Sialylated immunoglobulin G can neutralize influenza virus infection through receptor mimicry

// Tao Huang 1, * , Xueling Chen 1, * , Conghui Zhao 2, 3 , Xingmu Liu 1, 4 , Zaiping Zhang 1 , Tongfei Li 1 , Ruiman Sun 1 , Huan Gu 1 , Jiang Gu 1, 3 1 Department of Pathology and Provincial Key Laboratory of Infectious Diseases and Immunopathology, Collaborative and Creative Center, Shantou University Medical College, Shantou, Guangdong, 515041, China 2 Department of Oral Pathology, Beijing Stomatological Hospital, Capital Medical University, Beijing, 100050, China 3 Department of Pathology, Beijing University Health Science Center, Beijing, 100083, China 4 Department of General Surgery, Second Affiliated Hospital, Shantou University Medical College, Shantou, Guangdong, 515041, China * These authors have contributed equally to this work Correspondence to: Jiang Gu, e-mail: 2523381625@qq.com Keywords: IVIG, sialylation, influenza virus, neutralizing activity, receptor Received: October 24, 2015     Accepted: January 24, 2016     Published: February 08, 2016 ABSTRACT Influenza viruses possess a great threat to human health, but there is still no effective drug to deal with the outbreak of possible new influenza subtypes. In this study, we first fractionated sialylated immunoglobulin G (IgG), mainly Fab sialylated fraction, with sambucus nigra agglutinin affinity chromatography. We then demonstrated that sialylated IgG possessed more effective neutralizing activity against 2009 A (H1N1) subtype than that of IgG mixture, and sialosides on the Fab is crucial in this neutralization reaction as when such residues were removed with neuraminidase A digestion the blocking effect was significantly reduced. It appears that sialic acid residues attached to Fab could serve as binding moieties to receptor binding site of influenza virus. These findings indicate that sialylated IgG probably is an effective anti-influenza broad-spectrum drug utilizing its receptor mimicry to competitively inhibit the attachment of influenza viruses with sialic acid receptors on target cells. This property would be particularly useful if it can be applied to prevent newly emerged influenza virus strain infections in future epidemics.