Immunocapture isotope dilution mass spectrometry in response to a pandemic influenza threat

As a result of recent advances in mass spectrometry-based protein quantitation methods, these techniques are now poised to play a critical role in rapid formulation of pandemic influenza vaccines. Analytical techniques that have been developed and validated on seasonal influenza strains can be used to increase the quality and decrease the time required to deliver protective pandemic vaccines to the global population. The emergence of a potentially pandemic avian influenza A (H7N9) virus in March of 2013, prompted the US public health authorities and the vaccine industry to initiate production of a pre-pandemic vaccine for preparedness purposes. To this end, we evaluated the feasibility of using immunocapture isotope dilution mass spectrometry (IC-IDMS) to evaluate the suitability of the underlying monoclonal and polyclonal antibodies (mAbs and pAbs) for their capacity to isolate the H7 hemagglutinin (HA) in this new vaccine for quantification by IDMS. A broad range of H7 capture efficiencies was observed among mAbs tested by IC-IDMS with FR-545, 46/6, and G3 A533 exhibiting the highest cross-reactivity capabilities to H7 of A/Shanghai/2/2013. MAb FR-545 was selected for continued assessment, evaluated by IC-IDMS for mAb reactivity against H7 in the H7N9 candidate vaccine virus and compared with/to reactivity to the reference polyclonal antiserum in allantoic fluid, purified whole virus, lyophilized whole virus and final detergent-split monovalent vaccine preparations for vaccine development. IC-IDMS assessment of FR-545 alongside IC-IDMS using the reference polyclonal antiserum to A/Shanghai/2/2013 and with the regulatory SRID method showed strong correlation and mAb IC-IDMS could have played an important role in the event a potential surrogate potency test was required to be rapidly implemented.

Predictors for fatal human infections with avian H7N9 influenza, evidence from four epidemic waves in Jiangsu Province, Eastern China, 2013-2016

Background

Four epidemic waves of human infection with H7N9 have been recorded in China up to 1 June 2016, including in Jiangsu Province. However, few studies have investigated the differences in patients' characteristics among the four epidemic waves, and the analyses of factors associated with fatal infection lacked statistical power in previous studies due to limited sample size.

Methods

All laboratory‐confirmed A(H7N9) patients in Jiangsu province were analysed. Patients' characteristics were compared across four waves and between survivors and those who died. Multivariate analyses were used to identify independent predictors of death.

Results

Significant differences were found in the lengths of several time intervals (from onset of disease to laboratory confirmation, to onset of ARDS and respiratory failure, and to death) and in the development of heart failure. The proportions of overweight patients and rural patients increased significantly across the four waves. Administration of glucocorticoids and double‐dose neuraminidase inhibitors became the norm. Predictors of death included complications such as ARDS, heart failure and septic shock, administration of glucocorticoids, and disease duration.

Conclusion

Characteristics of H7N9 patients and clinical treatment options changed over time. Particular complications and the use of particular treatment, along with disease duration, could help clinicians predict the outcome of H7N9 infections.

A meta-analysis of transcriptomic characterization revealed extracellular matrix pathway involved in the H5N1 and H7N9 infections

Avian-origin H5N1 and H7N9 influenza A viruses are capable of causing lethal infection in humans, with serious lung pathology and leading to acute respiratory distress syndrome. The contribution of host response associated with the poor prognosis of H5N1 and H7N9 infections remains unclear. The aim of this study was to identify the host factors involved in the high pathogenicity of H5N1 and H7N9 by a systematical meta-analysis. The RNA-seq datasets related to H5N1, H7N9, and H1N1 infections with time series were retrieved from GEO. After merging the data from different series, ComBat was used to adjust the known variances from different batches. The transcription factors binding the genes in each cluster were predicted by PASTAA. We figured out the genes that were differentially expressed at any time point in samples infected with H5N1, H7N9, or H1N1. The analysis of biological function showed that genes related with cytokine were up-regulated in all three viruses. However, genes associated with carbon metabolism were found exclusively down-regulated in H7N9 and the extracellular matrix pathway were only enriched in H5N1 and H7N9. To summary, our study suggested that the extracellular matrix might be associated with the high fatality of H5N1 and H7N9 viruses in humans.

H7N9 avian influenza A virus in China: a short report on its circulation, drug resistant mutants and novel antiviral drugs

INTRODUCTION

The first human H7N9 avian influenza virus case was reported in Shanghai in 2013. Shortly thereafter, this virus spread to other regions in China. Molecular analysis indicated that the H7N9 virus is a reassortant virus containing internal genes from the H9N2 virus and previously described mammalian adaption markers, which could allow the virus to adapt efficiently to a mammalian host. Fortunately, there is no evidence of sustained person-to-person spread. Most of the human H7N9 cases have a history of exposure to live poultry markets (LPMs). The circulating H7N9 were low pathogenic viruses, however highly pathogenic H7N9 viruses were recently identified in human cases. Areas covered: In the present article, the circulation of H7N9 in LPMs of China, the five waves of H7N9 infection in humans, recently identified drug resistant mutants and potential antiviral drugs against H7N9 are discussed; this may provide further understanding of the evolution and pandemic potential of the H7N9 influenza viruses. Expert commentary: All the data reveal that the major source of H7N9 viruses are LPMs and the H7N9 virus is still circulating widely in China. It is concerning that the recent emergence of highly pathogenic H7N9 viruses may result in highly transmissible viruses in mammalian species.

Detection of Avian H7N9 Influenza A Viruses in the Yangtze Delta Region of China During Early H7N9 Outbreaks

Since the first H7N9 human case in Shanghai, February 19, 2013, the emerging avian-origin H7N9 influenza A virus has become an epizootic virus in China, posing a potential pandemic threat to public health. From April 2 to April 28, 2013, some 422 oral-pharyngeal and cloacal swabs were collected from birds and environmental surfaces at five live poultry markets (LPMs) and 13 backyard poultry farms (BPFs) across three cities, Wuxi, Suzhou, and Nanjing, in the Yangtze Delta region. In total 22 isolates were recovered, and six were subtyped as H7N9, nine as H9N2, four as H7N9/H9N2, and three unsubtyped influenza A viruses. Genomic sequences showed that the HA and NA genes of the H7N9 viruses were similar to those of the H7N9 human isolates, as well as other avian-origin H7N9 isolates in the region, but the PB1, PA, NP, and MP genes of the sequenced viruses were more diverse. Among the four H7N9/H9N2 mixed infections, three were from LPM, whereas the other one was from the ducks at one BPF, which were H7N9 negative in serologic analyses. A survey of the bird trading records of the LPMs and BPFs indicates that trading was a likely route for virus transmission across these regions. Our results suggested that better biosecurity and more effective vaccination should be implemented in backyard farms, in addition to biosecurity management in LPMs.

