CROI 2016 Abstract eBook

Abstract Listing

Oral Abstracts

HIV infections attributable to injection drug use in the U.S. have declined steadily since the early 1990s and have accounted for less than 8% of all diagnosed infections since 2010. In early 2015, public health workers serving a small rural Indiana community (adult population approximately 3,100) detected an outbreak of HIV infections within a network of persons who injected drugs. The ensuing investigation identified over 180 new HIV infections that had mostly occurred since mid-2014. Controlling the outbreak demanded a large and coordinated response by county, state and federal partners working closely with the community and other stakeholders. Fueled by the growing national epidemic of opioid drug abuse, injection drug use – heralded by viral hepatitis C infections – is spreading among populations not previously considered to be at high risk of HIV infection. Clinicians and public health authorities will need to work together with policy makers and at-risk communities to prevent similar future HIV outbreaks as the context of injection drug use in the U.S. evolves. 133 Type 1 Interferon Resistance Is a Hallmark of Mucosally Transmitted HIV-1 Frederic Bibollet-Ruche 1 ; Shilpa Iyer 1 ; Ronnie Russell 1 ; Andrew G. Smith 1 ; Christiana M. Shaw 1 ;Yingying Li 1 ;Timothy Decker 1 ; George M. Shaw 2 ; Persephone Borrow 3 ; Beatrice Hahn 1 1 Univ of Pennsylvania, Philadelphia, PA, USA; 2 Perelman Sch of Med, Univ of Pennsylvania, Philadelphia, PA, USA; 3 Univ of Oxford, Oxford, UK Background: Mucosally transmitted founder (TF) viruses are more resistant to the antiviral effects of type 1 interferons (IFNs) than HIV-1 strains that predominate during chronic infection. To determine whether IFN-resistant viruses are specifically selected during the HIV-1 transmission process, we generated viral isolates by limiting dilution of both plasma and genital fluids of epidemiologically linked transmission pairs and examined their relative IFN resistance. Methods: Plasma was collected from the chronically infected donor (CD) and acute recipient (AR) of transmission pairs (n=7); donor genital secretion samples (cervico-vaginal lavage or semen) were available for 3 of these pairs. Plasma and the non-cellular fraction of genital secretions were incubated with activated CD4+T-cells to generate limiting- dilution isolates. The infectivity of each virus isolate was determined in the TZM-bl assay. IFNα2 sensitivity of each isolate was analyzed by determining the IC 50 in primary CD4+ T-cells. Env content was determined using a modified ELISA to quantify gp120. Results: We obtained a total of 283 single-genome derived isolates, 191 from CDs and 92 from ARs. Plasma isolates from CDs were significantly more sensitive to type I IFNs than isolates derived from the genital secretions (mean IC 50 45 U/ml and 92 U/ml respectively, p <0.0001). In all transmission pairs, isolates derived from ARs were significantly more IFN resistant (mean IC 50 215 U/ml, p <0.0001) than isolates derived from plasma or genital secretion of CDs. AR isolates replicated to higher titers than CD isolates in the absence of IFN (p <0.0001), and unlike most donor isolates, were not fully inhibited at maximal IFNα2 concentrations. In CD, the IFNα2 IC 50 of isolates positively correlated with virus particle infectivity (p <0.0001) and negatively correlated with the replication potential in CD4+ T-cells (p <0.0001). Additionally, AR isolates had significantly higher Env content per virus particle compared to CD isolates (p <0.0001) yet Env content was not correlated with IFNα2 IC 50 (p=0.09). Conclusions: Viruses circulating in plasma and sexual secretions of chronically infected individuals exhibit a wide range of IFN resistance, and are generally more IFN sensitive than TF viruses. IFN-resistant viruses are specifically selected from a pool of biologically diverse viruses during mucosal HIV-1 transmission. 134 Expression and Potency of IFNa Subtypes in an Ex Vivo Model of Acute HIV-1 Infection Mario L. Santiago 1 ; Michael S. Harper 1 ; Kejun Guo 1 ; Kathrin Gibbert 2 ; Eric L. Lee 1 ; Stephanie M. Dillon 1 ; Martin D. McCarter 1 ; Kim J. Hasenkrug 3 ; Ulf Dittmer 2 ; CaraWilson 4 1 Univ of Colorado Anschutz Med Campus, Aurora, CO, USA; 2 Univ of Duisburg-Essen, Essen, Germany; 3 NIAID, NIH, Hamilton, MT, USA; 4 Univ of Colorado Hosp, Aurora, Aurora, CO, USA Background: HIV-1 is transmitted primarily across mucosal surfaces and rapidly spreads within the intestinal mucosa during acute infection. The type I interferons (IFNs) likely serve as a first line of defense, but the relative expression, antiviral properties and effector mechanisms utilized by the 12 IFNα subtypes against HIV-1 infection of mucosal tissues remain unknown. Methods: