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Meganck RM, Edwards CE, Mallory ML, Lee RE, Dang H, Bailey AB, Wykoff JA, Gallant SC, Zhu DR, Yount BL, Kato T, Shaffer KM, Nakano S, Cawley AM, Sontake V, Wang JR, Hagan RS, Miller MB, Tata PR, Randell SH, Tse LV, Ehre C, Okuda K, Boucher RC, Baric RS. SARS-CoV-2 variant of concern fitness and adaptation in primary human airway epithelia. Cell Rep 2024; 43:114076. [PMID: 38607917 PMCID: PMC11165423 DOI: 10.1016/j.celrep.2024.114076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 02/09/2024] [Accepted: 03/21/2024] [Indexed: 04/14/2024] Open
Abstract
The severe acute respiratory syndrome coronavirus 2 pandemic is characterized by the emergence of novel variants of concern (VOCs) that replace ancestral strains. Here, we dissect the complex selective pressures by evaluating variant fitness and adaptation in human respiratory tissues. We evaluate viral properties and host responses to reconstruct forces behind D614G through Omicron (BA.1) emergence. We observe differential replication in airway epithelia, differences in cellular tropism, and virus-induced cytotoxicity. D614G accumulates the most mutations after infection, supporting zoonosis and adaptation to the human airway. We perform head-to-head competitions and observe the highest fitness for Gamma and Delta. Under these conditions, RNA recombination favors variants encoding the B.1.617.1 lineage 3' end. Based on viral growth kinetics, Alpha, Gamma, and Delta exhibit increased fitness compared to D614G. In contrast, the global success of Omicron likely derives from increased transmission and antigenic variation. Our data provide molecular evidence to support epidemiological observations of VOC emergence.
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Affiliation(s)
- Rita M Meganck
- Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Caitlin E Edwards
- Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Michael L Mallory
- Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Rhianna E Lee
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Hong Dang
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Alexis B Bailey
- Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Jason A Wykoff
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Samuel C Gallant
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Deanna R Zhu
- Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Boyd L Yount
- Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Takafumi Kato
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Kendall M Shaffer
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Satoko Nakano
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Anne Marie Cawley
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | | | - Jeremy R Wang
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Robert S Hagan
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA; Division of Pulmonary Diseases and Critical Care Medicine, UNC School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Melissa B Miller
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | | | - Scott H Randell
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Longping V Tse
- Department of Molecular Microbiology & Immunology, Saint Louis University, St. Louis, MO 63104, USA
| | - Camille Ehre
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Kenichi Okuda
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Richard C Boucher
- Marsico Lung Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Ralph S Baric
- Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA.
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Partakusuma LG, Budiailmiawan L, Budiman, Parwati I, Aryati, Andriyoko B, Markus L, Niswara C, Cinthia Alamanda CN. The Single-Nucleotide Polymorphism (SNP) Validity to Detect Omicron Variants. Adv Virol 2023; 2023:6618710. [PMID: 37719318 PMCID: PMC10501844 DOI: 10.1155/2023/6618710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 08/01/2023] [Accepted: 08/26/2023] [Indexed: 09/19/2023] Open
Abstract
Introduction Mutation of SARS-CoV-2 has generated several variants of concern (VOC) which spread promptly worldwide. These emerging variants affected global strategies to overcome COVID-19. Variants of SARS-CoV-2 are determined by the whole genome sequencing (WGS) assay, which is time-consuming, with limited availability (only in several laboratories). Hence, a faster and more accessible examination is needed. The single-nucleotide polymorphism (SNP) method is one of the options for genomic variation surveillance that can help provide an answer to this challenge. This study aims to determine the validity of the SNP method with PCR to detect omicron variants of SARS-CoV-2 compared with the gold standard, WGS. Methods This is a diagnostic analysis of 140 confirmed COVID-19 nasopharyngeal samples taken from the Kemayoran COVID Emergency Hospital Laboratory and the West Java Provincial Health Laboratory from April to October 2022. Data analysis was carried out to determine conformity and validity values. Results Analysis using Cohen's kappa coefficient test showed high conformity between SNP and WGS (p value <0.001; kappa coefficient = 0.948). SNP showed great validity values on omicron BA.1 (90% sensitivity; 100% specificity), omicron BA.2 (100% sensitivity; 99% specificity), and omicron BA.4/5 (99.2% sensitivity; 100% specificity). Conclusion The SNP method can be a more time-efficient alternative to detect omicron variants of SARS-CoV-2 and distinguish their sublineages (BA.1, BA.2, and BA.4/5) by two different specific gene mutations in combination analysis (ΔH69/V70 and Q493R mutations).
