Impact of drug resistance genotypes on CD4+ counts and plasma viremia in heavily antiretroviral-experienced HIV-infected patients.
ABSTRACT The number of HIV-infected individuals with prior multiple treatment failures is increasing as time passes by. The success of antiretroviral therapy in these patients is often compromised by the selection of drug-resistant viruses. Despite initial concerns, a rebound in AIDS cases among heavily treatment-experienced patients failing virologically their antiretroviral therapy has not occurred yet. In a multicenter study conducted in Spain, HIV-infected patients were assessed with prior failure to antiretrovirals from the three main drug families who presented during the last semester of the year 2003 with plasma HIV-RNA values above 1,000 copies/ml, despite good treatment adherence. The relationships between CD4+ T cell counts, viral loads and drug-resistant genotypes were examined. A total of 273 patients were identified in 12 centers (78% male, median age: 41 years). The mean viral load was 50,438 copies/ml and the mean CD4+ count was 328 cells/mul. Only 19.5% had less than 200 CD4+ T cells/mul. Most patients (95%) were receiving nucleoside reverse transcriptase inhibitors (NRTI) in their last antiretroviral regimen, while 63% were treated with protease inhibitors (PI) and 27% on non-nucleoside reverse transcriptase inhibitors (NNRTI). Overall, 97.4% had at least one drug resistance mutation (87.2% for NRTI, 68.5% for NNRTI, and 92.7% for PI). Using the virtual phenotype, resistance to three or more drugs within each class was recognized in 45.8% for NRTI, 40.7% for NNRTI, and 44.7% for PI. Moreover, cross-resistance to compounds from two or three drug families was recognized in 41% and 19.4% of patients, respectively. Nearly half of the patients had plasma HIV-RNA below 10,000 copies/ml and they showed significantly higher CD4 + counts than those with greater viremia (408 versus 259 cells/mul; P < 0.001). Patients with higher plasma viremia had significantly more drug resistance mutations than those with lower viremia. No favorable effect on viral load could be recognized for individual drug resistance mutations known to reduce viral fitness in vitro (i.e., rtM184V, rtL74V, rtK65R, proD30N, or proI50L). In summary, a large proportion of treatment-experienced patients failing their current antiretroviral regimen carry viruses with broad cross-resistant genotypes. Nearly half of the patients with these multi-drug resistant viruses had < 10,000 HIV-RNA copies/ml and 80% have more than 200 CD4 + T cells/mul. Thus, maintaining treatment HIV-infected individuals failing virologically and harboring drug-resistant viruses might ameliorate immunological deterioration until new drugs became available. J. Med. Virol. 77:23-28, 2005. (c) 2005 Wiley-Liss, Inc.
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ABSTRACT: ENGLISH ABSTRACT: Introduction: Reactivation of human cytomegalovirus (HCMV) infection in individuals infected with human immunodeficiency virus (HIV) may lead to life-threatening end-organ diseases (EOD). The EOD becomes clinically apparent when a critical number of cells in the affected organs become damaged as a consequence of HCMV-infection. Treatment of the HCMV-associated disease at this point may not be effective. Therefore, early detection of HCMV reactivation may be useful to guide pre-emptive therapy. Aim: The aim of this study was to determine whether there is a point at which the HCMV-specific cellular immune response breaks down, as determined by the interferon-gamma (IFN-γ) enzyme-linked immunospot (ELISPOT) assay, and HCMV reactivation occurs in HIV-positive, antiretroviral therapy (ART)-naïve individuals in a South African setting. This was done in relation to the CD4+ T cell count and the HCMV viral load as determined by real-time polymerase chain reaction (qPCR). Materials and methods: Fifty-two (52) HIV-infected, ART-naïve subjects were recruited from primary healthcare centres that they attended for the management of their HIV infection. Heparinised blood samples were collected to