Preclinical and Clinical Demonstration of Immunogenicity by mRNA Vaccines against H10N8 and H7N9 Influenza Viruses

Recently, the World Health Organization confirmed 120 new human cases of avian H7N9 influenza in China resulting in 37 deaths, highlighting the concern for a potential pandemic and the need for an effective, safe, and high-speed vaccine production platform. Production speed and scale of mRNA-based vaccines make them ideally suited to impede potential pandemic threats. Here we show that lipid nanoparticle (LNP)-formulated, modified mRNA vaccines, encoding hemagglutinin (HA) proteins of H10N8 (A/Jiangxi-Donghu/346/2013) or H7N9 (A/Anhui/1/2013), generated rapid and robust immune responses in mice, ferrets, and nonhuman primates, as measured by hemagglutination inhibition (HAI) and microneutralization (MN) assays. A single dose of H7N9 mRNA protected mice from a lethal challenge and reduced lung viral titers in ferrets. Interim results from a first-in-human, escalating-dose, phase 1 H10N8 study show very high seroconversion rates, demonstrating robust prophylactic immunity in humans. Adverse events (AEs) were mild or moderate with only a few severe and no serious events. These data show that LNP-formulated, modified mRNA vaccines can induce protective immunogenicity with acceptable tolerability profiles.

H7N9 not only endanger human health but also hit stock marketing

OBJECTIVE

This study aims to discuss the correlation between daily reported H7N9 cases and stock price indices in China.

METHODS

Information on daily reported H7N9 cases and stock market sectors indices between February 19, 2013 and March 31, 2014 were collected. A distributed lag non-linear model was used to describe the variation trend for the stock indices.

RESULTS

The daily reported number of H7N9 cases was associated with the closing price of the Avian Influenza Sector Index (P < 0.05) and the opening price of the Shanghai Composite Index (P = 0.029). The Avian Influenza Sector Index decreased with increasing of daily reported case number when daily reported cases ≤ 4. Case number was associated with the opening/closing price of the Chinese Traditional Medicine Sector Index, the Biological Product Sector Index, and the Biomedicine Sector Index (P < 0.05).

CONCLUSION

New or reemerging infectious diseases epidemic cause economic loss which is reflected in movements in stock prices.

Significantly elevated number of human infections with H7N9 virus in Jiangsu in eastern China, October 2016 to January 2017

Since first identified in 2013, the H7N9 virus has caused several waves of human infections in China, with a current wave including a number of patients with very severe disease. Jiangsu is one of the most impacted provinces, whereby as of 31 January 2017, the number of human infections (n = 109) in the ongoing fifth H7N9 wave has exceeded the sum of those in the four preceding ones. Ten of 13 cities in Jiangsu have been affected, and clustered infections as well as one co-infection with seasonal influenza have been observed. With a median age of 58 years and 74.3% (81/109) of patients being male, the characteristics of cases are similar to those in previous waves, however patients with H7N9 seem to have an accelerated disease progression. Preliminary case fatality remains above 30%. No significant viral mutations have been found in key functional loci. Environmental H7N9 detection rate and number of days with high risk ambient temperatures were both significantly elevated during the month of December 2016 when most human infections were reported. A number of municipal governments in Jiangsu have implemented live poultry market closures to impede viral transmission to humans. A detectable decline in human infections has been observed in these municipalities and the entire province since January 2017.

Attitudes of consumers and live-poultry workers to central slaughtering in controlling H7N9: a cross-sectional study

Background

Guangdong Province in the Pearl River Delta of Southeast China is among the areas in the country with the highest rates of avian flu cases. In order to control the outbreak of human-infected H7N9 cases, Guangdong launched a new policy on the central slaughtering of live poultry in 2015. This study aims to evaluate attitudes of consumers and live-poultry workers toward the policy. The live-poultry workers consisted of two sub-groups: live-poultry traders and poultry farm workers.

Methods

Consumers and live-poultry workers from Guangdong were enrolled by stratified multi-stage random sampling. Online and field surveys were conducted to investigate participants’ attitudes on policy implementation. Questionnaires were developed to quantify participant demographics, to collect information about attitudes toward the policy, and to identify influential factors of policy acceptability. Proportional odds logistics regression was used in the univariate and multivariate analyses. A total of 1449 consumers, 181 live-poultry traders, and 114 poultry farm workers completed the study.

Results

Policy acceptability percentages among consumers, live-poultry traders, and poultry farm workers were 57.1, 37.9, and 62.6%, respectively. Logistics regression shows that consumers tended not to support the policy if they were males, if they were concerned with the food safety of chilled products, and if they preferred purchasing live poultry. Live-poultry traders tended not to support if they were subsidized by the government, if they were males, if they experienced a drop in trading volume, and if they were unclear whether avian flu was a preventable disease. Finally, poultry farm workers tended not to support if they experienced a drop in trading volume, if they operated a poultry farm on a small to medium scale, and if they experienced inconvenience in their work due to the policy.

Conclusions

The study reveals a substantial refusal or slowness to accept the policy. Failure to accept the policy results from varying reasons. Among consumers, concern about food safety and dietary preference are two major causes of disapproval. Policy acceptability among live-poultry workers diverges within the two sub-groups. While a large percentage of poultry farm workers accept the policy, the drop in trading and an insufficient subsidy hamper acceptance by live-poultry traders. We recommend that policy-makers promote health education and alleviate the policy impact on trading with a reformed subsidy policy to increase acceptability. These findings are crucial for the prevention of human-infected H7N9 cases in Guangdong.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-017-4374-9) contains supplementary material, which is available to authorized users.

pH Optimum of Hemagglutinin-Mediated Membrane Fusion Determines Sensitivity of Influenza A Viruses to the Interferon-Induced Antiviral State and IFITMs

