Résumé
Objective@#To recover broad-neutralizing monoclonal antibodies (BnAbs) from avian influenza A (H5N1) virus infection cases and investigate their genetic and functional features.@*Methods@#We screened the Abs repertoires of expanded B cells circulating in the peripheral blood of H5N1 patients. The genetic basis, biological functions, and epitopes of the obtained BnAbs were assessed and modeled.@*Results@#Two BnAbs, 2-12D5, and 3-37G7.1, were respectively obtained from two human H5N1 cases on days 12 and 21 after disease onset. Both Abs demonstrated cross-neutralizing and Ab-dependent cellular cytotoxicity (ADCC) activity. Albeit derived from distinct Ab lineages, , V 1-69-D2-15-J 4 (2-12D5) and V 1-2-D3-9-J 5 (3-32G7.1), the BnAbs were directed toward CR6261-like epitopes in the HA stem, and HA I45 in the hydrophobic pocket was the critical residue for their binding. Signature motifs for binding with the HA stem, namely, IFY in V 1-69-encoded Abs and LXYFXW in D3-9-encoded Abs, were also observed in 2-12D5 and 3-32G7.1, respectively.@*Conclusions@#Cross-reactive B cells of different germline origins could be activated and re-circulated by avian influenza virus. The HA stem epitopes targeted by the BnAbs, and the two Ab-encoding genes usage implied the VH1-69 and D3-9 are the ideal candidates triggered by influenza virus for vaccine development.
Résumé
Objective To observe the inhibitory effect of the extracts of Nidus Collocaliae on avian influenza A H5N1 virus in vitro. Methods Nidus Collocaliae water extract, artificial gastric juice digestion products of Nidus Collocaliae water extract, and artifitial intestinal juice digestion products of Nidus Collocaliae water extract were prepared for the experimental study. 293T cells transfection in vitro was carried out. The effects of 3 kinds of Nidus Collocaliae extracts on H5N1 pseudovirus and VSV-G pseudovirus were determined by luciferase detection kit. Blood clotting response to erythrocyte hemagglutinin subtypes H5, H7, H9 antigens and the inhibitory effects of 3 kinds of Nidus Collocaliae extracts were observed. The effects of 3 kinds of Nidus Collocaliae extracts on neuraminidase activity were determined by neuraminidase inhibitor screen kit. Results The 3 kinds of Nidus Collocaliae extracts had inhibitory effects on H5N1 avian influenza pseudovirus, the effects being enhanced with the increase of the concentrations of Nidus Collocaliae extracts. Of the 3 extracts, artificial intestinal digestion products had the strongest inhibitory effect, while Nidus Collocaliae water extract had the weakest effect. However, Nidus Collocaliae extracts had no obvious effect on VSV-G pseudovirus. The concentration of H5, H7 antigen for positive blood clotting response was 1 ∶ 128, and that of H9 antigen was 1 ∶ 256. The 3 kinds of Nidus Collocaliae extracts at certain concentrations could inhibit blood clotting response to H5, H7, H9 antigen, but had no obvious effect on neuraminidase. Conclusion The anti-H5N1 virus effect of Nidus Collocaliae extracts has been achieved probably through resisting hemagglutinin.