL4-3 wild-type plasmid using a
QuikChange SDM kit as specified by the manufacturer (Stratagene).
For SDM of K103N, primers K103N B Fw (5'-CTG CAG GGT TAA AAC
AGA ACA AAT CAG TAA CAG TAC TG-3'; nt 2839 to 2876) and K103N
B Rev (5'-CAG TAC TGT TAC TGA TTT GTT CTG TTT TAA CCC TGC AG-3';
nt 2839 to 2876) were used. For M184V, primers M184V B Fw (5'-GAC
ATA GTC ATC TAT CAA TAC GTG GAT GAT TTG TAT GTA GGA TC-3'; nt
3078 to 3121) and M184V B Rev (5' GAT CCT ACA TAC AAA TCA TCC
ACG TAT TGA TAG ATG ACTA TGT C-3'; nt 3078 to 3121) were employed.

Detection of minority resistance variants.
The mean plasma HIV-1 RNA level of the 30 subjects evaluated
was 4.6 log
10 (the median was 4.7), with a range of 2.6 to 7.4.
Amino acid substitutions in PR and RT are shown in Table
1.
Seven of these individuals appeared to be resistant to at least
one PI and to at least one nucleoside RT inhibitor (NRTI) or
NNRTI. One individual possessed the D30N and N88D mutations
in PR, associated with resistance to nelfinavir. Minor resistance
mutations were observed at positions 10, 33, 36, 63, 70, 71,
77, and 93 in PR. In regard to RT, two and four subjects were
resistant to at least one NRTI and one NNRTI, respectively.
The thymidine-associated mutations included M41L, L210W, and
T215Y, while V118I, L210F/M, and G333E were observed in some
samples. One sample (specimen 2) appeared to be resistant to
both some NRTIs and some PIs.
The results (Table
1) show that K103N and M184V minority species
were found in three and four patients, respectively. One sample
that was found to contain M184V by AS-PCR (sample 12) did not
contain other detectable RT resistance mutations. In contrast,
other samples, e.g., numbers 1, 10, and 23, contained other
NRTI or NNRTI resistance mutations as determined by bulk sequencing.
No major resistance mutations were found in any of the viruses (samples 18, 21, and 29) that contained K103N minority species. All these patients had high viral loads (mean plasma viral load, 4.3 ± 0.5 log10 copies/ml).
In summary, we studied the prevalences of the K103N and M184V mutations in a group of 30 PHI patients who showed resistance to at least one drug as determined by conventional resistance testing. Circulation of such resistant strains can result in impairment of responsiveness to first-line therapy (2). Using an AS-PCR approach, we have now shown that both the K103N and the M184V mutations were detectable as minority variants in acute seroconverters, regardless of the low prevalence of the M184V mutation in such individuals as observed by bulk sequencing (12). The K103N mutation, in contrast to M184V, has only a low impact on replicative fitness (1, 9). In the absence of drug pressure, viruses harboring M184V can rapidly revert to the wild type or deselect this mutation and, consequently, are less well detected by bulk sequencing (12). One recent report found an association between the presence of baseline minority resistance variants and nonresponsiveness to highly active antiretroviral therapy (5), although other studies have not obtained similar results (8, 10).
Although M184V-containing viruses can rapidly revert to the wild type, the persistence of M184V-containing strains is of concern in the management of antiretroviral therapy. Despite the impact of M184V on HIV fitness, our results document that this mutation can be detected in acutely infected, ARV-naive patients, suggesting that transmission of this mutation takes place at a higher frequency than suggested by the results of bulk sequencing (12).

Nucleotide sequence accession numbers.
The sequences described in this study have been deposited in
GenBank under accession numbers EU375800-801 and EU 906882-907.

ACKNOWLEDGMENTS
This work was sponsored by the Canadian Institutes of Health
Research (CIHR).
Thomas d'Aquin Toni is the recipient of a CIHR postdoctoral fellowship award. Michel Ntemgwa is the recipient of a CIHR doctoral fellowship award.

FOOTNOTES
* Corresponding author. Mailing address: McGill AIDS Centre, Jewish General Hospital, 3755 Cote Ste Catherine Rd., Montreal, Quebec, Canada H3T 1E2. Phone: (514) 340-8260. Fax: (514) 340-7537. E-mail:
mark.wainberg{at}mcgill.ca 
Published ahead of print on 26 January 2009. 

