Maintaining genomic surveillance using whole-genome sequencing of SARS-CoV-2 from rapid antigen test devices

Optimising nucleic acid recovery from rapid antigen tests for whole genome sequencing of respiratory viruses

BACKGROUND

Whole genome sequencing (WGS) of respiratory viruses from rapid antigen tests (RAT-WGS) is a novel approach to expanding genomic surveillance of respiratory infections. To date however, there are limited data on the genomic stability of these viruses on RATs. In this study, we investigated the effect of storage conditions and nucleic acid preservatives on the ability to enhance stability and improve recovery of respiratory virus genomes from RATs.

METHODS

A mixture of common respiratory viruses was used to inoculate RATs at different environmental temperatures (4°C, 20°C and 36°C), with two preservative reagents (RNALater and DNA/RNA shield) Nucleic acid was extracted from RATs at two different timepoints (72 h and seven days) and subject to real-time multiplex respiratory PCR to detect a range of respiratory viruses. WGS was performed using target-enrichment with the TWIST Comprehensive Viral Research Panel. Defined metrics from an automated in-house bioinformatic pipeline were used to assess and compare viral genome recovery under different conditions.

RESULTS

Nucleic acid degradation (indicated by relative change in PCR cycle threshold and WGS-based metrics) was most notable at 20 °C and 36 °C. Storage in either RNALater or DNA / RNA shield improved genome recovery for respiratory viruses across all temperature conditions, although this was most pronounced for RNALater. Subtyping of Influenza viruses demonstrated the applicability of RAT-WGS in downstream genomic epidemiological surveillance.

CONCLUSIONS

Under simulated conditions, RAT-WGS demonstrated that (i) viral genomes were generally stable at 4°C at 72 h and 1 week, (ii) RNALater has a more significant preservation of nucleic acids compared to DNA/RNA Shield and (iii) genome recovery can be achieved using a sequencing depth of 500,000 reads per sample in RNALater, across all respiratory viruses and conditions.

Optimisation and evaluation of viral genomic sequencing of SARS-CoV-2 rapid diagnostic tests: a laboratory and cohort-based study

BACKGROUND

Sequencing of SARS-CoV-2 from rapid diagnostic tests (RDTs) can bolster viral genomic surveillance efforts; however, approaches to maximise and standardise pathogen genome recovery from RDTs remain underdeveloped. We aimed to systematically optimise the elution of genetic material from RDT components and to evaluate the efficacy of RDT sequencing for outbreak investigation.

METHODS

In this laboratory and cohort-based study we seeded RDTs with inactivated SARS-CoV-2 to optimise the elution of genomic material from RDT lateral flow strips. We measured the effect of changes in buffer type, time in buffer, and rotation on PCR cycle threshold (Ct) value. We recruited individuals older than 18 years residing in the greater Boston area, MA, USA, from July 18 to Nov 5, 2022, via email advertising to students and staff at Harvard University, MA, USA, and via broad social media advertising. All individuals recruited were within 5 days of a positive diagnostic test for SARS-CoV-2; no other relevant exclusion criteria were applied. Each individual completed two RDTs and one PCR swab. On Dec 29, 2022, we also collected RDTs from a convenience sample of individuals who were positive for SARS-CoV-2 and associated with an outbreak at a senior housing facility in MA, USA. We extracted all returned PCR swabs and RDT components (ie, swab, strip, or buffer); samples with a Ct of less than 40 were subject to amplicon sequencing. We compared the efficacy of elution and sequencing across RDT brands and components and used RDT-derived sequences to infer transmission links within the outbreak at the senior housing facility. We conducted metagenomic sequencing of negative RDTs from symptomatic individuals living in the senior housing facility.

