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.

Risk assessment on the epidemics of human infection with a novel avian influenza A (H7N9) virus in Jiangsu Province, China

A novel avian influenza A （H7N9） virus was discovered in February 2013 in China and has resulted in more than 100 comfirmed human infections including 26 fatal cases as of May 2, 2013. The situation raises many ur- gent questions and global public health concerns. In this study, epidemiologic characteristics of infected human cases in Jiangsu province were analyzed and risk assessment was undertaken based on the information available. Briefly, it is highly unlikely that a pandemic of human infection with avian influenza A （HTN9） virus will happen in Jiangsu Province in the near future. Iia the end, some measures are recommended to prevent the situation from becoming worse.

Distribution of Avian Influenza A Viruses in Poultry-Related Environment and Its Association with Human Infection in Henan, 2016 to 2017

Objective To survey avian influenza A viruses(AIVs) in the environment and explore the reasons for the surge in human H7 N9 cases.Methods A total of 1,045 samples were collected from routine surveillance on poultry-related environments and 307 samples from human H7 N9 cases-exposed environments in Henan from 2016 to2017. The nucleic acids of influenza A(Flu A), H5, H7, and H9 subtypes were detected by real-time polymerase chain reaction.Results A total of 27 H7 N9 cases were confirmed in Henan from 2016 to 2017, 24 had a history of live poultry exposure, and 15 had H7 N9 virus detected in the related live poultry markets(LPMs). About 96%(264/275) Flu A positive-environmental samples were from LPMs. H9 was the main AIV subtype(10.05%) from routine surveillance sites with only 1 H7-positive sample, whereas 21.17% samples were H7-positive in H7 N9 cases-exposed environments. Samples from H7 N9 cases-exposed LPMs(47.56%)had much higher AIVs positive rates than those from routine surveillance sites(12.34%). The H7+H9 combination of mixed infection was 78.18%(43/55) of H7-positive samples and 41.34%(43/104) of H9-positive samples.Conclusion The contamination status of AIVs in poultry-related environments is closely associated with the incidence of human infection caused by AIVs. Therefore, systematic surveillance of AIVs in LPMs in China is essential for the detection of novel reassortant viruses and their potential for interspecies transmission.

Effects of closing and reopening live poultry markets on the epidemic of human infection with avian influenza A virus

Live poultry markets（LPMs） are crucial places for human infection of influenza A（H7N9 virus）.In Yangtze River Delta,LPMs were closed after the outbreak of human infection with avian influenza A（H7N9） virus,and then reopened when no case was found.Our purpose was to quantify the effect of LPMs＇ operations in this region on the transmission of influenza A（H7N9） virus.We obtained information about dates of symptom onset and locations for all human influenza A（H7N9） cases reported from Shanghai,Jiangsu and Zhejiang provinces by May 31,2014,and acquired dates of closures and reopening of LPMs from official media.A two-phase Bayesian model was fitted by Markov Chain Monte Carlo methods to process the spatial and temporal influence of human cases.A total of 235 cases of influenza A（H7N9） were confirmed in Shanghai,Jiangsu and Zhejiang by May 31,2014.Using these data,our analysis showed that,after LPM closures,the influenza A（H7N9） outbreak disappeared within two weeks in Shanghai,one week in Jiangsu,and one week in Zhejiang,respectively.Local authorities reopened LPMs when there was no outbreak of influenza A（H7N9）,which did not lead to reemergence of human influenza A（H7N9）.LPM closures were effective in controlling the H7N9 outbreak.Reopening of LPM in summer did not increase the risk of human infection with H7N9.Our findings showed that LPMs should be closed immediately in areas where the H7N9 virus is confirmed in LPM.When there is no outbreak of H7N9 virus,LPMs can be reopened to satisfy the Chinese traditional culture of buying live poultry.In the long term,local authorities should take a cautious attitude in permanent LPM closure.