REFERENCES
1 - Bacheler, L., S. Jeffrey, G. Hanna, R. D'Aquila, L. Wallace, K. Logue, B. Cordova, K. Hertogs, B. Larder, R. Buckery, D. Baker, K. Gallagher, H. Scarnati, R. Tritch, and C. Rizzo. 2001. Genotypic correlates of phenotypic resistance to efavirenz in virus isolates from patients failing nonnucleoside reverse transcriptase inhibitor therapy. J. Virol. 75:4999-5008.[Abstract/Free Full Text]
2 - Chaix, M. L., L. Desquilbet, D. Descamps, D. Costagliola, C. Deveau, J. Galimand, C. Goujard, A. Signori-Schmuck, V. Schneider, C. Tamalet, I. Pellegrin, M. Wirden, B. Masquelier, F. Brun-Vezinet, C. Rouzioux, L. Meyer, et al. 2007. Response to HAART in French patients with resistant HIV-1 treated at primary infection. Antivir. Ther. 12:1305-1310.[Medline]
3 - Diallo, K., B. Marchand, X. Wei, L. Cellai, M. Gotte, and M. A. Wainberg. 2003. Diminished RNA primer usage associated with the L74V and M184V mutations in the reverse transcriptase of human immunodeficiency virus type 1 provides a possible mechanism for diminished viral replication capacity. J. Virol. 77:8621-8632.[Abstract/Free Full Text]
4 - Grubb, J. R., E. Singhatiraj, K. Mondy, W. G. Powderly, and E. T. Overton. 2006. Patterns of primary antiretroviral drug resistance in antiretroviral-naive HIV-1-infected individuals in a midwest university clinic. AIDS 20:2115-2116.[Medline]
5 - Johnson, J. A., J. F. Li, X. Wei, J. Lipscomb, D. Irlbeck, C. Craig, A. Smith, D. E. Bennett, M. Monsour, P. Sandstrom, E. R. Lanier, and W. Heneine. 2008. Minority HIV-1 drug resistance mutations are present in antiretroviral treatment-naive populations and associate with reduced treatment efficacy. PLoS Med. 5:e158.[CrossRef][Medline]
6 - Masquelier, B., K. Bhaskaran, D. Pillay, R. Gifford, E. Balestre, L. B. Jorgensen, C. Pedersen, L. van der Hoek, M. Prins, C. Balotta, B. Longo, C. Kucherer, G. Poggensee, M. Ortiz, C. de Mendoza, J. Gill, H. Fleury, and K. Porter. 2005. Prevalence of transmitted HIV-1 drug resistance and the role of resistance algorithms: data from seroconverters in the CASCADE collaboration from 1987 to 2003. J. Acquir. Immune Defic. Syndr. 40:505-511.[CrossRef][Medline]
7 - Metzner, K. J., S. Bonhoeffer, M. Fischer, R. Karanicolas, K. Allers, B. Joos, R. Weber, B. Hirschel, L. G. Kostrikis, and H. F. Gunthard. 2003. Emergence of minor populations of human immunodeficiency virus type 1 carrying the M184V and L90M mutations in subjects undergoing structured treatment interruptions. J. Infect. Dis. 188:1433-1443.[CrossRef][Medline]
8 - Metzner, K. J., P. Rauch, V. von Wyl, H. Kuster, H. J. Stellbrink, J. Böni, H. Trkola, R. Weber, and H. F. Günthard. 2007. Prevalence of minority quasispecies of drug-resistant HIV-1 in patients with primary HIV-1 infection in Zurich in the years 2002-2006. Antivir. Ther. 12:S47.
9 - Nicastri, E., L. Sarmati, G. d'Ettorre, L. Palmisano, S. G. Parisi, I. Uccella, A. Rianda, E. Concia, V. Vullo, S. Vella, and M. Andreoni. 2003. Replication capacity, biological phenotype, and drug resistance of HIV strains isolated from patients failing antiretroviral therapy. J. Med. Virol. 69:1-6.[CrossRef][Medline]
10 - Peuchant, O., R. Thiebaut, S. Capdepont, V. Lavignolle-Aurillac, D. Neau, P. Morlat, F. Dabis, H. Fleury, and B. Masquelier. 2008. Transmission of HIV-1 minority-resistant variants and response to first-line antiretroviral therapy. AIDS 22:1417-1423.[CrossRef][Medline]
11 - Salomon, H., M. A. Wainberg, B. Brenner, Y. Quan, D. Rouleau, P. Cote, R. LeBlanc, E. Lefebvre, B. Spira, C. Tsoukas, R. P. Sekaly, B. Conway, D. Mayers, J. P. Routy, et al. 2000. Prevalence of HIV-1 resistant to antiretroviral drugs in 81 individuals newly infected by sexual contact or injecting drug use. AIDS 14:F17-F23.[CrossRef][Medline]
12 - Turner, D., B. Brenner, J. P. Routy, D. Moisi, Z. Rosberger, M. Roger, and M. A. Wainberg. 2004. Diminished representation of HIV-1 variants containing select drug resistance-conferring mutations in primary HIV-1 infection. J. Acquir. Immune Defic. Syndr. 37:1627-1631.[CrossRef][Medline]
13 - Turner, D., and M. A. Wainberg. 2006. HIV transmission and primary drug resistance. AIDS Rev. 8:17-23.[Medline]
14 - Wei, X., C. Liang, M. Gotte, and M. A. Wainberg. 2003. Negative effect of the M184V mutation in HIV-1 reverse transcriptase on initiation of viral DNA synthesis. Virology 311:202-212.[CrossRef][Medline]
Antimicrobial Agents and Chemotherapy, April 2009, p. 1670-1672, Vol. 53, No. 4
0066-4804/09/$08.00+0 doi:10.1128/AAC.01494-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.