The case began in December 2022, when a 40-year-old male patient presented with symptomatic COVID-19 at the Sonoma County Public Health Laboratory. The patient, who had received a bivalent booster vaccination on October 24, 2022, following earlier doses in 2021, reported symptom onset on December 4, including fever above 38 degrees Celsius, chills, cough, and headache consistent with a mild influenza-like illness. He had been in close contact with a confirmed COVID-19 case and had a prior history of testicular teratoma, but no hospitalization or complications were reported. A nasal specimen collected on December 13, 2022 tested positive for SARS-CoV-2 RNA by an FDA-authorized reverse transcription real-time PCR assay targeting the ORF1ab and nucleocapsid genes, yielding a cycle threshold value of 22, indicative of a substantial viral load in the sample.

To characterize the virus genetically, the laboratory extracted RNA from 300 microliters of the nasal specimen using an automated Chemagic 360 Extractor and prepared a sequencing library with the Clear Dx SARS-CoV-2 Kit from Clear Labs. This automated workflow begins with complementary DNA synthesis from the extracted RNA, followed by multiplex tiling PCR using a panel of barcoded target capture primers to amplify the complete viral genome. After purification with Ampure XP beads to remove excess primers and short amplification products, the amplicons underwent a second round of PCR to incorporate a second set of barcodes using rapid library primers from Oxford Nanopore Technologies. Sequencing adapters were then ligated to the dual-barcoded amplicons, and the finished library was loaded onto a MinION flow cell and sequenced on a GridION instrument for 12 hours.

Bioinformatic processing was carried out with the TheiaCoV_ClearLabs workflow version 2.3.0 on the Terra platform, which employs a reference-based assembly approach using the Wuhan-Hu-1 reference genome. Raw reads were subjected to quality control and adapter trimming, human-derived reads were removed with the NCBI SRA Human Scrubber tool, and the remaining de-hosted reads were aligned to the reference with minimap2. After primer trimming, variant calling and consensus generation were performed with Medaka based on allele frequency thresholds. The sequencing run produced 75,041 raw reads, of which 42,135 were classified as SARS-CoV-2 reads. The resulting consensus genome, designated CA-SCPHL-22-02592, spanned 29,574 nucleotides with 100 percent coding-complete coverage and a mean read depth of 1,112-fold, providing an exceptionally high-quality assembly for downstream analysis.

Lineage assignment placed the virus in Pango lineage BQ.1.1.5 within Nextstrain clade 22E, an Omicron sublineage known to be circulating locally at the time of infection. However, during genome annotation the analysts identified something far less ordinary: a 69-nucleotide in-frame deletion at genomic positions 3272 to 3340 within nsp3 of the ORF1a gene. Because Nanopore sequencing can be prone to insertion-deletion errors, the team rigorously assessed read-level support for the deletion using a custom Python script that parsed CIGAR strings from the alignment file. After quality filtering, 707 of 718 informative reads spanning the deletion breakpoints supported the deletion, corresponding to 98.47 percent read support, with only 11 reads supporting the wild-type sequence. Applying a more stringent filter requiring a mean read quality score of at least 20 yielded consistent results, with 98.30 percent support, providing strong evidence that the deletion is biological rather than an artifact of the sequencing platform.

A search of the GISAID database revealed just how rare this event is. Among 17,624,674 SARS-CoV-2 genomes available at the time, only 23 contained the ORF1a delta-69 deletion at these positions. The earliest sequence carrying the deletion was collected in December 2021 in Brazil and the most recent in March 2023 in the Brazilian Amazon. Strikingly, the deletion appeared across multiple Pango lineages and Nextstrain clades, including both Delta and Omicron variants: four sequences belonged to AY.99.2, one each to BA.1 and BA.1.1, four to BA.2, one to BQ.1, ten to BQ.1.1.5, and two to XBB.1.5.102. This distribution suggests the deletion is not lineage-specific and may arise independently in different viral genetic backgrounds. Notably, nearly all of the BQ.1.1.5 sequences harboring the deletion, with the exception of one from Sweden, were detected in California and exhibited nucleotide sequence identity between 99.96 and 100 percent, hinting at a localized cluster of related viruses.

To place the finding in evolutionary context, the team performed phylogenetic and cluster analysis using the TheiaCoV_Augur_Run workflow, which executes subcommands from the Nextstrain Augur toolkit to generate maximum-likelihood and time-resolved phylogenetic trees visualized in the Auspice web application. The analysis grouped the deletion-containing genomes with representatives of 207 distinct deletion patterns identified within ORF1a positions 3250 to 3350. Broader mining of GISAID identified 2,817 high-coverage sequences carrying deletions of varying lengths in this region, observed across Alpha, Beta, Delta, Epsilon, Iota, Gamma, Kappa, Mu, and Omicron clades as well as recombinant lineages, with the majority belonging to the Delta clade. These deletions of varying lengths within the 3250 to 3350 window had not been previously described in this systematic form, underscoring how a single unusual case can open a window onto a broader landscape of viral genetic diversity.