quantify the HCMV-specific cellular immune response using the IFN-γ-ELISPOT assay and to determine the HCMV IgG serostatus. Ethylenediaminetetraacetic acid (EDTA) blood samples were collected for the determination of the CD4+ T cell counts and the HCMV viral loads. Results: All 52 subjects recruited were confirmed to be HIV-HCMV co-infected based on their HCMV IgG serostatus. The results of 34 subjects with completed data sets were analysed. The CD4+ T cell counts of these subjects ranged from 10 to 784 cells/μl. Twenty-two (22) (65%) subjects had positive HCMV IFN-γ-ELISPOT results with 94% having no detectable HCMV viral loads. All subjects (28) with a CD4+ T cell count above 100 cells/μl had undetectable HCMV viral loads. Two of the six subjects with CD4+ T cell counts <100 cells/μl had detectable HCMV viral loads. There was no statistically significant association between the CD4+ T cell counts and the HCMV IFN-γ-ELISPOT results. Conclusion: No specific point could be determined when there is loss of integrity of the HCMV-specific cellular immune response in HIV-positive individuals. Low CD4+ T cell counts did not correlate with HCMV IFN-γ-ELISPOT results suggesting that the HCMV-specific cellular immunity did not necessarily break down at low CD4+ T cell counts. Nevertheless, a CD4+ T cell count above 100 cells/μl appeared to be protective against viraemia as determined by the HCMV viral load qPCR. The IFN-γ-ELISPOT assay was employed as a tool to determine the integrity of the HCMV-specific cellular immune response in HIV-positive individuals. However, the IFN-γ-ELISPOT assay should be used in conjunction with the CD4+ T cell count and the HCMV viral load qPCR to determine when there is loss of integrity of the HCMV-specific cellular immune response and HCMV reactivation occurs. This may assist clinicians in their choice of management and appropriate pre-emptive treatment in the HIV-HCMV co-infected individual at a risk for HCMV reactivation. AFRIKAANSE OPSOMMING: Inleiding: Heraktivering van menslike sitomegaalvirus (MSMV) in menslike immuniteitsgebreksvirus (MIV)-MSMV ko-geïnfekteerde individue kan lei tot dodelike end-orgaan siektes (EOS). Die EOS word klinies duidelik wanneer 'n kritieke aantal selle in die organe beskadig raak as gevolg van die MSMV-infeksie. Behandeling van die MSMV-verwante siekte op hierdie punt mag moontlik nie meer effektief wees nie. Daarom kan die vroeë opsporing van MSMV heraktivering nuttig wees in die gebruik van voorkomende terapie. Doel: Die doel van hierdie studie is om die punt te bepaal wanneer die MSMV-spesifieke sellulêre immuun reaksie afgebreek word met behulp van die interferon gamma (IFN-γ) ensiem-gekoppelde immunospot (ELISPOT) toets en MSMV heraktivering voorkom in MIV-positiewe, antiretrovirale terapie (ART)-naïewe individue in' n Suid-Afrikaanse instelling. Dit word gedoen in verhouding met die CD4+ T sel telling en die MSMV virale lading. Materiale en metodes: Twee-en-vyftig (52) MIV-geïnfekteerde, ART-naïewe pasiënte is vanaf primêre gesondheidsentrums, wat hul bywoon vir die behandeling van hul MIV infeksie, genader. Gehepariniseerde bloedmonsters is gebruik om die MSMV-spesifieke sellulêre immuun reaksie met behulp van die IFN-γ-ELISPOT toets en die MSMV IgG serostatus te bepaal. Etileendiamientetra-asynsuur (EDTA) bloed monsters is versamel vir die bepaling van hul CD4+ T sel telling en hul MSMV virale lading met behulp van die ―real-time‖ polimerase kettingreaksie (qPKR) waardes. Resultate: Al 52 pasiënte is bevestigde MIV-MSMV ko-infeksies, gebasseer op hul serologiese status. Die resultate van 34 pasiënte met voltooide data is ontleed. Die CD4+ T sel tellings van hierdie pasiënte het gewissel 10-784 selle/μl. Twee-en-twintig (22) (65%) pasiënte het positiewe MSMV IFN-γ-ELISPOT resultate met 94% wat ‗n negatiewe qPKR resultate. Alle pasiënte (28) met 'n CD4+ T-seltelling bo 100 selle/μl het' n negatiewe qPKR resultate. Twee van die ses pasiënte met 'n CD4+ T-seltelling <100 selle/μl het waarneembare MSMV virale ladings oor die qPKR. Daar was geen statisties beduidende assosiasie tussen