Journal of Clinical Virology - Volume 82 - Supplement 1 - September 2016

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Abstracts / Journal of Clinical Virology 82S (2016) S1–S142 S95
Abstract no: 63
Presentation at ESCV 2016: Poster 149
Intermittent HIV-1 low level viremia detection
(blips) using the Abbott RealTime HIV assay
J. Niubo ∗, J. Camara, A. Imaz, M.A. Dominguez
Hospital Universitari de Bellvitge
Background: The efficacy of highly active antiretroviral ther-
apy (HAART) is mainly monitored by the HIV RNA viral load (VL)
in plasma. Baseline low CD4+ and sustained low level VL (LLVL)
have a prognostic value for virologic failure. Moreover, persistent
LLVL during HAART is of great concern for potential emergence of
drug resistance. Conversely, intermittent detectable VL (“blips”) are
regarded as having low clinical impact and are no indication for
switching HAART. However, increased number and amplitude of
blipsmay lead to a rise in the economic costs ofmonitoring patients.
Aims of this study were to evaluate the rate of blips detection using
the Abbott RealTime HIV assay and to analyze their clinical impact.
Methods: VL results from the VIH unit of the Hospital Univer-
sitari de Bellvitge (Barcelona, Spain) during the period 2009–2011
were included in the analysis. A blip episode was defined as a single
quantified VL detection of 50–2000 copies/mL preceded and fol-
lowed by <50 copies/mL samples, obtained from patients that were
under HAART therapy and had more than 1 year follow-up. Ethical
approval for the study was obtained from the Ethical Committee of
the Hospital Universitari de Bellvitge.
Results: During the study period, 1600 patients met the inclu-
sion criteria that accounted for a total number of samples of 13123.
Median age of the study populationwas 43 (range 17–86) and 77.1%
were males. A total number of 142 blips were identified in the
study population: 1.08% of all samples tested, and an 8.88% of the
patients. The blip rate remained stable during the three year study
period: 1.12, 0.85 and 1.29 respectively for the percentage of all
samples tested and 3.42, 2.44 and 3.64 for the annual percentage
of all patients. The median VL of blips was 72.5 copies/mL (range
50–1849) and an 83.8% of the detected blips showed a VL below
200 copies/mL (range 78.9–88.2%). Only 23 blip episodes showed
rebound above 200 copies/mL and thus, required additional diag-
nostic testings.
Conclusions: The rate of blips, measured using the Abbott Real
Time HIV assay, was very low and remained stable during the study
period. The number of episodes requiring additional testing did
not have a relevant impact on the economic costs of HIV viremia
detection.
Abstract no: 64
Presentation at ESCV 2016: Poster 150
Comparison of genotyping tropism test in
paired HIV-1 plasma RNA and proviral DNA
from Portuguese patients
I. Diogo abanas F. Goncalves
A.P. Carvalho , P. Gomes , I. Costa
1 Molecular Biology Lab, LMCBM, SPC, HEM, Centro
Hospitalar Lisboa Ocidental, Lisboa, Portugal
2 Centro de Investigac¸ ão Interdisciplinar Egas Moniz,
CiiEM, ISCSEM, Almada, Portugal
Background: The Human Immunodeficiency Virus type I (HIV-
I) infects the host cell, through a CD4 receptor that binds to the
gp120 glycoprotein and that requires contact with secondary core-
ceptors (chemokine receptors), CCR5 (R5) and/or CXCR4 (X4). The
viral tropism for HIV-1 is defined by the type of coreceptor used to
infect cell: R5, X4 or dual tropism.
Maraviroc (MVC) was the first R5 antagonist approved for the
treatment of patients. Viral coreceptor tropism determination is
mandatory when the use of CCR5 antagonists is considered. In
this context, in case a therapy change is necessary at undetectable
plasma viral load, tropism testing may need to be done on either
the proviral DNA or the latest plasma sample with sufficient viral
RNA; however, the experience with proviral DNA is still limited.
The aim of this study was to analyze the degree of genotyping
tropism test concordance between paired plasma HIV-1 RNA and
proviral DNA samples from Portuguese patients.
Materials and methods: In this study, we aimed to evaluating
the genotypically inferred tropism in paired plasma HIV-1 RNA and
proviral DNA samples from244HIV-1 Portuguese infected patients.
HIV-1 genotyping tropism test used was an in house test.
Viral RNA was extracted from 1.0ml of plasma using a com-
mercial platform (NucliSENS easyMag, bioMérieux). Proviral DNA
was extracted using ZR Genomic DNA column kit. Viral RNA was
amplified by RT-PCR and proviral DNA by a PCR in the env gene.
Nested-PCR was performed in both cases to amplify the V3 region
of the env gene. Each PCR product was sequenced in triplicate.
Sequences were analyzed using the ChromasPro software. Tropism
was predicted using Geno2Pheno with a false positive rate (FPR)
cutoff of 15% for the plasma RNA and 20% for the proviral DNA.
Results: From the 244 samples studied we obtained an ampli-
fication rate of 71.3% (174 samples). From these 174 samples, we
were able to amplify both plasma RNA and proviral DNA in paired
samples from 58 patients (33.4%). In this group, plasma viral RNA
and proviral DNA tropism test were concordant in 91.4%. 64.2%
of them were R5 and 35.9% X4 in both samples. Only 5 patients
had discordant tropism between RNA and proviral DNA. X4 was
mostly found in proviral DNA (3/5) and R5 mostly found in plasma
RNA (3/5). In 116 patients (66.7%) of the cases, we were only able
to detect tropism either in plasma RNA or proviral DNA. 82 were
detected only in the proviral DNA being 36, X4 and 46, R5. 37 were
detected only in plasma RNA being 15, X4 and 22, R5. In 19 samples
with viral load <20 RNA copies/ml we found 12 samples R5 and 7
samples X4 in the proviral DNA.
Conclusions: This study showed a good concordance of the
tropism test between plasma RNA and proviral DNA (91.4%) in
paired samples as found by others. It seems that the determina-
tion of coreceptor can be done either in plasma RNA or in proviral
DNA. This test seems to be useful at any stage of the disease. Among
discordant samples, the presence of X4 is mainly found in proviral
DNA, but when the patients were suppressed, R5 is more frequent
in the proviral DNA than X4. This reinforce that prediction of viral
tropism using PBMC DNA is feasible, mainly for plasma suppressed
patients. Further studies are needed to determine the importance
of tropism testing in both compartments, plasma RNA and proviral
DNA.