Project description:Recombination, the process whereby a segment of genetic material from one genome is inserted into another, producing a new chimeric genome, is an important evolutionary mechanism frequently observed in coronaviruses. The risks posed by recombination include the shuffling of advantageous mutations that may increase transmissibility, severity or vaccine escape. We present a genomic and epidemiological description of a new recombinant lineage of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), XR, first identified in Wales. The Pathogen Genomics Unit (Public Health Wales, UK) sequences positive SARS-CoV-2 PCR tests using the ARTIC SARS-CoV-2 sequencing protocol. Recombinants were detected using an in-house pipeline and the epidemiological data analysed in R. Nosocomial cases were defined as those with samples taken after >7 days in hospital. Between February and March 2022, we identified 78 samples with highly similar genomes, comprising a BA.1-like 5' end, a BA.2-like 3' end and a BA.2-like spike protein. This signature is consistent with recombination and was defined as XR by Pangolin (PANGO v1.8). A total of 50 % of cases had a sample collected whilst in hospital and the first three cases were immunocompromised patients. The patient median age was 58 years (range: 4-95 years) and most of the patients were fully vaccinated against SARS-CoV-2 (74 % third dose/booster). Three patients died within 28 days of their sample collection date, one of whom had COVID-19 listed amongst ICD10 (International Classification of Diseases 10) coded causes of death. Our integrated system enabled real-time monitoring of recombinant SARS-CoV-2 for early detection, in order to rapidly risk assess and respond. This work highlights the importance of setting-based surveillance of recombinant SARS-CoV-2, as well as the need to monitor immunocompromised populations through repeat testing and sequencing.
Project description:To investigate the virological properties of a SARS-CoV-2 variant, Omicron BA.2, we generated chimeric recombinant viruses that express GFP and encodes the S gene of B.1.1 (ancestral D614G-bearing virus), Delta, BA.1 and BA.2. To verify the genome sequence of the working viruses, we performed viral RNA-sequencing of the viral stock.
Project description:Distinct SARS-CoV-2 Omicron sublineages have evolved showing increased fitness and immune evasion than the original Omicron variant BA.1. Here, we report the neutralization activity of sera from BNT162b2 vaccinated individuals or unimmunized Omicron BA.1-infected individuals against Omicron sublineages and "Deltacron" variant (XD). BNT162b2 post-dose 3 immune sera neutralized USA-WA1/2020, Omicron BA.1-, BA.2-, BA.2.12.1-, BA.3-, BA.4/5-, and XD-spike SARS-CoV-2s with geometric mean titres (GMTs) of 1335, 393, 298, 315, 216, 103, and 301, respectively; thus, BA.4/5 SARS-CoV-2 spike variant showed the highest propensity to evade vaccine neutralization compared to the original Omicron variants BA.1. BA.1-convalescent sera neutralized USA-WA1/2020, BA.1-, BA.2-, BA.2.12.1-, BA.3-, BA.4/5-, and Deltacron-spike SARS-CoV-2s with GMTs of 15, 430, 110, 109, 102, 25, and 284, respectively. The unique mutation F486V in the BA.4/5 spike contributes to the increased evasion of antibody neutralization by sublineage BA.4/5. The low neutralization titres of vaccinated sera or convalescent sera from BA.1 infected individuals against the emerging and rapidly spreading Omicron BA.4/5 variants provide important results for consideration in the selection of an updated vaccine in the current Omicron wave.Trial registration: ClinicalTrials.gov; identifier: NCT04368728.
Project description:Recombinant sequences of the SARS-CoV-2 Omicron variant were detected in surveillance samples collected in north-western Finland in January 2022. We detected 191 samples with an identical genome arrangement in weeks 3 to 11, indicating sustained community transmission. The recombinant lineage has a 5'-end of BA.1, a recombination breakpoint between orf1a and orf1b (nucleotide position 13,296-15,240) and a 3'-end of BA.2 including the S gene. We describe the available genomic and epidemiological data about this currently circulating recombinant XJ lineage.
Project description:Tracking SARS-CoV-2 genetic diversity is strongly indicated because diversifying selection may lead to the emergence of novel variants resistant to naturally acquired or vaccine-induced immunity. To monitor New York City (NYC) for the presence of novel variants, we deep sequence most of the receptor binding domain coding sequence of the S protein of SARS-CoV-2 isolated from the New York City wastewater. Here we report detecting increasing frequencies of novel cryptic SARS-CoV-2 lineages not recognized in GISAID's EpiCoV database. These lineages contain mutations that had been rarely observed in clinical samples, including Q493K, Q498Y, E484A, and T572N and share many mutations with the Omicron variant of concern. Some of these mutations expand the tropism of SARS-CoV-2 pseudoviruses by allowing infection of cells expressing the human, mouse, or rat ACE2 receptor. Finally, pseudoviruses containing the spike amino acid sequence of these lineages were resistant to different classes of receptor binding domain neutralizing monoclonal antibodies. We offer several hypotheses for the anomalous presence of these lineages, including the possibility that these lineages are derived from unsampled human COVID-19 infections or that they indicate the presence of a non-human animal reservoir.
Project description:SARS-CoV-2 is the etiological agent of COVID19. There are currently several licensed vaccines approved for human use and most of them target the spike protein in the virion envelope to induce protective immunity. Recently, variants that spread more quickly have emerged. There is evidence that some of these variants are less sensitive to neutralization in vitro, but it is not clear whether they can evade vaccine induced protection. In this study, we tested SARS-CoV-2 spike RBD as a vaccine antigen and explored the effect of formulation with Alum/MPLA or AddaS03 adjuvants. Our results show that RBD induces high titers of neutralizing antibodies and activates strong cellular immune responses. There is also significant cross-neutralization of variants B.1.1.7 and B.1.351 and to a lesser extent, SARS-CoV-1. These results indicate that recombinant RBD can be a viable candidate as a stand-alone vaccine or as a booster shot to diversify our strategy for COVID19 protection.
Project description:Reporter-expressing recombinant severe acute respiratory syndrome coronavirus 2 (rSARS-CoV-2) represents an excellent tool to understand the biology of and ease studying viral infections in vitro and in vivo. The broad range of applications of reporter-expressing recombinant viruses is due to the facilitated expression of fluorescence or bioluminescence readouts. In this chapter, we describe a detailed protocol on the generation of rSARS-CoV-2 expressing Venus, mCherry, and NLuc that represents a valid surrogate to track viral infections.