die CD4+ T sel tellings en die MSMV IFN-γ-ELISPOT resultate nie. Gevolgtrekking: Geen spesifieke punt wanneer die MSMV-spesifieke sellulêre immuun reaksie afgebreek word kon in MIV-positiewe individue bepaal word nie. Lae CD4+ T sel tellings het nie ooreengestem met die MSMV IFN-γ-ELISPOT resultate nie en dui daarop dat die MSMV-spesifieke sellulêre immuniteit nie noodwendig afgebreek word teen 'n lae CD4+ T sel tellings nie. Tog blyk 'n CD4+ T-seltelling bo 100 selle/μl om beskerming teen viremie te bied. Die meriete van die gebruik van die IFN-γ-ELISPOT toets die integriteit van die MSMV-spesifieke sellulêre immuun response in MIV-positiewe individue te bepaal, is waargeneem in die opgehoopte data. Tog kan die gebruik van die IFN-γ-ELISPOT toets in samewerking met die CD4+ T sel telling en die MSMV virale lading meer voordelig in die bepaling van 'n punt wanneer die MSMV-spesifieke sellulêre immuun reaksie afbreek en herstel plaasvind. Dit kan help om klinici in hul keuse van bestuur en gepaste voorkomende behandeling in die MIV-MSMV mede-geïnfekteerde individu op 'n risiko vir herstel. Thesis (MScMedSc)--University of Stellenbosch, 2011.
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ABSTRACT: Star celebrities such as Rock Hudson, Freddie Mercury, Magic Johnson, and Isaac Asimov have unfortunately something in common: they were all victims of the HIV global pandemic. Since then HIV infection has become considered a pandemic disease, and it is regarded as a priority in healthcare worldwide. It is ranked as the first cause of death among young people in industrialized countries, and it is recognized as a public healthcare problem due to its human, social, mass media, and economic impact. Incorporation of new and highly active antiretroviral treatment, available since 1996 for HIV/AIDS treatment, has provoked a radical change in the disease pattern, as well as in the impact on patient survival and quality of life. The pharmaceutical industry's contribution, based on the research for more active new drugs, has been pivotal. Mortality rates have decreased significantly in 20 years by 50% and now AIDS is considered a chronic and controlled disease. In this review we have studied the impact of HAART treatment on infected patients, allowing them to maintain their status as active workers and the decreased absenteeism from work derived from this, contributing ultimately to overall social wealth and, thus, to economic growth. Furthermore, an analysis of the impact on healthcare costs, quality of life per year, life per year gained, cost economic savings and cost opportunity among other parameters has shown that society and governments are gaining major benefits from the inclusion of antiretroviral therapies in HIV/AIDS patients.AIDS reviews 11(2):79-90. · 4.08 Impact Factor
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ABSTRACT: Background: The prevalence of HIV drug resistance varies with geographic location, year, and treatment exposure. This study generated yearly estimates of non-nucleotide reverse transcriptase inhibitor (NNRTI) resistance in treatment-naïve (TN) and treatment-experienced (TE) patients in the United States (US), Europe (EU), and Canada. Methods: Studies reporting NNRTI resistance identified in electronic databases and 11 conferences were analyzed in three groups: 1) TN patients in one of four geographic regions (US, Canada, EU countries with larger surveillance networks ["EU1"], and EU countries with fewer data ["EU2"]); 2) TE patients from any region and 3) TN patients failing NNRTI-based treatments in clinical trials. Results: Analysis data included 158 unique studies from 22 countries representing 84 cohorts of TN patients, 21 cohorts of TE patients, and eight trials reporting resistance at failure. From 1995-2000, resistance prevalence in TN patients increased in US and EU1 from 3.1% to 7.5% and 0.8% to 3.6%, respectively. Resistance in both regions stabilized in 2006 onwards. Little resistance was identified in EU2 before 2000, and increased from 2006 (5.0%) to 2010 (13.7%). One TN Canadian study was identified and reported resistance of 8.1% in 2006. Half of TN clinical trial patients had resistance after treatment failure at weeks 48-144. Resistance in TE patients increased from 1998 (10.1%) to 2001 (44.0%), then decreased after 2004. Conclusions: Trends in NNRTI resistance among TN patients show an increased burden in the US and some EU countries compared to others. These findings signify a need for alternate 1st-line treatments in some regions.AIDS research and human retroviruses. 06/2014;
