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Background: New Omicron subvariants are emerging rapidly from BA.1 to BA.4 and BA.5. Their pathogenicity has changed from that of wild-type (WH-09) and Omicron variants have over time become globally dominant. The spike proteins of BA.4 and BA.5 that serve as the target for vaccine-induced neutralizing antibodies have also changed compared to the previous subvariants, which is likely to cause immune escape and the reduction of the protective effect of the vaccine. Our study addresses the above issues and provides a basis for formulating relevant prevention and control strategies.
Methods: We collected cellular supernatant and cell lysates and measured the viral titers, viral RNA loads, and E subgenomic RNA (E sgRNA) loads in different Omicron subvariants grown in Vero E6 cells, using WH-09 and Delta variants as a reference. Additionally, we evaluated the in vitro neutralizing activity of different Omicron subvariants and compared it to the WH-09 and Delta variants using macaque sera with different types of immunity.
Results: As the SARS-CoV-2 evolved into Omicron BA.1, the replication ability in vitro began to decrease. Then with the emergence of new subvariants, the replication ability gradually recovered and became stable in the BA.4 and BA.5 subvariants. In WH-09-inactivated vaccine sera, geometric mean titers of neutralization antibodies against different Omicron subvariants declined by 3.7~15.4-fold compared to those against WH-09. In Delta-inactivated vaccine sera, geometric mean titers of neutralization antibodies against Omicron subvariants declined by 3.1~7.4-fold compared to those against Delta.
Conclusion: According to the findings of this research, the replication efficiency of all Omicron subvariants declined compared with WH-09 and Delta variants, and was lower in BA.1 than in other Omicron subvariants. After two doses of inactivated (WH-09 or Delta) vaccine, cross-neutralizing activities against various Omicron subvariants were seen despite a decline in neutralizing titers.
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http://dx.doi.org/10.1002/ame2.12302 | DOI Listing |
Curr Pharm Des
September 2025
Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine.
Introduction: Pharmacological studies in vitro demonstrate the preventive and therapeutic potential of green tea and its constituent epigallocatechin-3-gallate (EGCG) in the fight against coronavirus disease 2019 (COVID-19). Previously reported correlations between per capita green tea consumption and COVID-19 morbidity/mortality suggest similar effects in vivo. Considering that some recent SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) sub-variants are less influenced by EGCG, this study aimed to determine whether this affects the aforementioned correlations, focusing on comparisons between the periods before (2021) and after (2022-2024) the emergence of the Omicron variant.
View Article and Find Full Text PDFVirus Res
August 2025
Center for Molecular Diagnosis and Precision Medicine, The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, 1519 Dongyue Dadao, Nanchang 330209, China; Jiangxi Provincial Center for Advanced Diagnostic Technology and Precision Medicine, The First Affiliated Hospital, Jiangxi
The ongoing mutation and evolution of SARS-CoV-2 have posed a severe threat to global health, and their functional impact remains to be further characterized. Here, we analyzed the selection pressure from 49 Omicron sub-strains at the gene and amino acid levels. We also examined the impact of mutations on the binding affinity between the receptor binding domain (RBD) and angiotensin-Converting Enzyme 2 (ACE2) and evaluated the immune escape ability of RBD responding to the monoclonal antibodies (mAbs) through molecular dynamics simulation on eight representative Omicron sub-variants (B.
View Article and Find Full Text PDFEClinicalMedicine
September 2025
Arcturus Therapeutics, San Diego, USA.
Background: A recently licenced self-amplifying mRNA (sa-mRNA) COVID-19 vaccine induces a robust, broad, and long-lasting immune response, extending the arsenal of efficacious COVID-19 countermeasures. We ran a clinical study to assess the benefits of vaccine strain update and the feasibility of co-administration with influenza vaccines.
Methods: Between March 27, 2024 and April 10, 2025, we performed a randomised, observer-blind, placebo-controlled, phase 3 study with 1499 adult participants to compare immune responses of sa-mRNA vaccine, encoding spike glycoprotein of the XBB.
Lancet Reg Health Southeast Asia
October 2025
International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, 1212, Bangladesh.
Background: There is limited global evidence on whether influenza sentinel surveillance platforms can be effectively adapted for long-term SARS-CoV-2 monitoring in low-resource contexts. We explored the utility of the hospital-based influenza sentinel surveillance (HBIS) platform for monitoring SARS-CoV-2 in Bangladesh by comparing SARS-CoV-2 detection in HBIS platform with national COVID-19 platform and assessing how its integration into influenza surveillance aligns with national trends.
Methods: From March 2020 to December 2024, we analysed data from patients with severe acute respiratory infection (SARI) and influenza-like illness (ILI) enrolled in HBIS.
bioRxiv
August 2025
Gladstone Institutes, San Francisco, CA 94158, USA.
mRNA vaccines emerged as a leading vaccine technology during the COVID-19 pandemic. However, their sustained protective efficacies were limited by relatively short-lived antibody responses and the emergence of SARS-CoV-2 variants, necessitating frequent and variant-updated boosters. We recently developed the ESCRT- and ALIX-binding region (EABR) mRNA vaccine platform, which encodes engineered immunogens that induce budding of enveloped virus-like particles (eVLPs) from the plasma membrane, thereby resulting in presentation of immunogens on cell surfaces and eVLPs.
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