Cross-neutralizing Anti-hemagglutinin Antibodies Isolated from Patients Infected with Avian Influenza A(H5N1) Virus

Objective To recover broad-neutralizing monoclonal antibodies(Bn Abs)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 Bn Abs were assessed and modeled.Results Two Bn Abs,2-12 D5,and 3-37 G7.1,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,i.e.,V^H1-69-D2-15-JH^4(2-12D5)and V^H1-2-D3-9-JH^5(3-32 G7.1),the Bn Abs were directed toward CR6261-like epitopes in the HA stem,and HA2 I45 in the hydrophobic pocket was the critical residue for their binding.Signature motifs for binding with the HA stem,namely,IFY in VH1-69-encoded Abs and LXYFXW in D3-9-encoded Abs,were also observed in 2-12D5 and 3-32 G7.1,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 Bn Abs,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.

Development and Assessment of Two Highly Pathogenic Avian Influenza(HPAI) H5N6 Candidate Vaccine Viruses for Pandemic Preparedness

Objective In China, 24 cases of human infection with highly pathogenic avian influenza(HPAI) H5 N6 virus have been confirmed since the first confirmed case in 2014. Therefore, we developed and assessed two H5 N6 candidate vaccine viruses(CVVs).Methods In accordance with the World Health Organization(WHO) recommendations, we constructed two reassortant viruses using reverse genetics(RG) technology to match the two different epidemic H5 N6 viruses. We performed complete genome sequencing to determine the genetic stability. We assessed the growth ability of the studied viruses in MDCK cells and conducted a hemagglutination inhibition assay to analyze their antigenicity. Pathogenicity attenuation was also evaluated in vitro and in vivo.Results The results showed that no mutations occurred in hemagglutinin or neuraminidase, and both CVVs retained their original antigenicity. The replication capacity of the two CVVs reached a level similar to that of A/Puerto Rico/8/34 in MDCK cells. The two CVVs showed low pathogenicity in vitro and in vivo, which are in line with the WHO requirements for CVVs.Conclusion We obtained two genetically stable CVVs of HPAI H5N6 with high growth characteristics,which may aid in our preparedness for a potential H5N6 pandemic.

Knowledge and Use of Personal Protective Measures for Mitigating Acute Respiratory Infections in Children 6-16 Years of Age in Rural Communities of Macheng City,Hubei,China

Acute respiratory infections are the most common illnesses experienced by people of all ages worldwide.Previous epidemiologic studies have shown that viruses cause most of these acute respiratory illnesses[1].