Journal of Medical Virology 77:23–28 (2005)
Impact of Drug Resistance Genotypes on
CD4þ Counts and Plasma Viremia in Heavily
Antiretroviral-Experienced HIV-Infected Patients
Berta Rodes,1Federico Garcı ´a,2Carolina Gutierrez,3Javier Martinez-Picado,4Antonio Aguilera,5
Maria Saumoy,6Alex Vallejo,7Pere Domingo,8David Dalmau,9Maria Angels Ribas,10
Jose ´ Luis Blanco,11Jose ´ Pedreira,12Maria Jesu ´s Perez-Elias,3Manuel Leal,7
Carmen de Mendoza,1and Vincent Soriano1* On behalf of the Red de Investigacio ´n en SIDA (RIS)
1Hospital Carlos III, Madrid, Spain
2Hospital San Cecilio, Granada, Spain
3Hospital Ramon y Cajal, Madrid, Spain
4IrsiCaixa Foundation, Hospital Germans Trias i Pujol, Universitat Auto `noma de Barcelona, Badalona,
5Hospital Universitario, Santiago de Compostela, A Corun ˜a, Spain
6Hospital Joan XXIII-Universitat Rovira i Virgili, Tarragona, Spain
7Hospital Virgen del Rocio, Sevilla, Spain
8Hospital de Sant Pau, Barcelona, Spain
9Mutua de Terrassa, Terrassa, Barcelona, Spain
10Hospital Son Dureta, Palma de Mallorca, Spain
11Hospital Clinic, Barcelona, Spain
12Hospital Juan Canalejo, A Corun ˜a, Spain
multiple treatment failures is increasing as time
passes by. The success of antiretroviral therapy
in these patients is often compromised by the
selection of drug-resistant viruses. Despite ini-
tial concerns, a rebound in AIDS cases among
heavily treatment-experienced patients failing
virologically their antiretroviral therapy has not
occurred yet. In a multicenter study conducted in
Spain, HIV-infected patients were assessed with
drug families who presented during the last
semester of the year 2003 with plasma HIV-RNA
values above 1,000 copies/ml, despite good
treatment adherence. The relationships between
genotypes were examined. A total of 273 pati-
ents were identified in 12 centers (78% male,
median age: 41 years). The mean viral load was
50,438 copies/ml and the mean CD4þ count was
328 cells/ml. Only 19.5% had less than 200 CD4þ
T cells/ml. Most patients (95%) were receiving nu-
their last antiretroviral regimen, while 63% were
treated with protease inhibitors (PI) and 27% on
non-nucleoside reverse transcriptase inhibitors
(NNRTI). Overall, 97.4% had at least one drug
resistance mutation (87.2% for NRTI, 68.5% for
type, resistance to three or more drugs within
each class was recognized in 45.8% for NRTI,
40.7% for NNRTI, and 44.7% for PI. Moreover,
cross-resistance to compounds from two or
three drug families was recognized in 41%
and 19.4% of patients, respectively. Nearly half
of the patients had plasma HIV-RNA below
10,000 copies/ml and they showed significantly
higher CD4þ counts than those with greater
viremia (408 versus 259 cells/ml; P<0.001). Pa-
tients with higher plasma viremia had signi-
ficantly more drug resistance mutations than
those with lower viremia. No favorable effect on
viral load could be recognized for individual drug
resistance mutations known to reduce viral fit-
ness in vitro (i.e., rtM184V, rtL74V, rtK65R,
proD30N, or proI50L). In summary, a large pro-
portion of treatment-experienced patients failing
Grant sponsor: Redes de Investigacio ´n en SIDA.
*Correspondence to: Dr. Vincent Soriano, Department of
Infectious Diseases, Hospital Carlos III, Calle Sinesio Delgado
10, 28010 Madrid, Spain. E-mail: email@example.com
Accepted 10 May 2005
Published online in Wiley InterScience
? 2005 WILEY-LISS, INC.
their current antiretroviral regimen carry viruses
with broad cross-resistant genotypes. Nearly
half of the patients with these multi-drug re-
sistant viruses had <10,000 HIV-RNA copies/ml
and80% have more than 200 CD4þ T cells/ml.