Estimation of the actual disease burden of human H7N9 infection in Jiangsu of eastern China from March 2013 to September 2017

The actual incidence of human H7N9 infection is supposed to be much higher than the documented laboratoryconfirmed cases.In this study,we estimated the number of the actual H7N9 cases in Jiangsu,China using a probabilistic multiplier model.Then,disability adjusted life years(DALYs),direct and indirect economic loss caused by this disease were calculated and analyzed.Till September 2017,the estimated total number of H7N9 cases was 2952[median,90%probability range(PR):1487-22094],which was 11.8 times(5.9-88.4)as large as the reported number.The median morbidity was estimated to be 4(90%PR:2-29)per 100000 population.The total DALYs loss was 16548 years,and the total economic loss(direct and indirect)was estimated to be RMB 1044618758(US$16.7 M).The average economic loss for per case and for per year was RMB 353868(US$56440)and RMB 232137502(US$37.0 M),respectively.The actual burden of human H7N9 infections was much heavier than what was documented.Our study provided an approach to estimate actual burden of infectious diseases using laboratory-confirmation.

Human infection with avian influenza A（H7N9） virus in Shanghai： current status and future trends

Avian influenza A（H7N9） virus is one subgroup among the larger group of H7 viruses,which normally circulate among birds.The H7N9 subtype of avian influenza viruses has not been known to infect humans until only recently.On March 31,2013,China confirmed the first three human cases of novel avian influenza A（H7N9）infection in Shanghai and Anhui,two of these patients died.1 As of February 27,2014,367 laboratory-confirmed human cases have been reported from 15 provinces/municipalities in China's Mainland,

First outbreak of human infection with avian influenza A(H7N9) virus in Guangxi, China, 2016 to 2017

To the Editor: Since avian influenza A(H7N9) was first identified in Shanghai, China, in March 2013, there have been a total of five epidemics. These have amounted to 1564 laboratory-confirmed cases up to September 2017, with a fatality rate of about 40%.[1] In the fifth wave, 4.09% of cases (31/758) were infected with the highly pathogenic avian influenza (HPAI) A(H7N9). This indicated that the pathotype of the A(H7N9) had switched from low pathogenic avian influenza (LPAI) to HPAI.

Environmental connections of novel avian-origin H7N9 influenza virus infection and virus adaptation to the human

A novel H7N9 influenza A virus has been discovered as the causative identity of the emerging acute respiratory infection cases in Shanghai,China.This virus has also been identified in cases of infection in the neighboring area Hangzhou City in Zhejiang Province.In this study,epidemiologic,clinical,and virological data from three patients in Hangzhou who were confirmed to be infected by the novel H7N9 influenza A virus were collected and analyzed.Human respiratory specimens and chicken feces from a contacted free market were tested for influenza virus by real-time reverse transcription PCR(RT-PCR) and sequencing.The clinical features of the three cases were similar featured with high fever and severe respiratory symptoms;however,only one of the patients died.A certain degree of diversity was observed among the three Hangzhou viruses sequenced from human samples compared with other reported H7N9 influenza A viruses.The sequences of the novel avian-origin H7N9 influenza viruses from Hangzhou City contained important amino acid substitutions related to human adaptation.One of the Hangzhou viruses had gained a novel amino acid substitution(Q226I) in the receptor binding region of hemagglutinin.More importantly,the virus sequenced from the chicken feces had a 627E substitution in the PB2 protein instead of the mammalian-adapted 627K substitution that was found in the PB2 proteins from the Hangzhou viruses from the three patients.Therefore,the newly-emerging H7N9 virus might be under adaptation pressure that will help it "jump" from avian to human hosts.The significance of these substitutions needs further exploration,with both laboratory experiments and extensive field surveillance.