FINDINGS

Neither elution duration of greater than 10 min nor rotation during elution impacted viral titres. Elution in Buffer AVL (Ct=31·4) and Tris-EDTA Buffer (Ct=30·8) were equivalent (p=0·34); AVL outperformed elution in lysis buffer and 50% lysis buffer (Ct=40·0, p=0·0029 for both) as well as Universal Viral Transport Medium (Ct=36·7, p=0·079). Performance of RDT strips was poorer than that of matched PCR swabs (mean Ct difference 10·2 [SD 4·3], p<0·0001); however, RDT swabs performed similarly to PCR swabs (mean Ct difference 4·1 [5·2], p=0·055). No RDT brand significantly outperformed another. Across sample types, viral load predicted the viral genome assembly length. We assembled greater than 80% complete genomes from 12 of 17 RDT-derived swabs, three of 18 strips, and four of 11 residual buffers. We generated outbreak-associated SARS-CoV-2 genomes using both amplicon and metagenomic sequencing and identified multiple introductions of the virus that resulted in downstream transmission.

INTERPRETATION

RDT-derived swabs are a reasonable alternative to PCR swabs for viral genomic surveillance and outbreak investigation. RDT-derived lateral flow strips yield accurate, but significantly fewer, viral reads than matched PCR swabs. Metagenomic sequencing of negative RDTs can identify viruses that might underlie patient symptoms.

FUNDING

The National Science Foundation, the Hertz Foundation, the National Institute of General Medical Sciences, Harvard Medical School, the Howard Hughes Medical Institute, the US Centers for Disease Control and Prevention, the Broad Institute and the National Institute of Allergy and Infectious Diseases.

Non-SARS-CoV-2 respiratory viral detection and whole genome sequencing from COVID-19 rapid antigen test devices: a laboratory evaluation study

BACKGROUND

There has been high uptake of rapid antigen test device use for point-of-care COVID-19 diagnosis. Individuals who are symptomatic but test negative on COVID-19 rapid antigen test devices might have a different respiratory viral infection. We aimed to detect and sequence non-SARS-CoV-2 respiratory viruses from rapid antigen test devices, which could assist in the characterisation and surveillance of circulating respiratory viruses in the community.

METHODS

We applied archival clinical nose and throat swabs collected between Jan 1, 2015, and Dec 31, 2022, that previously tested positive for a common respiratory virus (adenovirus, influenza, metapneumovirus, parainfluenza, rhinovirus, respiratory syncytial virus [RSV], or seasonal coronavirus; 132 swabs and 140 viral targets) on PCR to two commercially available COVID-19 rapid antigen test devices, the Panbio COVID-19 Ag Rapid Test Device and Roche SARS-CoV-2 Antigen Self-Test. In addition, we collected 31 COVID-19 rapid antigen test devices used to test patients who were symptomatic at The Royal Melbourne Hospital emergency department in Melbourne, Australia. We extracted total nucleic acid from the device paper test strips and assessed viral recovery using multiplex real-time PCR (rtPCR) and capture-based whole genome sequencing. Sequence and genome data were analysed through custom computational pipelines, including subtyping.

FINDINGS

Of the 140 respiratory viral targets from archival samples, 89 (64%) and 88 (63%) were positive on rtPCR for the relevant taxa following extraction from Panbio or Roche rapid antigen test devices, respectively. Recovery was variable across taxa: we detected influenza A in nine of 18 samples from Panbio and seven of 18 from Roche devices; parainfluenza in 11 of 20 samples from Panbio and 12 of 20 from Roche devices; human metapneumovirus in 11 of 16 from Panbio and 14 of 16 from Roche devices; seasonal coronavirus in eight of 19 from Panbio and two of 19 from Roche devices; rhinovirus in 24 of 28 from Panbio and 27 of 28 from Roche devices; influenza B in four of 15 in both devices; and RSV in 16 of 18 in both devices. Of the 31 COVID-19 devices collected from The Royal Melbourne Hospital emergency department, 11 tested positive for a respiratory virus on rtPCR, including one device positive for influenza A virus, one positive for RSV, four positive for rhinovirus, and five positive for SARS-CoV-2. Sequences of target respiratory viruses from archival samples were detected in 55 (98·2%) of 56 samples from Panbio and 48 (85·7%) of 56 from Roche rapid antigen test devices. 98 (87·5%) of 112 viral genomes were completely assembled from these data, enabling subtyping for RSV and influenza viruses. All 11 samples collected from the emergency department had viral sequences detected, with near-complete genomes assembled for influenza A and RSV.