Thus, maintaining treatment HIV-infected indivi-
duals failing virologically and harboring drug-
resistant viruses might ameliorate immunolo-
gical deterioration until new drugs became
available. J. Med. Virol. 77:23–28, 2005.
? 2005 Wiley-Liss, Inc.
drug resistance; antiretroviral
therapy; HIV; viral fitness; pro-
The number of HIV-infected patients with prior
multiple treatment failures is increasing as time passes
by. The success of antiretroviral therapy in these
patients is often compromised by the selection of drug-
resistant viruses [Cheung et al., 2004; Richman et al.,
2004]. When resistance has developed to almost all
currently available antiretroviral agents, salvage inter-
ventions including mega-HAART or structured treat-
ment interruptions have been attempted, generally
without major benefits [Lawrence et al., 2003; Ruiz
et al., 2003]. In patients with high CD4þ T cell counts,
drug holidays may be advisable to spare drug toxicities
and give a chance to wild-type viruses to reappear
[Halfon et al., 2003]. However, in patients with low
CD4þ counts, continuation of antiretroviral therapy
despite virological failure has shown to provide immu-
nological benefit as long as plasma viremia is not in-
creasing beyond 10,000–20,000HIV-RNA copies/ml [Le
Moing et al., 2002; Raffanti et al., 2004; The PLATO
heavily pre-treated patients failing their current anti-
retroviral regimen. However, it is unclear what should
be expected from new agents when they belong to
the available drug families, since accumulation of mul-
tiple resistance mutations within the reverse transcrip-
tase (RT) or protease genes most likely will impact
deleteriously on virus susceptibility to these new drugs
to a more or less extent [Turner et al., 2004]. In this
setting, inhibitors of new targets may be the ultimate
unique option to regain the goal of complete virus sup-
pression. This has been clearly demonstrated recently
2003; Clotet et al., 2004].
In the present study, the main characteristics of a
large group of HIV-infected patients failing their cur-
rent antiretroviral regimen after exposure to agents
from all three main drug classes were evaluated.
The relationships between drug resistance genotypes,
CD4þ counts and plasma viremia were investigated
PATIENTS AND METHODS
prior virological failure under compounds from all three
the last semester of year 2003, and had plasma HIV-
RNA values above 1,000 copies/ml, despite good treat-
ment adherence, were assessed in a large multicenter,
in Spain. The main demographics and clinical charac-
teristics were recorded in a uniform case report form.
CD4þ T cell counts were measured using monoclonal
antibodies followed by cytofluorometry at each insti-
tution. Plasma HIV-RNA was quantified using one of
three commercially available viral load tests (Bayer
Population-based sequences of the HIV-1 pol gene were
obtained after RT-PCR amplification of HIV-RNA
extracted from plasma specimens using one of two com-
mercially available automatic sequencers (Celera Diag-
nostics and Visible Genetics).
The definitions of broad cross-resistance to a given
drug family were considered as follows. For NRTI, the
term was applied to genotypes known to confer reduced
susceptibility to at least three compounds within this
class [Gallego et al., 2004]. This definition applied to
samples with three or more thymidine analogue muta-
tions (TAMs), including T215Y/F, since this genotype
has been associated with resistance to zidovudine,
stavudine, and abacavir [Larder and Bloor, 2001]. If
TAMs included changes M41L or L210W, resistance to
tenofovir should further be expected [Barrios et al.,
2003; Miller et al., 2004].
For NNRTI, the presence of two or more mutations of
a list of nine changes (codons 100, 101, 103, 106, 108,
cross-resistance a given genotype. Although unique
single changes (i.e., K103N) may probably compromise
drug [Casado et al., 2002; Gonzalez de Requena et al.,
The definition of broad cross-resistance to PI was
based on the presence of a minimum of five resistance
mutations at the protease gene, following clinical data
reported in several studies [Barreiro et al., 2002; Valer
et al., 2002; De Mendoza and Soriano, 2004].