The replication and pathogenicity of influenza A viruses (IAVs) critically depend on their ability to tolerate the antiviral interferon (IFN) response. To determine a potential role for the IAV hemagglutinin (HA) in viral sensitivity to IFN, we studied the restriction of IAV infection in IFN-β-treated human epithelial cells by using 2:6 recombinant IAVs that shared six gene segments of A/Puerto Rico/8/1934 virus (PR8) and contained HAs and neuraminidases of representative avian, human, and zoonotic H5N1 and H7N9 viruses. In A549 and Calu-3 cells, viruses displaying a higher pH optimum of HA-mediated membrane fusion, H5N1-PR8 and H7N9-PR8, were less sensitive to the IFN-induced antiviral state than their counterparts with HAs from duck and human viruses, which fused at a lower pH. The association between a high pH optimum of fusion and reduced IFN sensitivity was confirmed by using HA point mutants of A/Hong Kong/1/1968-PR8 that differed solely by their fusion properties. Furthermore, similar effects of the viral fusion pH on IFN sensitivity were observed in experiments with (i) primary human type II alveolar epithelial cells and differentiated cultures of human airway epithelial cells, (ii) nonrecombinant zoonotic and pandemic IAVs, and (iii) preparations of IFN-α and IFN-λ1. A higher pH of membrane fusion and reduced sensitivity to IFN correlated with lower restriction of the viruses in MDCK cells stably expressing the IFN-inducible transmembrane proteins IFITM2 and IFITM3, which are known to inhibit viral fusion. Our results reveal that the pH optimum of HA-driven membrane fusion of IAVs is a determinant of their sensitivity to IFN and IFITM proteins.IMPORTANCE The IFN system constitutes an important innate defense against viral infection. Substantial information is available on how IAVs avoid detection by sensors of the IFN system and disable IFN signaling pathways. Much less is known about the ability of IAVs to tolerate the antiviral activity of IFN-induced cellular proteins. The IFN-induced proteins of the IFITM family block IAV entry into target cells and can restrict viral spread and pathogenicity. Here we show for the first time that the sensitivity of IAVs to the IFN-induced antiviral state and IFITM2 and IFITM3 proteins depends on the pH value at which the viral HA undergoes a conformational transition and mediates membrane fusion. Our data imply that the high pH optimum of membrane fusion typical of zoonotic IAVs of gallinaceous poultry, such as H5N1 and H7N9, may contribute to their enhanced virulence in humans.

Evaluation of the Immune Responses to and Cross-Protective Efficacy of Eurasian H7 Avian Influenza Viruses

Due to increasing concerns about human infection by various H7 influenza viruses, including recent H7N9 viruses, we evaluated the genetic relationships and cross-protective efficacies of three different Eurasian H7 avian influenza viruses. Phylogenic and molecular analyses revealed that recent Eurasian H7 viruses can be separated into two different lineages, with relatively high amino acid identities within groups (94.8 to 98.8%) and low amino acid identities between groups (90.3 to 92.6%). In vivo immunization with representatives of each group revealed that while group-specific cross-reactivity was induced, cross-reactive hemagglutination inhibition (HI) titers were approximately 4-fold lower against heterologous group viruses than against homologous group viruses. Moreover, the group I (RgW109/06) vaccine protected 100% of immunized mice from various group I viruses, while only 20 to 40% of immunized mice survived lethal challenge with heterologous group II viruses and exhibited high viral titers in the lung. Moreover, while the group II (RgW478/14) vaccine also protected mice from lethal challenge with group II viruses, it failed to elicit cross-protection against group I viruses. However, it is noteworthy that vaccination with RgAnhui1/13, a virus of a sublineage of group I, cross-protected immunized mice against lethal challenge with both group I and II viruses and significantly attenuated lung viral titers. Interestingly, immune sera from RgAnhui1/13-vaccinated mice showed a broad neutralizing spectrum rather than the group-specific pattern observed with the other viruses. These results suggest that the recent human-infective H7N9 strain may be a candidate broad cross-protective vaccine for Eurasian H7 viruses.IMPORTANCE Genetic and phylogenic analyses have demonstrated that the Eurasian H7 viruses can be separated into at least two different lineages, both of which contain human-infective fatal H7 viruses, including the recent novel H7N9 viruses isolated in China since 2013. Due to the increasing concerns regarding the global public health risk posed by H7 viruses, we evaluated the genetic relationships between Eurasian H7 avian influenza viruses and the cross-protective efficacies of three different H7 viruses: W109/06 (group I), W478/14 (group II), and Anhui1/13 (a sublineage of group I). While each vaccine induced group-specific antibody responses and cross-protective efficacy, only Anhui1/13 was able to cross-protect immunized hosts against lethal challenge across groups. In fact, the Anhui1/13 virus induced not only cross-protection but also broad serum neutralizing antibody responses against both groups of viruses. This suggests that Anhui1/13-like H7N9 viruses may be viable vaccine candidates for broad protection against Eurasian H7 viruses.

Induction of Broadly Cross-Reactive Stalk-Specific Antibody Responses to Influenza Group 1 and Group 2 Hemagglutinins by Natural H7N9 Virus Infection in Humans

Background

The outbreak of novel avian H7N9 influenza virus infections in China in 2013 has demonstrated the continuing threat posed by zoonotic pathogens. Deciphering the immune response during natural infection will guide future vaccine development.

Methods

We assessed the induction of heterosubtypic cross-reactive antibodies induced by H7N9 infection against a large panel of recombinant hemagglutinins and neuraminidases by quantitative enzyme-linked immunosorbent assay, and novel chimeric hemagglutinin constructs were used to dissect the anti-stalk or -head humoral immune response.

Results

H7N9 infection induced strong antibody responses against divergent H7 hemagglutinins. Interestingly, we also found induction of antibodies against heterosubtypic hemagglutinins from both group 1 and group 2 and a boost in heterosubtypic neutralizing activity in the absence of hemagglutination inhibitory activity. Kinetic monitoring revealed that heterosubtypic binding/neutralizing antibody responses typically appeared and peaked earlier than intrasubtypic responses, likely mediated by memory recall responses.

Conclusions

Our results indicate that cross-group binding and neutralizing antibody responses primarily targeting the stalk region can be elicited after natural influenza virus infection. These data support our understanding of the breadth of the postinfection immune response that could inform the design of future, broadly protective influenza virus vaccines.

Mutation of the Second Sialic Acid-Binding Site, Resulting in Reduced Neuraminidase Activity, Preceded the Emergence of H7N9 Influenza A Virus

The emergence of the novel influenza A virus (IAV) H7N9 since 2013 has caused concerns about the ability of the virus to spread between humans. Analysis of the receptor-binding properties of the H7 protein of a human isolate revealed modestly increased binding to α2,6 sialosides and reduced, but still dominant, binding to α2,3-linked sialic acids (SIAs) compared to a closely related avian H7N9 virus from 2008. Here, we show that the corresponding N9 neuraminidases (NAs) display equal enzymatic activities on a soluble monovalent substrate and similar substrate specificities on a glycan array. In contrast, solid-phase activity and binding assays demonstrated reduced specific activity and decreased binding of the novel N9 protein. Mutational analysis showed that these differences resulted from substitution T401A in the 2nd SIA-binding site, indicating that substrate binding via this site enhances NA catalytic activity. Substitution T401A in the novel N9 protein appears to functionally mimic the substitutions that are found in the 2nd SIA-binding site of NA proteins of avian-derived IAVs that became human pandemic viruses. Our phylogenetic analyses show that substitution T401A occurred prior to substitutions in hemagglutinin (HA), causing the altered receptor-binding properties mentioned above. Hence, in contrast to the widespread assumption that such changes in NA are obtained only after acquisition of functional changes in HA, our data indicate that mutations in the 2nd SIA-binding site may have enabled and even driven the acquisition of altered HA receptor-binding properties and may have contributed to the spread of the novel H7N9 viruses.IMPORTANCE Novel H7N9 IAVs continue to cause human infections and pose an ongoing public health threat. Here, we show that their N9 proteins display reduced binding to and lower enzymatic activity against multivalent substrates, resulting from mutation of the 2nd sialic acid-binding site. This mutation preceded and may have driven the selection of substitutions in H7 that modify H7 receptor-binding properties. Of note, all animal IAVs that managed to cross the host species barrier and became human viruses carry mutated 2nd sialic acid-binding sites. Screening of animal IAVs to monitor their potential to cross the host species barrier should therefore focus not only on the HA protein, but also on the functional properties of NA.