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Affiliation(s)
- Lia Gardenia Partakusuma
- Faculty of Medicine and Post Graduate Programme, YARSI University, Jakarta, West Java, Indonesia
| | | | - Budiman
- COVID Emergency Hospital, Kemayoran, Jakarta, West Java, Indonesia
| | - Ida Parwati
- Department of Clinical Pathology, Faculty of Medicine Padjadjaran University, Dr. Hasan Sadikin General Hospital, Bandung, West Java, Indonesia
| | - Aryati
- Department of Clinical Pathology, Faculty of Medicine Airlangga University, Dr. Soetomo General Hospital, Surabaya, East Java, Indonesia
| | - Basti Andriyoko
- Department of Clinical Pathology, Faculty of Medicine Padjadjaran University, Dr. Hasan Sadikin General Hospital, Bandung, West Java, Indonesia
| | - Louisa Markus
- Cengkareng Hospital, Jakarta, West Jakarta, Indonesia
| | - Corine Niswara
- COVID Emergency Hospital, Kemayoran, Jakarta, West Java, Indonesia
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Chen WC, Hu SY, Shen CF, Chuang HY, Ker CR, Shen CJ, Cheng CM. COVID-19 Bivalent Booster in Pregnancy: Maternal and Neonatal Antibody Response to Omicron BA.5, BQ.1, BF.7 and XBB.1.5 SARS-CoV-2. Vaccines (Basel) 2023; 11:1425. [PMID: 37766102 PMCID: PMC10537670 DOI: 10.3390/vaccines11091425] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 08/25/2023] [Accepted: 08/25/2023] [Indexed: 09/29/2023] Open
Abstract
Our study was to investigate the effects of bivalent COVID-19 booster vaccination during pregnancy on neutralizing antibody (Nab) levels in maternal blood (MB), transplacental transmission in umbilical cord blood (CB), and efficacy against Omicron SARS-CoV-2 subvariants including BA.5, BF.7, BQ.1, and XBB.1.5. We collected MB and CB from 11 pregnant participants during baby delivery and detected Nab inhibition by enzyme-linked immunosorbent assays (ELISA). Nab inhibition was 89-94% in MB and 82-89% in CB for Omicron subvariants. Those receiving AZD1222 vaccines in previous monovalent vaccination demonstrated poorer maternal Nab inhibition of BA.5, BQ.1, and XBB.1.5 than others. Poorer maternal Nab inhibition of BA.5, BF.7, and BQ.1 was found in those receiving two-dose AZD1222 vaccinations than with either one or no AZD1222 vaccination. MB from those with infants weighing < 3100 g demonstrated better Nab inhibition of BF.7 than those > 3100 g (97.99 vs. 95.20%, p = 0.048), and there were also similar trends for Nab inhibition of BA.5 and BQ.1. No significant differences were seen in CB samples. Although diminished maternal Nab inhibition was seen in those with previous monovalent AZD1222 vaccination and heavier newborns, neonatal Nab inhibition was still strong after bivalent COVID-19 booster vaccination.
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Affiliation(s)
- Wei-Chun Chen
- Institute of Biomedical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan; (W.-C.C.); (S.-Y.H.)
- Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital at Linkou, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan
- Department of Obstetrics and Gynecology, New Taipei City Municipal Tucheng Hospital, New Taipei City 236, Taiwan
- International Intercollegiate Ph.D. Program, National Tsing Hua University, Hsinchu 300, Taiwan
- School of Traditional Chinese Medicine, Chang Gung University, Taoyuan 333, Taiwan
| | - Shu-Yu Hu
- Institute of Biomedical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan; (W.-C.C.); (S.-Y.H.)
| | - Ching-Fen Shen
- Department of Pediatrics, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan;
| | - Hui-Yu Chuang
- Department of Obstetrics and Gynecology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 807, Taiwan; (H.-Y.C.); (C.-R.K.)
| | - Chin-Ru Ker
- Department of Obstetrics and Gynecology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 807, Taiwan; (H.-Y.C.); (C.-R.K.)
- Graduate Institute of Clinical Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan
| | - Ching-Ju Shen
- Department of Obstetrics and Gynecology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 807, Taiwan; (H.-Y.C.); (C.-R.K.)
| | - Chao-Min Cheng
- Institute of Biomedical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan; (W.-C.C.); (S.-Y.H.)
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Ye C, Zhang G, Zhang A, Xin H, Wu K, Li Z, Jia Y, Hao L, Xue C, Wang Y, Xu H, Zhu W, Zhou Y. The Omicron Variant Reinfection Risk among Individuals with a Previous SARS-CoV-2 Infection within One Year in Shanghai, China: A Cross-Sectional Study. Vaccines (Basel) 2023; 11:1146. [PMID: 37514962 PMCID: PMC10386598 DOI: 10.3390/vaccines11071146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Revised: 06/15/2023] [Accepted: 06/19/2023] [Indexed: 07/30/2023] Open
Abstract
Reinfection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants due to immune escape is challenging for the global response to the pandemic. We estimated the Omicron reinfection prevalence among people who had a previous SARS-CoV-2 infection in Shanghai, China. We conducted a telephone survey in December 2022 with those who had previously been infected with Omicron between March and May 2022. Information on their demographics, coronavirus disease 2019 (COVID-19) testing, and vaccination history was collected. The overall and subgroup reinfection rates were estimated and compared. Among the 1981 respondents who were infected between March and May 2022, 260 had positive nucleic acid or rapid antigen tests in December 2022, with an estimated reinfection rate of 13.1% (95% confidence interval [95% CI]: 11.6-14.6). The reinfection rate for those who had a booster vaccination was 11.4% (95% CI: 9.2-13.7), which was significantly lower than that for those with an incomplete vaccination series (15.2%, 95% CI: 12.3-18.1) (adjusted odds ratio [aOR]: 0.579; 95% CI: 0.412-0.813). Reinfection with the Omicron variant was lower among individuals with a previous SARS-CoV-2 infection and those who had a booster vaccination, suggesting that hybrid immunity may offer protection against reinfection with Omicron sublineages.
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Affiliation(s)
- Chuchu Ye
- Shanghai Pudong New Area Center for Disease Control and Prevention, Shanghai 200136, China
| | - Ge Zhang
- School of Public Health, Dali University, Dali 671003, China
| | - Anran Zhang
- Shanghai Pudong New Area Center for Disease Control and Prevention, Shanghai 200136, China
| | - Hualei Xin
- World Health Organization Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Kang Wu
- Shanghai Pudong New Area Center for Disease Control and Prevention, Shanghai 200136, China
| | - Zhongjie Li
- School of Population Medicine and Public Health, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100073, China
| | - Yilin Jia
- Shanghai Pudong New Area Center for Disease Control and Prevention, Shanghai 200136, China
| | - Lipeng Hao
- Shanghai Pudong New Area Center for Disease Control and Prevention, Shanghai 200136, China
| | - Caoyi Xue
- Shanghai Pudong New Area Center for Disease Control and Prevention, Shanghai 200136, China
| | - Yuanping Wang
- Shanghai Pudong New Area Center for Disease Control and Prevention, Shanghai 200136, China
| | - Hongmei Xu
- Shanghai Pudong New Area Center for Disease Control and Prevention, Shanghai 200136, China
| | - Weiping Zhu
- Shanghai Pudong New Area Center for Disease Control and Prevention, Shanghai 200136, China
| | - Yixin Zhou
- Shanghai Pudong New Area Center for Disease Control and Prevention, Shanghai 200136, China
