The novel coronavirus (Severe acute respiratory syndrome coronavirus 2, SARS-CoV-2) is a positive-sense single-stranded RNA virus belonging to the family Coronaviridae[1]. Its genome consists of multiple segments with a total length of approximately 29,000 nucleotides[2]. The disease caused by this virus is termed Coronavirus Disease 2019 (COVID-19), primarily affecting the respiratory system. Symptoms include fever, cough, dyspnea, and in severe cases, may lead to pneumonia, acute respiratory distress syndrome, coagulation dysfunction, and multiple organ failure[3]. The global pandemic of COVID-19 has resulted in significant loss of life and economic damage, posing unprecedented challenges to public health systems worldwide. As of February 23, 2025, there have been over 770 million confirmed cases globally, with 7.09 million deaths (https://data.who.int/dashboards/covid19/cases?n=c).
Since its emergence, SARS-CoV-2 has developed multiple genetic lineages and major variants of concern. The World Health Organization assigns specific names to variants that may affect transmissibility, immune evasion capability, or vaccine response (https://www.who.int/activities/tracking-SARS-CoV-2-variants). These are broadly categorized into five variants: Alpha (B.1.1.7), Beta (501Y.V2 or B.1.351), Gamma (P.1), Delta (B.1.617.2), and Omicron (B.1.1.529).
First identified in South Africa in November 2021, the Omicron variant has undergone continuous evolution. All subsequently dominant global variants have been descendants of Omicron[4], including the BA.2 and BA.5 sublineages prevalent in 2022, the XBB sublineage widespread in 2023, and the currently dominant JN.1 lineage. The Omicron variant exhibits numerous mutations in the spike (S) protein, particularly in key amino acid changes within the receptor-binding domain (RBD), which may enhance viral binding affinity to host cell receptors and increase transmissibility. As Omicron spread globally, many sublineages have shown convergent mutation patterns in the RBD[5], potentially influencing viral transmission efficiency, immune escape potential, and pathogenicity[6].
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[1] WU F, ZHAO S, YU B, et al. A new coronavirus associated with human respiratory disease in China [J]. Nature, 2020, 579(7798): 265-9.
[2] KIM D, LEE J Y, YANG J S, et al. The Architecture of SARS-CoV-2 Transcriptome [J]. Cell, 2020, 181(4): 914-21.e10.
[3] STEIN S R, RAMELLI S C, GRAZIOLI A, et al. SARS-CoV-2 infection and persistence in the human body and brain at autopsy [J]. Nature, 2022, 612(7941): 758-63.
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[5] CAO Y, JIAN F, WANG J, et al. Imprinted SARS-CoV-2 humoral immunity induces convergent Omicron RBD evolution [J]. Nature, 2023, 614(7948): 521-9.
[6] 张林,姚卓成,陆剑,等.新型冠状病毒基因组的适应性进化研究进展 [J]. 遗传, 2025, 47(02): 211-227.