The functional implications of the deletion remain speculative but are grounded in what is known about nsp3 biology. ORF1a encodes a large polyprotein that is proteolytically processed into multiple non-structural proteins essential for viral replication and host interaction, and nsp3 is the largest and most functionally diverse of these, containing domains involved in proteolytic processing, replication complex organization, and interactions with host factors. The ORF1a delta-69 deletion lies predominantly within the N-terminal hypervariable region of nsp3, with a small portion extending into the ADP-ribose-1-phosphatase domain, also known as the macrodomain or Mac1. This region sits outside the well-characterized catalytic papain-like protease domain and is associated with protein-protein interactions and structural organization. Structural and evolutionary analyses of SARS-CoV-2 proteins indicate that insertions and deletions tend to occur in flexible, surface-exposed regions that tolerate localized sequence variation without disrupting overall protein architecture, consistent with the deletion’s placement in the hypervariable region.

Nevertheless, the partial overlap with the Mac1 domain is noteworthy because this domain counteracts host ADP-ribosylation-mediated antiviral responses, thereby facilitating viral replication and immune evasion. Although the deletion does not encompass the full domain, its partial overlap with a functional region raises the possibility of effects on domain stability or host interaction, and alterations within nsp3 could influence host-virus interactions and contribute to functional differences between SARS-CoV-2 and related coronaviruses such as SARS-CoV. The authors caution that, given the limited functional data available for this specific deletion and its rarity, these potential effects remain speculative. Confirmation using orthogonal approaches such as RT-PCR with flanking primers or Sanger sequencing would further strengthen confidence in the finding, and future studies using reverse genetics systems, protein structural modeling, and in vitro replication assays will be needed to assess any effects on viral replication, host interaction, and immune modulation.

The study also carries practical implications for diagnostics and surveillance. Deletions in viral genomes can affect the performance of molecular assays, particularly those relying on RT-PCR, where primer or probe binding sites could be disrupted, and they are equally relevant for amplicon-based enrichment approaches used prior to sequencing. A limitation of the work is the lack of clinical metadata for the other genomes harboring the ORF1a delta-69 deletion in public databases, which made it impossible to assess whether the deletion is associated with specific clinical outcomes or disease severity. The consensus genome from this case has been deposited in GISAID under accession number EPI_ISL_16171374, and the custom Python code used to quantify read-level deletion support is publicly available on GitHub. As SARS-CoV-2 continues to evolve, the integration of next-generation sequencing into routine surveillance frameworks remains essential for detecting emerging mutations, characterizing their functional consequences, and informing public health response and diagnostic strategies.

Subject of Research: A rare in-frame deletion in the SARS-CoV-2 ORF1a nsp3 gene detected through genomic surveillance

Article Title: Genomic monitoring of SARS-CoV-2 uncovers rare in-frame deletion in ORF1a (nsp3) gene: A case report

Article References: Goraichuk, I. V., Critchett, L., Gonzalez, C., Rubin, J., & Rees, R. (2026). Genomic monitoring of SARS-CoV-2 uncovers rare in-frame deletion in ORF1a (nsp3) gene: A case report. Heliyon, 12(15), Article e45522. https://doi.org/10.1016/j.heliyon.2026.e45522

Image Credits: AI Generated

DOI: 10.1016/j.heliyon.2026.e45522

Keywords: SARS-CoV-2, genomic surveillance, ORF1a, nsp3, in-frame deletion, next-generation sequencing, Oxford Nanopore, GISAID, BQ.1.1.5, Omicron, macrodomain, public health laboratory

Lassa fever presents a formidable diagnostic challenge. Early symptoms, including fever, malaise, headache, and muscle pain, overlap substantially with malaria, typhoid fever, and other common febrile illnesses that dominate the clinical landscape of the region. As a result, many infections are treated empirically as malaria and never confirmed as Lassa, obscuring the true burden of disease and delaying interventions such as isolation, contact tracing, and timely administration of ribavirin, the antiviral most often used in management. Case fatality is highest among patients hospitalized late in illness, which makes early laboratory confirmation not merely an academic exercise but a direct determinant of survival.

Historically, suspected cases in Forest Guinea had to be referred to distant reference laboratories, often outside the country, for confirmatory testing. Transport of samples over long distances on poor roads introduced delays of days or weeks, degraded sample quality, and severed the connection between laboratory results and the clinical decisions that needed to inform them. During that interval, patients could deteriorate, contacts could be exposed, and outbreak signals could be missed entirely. Strengthening in-country and, ultimately, in-region diagnostic capacity has therefore been a central pillar of Guinea’s post-epidemic health security agenda, accelerated by the hard lessons of the 2014–2016 Ebola virus disease epidemic in West Africa.