Detection of a novel highly pathogenic H7 influenza virus by duplex real-time reverse transcription polymerase chain reaction

On February 19, 2017, China announced that the mutant H7N9 virus appeared in human cases, which showed molecular characteristic of highly pathogenic virus for poultry. In this study, a duplex real-time reverse transcription polymerase chain reaction (rRT-PCR) assay was developed for distinguish between highly pathogenic H7 virus and low pathogenic H7 virus. The sensitivity, specificity, stability and conformance tests were conducted for this method. The data showed that the new method is sensitive. The minimum detection limit for the RNA of highly pathogenic H7 virus is 0.0052fg and the minimum detection limit for the RNA of low pathogenic H7 virus is 0.36fg. The method gave specific results in detecting novel highly pathogenic H7 virus and will play an important role in the rapid identification of novel highly pathogenic H7 virus.

Immunogenicity and safety of an AS03-adjuvanted H7N1 vaccine in adults 65years of age and older: A phase II, observer-blind, randomized, controlled trial

BACKGROUND

H7 influenza strains can cause severe and often fatal human infections, especially in the elderly. This phase II, observer-blind, randomized trial (www.ClinicalTrials.gov: NCT01949090) assessed the immunogenicity and safety of a novel AS03-adjuvanted H7N1 vaccine that may serve as a model H7-subtype vaccine.

METHODS

360 adults ≥65years of age in stable health received either 1 of 4 adjuvanted A/mallard/Netherlands/12/2000 split virion vaccine formulations (3.75μg or 7.5μg hemagglutinin adjuvanted with either AS03_A or AS03_B) or saline placebo, given as a 2-dose series. Immunogenicity was assessed using hemagglutination-inhibition (HI) and microneutralization (MN) assays for the per-protocol cohort, comprising 332 participants at 21days post-each dose, 332 at month 6, and 309 at month 12 (HI assay only). Safety was assessed up to month 12 for all participants who had received ≥1 dose (360 participants).

RESULTS

For H7N1 HI antibody assessment at day 42 (21days post-dose 2), seroprotection rates (SPR) in the vaccinated groups were 69.6%-88.7%, seroconversion rates (SCR) 69.6%-88.5%, mean geometric increase (MGI) 11.0-18.9, and HI geometric mean titers (GMTs) 55.0-104.8. These parameters declined by month 6 and month 12. Microneutralization GMTs were 46.2-74.7 in the vaccinated groups at day 42, while vaccine response rate (VRR; proportion with ≥4-fold increase in MN titer) was 46.4%-81.5%. For the cross-reactive H7N9 strain, at day 42, HI GMT were 64.3-201.3, SPR 78.6%-96.3%, SCR 79.3%-96.3%, and MGI 14.1-37.7; MN GMTs were 44.0-85.6, and VRR 46.4-85.2%. The most frequent solicited symptom was injection site pain (41.7%-65.0% of vaccine recipients). In total, 40 participants reported 67 serious adverse events; none were considered causally related to vaccination.

CONCLUSIONS

In adults aged ≥65years, the adjuvanted H7N1 vaccine was immunogenic after 2 doses, and had an acceptable safety profile. www.ClinicalTrials.gov: NCT01949090.

Dynamic variations of the peripheral blood immune cell subpopulation in patients with critical H7N9 swine-origin influenza A virus infection: A retrospective small-scale study

H7N9 influenza is a recently emerging infection with a high mortality rate. The aim of the present study was to investigate dynamic fluctuations of peripheral blood immune cell subgroups in patients with critical H7N9 infection. Flow cytometry was used to assess the cells in whole blood samples from 9 cases. With regard to the innate immune system, in the majority of patients, the natural killer (NK) cell counts were similar to those of monocytes, which demonstrated a gradual increase in the progression period and an early increase followed by a reduction during recovery. B cells exhibited a reduction during progression and were further decreased during recovery. The CD4⁺T cells of all patients decreased during progression, and further decreased during recovery. By contrast, CD8⁺T cells increased in the majority of patients in the progression stage, and underwent an initial reduction followed by a gradual increase during recovery. However, CD8⁺ programmed death (PD)-1⁺T cell and T helper (Th) 1 cell frequencies demonstrated a moderate increase in all patients during the progression stage, and regulatory T cell (Treg) frequencies tended to be reduced during progression and increased during recovery. Notably, this preliminary data also showed that the frequencies of B cells, Th2 cells and Th17 cells in the progression period were higher than those in the recovery period. The frequencies of monocytes, CD4⁺T cell, CD8⁺T cell, CD4⁺PD-1⁺T cells and CD8⁺PD-1⁺T cells in the progression period were lower than those during recovery. In conclusion, different levels of peripheral blood immune cell subgroups during the pathogenesis of H7N9 infection may be associated with elimination of the virus and immune damage.

Immunogenicity and safety of an AS03-adjuvanted H7N1 vaccine in healthy adults: A phase I/II, observer-blind, randomized, controlled trial

BACKGROUND

H7 influenza strains have pandemic potential. AS03-adjuvanted H7N1 A/mallard/Netherlands/12/2000 split-virion vaccine formulations were evaluated as model H7-subtype vaccine and tested after H7N9 emerged in China, and caused severe human disease with high mortality.

METHODS

In this phase I/II, observer-blind, randomized trial in US and Canada, 420 healthy adults (21-64years) were randomized to receive 1 of 4 H7N1 vaccine formulations (3.75 or 7.5μg hemagglutinin adjuvanted with either AS03_A or AS03_B), 15μg unadjuvanted H7N1 hemagglutinin, or saline placebo, given as 2-dose series. Immunogenicity was assessed using hemagglutination-inhibition (HI) and microneutralization (MN) assays, at day 42 (21days post-dose 2), month 6, and month 12 (HI only) for the per-protocol cohorts (398, 379 and 368 participants, respectively). Safety is reported up to month 12.

