Emergence and antibody evasion of BQ and BA.2.75 SARS-CoV-2 sublineages in the face of maturing antibody breadth at the population level

The Omicron era of the COVID-19 pandemic commenced at the beginning of 2022 and whilst it started with primarily BA.1, it was latter dominated by BA.2 and related sub-lineages. Over the course of 2022, we monitored the potency and breadth of antibody neutralization responses to many emerging variants at two levels: (i) we tracked over 400,000 U.S. plasma donors over time through various vaccine booster roll outs and Omicron waves using antibody pools. (ii) we mapped the antibody response at the individual level using blood from strigently curated vaccine and convalescent cohorts. In pooled antibody samples, we observed the maturation of neutralization breadth to Omicron variants over time through continuing vaccine and infection waves. Importantly, in many cases we observed increased antibody breadth to variants that were yet to be in circulation. Resolution of viral neutralisation at the cohort level supported equivalent coverage across prior and emerging variants with emerging isolates BQ.1.1, XBB.1 and BR.2.1 the most evasive. Further, these emerging variants were resistant to Evusheld, whilst neutralization resistance to Sotrovimab was restricted to BQ.1.1 and further supported by lack of Spike glycoprotein binding to this variant. An outgrowth advantage through better utilization of TMPRSS2 was observed across BQ lineages and not those derived from BA.2.75. We conclude at this current point in time that variants derived from BQ lineages can evade antibodies at levels equivalent to their most evasive BA.2.75 counterparts but sustain an entry phenotype that would promote an additional outgrowth advantage.

SARS-CoV-2 Omicron BA.5: Evolving tropism and evasion of potent humoral responses and resistance to clinical immunotherapeutics relative to viral variants of concern.

Genetically distinct viral variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been recorded since January 2020. Over this time global vaccine programs have been introduced, contributing to lower COVID-19 hospitalisation and mortality rates, particularly in developed countries. In late 2021, the Omicron BA.1 variant emerged, with substantially different genetic differences and clinical effects from other variants of concern (VOC). This variant demonstrated higher numbers of polymorphisms in the gene encoding the Spike (S) protein, and it has displaced the previously dominant Delta variant. Shortly after dominating global spread in early 2022, BA.1 was supplanted by the genetically distinct Omicron lineage BA.2. A sub-lineage of BA.2, designated BA.5 has now started to dominate globally, with the potential to supplant BA.2. To address the relative threat of BA.5, we determined infectivity to particle ratios in primary nasopharyngeal samples and expanded low passage isolates in a well characterised, genetically engineered ACE2/TMPRSS2 cell line. We then assessed the impact of BA.5 infection on humoral neutralisation in vitro, in vaccinated and convalescent cohorts, using concentrated human IgG pooled from thousands of plasma donors, and licensed monoclonal antibody therapies. The infectivity of virus in primary swabs and expanded isolates revealed that whilst BA.1 and BA.2 are attenuated through ACE2/TMPRSS2, BA.5 infectivity is equivalent to that of an early 2020 circulating clade and has greater sensitivity to the TMPRSS2 inhibitor Nafamostat. As with BA.1, we observed BA.5 to significantly reduce neutralisation titres across all donors. Concentrated pooled human IgG from convalescent and vaccinated donors had greater breadth of neutralisation, although the potency was still reduced 7-fold with BA.5. Of all therapeutic antibodies tested, we observed a 14.3-fold reduction using Evusheld and 16.8-fold reduction using Sotrovimab when neutralising a Clade A versus BA.5 isolate. These results have implications for ongoing tracking and management of Omicron waves globally.

SARS-CoV-2 Omicron: reduction of potent humoral responses and resistance to clinical immunotherapeutics relative to viral variants of concern

Genetically distinct viral variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been recorded since January 2020. Over this time global vaccine programs have been introduced, contributing to lowered COVID-19 hospitalisation and mortality rates, particularly in the first world. In late 2021, the Omicron (B.1.1.529) virus variant emerged, with significant genetic differences and clinical effects from other variants of concern (VOC). This variant demonstrated higher numbers of polymorphisms in the gene encoding the Spike (S) protein, and there has been displacement of the dominant Delta variant. We assessed the impact of Omicron infection on the ability of: serum from vaccinated and / or previously infected individuals; concentrated human IgG from plasma donors, and licensed monoclonal antibody therapies to neutralise virus in vitro. There was a 17 to 22-fold reduction in neutralisation titres across all donors who had a detectable neutralising antibody titre to the Omicron variant. Concentrated pooled human IgG from convalescent and vaccinated donors had greater breadth of neutralisation, although the potency was still reduced 16-fold. Of all therapeutic antibodies tested, significant neutralisation of the Omicron variant was only observed for Sotrovimab, with other monoclonal antibodies unable to neutralise Omicron in vitro. These results have implications for ongoing therapy of individuals infected with the Omicron variant.

Heart Transplantation From Hepatitis C-Positive Donors in the Era of Direct Acting Antiviral Therapy: A Comprehensive Literature Review.

While heart transplantation is a highly effective treatment in patients with advanced heart failure, the number of people waiting for a transplant exceeds the number of available donors. With the advent of direct acting antivirals (DAA) for the eradication of Hepatitis C, the heart transplant donor pool has been expanded to include donors with untreated Hepatitis C. To help with the development of future protocols for Hepatitis C-positive heart transplants, we performed a review of the literature on DAA therapy in the context of heart transplantation. METHODS: We searched MEDLINE, EMBASE, OVIDE JOURNAL, and GOOGLE SCHOLAR for papers published between 01.01.2011 and 01.06.2019 using key words "heart transplantation" associated with "hepatitis C." RESULTS: After removing duplicates, we screened 78 articles and retained 16 for primary analysis and 20 for sustained virologic response 12 weeks after completion of the DAA therapy (SVR-12). The data from 62 patients were extracted from these publications. Fifty-six (90%) patients had donor-derived hepatitis C and 6 (10%) patients were chronically infected with hepatitis C before transplantation. All living transplanted patients achieved SVR-12, defined as hepatitis C virus RNA below the limit of detection 12 weeks after treatment completion. Treatment duration ranged from 4 to 24 weeks. Clinically relevant modification to the dosing of immunosuppressive mediations during DAA therapy was documented in only 1 patient (1.6%). Six (14%) patients experienced rejection during DAA therapy. CONCLUSIONS: Despite different timings of initiation of DAA therapy across the included studies, there were no differences in sustained viral clearance. Early commencement of DAA with a potentially shorter treatment duration (<8 wk) is appealing; however, further studies are required before recommending this approach.