SummaryThe RV144 trial demonstrated 31% vaccine efficacy (VE) at preventing HIV-1 infection1. Antibodies against the HIV-1 envelope variable loops 1 and 2 (V1/V2) domain correlated inversely with infection risk2. We hypothesized that vaccine-induced immune responses against V1/V2 would selectively impact, or sieve, HIV-1 breakthrough viruses. 936 HIV-1 genome sequences from 44 vaccine and 66 placebo recipients were examined. We show that vaccine-induced immune responses were associated with two signatures in V1/V2 at amino-acid positions 169 and 181. VE against viruses matching the vaccine at position 169 was 48% (CI: 18 to 66%; p=0.0036), whereas VE against viruses mismatching the vaccine at position 181 was 78% (CI: 35% to 93%; p=0.0028). Residue 169 is in a cationic glycosylated region recognized by broadly neutralizing and RV144-derived antibodies. The predicted distance between the two signatures sites (21±7 Å), and their match/mismatch dichotomy, suggest that multiple factors may be involved in the protection observed in RV144. Genetic signatures of RV144 vaccination in V2 complement the finding of an association between high V1/V2 binding antibodies and reduced risk of HIV-1 acquisition and provide evidence that vaccine-induced V2 responses plausibly played a role in the partial protection conferred by the RV144 regimen.

Two chimeric receptors were constructed by transposing the coding regions for the putative N-terminal domains of the human calcitonin (hCTR) and glucagon (hGGR) receptors. These receptors were stably expressed as glycosylated proteins with molecular masses of 80 kDa for the calcitonin receptor N-terminus chimera (NtCTr) and 65 kDa for the glucagon receptor N-terminus chimera (NtGGr). The NtCTr chimera binds salmon calcitonin (sCT) with an apparent Kd of 12 nM relative to 0.3 nM for the native hCTR. However, this chimera does not mediate a cAMP response even with a transfectant expressing 1.8 x 10(6) cell surface receptors. Stable transfectants expressing the NtGGr chimera show no detectable binding of 125I-sCT or 125I-human glucagon. Surprisingly, adenylate cyclase is activated through the NtGGr chimera by sCT, pCT, and hCT with half-maximal activation at 2.2 +/- 0.6, 5.8 +/- 2.1, and 810 +/- 151 nM, respectively, and the maximum response is similar to that induced by 25 microM forskolin. The rank-order of competition for sCT binding to the NtCTr chimera is similar to the hCTR (sCT > pCT > hCT), but the concentrations required for half-maximal competition are 100- to > 2000-fold higher. In addition, salmon calcitonin binds with a much more rapid on-rate and off-rate to the NtCTr chimera relative to the hCTR which binds hormone irreversibly. Cross-linking of 125I-sCT to the NtCTr chimera with bis(sulfosuccinimidyl) suberate is much greater than to the hCTR, suggesting unique conformations for the two receptor-hormone complexes.(ABSTRACT TRUNCATED AT 250 WORDS)

Clonal expansion of HIV-infected cells contributes to the long-term persistence of the HIV reservoir in ART-suppressed individuals. However, the contribution from cell clones that harbor inducible proviruses to plasma viremia is poorly understood. Here, we describe a single-cell approach to simultaneously sequence the TCR, integration sites and proviral genomes from translation-competent reservoir cells, called STIP-Seq. By applying this approach to blood samples from eight participants, we show that the translation-competent reservoir mainly consists of proviruses with short deletions at the 5’-end of the genome, often involving the major splice donor site. TCR and integration site sequencing reveal that cell clones with predicted pathogen-specificity can harbor inducible proviruses integrated into cancer-related genes. Furthermore, we find several matches between proviruses retrieved with STIP-Seq and plasma viruses obtained during ART and upon treatment interruption, suggesting that STIP-Seq can capture clones that are responsible for low-level viremia or viral rebound.