RESULTS

Beneficial AS03 adjuvant effect was demonstrated. Committee for Medical Products for Human Use, and Center for Biologics Evaluation and Research (CBER) criteria were met for all adjuvanted formulations at day 42 (H7N1 HI assay); seroprotection (SPR) and seroconversion rates (SCR) were 88.5-94.8%, mean geometric increase (MGI) 19.2-34.9, and geometric mean titers (GMT) 98.3-180.7. Unadjuvanted H7N1 vaccine did not meet CBER criteria. In adjuvanted groups, antibody titers decreased over time; month 12 SPRs and GMTs were low (2.0-18.8% and 8.1-12.2). MN antibodies showed similar kinetics, with titers persisting at higher range than HI at month 6. All adjuvanted groups showed cross-reactivity against H7N9, with HI responses similar to H7N1. The most frequent solicited symptom in adjuvanted groups was injection site pain (71.2-86.7%); grade 3 solicited symptoms were infrequent. Nine participants reported 17 serious adverse events; none were considered causally related to vaccination.

CONCLUSIONS

Adjuvanted H7N1 vaccine formulations had an acceptable safety profile and induced an antibody response after 2 doses with cross-reactivity to H7N9. ClinicalTrials.gov: NCT01934127.

Nosocomial Co-Transmission of Avian Influenza A(H7N9) and A(H1N1)pdm09 Viruses between 2 Patients with Hematologic Disorders

Transmission of these viruses was limited to 2 immunocompromised patients in the same ward.

A nosocomial cluster induced by co-infections with avian influenza A(H7N9) and A(H1N1)pdm09 (pH1N1) viruses occurred in 2 patients at a hospital in Zhejiang Province, China, in January 2014. The index case-patient was a 57-year-old man with chronic lymphocytic leukemia who had been occupationally exposed to poultry. He had co-infection with H7N9 and pH1N1 viruses. A 71-year-old man with polycythemia vera who was in the same ward as the index case-patient for 6 days acquired infection with H7N9 and pH1N1 viruses. The incubation period for the second case-patient was estimated to be <4 days. Both case-patients died of multiple organ failure. Virus genetic sequences from the 2 case-patients were identical. Of 103 close contacts, none had acute respiratory symptoms; all were negative for H7N9 virus. Serum samples from both case-patients demonstrated strong proinflammatory cytokine secretion but incompetent protective immune responses. These findings strongly suggest limited nosocomial co-transmission of H7N9 and pH1N1 viruses from 1 immunocompromised patient to another.

Prevalence and related factors of post-traumatic stress disorder among medical staff members exposed to H7N9 patients

Objective

This study aimed to evaluate the prevalence and related factors of post-traumatic stress disorder (PTSD) symptoms among doctors and nurses who were exposed to H7N9 patients during the H7N9 influenza epidemic. To provide scientific basis for promoting the physical and psychological health of these staff members.

Method

The 102 medical staff workers who were exposed to H7N9 patients were recruited through convenient sampling between January 2015 and May 2016. We used a self-reported questionnaire, the PTSD Checklist-Civilian Version (PCL-C), to evaluate the PTSD symptoms among doctors and nurses from an intensive care unit (n = 61), a respiratory department (n = 20), and an emergency department (n = 21). We then analyzed the related factors.

Results

Around 20.59% of the tested doctors and nurses showed PTSD symptoms. The sample had a mean PCL-C score of 30.00 ± 9.95. The differences in the scores of doctors and nurses with different genders, ages, professional titles, contact frequencies, trainings, and experiences were statistically significant (P < 0.05, P < 0.01). Moreover, t-tests and one-way analysis of variance showed that nurses received higher scores than doctors, female participants received higher scores than male participants, and the participants with low professional title and high contact frequency, aged between 20 years and 30 years, with less than five years of work experience, having not received related training and with no related experience obtained higher PCL-C scores than the others (P < 0.05, P < 0.01).

Conclusion

The PTSD level of doctors and nurses after their exposure to H7N9 patients was high, which warrant further research. Health and medical institutions should pay attention to the physical and psychological health of these staff members.

Comparison of the first three waves of avian influenza A(H7N9) virus circulation in the mainland of the People's Republic of China

BACKGROUND

H7N9 human cases were first detected in mainland China in March 2013. Circulation of this virus has continued each year shifting to typical winter months. We compared the clinical and epidemiologic characteristics for the first three waves of virus circulation.

METHODS

The first wave was defined as reported cases with onset dates between March 31-September 30, 2013, the second wave was defined as October 1, 2013-September 30, 2014 and the third wave was defined as October 1, 2014-September 30, 2015. We used simple descriptive statistics to compare characteristics of the three distinct waves of virus circulation.

RESULTS

In mainland China, 134 cases, 306 cases and 219 cases were detected and reported in first three waves, respectively. The median age of cases was statistically significantly older in the first wave (61 years vs. 56 years, 56 years, p < 0.001) compared to the following two waves. Most reported cases were among men in all three waves. There was no statistically significant difference between case fatality proportions (33, 42 and 45%, respectively, p = 0.08). There were no significant statistical differences for time from illness onset to first seeking healthcare, hospitalization, lab confirmation, initiation antiviral treatment and death between the three waves. A similar percentage of cases in all waves reported exposure to poultry or live poultry markets (87%, 88%, 90%, respectively). There was no statistically significant difference in the occurrence of severe disease between the each of the first three waves of virus circulation. Twenty-one clusters were reported during these three waves (4, 11 and 6 clusters, respectively), of which, 14 were considered to be possible human-to-human transmission.

CONCLUSION

Though our case investigation for the first three waves found few differences between the epidemiologic and clinical characteristics, there is continued international concern about the pandemic potential of this virus. Since the virus continues to circulate, causes more severe disease, has the ability to mutate and become transmissible from human-to-human, and there is limited natural protection from infection in communities, it is critical that surveillance systems in China and elsewhere are alert to the influenza H7N9 virus.

Cardiac complications associated with the influenza viruses A subtype H7N9 or pandemic H1N1 in critically ill patients under intensive care

BACKGROUND AND OBJECTIVE

The clinical presentations and disease courses of patients hospitalized with either influenza A virus subtype H7N9 (H7N9) or 2009 pandemic H1N1 influenza virus were compared in a recent report, but associated cardiac complications remain unclear. The present retrospective study investigated whether cardiac complications in critically ill patients with H7N9 infections differed from those infected with the pandemic H1N1 influenza virus strain.

METHODS

Suspect cases were confirmed by reverse transcription polymerase chain reaction assays with specific confirmation of the pandemic H1N1 strain at the Centers for Disease Control and Prevention. Comparisons were conducted at the individual-level data of critically ill patients hospitalized with H7N9 (n=24) or pandemic H1N1 influenza virus (n=22) infections in Suzhou, China. Changes in cardiac biochemical markers, echocardiography, and electrocardiography during hospitalization in the intensive care unit were considered signs of cardiac complications.

