Taking CRISPR technology further: CRISPR techniques are allowing the development of technologies for nucleic acid detection (see the Perspective by Chertow). Taking advantages of the distinctive enzymatic properties of CRISPR enzymes, Gootenberg et al. developed an improved nucleic acid detection technology for multiplexed quantitative and highly sensitive detection, combined with lateral flow for visual readout. Myhrvold et al. added a sample preparation protocol to create a field-deployable viral diagnostic platform for rapid detection of specific strains of pathogens in clinical samples. Cas12a (also known as Cpf1), a type V CRISPR protein, cleaves double-stranded DNA and has been adapted for genome editing. Chen et al. discovered that Cas12a also processes single-stranded DNA threading activity. A technology platform based on this activity detected human papillomavirus in patient samples with high sensitivity. Science , this issue p. 439 , p. 444 , p. 436 ; see also p. 381

A low-cost, equipment-free rapid antigen test distinguishes dengue virus serotypes and Zika virus in patient sera without detectable cross-reactivity.

Metagenomic sequencing has the potential to transform microbial detection and characterization, but new tools are needed to improve its sensitivity. Here we present CATCH, a computational method to enhance nucleic acid capture for enrichment of diverse microbial taxa. CATCH designs optimal probe sets, with a specified number of oligonucleotides, that achieve full coverage of, and scale well with, known sequence diversity. We focus on applying CATCH to capture viral genomes in complex metagenomic samples. We design, synthesize, and validate multiple probe sets, including one that targets the whole genomes of the 356 viral species known to infect humans. Capture with these probe sets enriches unique viral content on average 18-fold, allowing us to assemble genomes that could not be recovered without enrichment, and accurately preserves within-sample diversity. We also use these probe sets to recover genomes from the 2018 Lassa fever outbreak in Nigeria and to improve detection of uncharacterized viral infections in human and mosquito samples. The results demonstrate that CATCH enables more sensitive and cost-effective metagenomic sequencing.

Significance: We describe the ability of the Zika virus to infect various cells of the fetal brain, modeled from induced pluripotent stem cells derived from a patient and grown in identical conditions. Zika is associated with microcephaly, while the similar dengue virus is not. We described differences in the behavior of these two viruses. Zika often fails to trigger efficient antiviral responses, surviving encounters with brain immune cells, and killing immature nerve cell precursors that have poor innate antiviral defenses. Precursors of the brain’s immune cells, microglia, circulating in the fetus, may take the virus to the fetal brain where it will stall growth or cause cell death. We show that interferon-γ efficiently protects against this viral transfer.

Significance: Zika virus (ZIKV) is a neurotropic and neurovirulent arbovirus that has severe detrimental impact on the developing human fetal brain. We used a genome-wide CRISPR-Cas9 knockout screen to identify ZIKV host genes in human neural progenitors. The screen identified host factors involved in heparan sulfation, endocytosis, endoplasmic reticulum processing, Golgi function, and interferon activity. Our findings provide insights into host-dependent mechanisms for ZIKV infection in the highly vulnerable human neural progenitor cells and identify molecular targets for potential therapeutic intervention.

Point-of-care (POC) diagnostics such as lateral flow and dipstick immunoassays use gold nanoparticle (NP)-antibody conjugates for visual readout. We investigated the effects of NP conjugation, surface chemistries, and antibody immobilization methods on dipstick performance. We compared orientational, covalent conjugation, electrostatic adsorption, and a commercial conjugation kit for dipstick assays to detect dengue virus NS1 protein. Assay performance depended significantly on their conjugate properties. We also tested arrangements of multiple test lines within strips. Results show that orientational, covalent conjugation with PEG shield could improve NS1 detection. These approaches can be used to optimize immunochromatographic detection for a range of biomarkers.