In our cohort of HIV-positive women in Lima, Peru, poverty and socioeconomic vulnerability contributed to depression. Findings highlight the heavy burden of depression in this cohort of poor women and the need to incorporate mental health services as an integral component of HIV care.

Base-modified aptamers that incorporate non-natural chemical moieties can achieve greatly improved affinity and specificity relative to natural DNA or RNA aptamers. However, conventional methods for generating base-modified aptamers require considerable expertise and resources. In this work, we have accelerated and generalized the process of generating base-modified aptamers by combining a click-chemistry strategy with a fluorescence-activated cell sorting (FACS)-based screening methodology that measures the affinity and specificity of individual aptamers at a throughput of ∼107 per hour. Our “click-particle display (PD)” strategy offers many advantages. First, almost any chemical modification can be introduced with a commercially available polymerase. Second, click-PD can screen vast numbers of individual aptamers on the basis of quantitative on- and off-target binding measurements to simultaneously achieve high affinity and specificity. Finally, the increasing availability of FACS instrumentation in academia and industry allows for easy adoption of click-PD in a broader scientific community. Using click-PD, we generated a boronic acid-modified aptamer with ∼1 μM affinity for epinephrine, a target for which no aptamer has been reported to date. We subsequently generated a mannose-modified aptamer with nanomolar affinity for the lectin concanavalin A (Con A). The strong affinity of both aptamers is fundamentally dependent upon the presence of chemical modifications, and we show that their removal essentially eliminates aptamer binding. Importantly, our Con A aptamer exhibited exceptional specificity, with minimal binding to other structurally similar lectins. Finally, we show that our aptamer has remarkable biological activity. Indeed, this aptamer is the most potent inhibitor of Con A-mediated hemagglutination reported to date.

Aptamers incorporating chemically modified bases can achieve superior affinity and specificity compared to natural aptamers, but their discovery remains a labor-intensive, low-throughput task.Here we describe the 'non-natural aptamer array' (N2A2) system, which enables fully automated, high-throughput screening of base-modified aptamers using a minimally modified Illumina MiSeq instrument. We demonstrate the capability to screen multiple different base modifications to identify the optimal choice for high-affinity target binding. We further use N2A2 to generate aptamers that specifically recognize protein posttranslational modifications, and which maintain strong target affinity in serum. Finally, we demonstrate comprehensive profiling of single-and double-base aptamer mutations to rapidly identify key sequence motifs responsible for binding activity in a single run. N2A2 requires only minor mechanical modifications to the MiSeq and a software suite for automation that we have made freely available. As such, we believe our platform offers a broadly accessible and user-friendly tool for generating custom reagents on-demand.

doi: bioRxiv preprint alkyne-modified nucleobases, and then performs a click reaction to couple those nucleobases to an azide-modified chemical moiety. This yields a sequence-defined array of tens of millions of base-modified sequences, which can then be characterized in a high-throughput fashion.Collectively, we believe that these advancements are helping to make aptamer technology more accessible, efficient, and robust, thereby enabling the use of these affinity reagents for a wider range of molecular recognition and detection-based applications.

Glycosylation is one of the most abundant forms of post-translational modification, and can have a profound impact on a wide range of biological processes and diseases. Unfortunately, efforts to characterize the biological function of such modifications have been greatly hampered by the lack of affinity reagents that can differentiate protein glycoforms with robust affinity and specificity. In this work, we use a fluorescence-activated cell sorting (FACS)-based approach to generate and screen aptamers with indole-modified bases, which are capable of recognizing and differentiating between specific protein glycoforms. Using this approach, we were able to select base-modified aptamers that exhibit strong selectivity for specific glycoforms of two different proteins. These aptamers can discriminate between molecules that differ only in their glycan modifications, and can also be used to label glycoproteins on the surface of cultured cells. We believe our strategy should offer a generally-applicable approach for developing useful reagents for glycobiology research.