RESULTS

The following findings were more common among the H7N9 group relative to the pandemic H1N1 influenza virus group: greater tricuspid regurgitation pressure gradient, sinus tachycardia (heartbeat≥130bpm), ST segment depression, right ventricular dysfunction, and elevated cardiac biochemical markers. Pericardial effusion was more often found among pandemic H1N1 influenza virus patients than in the H7N9 group. In both groups, most of the cardiac complications were detected from day 6 to 14 after the onset of influenza symptoms. Those who developed cardiac complications were especially vulnerable during the first four days after initiation of mechanical ventilation. Cardiac complications were reversible in the vast majority of discharged H7N9 patients.

CONCLUSIONS

Critically ill hospitalized H7N9 patients experienced a higher rate of cardiac complications than did patients with 2009 pandemic H1N1 influenza virus infections, with the exception of pericardial effusion. This study may help in the prevention, identification, and treatment of influenza-induced cardiac complications in both pandemic H1N1 influenza virus and H7N9 infections.

Influenza H7N9 LAH-HBc virus-like particle vaccine with adjuvant protects mice against homologous and heterologous influenza viruses

The long alpha-helix (LAH) region located in influenza virus hemagglutinin (HA) shows conservation among different influenza A strains, which could be used as a candidate target of influenza vaccines. Moreover, the hepatitis B virus core protein (HBc) is a carrier for heterologous epitopes in eliciting effective immune responses. We inserted the LAH region of H7N9 influenza virus into the HBc and prepared the LAH-HBc protein, which were capable of self-assembly into virus-like particles (VLP), by using E. coli expression system. Intranasal immunization of the LAH-HBc VLP in combination with chitosan adjuvant or CTB^∗ adjuvant in mice could induce both humoral and cellular immune responses effectively and provide complete protection against lethal challenge of homologous H7N9 virus or heterologous H3N2 virus, as well as partial protection against lethal challenge of heterologous H1N1 virus. These results provide a proof of concept for LAH-HBc VLP vaccine that would be fast and easy to be produced and might be an ideal candidate as a rapid-response tool against a future influenza pandemic.

An influenza A virus (H7N9) anti-neuraminidase monoclonal antibody with prophylactic and therapeutic activity in vivo

Zoonotic A(H7N9) avian influenza viruses emerged in China in 2013 and continue to be a threat to human public health, having infected over 800 individuals with a mortality rate approaching 40%. Treatment options for people infected with A(H7N9) include the use of neuraminidase (NA) inhibitors. However, like other influenza viruses, A(H7N9) can become resistant to these drugs. The use of monoclonal antibodies is a rapidly developing strategy for controlling influenza virus infection. Here we generated a murine monoclonal antibody (3c10-3) directed against the NA of A(H7N9) and show that prophylactic systemic administration of 3c10-3 fully protected mice from lethal challenge with wild-type A/Anhui/1/2013 (H7N9). Further, post-infection treatment with a single systemic dose of 3c10-3 at either 24, 48 or 72 h post A(H7N9) challenge resulted in both dose- and time-dependent protection of up to 100% of mice, demonstrating therapeutic potential for 3c10-3. Epitope mapping revealed that 3c10-3 binds near the enzyme active site of NA, and functional characterization showed that 3c10-3 inhibits the enzyme activity of NA and restricts the cell-to-cell spread of the virus in cultured cells. Affinity analysis also revealed that 3c10-3 binds equally well to recombinant NA of wild-type A/Anhui/1/2013 and to a variant NA carrying a R289K mutation known to infer NAI resistance. These results suggest that 3c10-3 has the potential to be used as a therapeutic to treat A(H7N9) infections either as an alternative to, or in combination with, current NA antiviral inhibitors.

Immunogenicity and Safety of an AS03-Adjuvanted H7N9 Pandemic Influenza Vaccine in a Randomized Trial in Healthy Adults

Background

Almost 700 cases of human infection with avian influenza A/H7N9 have been reported since 2013. Pandemic preparedness strategies include H7N9 vaccine development.

Methods

We evaluated an inactivated H7N9 vaccine in an observer-blind study in healthy adults aged 18–64 years. Participants (420) were randomized to receive 1 of 4 AS03-adjuvanted vaccines (low or medium dose of hemagglutinin with AS03_A or AS03_B), one nonadjuvanted vaccine, or placebo. The coprimary immunogenicity objective determined whether adjuvanted vaccines elicited an immune response against the vaccine-homologous virus, 21 days after the second vaccine dose per US and European licensure criteria in the per-protocol cohort (n = 389).

Results

All adjuvanted vaccines met regulatory acceptance criteria. In groups receiving adjuvanted formulations, seroconversion rates were ≥85.7%, seroprotection rates ≥91.1%, and geometric mean titers ≥92.9% versus 23.2%, 28.6%, and 17.2 for the nonadjuvanted vaccine. The AS03 adjuvant enhanced immune response at antigen-sparing doses. Injection site pain occurred more frequently with adjuvanted vaccines (in ≤98.3% of vaccinees) than with the nonadjuvanted vaccine (40.7%) or placebo (20.0%). None of the 20 serious adverse events reported were related to vaccination.

Conclusions

Two doses of AS03-adjuvanted H7N9 vaccine were well tolerated and induced a robust antibody response at antigen-sparing doses in healthy adults.

Clinical Trials Registration

NCT01999842.

Economic burden and its associated factors of hospitalized patients infected with A (H7N9) virus: a retrospective study in Eastern China, 2013-2014

BACKGROUND

H7N9 continues to cause human infections and remains a pandemic concern. Understanding the economic impacts of this novel disease is important for making decisions on health resource allocation, including infectious disease prevention and control investment. However, there are limited data on such impacts.

METHODS

Hospitalized laboratory-confirmed H7N9 patients or their families in Jiangsu Province of China were interviewed. Patients' direct medical costs of hospitalization were derived from their hospital bills. A generalized linear model was employed to estimate the mean direct medical costs of patients with different characteristics.

RESULTS

The mean direct cost of hospitalization for H7N9 was estimated to be ¥ 71 060 (95 % CI, 48 180-104 820), i.e., US$ 10 996 (95 % CI, 7 455-16 220), and was ¥12 060 (US$ 1 861), ¥136 120 (US$ 21 001) and ¥218 610 (US$ 33 728) for those who had mild or severe symptoms or who died, respectively. The principal components of the total fees differed among patients with different disease severity, although medication fees were always the largest contributors. Disease severity, proportion of reimbursement and family member monthly average income were identified as the key factors that contributed to a patient's direct medical cost of hospitalization.

CONCLUSIONS

The direct medical costs of hospitalized patients with H7N9 are significant, and far surpass the annual per capita income of Jiangsu Province, China. The influencing factors identified should be taken into account when developing related health insurance policies and making health resource allocation.

TRIAL REGISTRATION

Not applicable. This is a survey study with no health care intervention implemented on human participants.