INTERPRETATION

Non-SARS-CoV-2 respiratory viruses can be detected and sequenced from COVID-19 rapid antigen devices. Recovery of near full-length viral sequences from these devices provides a valuable opportunity to expand genomic surveillance programmes for public health monitoring of circulating respiratory viruses.

FUNDING

Australian Government Medical Research Future Fund and Australian National Health and Medical Research Council.

Repurposing rapid diagnostic tests to detect falsified vaccines in supply chains

Substandard (including degraded) and falsified (SF) vaccines are a relatively neglected issue with serious global implications for public health. This has been highlighted during the rapid and widespread rollout of COVID-19 vaccines. There has been increasing interest in devices to screen for SF non-vaccine medicines including tablets and capsules to empower inspectors and standardise surveillance. However, there has been very limited published research focussed on repurposing or developing new devices for screening for SF vaccines. To our knowledge, rapid diagnostic tests (RDTs) have not been used for this purpose but have important potential for detecting falsified vaccines. We performed a proof-in-principle study to investigate their diagnostic accuracy using a diverse range of RDT-vaccine/falsified vaccine surrogate pairs. In an initial assessment, we demonstrated the utility of four RDTs in detecting seven vaccines. Subsequently, the four RDTs were evaluated by three blinded assessors with seven vaccines and four falsified vaccines surrogates. The results provide preliminary data that RDTs could be used by multiple international organisations, national medicines regulators and vaccine manufacturers/distributors to screen for falsified vaccines in supply chains, aligned with the WHO global 'Prevent, Detect and Respond' strategy.

Global genomic diversity and conservation of SARS-CoV-2 since the COVID-19 outbreak

IMPORTANCE

Our results indicate that most severe acute respiratory syndrome coronavirus 2 genomes sampled from patients had a mutation rate ≤1.07 ‰ and genome-tail proteins (including S protein) were the main sources of genetic polymorphism. The analysis of the virus-host interaction network of genome-tail proteins showed that they shared some antiviral signaling pathways, especially the intracellular protein transport pathway.

SARS-CoV-2 molecular testing and whole genome sequencing following RNA recovery from used BinaxNOW COVID-19 Antigen Self Tests

Widespread use of over-the-counter rapid diagnostic tests for SARS-CoV-2 has led to a decrease in availability of clinical samples for viral genomic surveillance. As an alternative sample source, we evaluated RNA isolated from BinaxNOW swabs stored at ambient temperature for SARS-CoV-2 rRT-PCR and full viral genome sequencing. 81 of 103 samples (78.6%) yielded detectable RNA, and 46 of 57 samples (80.7 %) yielded complete genome sequences. Our results illustrate that SARS-CoV-2 RNA extracted from used Binax test swabs provides an important opportunity for improving SARS-CoV-2 genomic surveillance, evaluating transmission clusters, and monitoring within-patient evolution.

Sequencing directly from antigen-detection rapid diagnostic tests in Belgium, 2022: a gamechanger in genomic surveillance?

BackgroundLateral flow antigen-detection rapid diagnostic tests (Ag-RDTs) for viral infections constitute a fast, cheap and reliable alternative to nucleic acid amplification tests (NAATs). Whereas leftover material from NAATs can be employed for genomic analysis of positive samples, there is a paucity of information on whether viral genetic characterisation can be achieved from archived Ag-RDTs.AimTo evaluate the possibility of retrieving leftover material of several viruses from a range of Ag-RDTs, for molecular genetic analysis.MethodsArchived Ag-RDTs which had been stored for up to 3 months at room temperature were used to extract viral nucleic acids for subsequent RT-qPCR, Sanger sequencing and Nanopore whole genome sequencing. The effects of brands of Ag-RDT and of various ways to prepare Ag-RDT material were evaluated.ResultsSARS-CoV-2 nucleic acids were successfully extracted and sequenced from nine different brands of Ag-RDTs for SARS-CoV-2, and for five of these, after storage for 3 months at room temperature. The approach also worked for Ag-RDTs for influenza virus (n = 3 brands), as well as for rotavirus and adenovirus 40/41 (n = 1 brand). The buffer of the Ag-RDT had an important influence on viral RNA yield from the test strip and the efficiency of subsequent sequencing.ConclusionOur finding that the test strip in Ag-RDTs is suited to preserve viral genomic material, even for several months at room temperature, and therefore can serve as source material for genetic characterisation could help improve global coverage of genomic surveillance for SARS-CoV-2 as well as for other viruses.