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Sugimoto S, Kakizaki M, Kawase M, Kawachi K, Ujike M, Kamitani W, Sentsui H, Shirato K. Single Amino Acid Substitution in the Receptor Binding Domain of Spike Protein Is Sufficient To Convert the Neutralization Profile between Ethiopian and Middle Eastern Isolates of Middle East Respiratory Coronavirus. Microbiol Spectr 2023; 11:e0459022. [PMID: 36744940 PMCID: PMC10100835 DOI: 10.1128/spectrum.04590-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 01/25/2023] [Indexed: 02/07/2023] Open
Abstract
Middle East respiratory syndrome coronavirus (MERS-CoV) is a zoonotic virus that causes MERS, which is endemic in the Middle East. The absence of human cases in Africa despite the presence of MERS-CoV suggests virological differences between MERS-CoVs in Africa and the Middle East. In fact, in the laboratory, recombinant MERS-CoV carrying the spike (S) protein of Ethiopian isolates exhibits attenuated properties, being more easily neutralized and replicating slower than viruses carrying the S protein of Middle Eastern isolate, EMC. In this study, to identify the amino acids that define the different virological features between Ethiopian and Middle Eastern MERS-CoVs, neutralization titers and viral replication were evaluated using recombinant MERS-CoVs carrying amino acid substitution(s) in the S protein. A single amino acid difference introduced into the receptor binding domain was sufficient to reverse the difference in the neutralizing properties of the S protein between Ethiopian and Middle Eastern MERS-CoVs. Furthermore, amino acid mutations in the S1 and S2 regions of S protein were collectively involved in slow viral replication. Since even a single amino acid difference in S protein can reverse the viral properties of MERS-CoV, it should be noted that multiple mutations may induce a significant change. Careful monitoring of genetic alterations in MERS-CoVs in Africa is therefore required to detect the emergence of virulent strains generated by a few genetic differences. IMPORTANCE There have been no reported cases of human Middle East respiratory syndrome (MERS) in Africa, despite the presence of MERS coronavirus (MERS-CoV). Previous studies have shown that recombinant MERS-CoV carrying the S protein of an Ethiopian isolate replicated slower and was more easily neutralized relative to MERS-CoV carrying the S protein of a Middle Eastern isolate. In this study, we investigated the amino acid(s) in S protein associated with the different viral characteristics between Ethiopian and Middle Eastern MERS-CoVs. The results revealed that a single amino acid difference in the receptor binding domain was sufficient to reverse the neutralization profile. This implies that slight genetic changes can alter the predominant population of MERS-CoV, similar to the transition of variants of severe acute respiratory syndrome coronavirus-2. Careful genetic monitoring of isolates is important to detect the spread of possible virulent MERS-CoVs generated by mutation(s).
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Affiliation(s)
- Satoko Sugimoto
- Department of Virology III, National Institute of Infectious Diseases, Musashimurayama, Tokyo, Japan
- Management Department of Biosafety, Laboratory Animals, and Pathogen Bank, National Institute of Infectious Diseases, Musashimurayama, Tokyo, Japan
| | - Masatoshi Kakizaki
- Department of Virology III, National Institute of Infectious Diseases, Musashimurayama, Tokyo, Japan
| | - Miyuki Kawase
- Department of Virology III, National Institute of Infectious Diseases, Musashimurayama, Tokyo, Japan
| | - Kengo Kawachi
- Laboratory of Clinical Research on Infectious Diseases, Department of Pathogen Molecular Biology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan
| | - Makoto Ujike
- Faculty of Veterinary Medicine, Nippon Veterinary and Life Science University, Musashino, Tokyo, Japan
| | - Wataru Kamitani
- Laboratory of Clinical Research on Infectious Diseases, Department of Pathogen Molecular Biology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan
- Department of Infectious Diseases and Host Defense, Graduate School of Medicine, Gunma University, Maebashi, Gunma, Japan
| | - Hiroshi Sentsui
- Laboratory of Veterinary Epizootiology, Department of Veterinary Medicine, Nihon University, Fujisawa, Kanagawa, Japan
| | - Kazuya Shirato
- Department of Virology III, National Institute of Infectious Diseases, Musashimurayama, Tokyo, Japan