Quantified degree of poultry exposure differs for human cases of avian influenza H5N1 and H7N9

Preliminary evidence suggests that direct poultry contact may play a lesser role in transmission of avian influenza A(H7N9) than A(H5N1) to humans. To better understand differences in risk factors, we quantified the degree of poultry contact reported by H5N1 and H7N9 World Health Organization-confirmed cases. We used publicly available data to classify cases by their degree of poultry contact, including direct and indirect. To account for potential data limitations, we used two methods: (1) case population method in which all cases were classified using a range of sources; and (2) case subset method in which only cases with detailed contact information from published research literature were classified. In the case population, detailed exposure information was unavailable for a large proportion of cases (H5N1, 54%; H7N9, 86%). In the case subset, direct contact proportions were higher in H5N1 cases (70·3%) than H7N9 cases (40·0%) (χ 2 = 18·5, P < 0·001), and indirect contact proportions were higher in H7N9 cases (44·6%) than H5N1 cases (19·4%) (χ 2 = 15·5, P < 0·001). Together with emerging evidence, our descriptive analysis suggests direct poultry contact is a clearer risk factor for H5N1 than for H7N9, and that other risk factors should also be considered for H7N9.

Human mucosal-associated invariant T cells contribute to antiviral influenza immunity via IL-18-dependent activation. Proc Natl Acad Sci U S A. 2016;113:10133-10138. [PMID: 27543331 DOI: 10.1073/pnas.1610750113]

Mucosal-associated invariant T (MAIT) cells are innate-like T lymphocytes known to elicit potent immunity to a broad range of bacteria, mainly via the rapid production of inflammatory cytokines. Whether MAIT cells contribute to antiviral immunity is less clear. Here we asked whether MAIT cells produce cytokines/chemokines during severe human influenza virus infection. Our analysis in patients hospitalized with avian H7N9 influenza pneumonia showed that individuals who recovered had higher numbers of CD161(+)Vα7.2(+) MAIT cells in peripheral blood compared with those who succumbed, suggesting a possible protective role for this lymphocyte population. To understand the mechanism underlying MAIT cell activation during influenza, we cocultured influenza A virus (IAV)-infected human lung epithelial cells (A549) and human peripheral blood mononuclear cells in vitro, then assayed them by intracellular cytokine staining. Comparison of influenza-induced MAIT cell activation with the profile for natural killer cells (CD56(+)CD3(-)) showed robust up-regulation of IFNγ for both cell populations and granzyme B in MAIT cells, although the individual responses varied among healthy donors. However, in contrast to the requirement for cell-associated factors to promote NK cell activation, the induction of MAIT cell cytokine production was dependent on IL-18 (but not IL-12) production by IAV-exposed CD14(+) monocytes. Overall, this evidence for IAV activation via an indirect, IL-18-dependent mechanism indicates that MAIT cells are protective in influenza, and also possibly in any human disease process in which inflammation and IL-18 production occur.

Expression of inflammation-related genes in the lung of BALB/c mice response to H7N9 influenza A virus with different pathogenicity

H7N9 influenza A virus (IAV)-infected human cases are increasing and reported over 200 mortalities since its first emergence in 2013. Host inflammatory response contributes to the clearance of influenza virus; meanwhile, the induced "cytokine storm" also leads to pathological lesions. However, what inflammation-related response of the host for H7N9 influenza A virus infection to survival from injures of exuberant cytokine release is still obscure. In this research, expression pattern and histological distribution of inflammation-related genes, RIP3, NLRP3, IL-1β, TNF-α, Slit2 and Robo4 in the lung of BALB/c mice infected with two H7N9 IAV strains with only a PB2 residue 627 difference were investigated, as well as the histopathological injury of the lung. Results showed that significantly higher expression level of NLRP3, RIP3, IL-1β and TNF-α in H7N9-infected groups compared with the control would play a key role in driving lung pathological lesion. While the expression level of Slit2 and Robo4 in H7N9 rVK627E group had significantly increased trend than VK627 which might be the main factor to inhibit the interstitial pneumonia and infiltration. Also, H7N9 induced the histopathological changes in the lung of infected mice, and RIP3, NLRP3, IL-1β, TNF-α, Slit2 and Robo4 showed cell-specific distribution in the lung. The results will provide basic data for further research on the mechanism of inflammatory response and understanding of the role of site 627 in PB2 in H7N9 IAVs infection. In addition, enhancing the resilience of the host vascular system to the inflammatory response by regulation of Slit2-Robo4 signaling pathway might provide a novel strategy for H7N9 IAVs infection.

Pathogenesis and Phylogenetic Analyses of Two Avian Influenza H7N1 Viruses Isolated from Wild Birds

The emergence of human infections with a novel H7N9 influenza strain has raised global concerns about a potential human pandemic. To further understand the character of other influenza viruses of the H7 subtype, we selected two H7N1 avian influenza viruses (AIVs) isolated from wild birds during routine surveillance in China: A/Baer's Pochard/Hunan/414/2010 (BP/HuN/414/10) (H7N1) and A/Common Pochard/Xianghai/420/2010 (CP/XH/420/10) (H7N1). To better understand the molecular characteristics of these two isolated H7N1 viruses, we sequenced and phylogenetically analyzed their entire genomes. The results showed that the two H7N1 strains belonged to a Eurasian branch, originating from a common ancestor. Phylogenetic analysis of their hemagglutinin (HA) genes showed that BP/HuN/414/10 and CP/XH/420/10 have a more distant genetic relationship with A/Shanghai/13/2013 (H7N9), with similarities of 91.6 and 91.4%, respectively. To assess the replication and pathogenicity of these viruses in different hosts, they were inoculated in chickens, ducks and mice. Although, both CP/XH/420/10 and BP/HuN/414/10 can infect chickens, ducks and mice, they exhibited different replication capacities in these animals. The results of this study demonstrated that two low pathogenic avian influenza (LPAI) H7N1 viruses of the Eurasian branch could infect mammals and may even have the potential to infect humans. Therefore, it is important to monitor H7 viruses in both domestic and wild birds.

Ecological Niche Modeling of Risk Factors for H7N9 Human Infection in China

China was attacked by a serious influenza A (H7N9) virus in 2013. The first human infection case was confirmed in Shanghai City and soon spread across most of eastern China. Using the methods of Geographic Information Systems (GIS) and ecological niche modeling (ENM), this research quantitatively analyzed the relationships between the H7N9 occurrence and the main environmental factors, including meteorological variables, human population density, bird migratory routes, wetland distribution, and live poultry farms, markets, and processing factories. Based on these relationships the probability of the presence of H7N9 was predicted. Results indicated that the distribution of live poultry processing factories, farms, and human population density were the top three most important determinants of the H7N9 human infection. The relative contributions to the model of live poultry processing factories, farms and human population density were 39.9%, 17.7% and 17.7%, respectively, while the maximum temperature of the warmest month and mean relative humidity had nearly no contribution to the model. The paper has developed an ecological niche model (ENM) that predicts the spatial distribution of H7N9 cases in China using environmental variables. The area under the curve (AUC) values of the model were greater than 0.9 (0.992 for the training samples and 0.961 for the test data). The findings indicated that most of the high risk areas were distributed in the Yangtze River Delta. These findings have important significance for the Chinese government to enhance the environmental surveillance at multiple human poultry interfaces in the high risk area.

