CROI 2015 Program and Abstracts

Abstract Listing

Poster Abstracts

Methods: 36 patients on cART were randomized to 3 immunizations with MDDC pulsed with HIV-1 (n=24) (cases) or with non-pulsed MDDCs (n=12) (controls). Virus for pulsing was isolated 56 weeks before the first immunization during a first cART interruption (STOP 1). Thereafter, cART was reinitiated and after 48 weeks 3 immunizations were performed and cART was interrupted again (STOP2). We measured total and integrated HIV-1 DNA in isolated CD4 T cells before any cART, before STOP1 (preSTOP1), before and after vaccination (VAC1 and VAC2) and at week 12 after second interruption of cART (STOP2). Data are expressed as mean log 10 copies/10 6 CD4 T cells. Results: As expected, we observed a drop in total and integrated DNA after the 3 years on cART from the precART period (3.8 and 2.6, respectively) to the time point before STOP1 (3.0 and 1.9, respectively) in the 36 patients (p<0.0001 for both comparisons). Three months of cART interruption at STOP1 followed by 9 months of cART did not modify total and integrated DNA in these 36 subjects (VAC1 values: 3.0 and 1.9) (p=0.41 and p=0.62 as compared with preSTOP1). Vaccination (VAC1 to VAC2 period) did not influence DNA levels in vaccinated subjects (n=24) [total DNA from 2.9 (VAC1) to 2.9 (VAC2), p=0.86 and integrated DNA 1.9 (VAC1) to 1.8 (VAC2), p=0.47]. After cART interruption post-vaccination (STOP2), while total DNA significantly increased in both vaccinees (n=24) and controls (n=12) (2.9 to 3.3, p=0.0004 and 3.2 to 3.7, p=0.009, respectively), integrated DNA did not change in vaccinees (1.8 to 1.9, p=0.22) and increased in controls (1.8 to 2.1, p=0.05). Moreover, these changes in integrated DNA after STOP2 were inversely correlated with changes in HIV specific T cell responses in cases (r= -0.54, p=0.03), while no correlation was observed in controls (r= -0.16, p=0.74). Conclusions: No change in total and integrated DNA was observed after 3 months of cART interruption followed by 9 months of cART. HIV-1 specific immune responses elicited by a therapeutic DC vaccine prevented an increase in integrated DNA after cART interruption. 355 HIV-1 Envelope Epitope Recognition Is Influenced by Immunoglobulin D H Gene Segment Repertoire YugeWang 2 ; Aaron Sanchez-Silva 2 ; Barton Haynes 1 ; Harry Schroeder 2 1 Duke University, Durham, NC, US; 2 University of Alabama at Birmingham, Birmingham, AL, US; 3 University of Alabama at Birmingham, Birmingham, AL, US Background: HIV-1-specific broadly neutralizing antibodies (BnAbs), such as the membrane proximal external region (MPER) antibodies 2F5 and 4E10, contain long H chain complementarity determining region 3 (CDR-H3) which is encoded by D H gene segment, that lacks tyrosine and includes patches of hydrophobic and charged amino acids. However, B cells bearing Igs with charged or hydrophobic CDR-H3s are normally culled frommature B cell subsets. Thus, elucidation of mechanisms that underlie the difficulty in generating HIV-1 can be seen as a part of fundamental need to better understand how to distinguish self and non-self receptors that can neutralize pathogenic antigens without self-inflicting dame to the host. Methods: Mice -BALB/c mice cohort limited to the use of single D H gene segments were generated. Δ D-DFL is a human-like repertoire control. Δ D-D m FS promotes the use of hydrophobic amino acid CDR-H3. The Δ D-iD is charged amino acid enriched CDR-H3. Immunization -each strain of 10 mice was immunized with HIV-1 JR-FL gp140 protein. Epitope Identification -Two group of mice (No. 4 & 5) of each strain were selected (prior to immunization, and after the 2 nd and 4 th immunizations) for PEPperPRINT Chip to detect their epitopes on HIV-1 JR-FL gp140. Serum Assay -Binding ability was examined by HIV-1 envelope protein ELISA. Blocking activity was examined by competitive ELISA with soluble CD4 (sCD4) and 2F5, 2G12 antibodies. Results: 1. We obtained evidence of strong and clear polyclonal responses to immunization with JR-FL gp140. As a general rule, the heterogeneity of the anti-JR-FL gp140 response varied by D H genotype with Δ D-DFL>Wild Type (WT)>> Δ D-D μ FS, Δ D-iD. Conversely, the intensity of the response was greatest in the Δ D-iD. 2. Linear response showed by PEPperPRINT chip was not identified with the response to natural HIV-1 epitopes, however, the Δ D-iD favored charged epitopes that is inconsistent with our hypothesis. 3. Anti-JR-FL gp140 antibodies present in the sera of the D H altered did not block HIV-1 envelope CD4, 2F5, 2G12 binding site. This suggests reduced affinity, stability or on rates, or increased off rates for Igs obtained from D H altered mice.

Poster Abstracts

271

CROI 2015