In order to confirm the reliability of the criteria used
for defining broad cross-resistance on the basis of geno-
types, when possible, the virtual phenotype (Tibotec-
Virco VA, Mechelen, Belgium) was obtained.
Descriptive statistics were expressed as mean and
standard deviations (CD4 counts and viral load) or
median and interquartile ranges (number of resistance
for categorical data. Median values were compared
using the Student’s t-test. The chi-square test was used
24Rodes et al.
were performed using the SPSS version 9.0 software
A total of 273 multitreated HIV-positive patients
failing theircurrent antiretroviralregimen were identi-
fied (78% male; median age, 41 years). Most individuals
were native Spaniards (96.1%), and the main risk
groups were injection drug users (39.2%), homosexual
men (31.9%), and heterosexuals (21.6%). The median
time on antiretroviral therapy was 8.5 years. The
median number of prior different antiretroviral regi-
mens was seven. At the time of the analysis, the mean
viral load was 50,438 copies/ml and the mean CD4þ
count was 328 cells/ml. Only 19.5% of patients had less
than 200 CD4þ cells/ml. Most patients (95%) were
receiving NRTIs in their last antiretroviral regimen,
while 63% were treated with PIs and 27% on NNRTIs.
Overall, 97.4% of patients showed at least one drug
resistance mutation recorded within the last IAS-USA
ing broad cross-resistance for each drug class were
recognized in 45.8% for NRTI, 40.7% for NNRTI, and
44.7% for PI (see Table I). Virtual phenotypic results
ed almost completely the interpretation based on geno-
types (data not shown). Phylogenetic analyses showed
that all patients were infected by HIV-1 subtype B
Overall, 87.2% of patients had mutations associated
with NRTI resistance. The genotypes causing more fre-
quently broad NRTI cross-resistance were: >3 TAMs
(37%), >3 TAMs þ M184V (14.7%), >3 TAMsþL74V
Besides, the Q151M complex and/or codon 69 inserts
were recognized in 5.1% of patients.
With NNRTIs, 68.5% of patients had at least one
NNRTI mutation, and 40.7% had ?2 mutations caus-
ing broad NNRTI cross-resistance. Finally, 92.7% of
patients had at least one protease resistance mutation,
and 44.7% carried ?5 protease resistance mutations,
which may cause multiple PI resistance. Broad cross-
resistance to compounds from two or three drug fami-
lies was recognized in 41% and 19.4% of patients,
Of note, mutations K65R (RT), whose rate has been
reported to be increasing following the approval of
tenofovir [Valer et al., 2004], and L33F/I/S (protease),
whose relevance on PI resistance has recently been
highlighted [Mayersetal.,2004],wereobserved in 6.2%
tested harbored the Q145M mutation, which has been
associated rarely with resistance to either NRTI and/or
NNRTI [Paolucci et al., 2003].
Overall, 59.7% of patients had less than 20,000 HIV-
RNA copies/ml and they had significantly higher CD4þ
counts than subjects with greater viral load values
(392 versus 234 cells/ml; P<0.001). This threshold of
of CD4þ T cell fall in patients with sustained virological
failure under antiretroviral therapy [Raffanti et al.,
2004], although similar studies have reduced this
critical threshold to 10,000 HIV-RNA copies/ml [Le
Moing et al., 2002; The PLATO collaboration, 2004].
CD4þ counts were significantly much higher in those
with lower viral loads (see Table II).
Patients with viruses harboring drug resistance
mutations known to reduce viral fitness in vitro (such
TABLE I. Resistance Mutations in 273 Heavily Antiretroviral-Experienced Patients
in Year 2003
NRTI, nucleoside reverse transcriptase inhibitors; NNRTI, non-nucleoside reverse transcriptase
inhibitors; PI, protease inhibitors.
 for interpreting resistance genotypes as well as the virtual phenotype for more than half of
Relationship Between Drug Resistance, Viral Load and CD4 Counts 25
as rtM184V, rtL74V, rtK65R, proD30N, or proI50L)
did not have plasma HIV-RNA values lower than the
rest (data not shown). Moreover, the number of resis-
tance mutations differed significantly when comparing
patients with low or high plasma viral load (Table III).