We evaluated the expression of all IFNα subtypes in HIV-1-exposed plasmacytoid dendritic cells by next-generation sequencing (NGS). The relative antiviral potency of each IFNα subtype against HIV-1 (BaL) and Transmitted/Founder HIV-1 strains CH40, CH58 and CH470 were determined ex vivo using the human intestinal Lamina Propria Aggregate Culture (LPAC) model (Steele et al, Retrovirology 2014). Gene expression levels of restriction factors Mx2, tetherin and APOBEC3 were evaluated in purified LP CD4 T cells. Virion infectivities were determined by computing the ratio of infectious titer using the TZM-bl assay and virus particle levels by p24 ELISA. G-to-A mutation rates were evaluated by NGS. Results: IFNα subtype transcripts from the centromeric half of the IFNA gene complex, particularly IFNα1, 5, 8, 14 and 2, were highly expressed in pDCs following HIV-1 exposure. There was an inverse relationship between IFNA subtype expression and potency. IFNα8, IFNα6 and IFNα14 were the most potent in restricting HIV-1 infection. IFNα2, the clinically- approved subtype, and IFNα1 were both highly expressed but exhibited relatively weak antiviral activity. The relative potencies correlated with binding affinity to the type I IFN receptor and the induction levels of HIV-1 restriction factors Mx2 and Tetherin/BST-2 but not APOBEC3G, D and F. However, despite the lack of APOBEC3 transcriptional induction, the higher relative potency of IFNα8 and IFNα14 correlated with stronger inhibition of virion infectivity, which is linked to deaminase-independent APOBEC3 restriction activity. By contrast, both potent (IFNα8) and weak (IFNα1) subtypes significantly induced HIV-1 GG-to-AG hypermutation. Conclusions: The results unravel skewed gene expression and non-redundant functions of the IFNα subtypes against HIV-1 infection, with strong implications for HIV-1 mucosal immunity, viral evolution and IFNα-based functional cure strategies. 135 Novel Mechanism of Interferon Restriction of HIV-1 in Humans Ramy El-Diwany 1 ; Michael Chattergoon 1 ; Justin R. Bailey 1 ; Stuart C. Ray 1 ; Sarah J.Wheelan 1 ; Joel N. Blankson 1 ; Robert Siliciano 2 ; David L.Thomas 1 ; Ashwin Balagopal 1 1 Johns Hopkins Univ Sch of Med, Baltimore, MD, USA; 2 Howard Hughes Med Inst, Baltimore, MD, USA Background: Type 1 interferons are critical to control of SIV and HIV-1. However, with several notable exceptions such as MX2, we do not know which of the hundreds of interferon-stimulated genes (ISGs) restrict HIV-1 replication. We hypothesized that the administration of interferon alfa to HIV-1 infected humans would reduce HIV-1 RNA by inducing expression of restriction factors in activated T cells, where HIV-1 chiefly replicates. Methods: HIV-1 kinetics were measured in plasma from 19 human subjects with untreated HIV-1 infection after administration of weight-based peginterferon alpha 2b (IFN). We purified HIV-1 permissive cells (CD38+/HLA-DR+/CD4+/CD3+ lymphocytes, or activated CD4+ T-Cells) from peripheral blood mononuclear cells by FACS sorting before and after IFN. mRNA abundance was quantified using paired end RNAseq. Alignments were performed with RSEM and differential expression was calculated using EBseq. Genes were discarded that had uncertain probabilities of equal expression (PPEE<0.95) or differential expression (PPDE<0.95) in the majority of subjects, after false discovery rate correction (FDR<0.05). ISGs were identified individually from the remaining genes by paired t test if they showed significant induction with IFN, adjusting for multiple comparisons. Spearman rank-correlations were performed between fold-changes of newly defined ISGs and HIV-1 RNA decline at 72 hours. Genes whose induction correlated with plasma HIV-1 RNA decline and that had not been previously described for HIV-1 were validated in vitro . Results: There were 99 ISGs differentially expressed in the activated CD4+ T cells of ≥11/19 participants. Of those 99, 13 were also strongly correlated with the resultant reduction in plasma HIV-1 RNA. Included were expected ISGs (e.g.s, MX2, APOBEC3A). In addition, we identified several novel candidate HIV-1 restriction factors ( Figure ) and used principal components analyses to select among these for ISGs that independently restrict HIV-1 replication. CMPK2 and BCL2L14 were selected for further study. In cell culture, both CMPK2 and BCL2L14 (and MX2, as control) were confirmed to be induced by IFN. With all three ISGs, restriction of HIV-1 production was attenuated by blocking expression of the gene using RNA interference. Conclusions: These studies identify CMPK2 and BCL2L14 as novel HIV restriction factors and may provide new insights into how interferon restricts the replication of HIV-1 and possibly other chronic viral infections.

Oral Abstracts

50

CROI 2016