Clinical characteristics of human infection with a novel avian-origin influenza A（H10N8） virus

Background Novel influenza A viruses of avian-origin may be the precursors of pandemic strains. This descriptive study aims to introduce a novel avian-origin influenza A （H10N8） virus which can infect humans and cause severe diseases. Methods Collecting clinical data of three cases of human infection with a novel reassortment avian influenza A （H10N8） virus in Nanchang, Jiangxi Province, China. Results Three cases of human infection with a new reassortment avian influenza A（H10N8） virus were described, of which two were fatal cases, and one was severe case. These cases presented with severe pneumonia that progressed to acute respiratory distress syndrome （ARDS） and intractable respiratory failure. Conclusion This novel reassortment avian influenza A （H10N8） virus in China resulted in fatal human infections, and should be added to concerns in clinical practice.

Veno-venous extracorporeal membrane oxygenation for patient with a history of open cholecystectomy and acute respiratory distress syndrome caused by coinfection of avian influenza A (H7N9) and Epstein-Barr virus

To the Editor:Most patients infected with avian influenza A (H7N9) rapidly develop progressive pneumonia and acute respiratory distress syndrome (ARDS), a heterogeneous disorder that is refractory to conventional mechanical ventilation. Most H7N9 patients also have underlying disease such as chronic obstructive pulmonary disease, hypertension, diabetes mellitus, and heart diseases, and are more susceptible to coinfections. For these patients with such serious complications, extracorporeal membrane oxygenation (ECMO) support can be adopted as a feasible life-saving therapy Here, we present our successful experience with ECMO utilized in a patient with ARDS and also with H 7N9 and Epstein-Barr virus (EBV) infection.

Case report for human infection with a highly pathogenic avian influenza A(H5N6) virus in Beijing, China 2019

Bird infections with highly pathogenic avian influenza A(H5N6) viruses have been identified since 2014. With very limited occasion, the virus could sporadically spilled over to infect humans. It has been recognized that all human infections were within southern region of China's Mainland until the case reported here in Beijing in Aug. 2019. This was the first human case infected with highly pathogenic avian influenza A(H5N6) virus in northern China. The infection was confirmed by real-time RT-PCR assay. The whole genome sequences were obtained from clinical sample. Genetic characteristics of the virus were identified similar to those of previous avian influenza A(H5N6) viruses, retaining the main features of the avian influenza virus.

Compiling of comprehensive data of human infections with novel influenza A(H7N9)virus

Starting from February,2013,avian-origin influenza A(H7N9)virus infection had been prevalent in Eastern China,with a total infected cases of 133 and,among them of 43 deaths as of July 4th(www.who.org),2013.It has caused serious worrisome concerns about a possible pandemic.

Vaccination of poultry successfully eliminated human infection with H7N9 virus in China

The H7 N9 viruses that emerged in China in 2013 were nonpathogenic in chickens but mutated to a highly pathogenic form in early 2017 and caused severe disease outbreaks in chickens. The H7 N9 influenza viruses have caused five waves of human infection, with almost half of the total number of human cases(766 of 1,567) being reported in the fifth wave, raising concerns that even more human infections could occur in the sixth wave. In September 2017, an H5/H7 bivalent inactivated vaccine for chickens was introduced, and the H7 N9 virus isolation rate in poultry dropped by 93.3% after vaccination. More importantly,only three H7 N9 human cases were reported between October 1, 2017 and September 30, 2018, indicating that vaccination of poultry successfully eliminated human infection with H7 N9 virus. These facts emphasize that active control of animal disease is extremely important for zoonosis control and human health protection.

Human avian influenza A (H5N1) virus infection in China

Highly pathogenic influenza A (H5N1) virus causes a widespread poultry deaths worldwide. The first human H5N1 infected case was reported in Hong Kong Special Administrative Region of China in 1997. Since then, the virus re-emerged in 2003 and continues to infect people worldwide. Currently, over 400 human infections have been reported in more than 15 countries and mortality rate is greater than 60%. H5N1 viruses still pose a potential pandemic threat in the future because of the continuing global spread and evolution. Here, we summarize the epidemiological, clinical and virological characteristics of human H5N1 infection in China monitored and identified by our national surveillance systems.

