HIV

Authors: Palma P, McManus M, Cotugno N, Rocca S, Rossi P, Luzuriaga K

Published in: Lancet HIV. 2020;7(5):e359-e365

Abstract Several assays have been developed to measure and characterise the replication-competent HIV-1 reservoir, which constitutes the barrier to cure. To date, the application of these assays to studies in children and in limited-resource settings has been minimal, primarily because of their expense, the large required blood volumes, and labour-intensive technologies. For children vertically infected with HIV-1 who initiated suppressive antiretroviral therapy (ART) regimens in infancy, HIV-1-specific antibody concentrations are associated with viral persistence and could be used to estimate the size of the residual latent reservoir on ART. This strategy could be particularly useful for screening children on suppressive ART for enrolment into therapeutic vaccine trials and other protocols aimed at achieving HIV-1 remission.

Authors: Dhummakupt A, Rubens JH, Andeson T, et al.

Published in: JCI Insight. 2020;5(4)

Abstract The HIV latent reservoir in resting memory CD4+ T cells precludes cure. Therapeutics to reactivate and eliminate this reservoir are in clinical trials in adults, but not yet in pediatric populations. We determined, ex vivo, the inducibility of the latent reservoir in perinatal infection as compared with adult infections using the Tat/rev induced limiting dilution assay (TILDA), in which a single round (12 hours) of CD4+ T cell stimulation with PMA/ionomycin maximally activates T cells and leads to proviral expression with multiply spliced HIV RNA production. Markers of immune activation and exhaustion were measured to assess interactions with inducibility. Although rates of T cell activation with PMA/ionomycin were similar, the latent reservoir in perinatal infection was slower to reactivate and of lower magnitude compared with adult infection, independent of proviral load. An enhanced TILDA with the addition of phytohemagglutin and a duration of 18 hours augmented proviral expression in perinatal but not adult infection. The baseline HLA-DR+CD4+ T cell level was significantly lower in perinatal compared with adult infections, but not correlated with induced reservoir size. These data support the hypothesis that there are differences in kinetics of latency reversal and baseline immune activation in perinatal compared with adult infections, with implications for latency reversal strategies toward reservoir clearance and remission.

Authors: Dhummakupt A, Reubens JH, Anderson T, et al.

Published: Poster presented at 27th Conference on Retroviruses and Opportunistic Infections, March 8th –11th, 2020 – Boston.

Abstract The HIV latent reservoir in resting memory CD4+ T cells prevents cure. Novel therapies to reactivate and eliminate the reservoir are in clinical trials in adults, but not yet in pediatric populations.

HIV proviral reservoir size was determined in perinatal (N=11) and adult infections (N=10) by digital droplet PCR (ddPCR) and with the intact proviral DNA assay (IPDA) in perinatal samples. The inducibility of the latent reservoir was determined with the Tat/rev Induced Limiting Dilution Assay (TILDA) that uses single-round (12 hr) T cell stimulation of CD4+ T cells with PMA/ ionomycin to maximally activate cells to induce proviral expression, measured as multiply-spliced HIV RNA Units per 10⁶ CD4 cells (msRUPM). Markers of immune activation (CD69, CD25 and HLA-DR) and exhaustion (PD-1, TIM-3 and TIGIT) were also assessed. An enhanced TILDA with addition of PHA and for 18 hours was performed to enhance proviral expression in perinatal infections. Non-parametric tests were used for differences between paired and unpaired measurements; correlations were quantified by Spearman rank coefficient.

