The current COVID-19 pandemic presents a serious public health crisis, and a better understanding of the scope and spread of the virus would be aided by more widespread testing. Nucleicacid based tests currently offer the most sensitive and early detection of COVID-19. However, the "gold standard" test pioneered by the United States Center for Disease Control & Prevention, takes several hours to complete and requires extensive human labor, materials such as RNA extraction kits that could become in short supply and relatively scarce qPCR machines. It is clear that a huge effort needs to be made to scale up current COVID-19 testing by orders of magnitude. There is thus a pressing need to evaluate alternative protocols, reagents, and approaches to allow nucleic-acid testing to continue in the face of these potential shortages. There has been a tremendous explosion in the number of papers written within the first weeks of the pandemic evaluating potential advances, comparable reagents, and alternatives to the "gold-standard" CDC RT-PCR test. Here we present a collection of these recent advances in COVID-19 nucleic acid testing, including both peer-reviewed and preprint articles. Due to the rapid developments during this crisis, we have included as many publications as possible, but many of the cited sources have not yet been peer-reviewed, so we urge researchers to further validate results in their own labs. We hope that this review can urgently consolidate and disseminate information to aid researchers in designing and implementing optimized COVID-19 testing protocols to increase the availability, accuracy, and speed of widespread COVID-19 testing.

Re-opening of communities in the midst of the ongoing COVID-19 pandemic has ignited new waves of infections in many places around the world. Mitigating the risk of reopening will require widespread SARS-CoV-2 testing, which would be greatly facilitated by simple, rapid, and inexpensive testing methods. This study evaluates several protocols for RNA extraction and RT-qPCR that are simpler and less expensive than prevailing methods. First, isopropanol precipitation is shown to provide an effective means of RNA extraction from nasopharyngeal (NP) swab samples. Second, direct addition of NP swab samples to RT-qPCRs is evaluated without an RNA extraction step. A simple, inexpensive swab collection solution suitable for direct addition is validated using contrived swab samples. Third, an open-source master mix for RT-qPCR is described that permits detection of viral RNA in NP swab samples with a limit of detection of approximately 50 RNA copies per reaction. Quantification cycle (Cq) values for purified RNA from 30 known positive clinical samples showed a strong correlation (r2 = 0.98) between this homemade master mix and commercial TaqPath master mix. Lastly, end-point fluorescence imaging is found to provide an accurate diagnostic readout without requiring a qPCR thermocycler. Adoption of these simple, open-source methods has the potential to reduce the time and expense of COVID-19 testing.

TFIIH, Mediator, and RNAPII (Figure S1). Experiments were completed with the native human HSP70 promoter (HSPA1B gene), because others have shown that it is a quintessential model for promoter-proximal RNAPII pausing (Core et al., 2012). Because chromatin per se does not appear to be an essential regulator of RNAPII pausing in Drosophila or mammalian cells Lai and Pugh, 2017;Li et al., 2013), the in vitro transcription assays were completed on naked DNA templates (also see below).Using purified PIC factors, primer extension assays established that transcription initiation occurred at the annotated HSPA1B start site in vitro (Figure S2A), as expected. An overview of the transcription assay is shown in Figure 1A, which was based in part upon in vitro pausing assays with nuclear extracts (Marshall and Price, 1992;Qiu and Gilmour, 2017;Renner et al., 2001). Following PIC assembly, transcription was initiated by adding ATP, GTP, and UTP at physiologically relevant concentrations, with a low concentration of CTP, primarily 32 P-CTP. After one minute, reactions were chased with a physiologically relevant concentration of cold CTP and transcription was allowed to proceed for an additional nine minutes. These "pulse-chase" assays allow better detection of short (potentially paused) transcripts, which otherwise would be drowned out by elongated transcripts that invariably possess more incorporated 32 P-C bases. By directly labeling all transcripts with 32 P-CTP, the method is highly sensitive and allowed detection of transcripts of varied lengths; furthermore, the 32 P-CTP pulse-chase protocol ensured that 32 P-labeled transcripts resulted almost exclusively from single-round transcription (see Methods). Control experiments confirmed that transcripts detected were driven by the HSP70 promoter (e.g. not any contaminating nucleic acid) and that transcription was dependent on added PIC factors, as expected (Figure S2B).A variety of methods have established that RNAPII pauses after transcribing 20-80 bases in Drosophila and mammalian cells (

The SAGA complex is a regulatory hub involved in gene regulation, chromatin modification, DNA damage repair and signaling. While structures of yeast SAGA (ySAGA) have been reported, there are noteworthy functional and compositional differences for this complex in metazoans. Here we present the cryogenic-electron microscopy (cryo-EM) structure of human SAGA (hSAGA) and show how the arrangement of distinct structural elements results in a globally divergent organization from that of yeast, with a different interface tethering the core module to the TRRAP subunit, resulting in a dramatically altered geometry of functional elements and with the integration of a metazoan-specific splicing module. Our hSAGA structure reveals the presence of an inositol hexakisphosphate (InsP6) binding site in TRRAP and an unusual property of its pseudo-(Ψ)PIKK. Finally, we map human disease mutations, thus providing the needed framework for structure-guided drug design of this important therapeutic target for human developmental diseases and cancer.

TFIIH, Mediator, and RNAPII (Figure S1). Experiments were completed with the native human HSP70 promoter (HSPA1B gene), because others have shown that it is a quintessential model for promoter-proximal RNAPII pausing (Core et al., 2012). Because chromatin per se does not appear to be an essential regulator of RNAPII pausing in Drosophila or mammalian cells Lai and Pugh, 2017;Li et al., 2013), the in vitro transcription assays were completed on naked DNA templates (also see below).Using purified PIC factors, primer extension assays established that transcription initiation occurred at the annotated HSPA1B start site in vitro (Figure S2A), as expected. An overview of the transcription assay is shown in Figure 1A, which was based in part upon in vitro pausing assays with nuclear extracts (Marshall and Price, 1992;Qiu and Gilmour, 2017;Renner et al., 2001). Following PIC assembly, transcription was initiated by adding ATP, GTP, and UTP at physiologically relevant concentrations, with a low concentration of CTP, primarily 32 P-CTP. After one minute, reactions were chased with a physiologically relevant concentration of cold CTP and transcription was allowed to proceed for an additional nine minutes. These "pulse-chase" assays allow better detection of short (potentially paused) transcripts, which otherwise would be drowned out by elongated transcripts that invariably possess more incorporated 32 P-C bases. By directly labeling all transcripts with 32 P-CTP, the method is highly sensitive and allowed detection of transcripts of varied lengths; furthermore, the 32 P-CTP pulse-chase protocol ensured that 32 P-labeled transcripts resulted almost exclusively from single-round transcription (see Methods). Control experiments confirmed that transcripts detected were driven by the HSP70 promoter (e.g. not any contaminating nucleic acid) and that transcription was dependent on added PIC factors, as expected (Figure S2B).A variety of methods have established that RNAPII pauses after transcribing 20-80 bases in Drosophila and mammalian cells (