The advances described in the study center on the establishment and progressive improvement of laboratory platforms capable of detecting Lassa virus and other hemorrhagic fever pathogens at or near the point of patient care. Molecular assays based on reverse transcription polymerase chain reaction (RT-PCR) remain the reference standard for acute case confirmation, targeting conserved regions of the viral S segment genome. Deploying these assays in Guinea required not only equipment and reagents but also reliable cold chains, uninterrupted power supply, quality management systems, and, critically, trained personnel able to perform testing to internationally recognized standards.

Serological methods complement molecular detection in the diagnostic arsenal. Indirect immunofluorescent antibody tests and enzyme-linked immunosorbent assays detecting Lassa-specific IgM and IgG antibodies extend the window of detection beyond the viremic phase and support seroprevalence studies that map the footprint of past transmission. Because antibody responses in Lassa fever can be variable and cross-reactivity with other arenaviruses complicates interpretation, the combination of molecular and serological approaches, applied with careful clinical context, provides the most complete picture of who is infected, who has been exposed, and where the virus is actively circulating.

A decisive element of the capacity-building effort has been the training of Guinean laboratory scientists and technicians in biosafe specimen handling, nucleic acid extraction, assay execution, and result interpretation. Working with Lassa virus requires appropriate biosafety precautions, since the virus can be transmitted through contact with infectious blood, tissues, or bodily fluids, and laboratory-acquired infections are a recognized occupational risk. Building a cadre of locally based experts reduces dependence on external missions, sustains testing throughput between outbreaks, and anchors diagnostic capability within the national public health system rather than in temporary emergency structures.

The study documents how these investments translated into operational gains: more suspected cases tested, shorter turnaround times between sample collection and result reporting, and a higher proportion of Lassa fever cases confirmed within the country. Each of these metrics matters. Faster confirmation enables clinicians to initiate appropriate treatment earlier, triggers more rapid deployment of outbreak response teams, and improves the accuracy of surveillance data used to allocate scarce resources. Improved detection also feeds back into research, since confirmed cases provide the samples and epidemiological context needed to study viral diversity, disease severity, and transmission dynamics.

Genomic surveillance is an increasingly important downstream benefit of strengthened diagnostics. Sequencing Lassa virus genomes from confirmed cases allows researchers to track viral lineages, identify introductions from rodent reservoirs into human populations, and reconstruct transmission chains. In Forest Guinea, where multiple Lassa virus lineages are known to circulate and where the ecological interface between humans and reservoir rodents is intimate, genomic data can distinguish persistent local transmission from repeated spillover events, information that shapes whether interventions should prioritize rodent control, food storage hygiene, community education, or vaccination once candidate vaccines advance through the pipeline.

The Guinea experience also carries lessons for regional health security more broadly. The same laboratory infrastructure, trained workforce, and specimen referral networks that support Lassa fever detection can be adapted for other viral hemorrhagic fevers, including Ebola, Dengue, and yellow fever, as well as for emerging pathogens of unknown origin. Integrated diagnostic platforms that can pivot between pathogens represent a more resilient investment than single-disease silos, a principle reinforced by the COVID-19 pandemic, which tested and in many places benefited from hemorrhagic fever diagnostic networks established in the preceding decade.

Challenges remain. Sustaining funding beyond donor-supported emergency cycles, maintaining reagent supply chains, retaining skilled staff, and expanding testing to peripheral health facilities all require continued commitment. Yet the trajectory documented in Forest Guinea demonstrates that endemic countries can move from being sample-shippers to being diagnostic leaders in the fight against viral hemorrhagic fevers. Every Lassa fever case confirmed quickly and accurately is a patient treated sooner, a contact list initiated earlier, and a piece of evidence added to the regional understanding of one of West Africa’s most persistent viral threats.

Subject of Research: Strengthening diagnostic capacity for Lassa fever and viral hemorrhagic fevers in Forest Guinea

Article Title: Strengthening diagnostic capacity for viral hemorrhagic fevers in Forest Guinea: advances in Lassa fever case detection

Article References: Koundouno, F. R., Sidibe, Y., Millimono, S. L., Ifono, K., Hinzmann, J., Soubrier, H., Kourouma, K., Millimouno, T. E., Tolno, F. M., Kamano, F. M., Barry, M. D., Koulemou, S., Sonomy, B., Traore, M., Keïta, K., Hinrichs, M., Ryter, S., van Gelder, C., Becker-Ziaja, B., … Annibaldis, G. (2026). Strengthening diagnostic capacity for viral hemorrhagic fevers in Forest Guinea: advances in Lassa fever case detection. npj Viruses, 4(1), Article 42. https://doi.org/10.1038/s44298-026-00239-9

Image Credits: AI Generated

DOI: 10.1038/s44298-026-00239-9

Keywords: Lassa fever, viral hemorrhagic fevers, diagnostic capacity, Forest Guinea, RT-PCR, serology, genomic surveillance, biosafety, public health laboratory, case detection, outbreak response, Strengthening