The median age was 15.8 yrs with a median duration of suppression of 6.7 yrs for perinatal infections, and 40.5 yrs with a median duration of suppression of 7.3 yrs for adult infections.  We found that despite a higher proviral reservoir size (median 132.1 vs. 66.7 c/10⁶ PBMCs) and similar rates of T cell activation with PMA/ionomycin (median %CD69 = 96.7% and 93.0%) in perinatal and adult infections, respectively, the size of the induced reservoir was significantly lower in perinatal than in adult infections (median msRUPM of 2.99 vs 11.92, p=0.020). With the enhanced TILDA, the size of the induced reservoir increased significantly in perinatal infections (1.5-fold to a median of 4.5 msRUPM; p=0.034), but not in adult infections. The proportion of induced provirus was significantly lower in perinatal infections at 1.6% compared with 4.0% in adult infections (p=0.030). At baseline, the proportion of HLA-DR+ T cells was significantly lower in perinatal compared with adult infections (median HLA-DR+ cells = 4.56% vs 10.5%, p=0.012), but not correlated with the induced reservoir size.

The inducibility of the latent reservoir is substantially lower in perinatal compared with adult infections, possibly due to differences in baseline states of immune activation, with implications for latency reversal strategies towards ART-free remission.

Authors: Schröter J, Anelone A,  Yates A, de Boer RJ;  on behalf of the EPIICAL Consortium

Published in: J Acquir Immune Defic Syndr. 2020;83(5):522-529

Background Interventions aiming for an HIV cure would benefit from rapid elimination of virus after the onset of antiretroviral therapy (ART), by keeping the latent HIV reservoir small.

Setting We investigated HIV suppression in 312 perinatally infected infants starting ART within 6 months after birth from the EPPICC (European Pregnancy and Paediatric HIV Cohort Collaboration).

Methods To better understand kinetic differences in HIV suppression among infants, we investigated their individual viral load (VL) decay dynamics. We identified VL decay patterns and determined times to viral suppression (TTS). For infants with strictly declining VLs (n = 188), we used parameter fitting methods to estimate baseline VLs, decay rates, and TTS. We subsequently identified the parameters determining TTS by linear modeling.

Results The majority of infants suppress HIV VL after the onset of ART. Some children experienced a long TTS due to an “erratic” VL decay pattern. We cannot exclude that this is partly due to treatment complications and subsequent treatment changes, but these children were characterized by significantly lower CD4 percentages (CD4%) at start of treatment compared with those with a “clean” VL decline. Focusing on this “clean” subset, the TTS could be predicted by mathematical modeling, and we identified baseline VL and CD4% as the major factors determining the TTS.

Conclusions As VL steeply increases and CD4% constantly decreases in untreated HIV-infected infants, the progression of an HIV infection is largely determined by these 2 factors. To prevent a further disease progression, treatment should be initiated early after contracting HIV, which consequently shortens TTS.

Authors: Dominguez-Rodriguez S, Rojo P, Lain MG,  Barnabas S, Lopez-Varela E, Otwombe K, Danaviah S, Nastouli E, Serna-Pasqual M, Gianuzzi V, Giaquointo C, Kuhn L, Tagarro A on behalf of the EPIICAL Consortium

Published in: 27th Conference on Retroviruses and Opportunistic Infections, March 8th –11th, 2020 – Boston.

Authors: Zicari S, Doria M, Domínguez-Rodríguez S, Cotugno N, Tagarro A, Rojo P, Nastouli E, Gartner K, Klein N, Foster C, Pahwa S, De Rossi A, Giaquinto C, Rossi P,  Palma P, for the EPIICAL consortium

Published in: 27th Conference on Retroviruses and Opportunistic Infections, March 8th –11th, 2020 – Boston.

Authors: Tagarro A, Domínguez-Rodríguez S, Violari A, Cotton M, Mhampossa T, Klein N, Ramsagar N, Van Rensburg AJ, Behuhuma O, Vaz P,  Oletto A, Palma P, Rossi P, Rojo P, on behalf of the EPIICAL Consortium

Published in:  27th Conference on Retroviruses and Opportunistic Infections, March 8th –11th, 2020 – Boston.

Authors: Gärtner K, Gkouleli T, Byott M, Heaney J, Spyer MJ, DeRossi A, Persaud D, Palma P, Giaquinto C, Rojo P, Foster C, Marcelin AG, Rossi P, Nastouli E, for the EPIICAL consortium

Published in:  27th Conference on Retroviruses and Opportunistic Infections, March 8th –11th, 2020 – Boston.