Accordingly, patients with less than 10,000 or 20,000
HIV-RNA copies/ml had viruses with less resistance
mutations than patients with higher plasma viremia.
This association was dependent mainly on a larger
number of drug-resistant genotypes against PI in
patients with elevated plasma viremia.
This study shows that a large proportion of heavily
treatment-experienced, HIV-infected patients failing
their current antiretroviral treatment in Spain carry
viruses with broad cross-resistant genotypes. Resis-
population, and 19.4% harbored viruses showing resis-
tance to multiple agents from all three main drug
patients. New agents which belong to the available
drug classes may have limited activity in this subset of
patients, given the large number of resistance muta-
tions found in their viruses. To overcome this problem,
to maximize the activity of new PIs such as atazanavir
and tipranavir in patients with prior PI exposure [De
Mendoza and Soriano, 2004; Turner et al., 2004]. Un-
fortunately, similar pharmacokinetic enhancement
cannot be done for RT inhibitors.
In this cross-sectional study, patients with less than
10,000 or 20,000 HIV-RNA copies/ml showed signifi-
cantly higher CD4þ counts than patients with greater
plasma viremia. This finding is in agreement with the
reported better immunological outcome of patients
failing antiretroviral therapy but showing viral load
values below a certain threshold [Le Moing et al., 2002;
Raffanti et al., 2004; The PLATO collaboration, 2004].
Although thereasonwhyCD4þ countsdonotdeclineas
expected in this subset of patients is not well under-
stood, an impaired virus replication capacity due to the
phenomenon [Barbour et al., 2002; Deeks et al., 2001;
Deval et al., 2004]. However, in our study patients with
viruses harboring classical resistance mutations known
rtK65R, proD30N, or proI50L [Martinez-Picado et al.,
1999; Menendez-Arias et al., 2003; De Mendoza et al.,
2004; Miller, 2004], did not show lower plasma HIV-
RNA values than the rest of patients. We believe that
the accumulation of compensatory mutations in these
heavily treatment-experienced patients may have pre-
cluded the recognition of any beneficial effect of such
resistance mutations on viral fitness [Nijhuis et al.,
1999; Barbour et al., 2002]. In support of this inter-
pretation is our finding of a much higher number of
resistance mutations in patients with viral loads above
10,000 or 20,000 HIV-RNA copies/ml with respect to
the accumulation of mutations in the protease gene was
the main force driving this association [Nijhuis et al.,
thymus by viruses carrying protease resistance muta-
tions could explain this finding [Stoddart et al., 2001;
Delgado et al., 2002].
The results of this study indicate that new inhibitors
targeting HIV elements other than the RT and pro-
tease enzymes are urgently needed. They may be the
only alternative to regain complete virus suppression in
heavily-treatment experienced patients. The recent
this concept [Lazzarin et al., 2003; Clotet et al., 2004],
although the low genetic barrier of this drug may has
precluded to maintain complete virus suppression for
[Poveda et al., 2004; Sista et al., 2004].
Finally, these data support indirectly the view that
antiretroviral therapy can provide immunological and
virological benefit even in patients with drug-resistant
viruses. It is noteworthy that only 20% of this heavily
TABLE II. Differences in the CD4þ T Cell Count
According to Plasma Viral Load Values in
TABLE III. Differences in the Median Number of Drug Resistance Mutations According to
Viral Load Values in 273 Heavily Treatment-Experienced Patients
Plasma HIV-RNA (copies/ml)No. NRTI NNRTI PITotal
NRTI, nucleoside reverse transcriptase inhibitors; NNRTI, non-nucleoside reverse transcriptase
inhibitors; PI, protease inhibitors.
26 Rodes et al.
less than 200 CD4þ T cells/ml. In a prior study, a shift
from drug-resistant to drug-sensitive viruses after dis-
continuing antiretroviral therapy was recognized in a
small group of chronically HIV-infected patients [Deeks
et al., 2002]. This shift was associated with an increase
in the viral load and a parallel sharp reduction in the
CD4þ count. Thus, keeping on treatment patients fail-
until new therapeutic options become available, as long
as drug toxicity issues are not relevant.
This work was supported in part by a grant from
Redes de Investigacio ´n en SIDA (project 173).
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plication capacity during long-term virological failure of protease
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