SARS-CoV-2 molecular testing and whole genome sequencing following RNA recovery from used BinaxNOW COVID-19 Antigen Self Tests

Widespread use of over-the-counter rapid diagnostic tests for SARS-CoV-2 has led to a decrease in availability of clinical samples for viral genomic surveillance. As an alternative sample source, we evaluated RNA isolated from BinaxNOW swabs stored at ambient temperature for SARS-CoV-2 rRT-PCR and full viral genome sequencing. 81 of 103 samples (78.6%) yielded detectable RNA, and 46 of 57 samples (80.7 %) yielded complete genome sequences. Our results illustrate that SARS-CoV-2 RNA extracted from used Binax test swabs provides an important opportunity for improving SARS-CoV-2 genomic surveillance, evaluating transmission clusters, and monitoring within-patient evolution.

SARS-CoV-2 diagnostic testing rates determine the sensitivity of genomic surveillance programs

The first step in SARS-CoV-2 genomic surveillance is testing to identify people who are infected. However, global testing rates are falling as we emerge from the acute health emergency and remain low in many low- and middle-income countries (mean = 27 tests per 100,000 people per day). We simulated COVID-19 epidemics in a prototypical low- and middle-income country to investigate how testing rates, sampling strategies and sequencing proportions jointly impact surveillance outcomes, and showed that low testing rates and spatiotemporal biases delay time to detection of new variants by weeks to months and can lead to unreliable estimates of variant prevalence, even when the proportion of samples sequenced is increased. Accordingly, investments in wider access to diagnostics to support testing rates of approximately 100 tests per 100,000 people per day could enable more timely detection of new variants and reliable estimates of variant prevalence. The performance of global SARS-CoV-2 genomic surveillance programs is fundamentally limited by access to diagnostic testing.

SARS-CoV-2 Variants Identification: Overview of Molecular Existing Methods

Since the beginning of COVID-19 pandemic the Real Time sharing of genome sequences of circulating virus supported the diagnostics and surveillance of SARS-CoV-2 and its transmission dynamics. SARS-CoV-2 straightaway showed its tendency to mutate and adapt to the host, culminating in the emergence of variants; so it immediately became of crucial importance to be able to detect them quickly but also to be able to monitor in depth the changes on the whole genome to early identify the new possibly emerging variants. In this scenario, this manuscript aims to provide an overview of the existing methods for the identification of SARS-CoV-2 variants (from rapid method based on identification of one or more specific mutations to Whole Genome sequencing approach-WGS), taking into account limitations, advantages and applications of them in the field of diagnosis and surveillance of SARS-CoV-2.

SARS-CoV-2 diagnostic testing rates determine the sensitivity of genomic surveillance programs

The first step in SARS-CoV-2 genomic surveillance is testing to identify infected people. However, global testing rates are falling as we emerge from the acute health emergency and remain low in many low- and middle-income countries (LMICs) (mean = 27 tests/100,000 people/day). We simulated COVID-19 epidemics in a prototypical LMIC to investigate how testing rates, sampling strategies, and sequencing proportions jointly impact surveillance outcomes and showed that low testing rates and spatiotemporal biases delay time-to-detection of new variants by weeks-to-months and can lead to unreliable estimates of variant prevalence even when the proportion of samples sequenced is increased. Accordingly, investments in wider access to diagnostics to support testing rates of ~100 tests/100,000 people/day could enable more timely detection of new variants and reliable estimates of variant prevalence. The performance of global SARS-CoV-2 genomic surveillance programs is fundamentally limited by access to diagnostic testing.