Antibodies elicited by Newcastle disease virus-vectored H7N9 avian influenza vaccine are functional in activating the complement system

H7N9 subtype avian influenza virus poses a great challenge for poultry industry.Newcastle disease virus(NDV)-vectored H7N9 avian influenza vaccines(NDV_(vec)H7N9)are effective in disease control because they are protective and allow mass administration.Of note,these vaccines elicit undetectable H7N9-specific hemagglutination-inhibition(HI)but high IgG antibodies in chickens.However,the molecular basis and protective mechanism underlying this particular antibody immunity remain unclear.Herein,immunization with an NDV_(vec)H7N9 induced low anti-H7N9 HI and virus neutralization titers but high levels of hemagglutinin(HA)-binding IgG antibodies in chickens.Three residues(S150,G151 and S152)in HA of H7N9 virus were identified as the dominant epitopes recognized by the NDV_(vec)H7N9 immune serum.Passively transferred NDV_(vec)H7N9 immune serum conferred complete protection against H7N9 virus infection in chickens.The NDV_(vec)H7N9 immune serum can mediate a potent lysis of HA-expressing and H7N9 virus-infected cells and significantly suppress H7N9 virus infectivity.These activities of the serum were significantly impaired after heat-inactivation or treatment with complement inhibitor,suggesting the engagement of the complement system.Moreover,mutations in the 150-SGS-152 sites in HA resulted in significant reductions in cell lysis and virus neutralization mediated by the NDV_(vec)H7N9 immune serum,indicating the requirement of antibody-antigen binding for complement activity.Therefore,antibodies induced by the NDV_(vec)H7N9 can activate antibody-dependent complement-mediated lysis of H7N9 virus-infected cells and complement-mediated neutralization of H7N9 virus.Our findings unveiled a novel role of the complement in protection conferred by the NDV_(vec)H7N9,highlighting a potential benefit of engaging the complement system in H7N9 vaccine design.

Bedside chest radiography of novel influenza A （H7N9） virus infections and follow-up findings after short-time treatment

Background Influenza A （H7Ng） virus infections were first observed in China in March 2013.This type virus can cause severe illness and deaths,the situation raises many urgent questions and global public health concerns.Our purpose was to investigate bedside chest radiography findings for patients with novel influenza A （H7Ng） virus infections and the followup appearances after short-time treatment.Methods Eight hospitalized patients infected with the novel influenza A （H7Ng） virus were included in our study.All of the patients underwent bedside chest radiography after admission,and all had follow-up bedside chest radiography during their first ten days,using AXIOM Aristos MX and/or AMX-Ⅳ portable X-ray units.The exposure dose was generally 90 kV and 5 mAs,and was slightly adjusted according to the weight of the patients.The initial radiography data were evaluated for radiological patterns （ground glass opacity,consolidation,and reticulation）,distribution type （focal,multifocal,and diffuse）,lung zones involved,and appearance at follow-up while the patients underwent therapy.Results All patients presented with bilateral multiple lung involvement.Two patients had bilateral diffuse lesions,three patients had unilateral diffuse lesions of the right lobe with multifocal lesions of the left lobe,and the remaining three had bilateral multifocal lung lesions.The lesions were present throughout bilateral lung zones in three patients,the whole right lung zone in three patients with additional involvement in the left middle and/or lower lung zone（s）,both lower and middle lung zones in one patient,and the right middle and lower in combination with the left lower lung zones in one patient.The most common abnormal radiographic patterns were ground glass opacity （8/8）,and consolidation （8/8）.In three cases examined by CT we also found the pattern of reticulation in combination with CT images.Four patients had bilateral and four had unilateral pleural effusion.After a short period of treatment the pneumonia in one patient had significantly improved and three cases demonstrated disease progression.In four cases the severity of the pneumonia fluctuated.Conclusions In patients with influenza A （H7N9） virus infection,the distribution of the lung lesions are extensive,and the disease usually involves both lung zones.The most common imaging findings are a mixture of ground glass opacity and consolidation.Pleural effusion is common.Most cases have a poor short-time treatment response,and seem to have either rapid progressive radiographic deterioration or fluctuating radiographic changes.Chest radiography is helpful for evaluating patients with severe clinical symptoms and for follow-up evaluation.