Discovery process, clinical characteristics, and treatment of patients infected with avian influenza virus （H7N9） in Shanghai

During the spring of 2013,a novel avian-origin influenza A （H7N9） virus emerged and spread in Shanghai.On May 9,2013,33 lab-confirmed cases （2 children and 31 adults） have been reported,among whom 13 died.Among the 31 adult cases of H7N9 avian influenza A virus infections in humans,80.6% （25/31） were older men （average age 65 years）.Clear history of poultry exposure was found in eight patients （8/33,24.3%） and the remaining 21 cases had been suspected poultry exposure.Clustered cases were found in two families （two cases from a father and his son,and the other two cases from a wife and her husband）.However,no evidence of human-to-human transmission had been identified.Avian influenza is one of the most dangerous contagions in poultry worldwide,and avian influenza A virus is the major pathogen responsible.Transmission from poultry to humans has now been proven.Some gene segments of the strain have mutated,and further mutations might result in human-to-human transmission.

2014 update of the Chinese guidelines for diagnosis and treatment of avian influenza A（H7N9） virus infection

The National Health and Family Planning Commission of China published an updated guidance （2014 version） on clinical management in Chinese on January 26, 2014.The guidelines come as human cases of avian influenza A（H7N9） virus infection undergo a seasonal spike.

A broadly neutralizing human monoclonal antibody against the hemagglutinin of avian influenza virus H7N9

Background:The new emerging avian influenza A H7N9 virus,causing severe human infection with a mortality rate of around 41%.This study aims to provide a novel treatment option for the prevention and control of H7N9.Methods:H7 hemagglutinin(HA)-specific B cells were isolated from peripheral blood plasma cells of the patients previously infected by H7N9 in Jiangsu Province,China.The human monoclonal antibodies(mAbs)were generated by amplification and cloning of these HA-specific B cells.First,all human mAbs were screened for binding activity by enzyme-linked immunosorbent assay.Then,those mAbs,exhibiting potent affinity to recognize H7 HAs were further evaluated by hemagglutination-inhibiting(HAI)and microneutralizationin vitro assays.Finally,the lead mAb candidate was selected and tested against the lethal challenge of the H7N9 virus using murine models.Results:The mAb 6-137 was able to recognize a panel of H7 HAs with high affinity but not HA of other subtypes,including H1N1 and H3N2.The mAb 6-137 can efficiently inhibit the HA activity in the inactivated H7N9 virus and neutralize 100 tissue culture infectious dose 50(TCID_(50))of H7N9 virus(influenza A/Nanjing/1/2013)invitro,with neutralizing activity as low as 78 ng/mL.In addition,the mAb 6-137 protected the mice against the lethal challenge of H7N9 prophylactically and therapeutically.Conclusion:The mAb 6-137 could be an effective antibody as a prophylactic or therapeutic biological treatment for the H7N9 exposure or infection.

New light shed on global epidemiology of avian influenza A H5N1 virus infection in humans,1997—2015

With the support by the National Natural Science Foundation of China,the research team led by Prof.Yu Hongjie(余宏杰)at the School of Public Health,Fudan University,Key Laboratory of Public Health Safety,Ministry of Education,and the Key Laboratory of Surveillance and Early Warning on Infectious Disease,Chinese Center for Disease Control and Prevention,has published the paper entitled“Global epi-

Novel human H7N9 influenza virus in China

Outbreaks of H7N9 avian influenza in humans in 5 provinces and 2 municipalities of China have reawakened concern that avian influenza viruses may again cross species barriers to infect the human population and thereby initiate a new influenza pandemic.Evolutionary analysis shows that human H7N9 influenza viruses originated from the H9N2,H7N3 and H11N9 avian viruses,and that it is as a novel reassortment influenza virus.This ar­ticle reviews current knowledge on 11 subtypes of influenza A virus from human which can cause human infec­tions.

A Suspected Person-to-person Transmission of Avian Influenza A （H7N9） Case in Ward

Since throat swab specimens obtained from three adult Chinese patients were confirmed as an avian-origin influenza A （H7N9） virus by local Centers for Disease Control and Prevention （CDC） in 2013,many confirmed cases have been reported in Mainland of China.