Journal of Dali University ›› 2026, Vol. 11 ›› Issue (2): 31-36.DOI: 10. 3969 / j. issn. 2096-2266. 2026. 02. 005

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Levels and Functional Effects of Cross-Reactive Antibodies against SARS-CoV-2 in the Yunnan Population

Wang Yang, Shang Fangjian, Yang Manqing, Shan Jing, Liu Qi*   

  1. (School of Basic Medical Sciences, Dali University, Dali, Yunnan 671000, China)
  • Received:2024-11-08 Revised:2024-11-18 Online:2026-02-15 Published:2026-03-18

Abstract: Objective: To investigate the levels of cross-reactive antibodies against SARS-CoV-2 in the Yunnan population and their
potential role during the early phase of SARS-CoV-2 circulation. Methods: Indirect ELISA was used to detect the positive rates of
cross-reactive antibodies against SARS-CoV-2 S, S1, and RBD proteins in 1 907 serum samples collected between January 2019 and
June 2020. Stratified analyzes were conducted according to sex, age, ethnicity, and region. A cell fusion model was employed to
evaluate the functional effects of antibodies on SARS-CoV-2 infection. Results: The seropositivity rates of cross-reactive antibodies
against S, S1, and RBD proteins were 16.68%, 10.75%, and 1.26%, respectively. Significant differences were observed among age
groups (P<0.001), and partial differences were found between urban and rural populations and among ethnic groups (P<0.05).
Functional assays showed that 76.80% of positive sera had no obvious effect on cell fusion, 21.87% enhanced fusion, and 1.33% inhibited
fusion. Sera with enhancement effects exhibited relatively higher P/N values. Conclusion: Cross-reactive antibodies against
SARS-CoV-2 are prevalent in the Yunnan population, and a subset may possess potential infection-enhancing activity, highlighting
their relevance in risk assessment and prevention strategies for emerging coronavirus infections.

Key words: SARS-CoV-2, cross-reactive antibody, antibody dependent enhancement, ELISA, Yunnan population

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