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King SM, Bryan SP, Hilchey SP, Wang J, Zand MS. First Impressions Matter: Immune Imprinting and Antibody Cross-Reactivity in Influenza and SARS-CoV-2. Pathogens 2023; 12:169. [PMID: 36839441 PMCID: PMC9967769 DOI: 10.3390/pathogens12020169] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 01/12/2023] [Accepted: 01/13/2023] [Indexed: 01/24/2023] Open
Abstract
Many rigorous studies have shown that early childhood infections leave a lasting imprint on the immune system. The understanding of this phenomenon has expanded significantly since 1960, when Dr. Thomas Francis Jr first coined the term "original antigenic sin", to account for all previous pathogen exposures, rather than only the first. Now more commonly referred to as "immune imprinting", this effect most often focuses on how memory B-cell responses are shaped by prior antigen exposure, and the resultant antibodies produced after subsequent exposure to antigenically similar pathogens. Although imprinting was originally observed within the context of influenza viral infection, it has since been applied to the pandemic coronavirus SARS-CoV-2. To fully comprehend how imprinting affects the evolution of antibody responses, it is necessary to compare responses elicited by pathogenic strains that are both antigenically similar and dissimilar to strains encountered previously. To accomplish this, we must be able to measure the antigenic distance between strains, which can be easily accomplished using data from multidimensional immunological assays. The knowledge of imprinting, combined with antigenic distance measures, may allow for improvements in vaccine design and development for both influenza and SARS-CoV-2 viruses.
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Affiliation(s)
- Samantha M. King
- Department of Medicine, Division of Nephrology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Shane P. Bryan
- Department of Medicine, Division of Nephrology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Shannon P. Hilchey
- Department of Medicine, Division of Nephrology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Jiong Wang
- Department of Medicine, Division of Nephrology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Martin S. Zand
- Department of Medicine, Division of Nephrology, University of Rochester Medical Center, Rochester, NY 14642, USA
- Clinical and Translational Science Institute, University of Rochester Medical Center, Rochester, NY 14618, USA
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7
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Su W, Choy KT, Gu H, Sia SF, Cheng KM, Nizami SIN, Krishnan P, Ng YM, Chang LDJ, Liu Y, Cheng SM, Peiris M, Poon LL, Nicholls JM, Yen HL. Omicron BA.1 and BA.2 sub-lineages show reduced pathogenicity and transmission potential than the early SARS-CoV-2 D614G variant in Syrian hamsters. J Infect Dis 2022; 227:1143-1152. [PMID: 35776136 PMCID: PMC9278237 DOI: 10.1093/infdis/jiac276] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Revised: 06/17/2022] [Accepted: 06/29/2022] [Indexed: 11/13/2022] Open
Abstract
Background The epidemiological advantage of Omicron variant is evidenced by its rapid spread and the ability to outcompete prior variants. Among Omicron sub-lineages, early outbreaks were dominated by BA.1 while BA.2 has gained dominance since February 2022. The relative pathogenicity and transmissibility of BA.1 and BA.2 have not been fully defined. Methods We compared viral loads and clinical signs in Syrian hamsters after infection with BA.1, BA.2, or D614G variant. A competitive transmission model and next generation sequencing were used to compare the relative transmission potential of BA.1 and BA.2. Results BA.1 and BA.2 caused no apparent clinical signs while D614G caused more than 10% weight loss. Higher viral loads were detected from the nasal washes, nasal turbinate and lungs of BA.1 than BA.2 inoculated hamsters. No aerosol transmission was observed for BA.1 or BA.2 under the experimental condition that D614G transmitted efficiently. BA.1 and BA.2 were able to transmit among hamsters via direct contact; however, BA.1 transmitted more efficiently than BA.2 under the competitive transmission model. No recombination was detected from direct contacts exposed simultaneously to BA.1 and BA.2. Conclusions Omicron BA.1 and BA.2 demonstrated attenuated pathogenicity and reduced transmission potential in hamsters when compared to early SARS-CoV-2 strains.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | - John M Nicholls
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
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