Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. Research Letters AIDS 2014, 28:1683–1692 T-cell activation positively correlates with cell- associated HIV-DNA level in viremic patients with primary or chronic HIV-1 infection Laurence Weiss a,b,c , Mathieu F. Chevalier b,d, M , Lambert Assoumou e,f , Ce ´line Didier b , Pierre-Marie Girard g , Christophe Piketty c , Dominique Costagliola e,f , Christine Rouzioux h , the ANRS 116 SALTO Study Group We investigated the relationship between the size of blood HIV reservoirs and T-cell activation in patients with primary HIV infection (PHI) and chronic HIV infection (CHI) before and after anti- retroviral therapy (ART) interruption. Levels of T-cell activation strongly positively correlated with HIV-DNA levels in viremic PHI and CHI patients. In ART-treated CHI patients, residual immune activation was not associated with HIV-DNA levels. Interestingly, early levels of HIV-DNAin PHI pre- dicted the extent of residual T-cell proliferation under ART. Although most HIV-infected patients receiving antiretroviral therapy (ART) exhibit an effective and sustained control of plasma viral load, HIV-1 persists in latently infected cells in the blood [1,2], as well as in tissues [3]. The persistence of T-cell activation in virally suppressed patients is associated with poor CD4 þ cell reconstitution and may result in increased mortality/ morbidity [4,5]. Low-level viremia supported by latently infected cells might contribute to this persistent chronic T-cell activation [6], whereas immune activation/T-cell proliferation may in turn be involved in HIV reservoir seeding [7]. Few data are available regarding the relationship between the size of HIV reservoirs and the level of residual immune activation in virally suppressed patients and inconsistent results have been reported [8,9]. The aim of this study was to evaluate the relationship between the size of blood HIV reservoirs and T-cell activation, in viremic patients with primary HIV infec- tion (PHI) and in patients with chronic HIV infection (CHI) before and after ART treatment interruption (TI). We also investigated the impact of the HIV reservoir size on residual immune activation after 6 months of ART in PHI patients. We used levels of total HIV-DNA in peripheral blood mononuclear cells (PBMCs) measured in whole blood by the ANRS real-time PCR assay (Biocentric, Bandol, France) [10] to estimate the HIV reservoir size, as this marker is representative and pre- dictive of disease progression [11]. Twenty-two individuals with PHI (median estimated time postinfection: 41 days) were recruited in a prospective study [12,13]. Patients were enrolled before ART might be initiated. Ten patients received ARTafter enrollment in the study. Twenty-five patients with CHI were enrolled in a substudy [14] of the ANRS 116 SALTO trial, a prospective multicentre study of TI in patients who had started treatment at CD4 þ cell counts above 350/ml (NCT00118677) [15]. ART was interrupted at day 0 (baseline). After 12 months of TI, none of the patients had resumed ART. Written informed consent was provided by the study participants, according to French ethical laws. Both studies were approved by French ethical committees. Ex-vivo T-cell activation was assessed by flow cytometry measuring expression of HLA-DR, CD38 and Ki-67 markers on CD4 þ and CD8 þ T cells (Fig. S1, http://links.lww.com/QAD/A524). Figure 1a depicts patients’ characteristics for both cohorts. At baseline, in untreated PHI patients, HIV-DNA levels strongly correlated with the level of CD8 þ T-cell activation as measured by the proportion of CD8 þ T cells expressing CD38 (R ¼ 0.64, P ¼ 0.001), Ki-67 (R ¼ 0.71, P ¼ 0.0002) and moderately with the pro- portion of CD8 þ T cells coexpressing HLA-DR and CD38 (R ¼ 0.47, P ¼ 0.034) (Fig. 1e, data not shown). Moreover, HIV-DNA levels also correlated with the proportion of CD4 þ T cells expressing CD38 (R ¼ 0.51, P ¼ 0.016), HLA-DR (R ¼ 0.53, P ¼ 0.013), and Ki67 (R ¼ 0.61, P ¼ 0.003) (data not shown). In multivariable analysis (assessing HLA-DR, CD38 and Ki-67 expression on CD8 þ T cells), CD38 expression was the only activation marker independently associated with HIV- DNA levels (b ¼ 0.62, P ¼ 0.003). At month 6, HIV-DNA levels significantly decreased in both ART-treated patients (P ¼ 0.004) and untreated patients (P ¼ 0.019) (Wilcoxon rank test; Fig. 1b, c). The decrease in HIV-DNA levels between baseline and M6 was significantly greater in treated patients compared to untreated patients (1.19 log versus 0.63 log copies/ 10 6 PBMCs, respectively; P ¼ 0.003 according to the Mann–Whitney test). We next analyzed the impact of total HIV-DNA levels at baseline on T-cell activation at M6 in untreated and in successfully ART-treated patients. In untreated patients, HIV-DNA levels at baseline were not predictive of the extent of T-cell activation at M6.In contrast, in ART-treated patients, baseline HIV-DNA levels positively correlated with Ki67-expressing CD8 þ T cells at M6 (R ¼ 0.82, P ¼ 0.004). There was also a ISSN 0269-9370 Q 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins 1683