Experimental Challenge of a Peridomestic Avian Species, European Starlings ( Sturnus vulgaris ), with Novel Influenza A H7N9 Virus from China

In 2013 a novel avian influenza H7N9 virus was isolated from several critically ill patients in China, and infection with this virus has since caused more than 200 human deaths. Live poultry markets are the likely locations of virus exposure to humans. Peridomestic avian species also may play important roles in the transmission and maintenance of H7N9 at live poultry markets. We experimentally challenged wild European Starlings ( Sturnus vulgaris ) with the novel H7N9 virus and measured virus excretion, clinical signs, and infectious dose. We found that European Starlings can be infected with this virus when inoculated with relatively high doses, and we predict that infected birds excrete sufficient amounts of virus to transmit to other birds, including domestic chickens. Infected European Starlings showed no clinical signs or mortality after infection with H7N9. This abundant peridomestic bird may be a source of the novel H7N9 virus in live poultry markets and may have roles in virus transmission to poultry and humans.

Limited transmission of emergent H7N9 influenza A virus in a simulated live animal market: Do chickens pose the principal transmission threat?

Emergent H7N9 influenza A virus has caused multiple public health and financial hardships. While some epidemiological studies have recognized infected chickens as an important bridge for human infections, the generality of this observation, the minimum infectious dose, and the shedding potential of chickens have received conflicting results. We experimentally tested the ability of domestic chickens (Gallus gallus domesticus) to transmit H7N9 to co-housed chickens and to several other animal species in an experimental live animal market. Results indicated that an infected chicken failed to initiate viral shedding of H7N9 to naïve co-housed chickens. The infected chicken did, however, successfully transmit the virus to quail (Coturnix sp.) located directly below the infected chicken cage. Oral shedding by indirectly infected quail was, on average, greater than ten-fold that of directly inoculated chickens. Best management practices in live animal market systems should consider the position of quail in stacked-cage settings.

Third Wave of Influenza A(H7N9) Virus from Poultry, Guangdong Province, China, 2014-2015

Fourteen influenza A(H7N9) viruses were isolated from poultry or the environment in live poultry markets in Guangdong Province, China during 2014−2015. Phylogenetic analysis showed that all viruses were descended from viruses of the second wave of influenza A(H7N9) virus infections during 2013. These viruses can be divided into 2 branches.

Effect of Live Poultry Market Closure on Avian Influenza A(H7N9) Virus Activity in Guangzhou, China, 2014

Temporary closure and disinfection can rapidly reduce levels of infectious virus in these settings.

We assessed the effect of closing live poultry markets in China on influenza A(H7N9) virus detection and viability. Intensive sampling was carried out before, during, and after a 2-week citywide market closure; the markets were cleaned and disinfected at the beginning of the closure period. Swab samples were collected at different sites within the markets and tested for H7N9 by real-time reverse transcription PCR and culture. During the closure, H7N9 viral RNA detection and isolation rates in retail markets decreased by 79% (95% CI 64%–88%) and 92% (95% CI 58%–98%), respectively. However, viable H7N9 virus could be cultured from wastewater samples collected up to 2 days after the market closure began. Our findings indicates that poultry workers and the general population are constantly exposed to H7N9 virus at these markets and that market closure and disinfection rapidly reduces the amount of viable virus.

Dynamic quantification of avian influenza H7N9(A) virus in a human infection during clinical treatment using droplet digital PCR

This study involved a human infection with avian influenza H7N9(A) virus in Zhejiang province, the first one after implementing the closure measures of living poultry markets in China. The clinical symptoms, epidemiological and virological characteristics of the case were described briefly, and as the emphasis, H7N9 virus was detected quantitatively and continuously from the collected samples in 10 different periods of the patient's treatment in order to reveal changes of viral load in patient's body during the treatment. This study first used reverse-transcription droplet digital PCR (RT-ddPCR) assays to monitor viral load dynamically for human H7N9 infection, synchronously performing real-time RT-PCR as a reference technology to obtain more comprehensive data for comparison. Our results indicated that RT-ddPCR compared to real-time RT-PCR is more sensitive and accurate for quantifying H7N9 viral load without the use of standard curves. Furthermore it can provide reference data for clinical policies including infectivity judgement, ward transferring and therapy adjustment for the patient during treatment.

Analysis of the immunogenicity and bioactivities of a split influenza A/H7N9 vaccine mixed with MF59 adjuvant in BALB/c mice

The H7N9 influenza virus caused significant mortality and morbidity in humans during an outbreak in China in 2013. A recombinant H7N9 influenza seed with hemagglutinin (HA) and neuraminidase (NA) gene segments from A/Zhejiang/DTID-ZJU01/2013(H7N9) and six internal protein gene segments from A/Puerto Rico/8/34(H1N1; PR8) were generated using reverse genetics. We sought to determine the immunogenic, protective properties, and mechanisms of a split avian influenza A/H7N9 vaccine mixed with MF59 adjuvant in comparison to vaccines that included other adjuvant. BALB/c mice were vaccinated with two doses of different amounts and combinations of this novel A/ZJU01/PR8/2013 split vaccine with adjuvant. Mice were subsequently challenged with A/Zhejiang/DTID-ZJU01/2013(H7N9) by intranasal inoculation. We verified that MF59 enhanced the HI, MN, and IgG antibody titers to influenza antigens. Compared with alum, MF59 could more potentially induce humoral immune responses and Th2 cytokine production after virus infection, while both MF59 and alum can slightly increase NK cell activity. This split H7N9 influenza vaccine with MF59 adjuvant could effectively induce antibody production and protect mice from H7N9 virus challenge. We have selected this vaccine for manufacture and future clinical studies to protect humans from H7N9 virus infection.

Human H7N9 virus induces a more pronounced pro-inflammatory cytokine but an attenuated interferon response in human bronchial epithelial cells when compared with an epidemiologically-linked chicken H7N9 virus

Background

Avian influenza virus H7N9 has jumped species barrier, causing sporadic human infections since 2013. We have previously isolated an H7N9 virus from a patient, and an H7N9 virus from a chicken in a live poultry market where the patient visited during the incubation period. These two viruses were genetically highly similar. This study sought to use a human bronchial epithelial cell line model to infer the virulence of these H7N9 viruses in humans.

Methods

Human bronchial epithelial cell line Calu-3 was infected with two H7N9 viruses (human H7N9-HU and chicken H7N9-CK), a human H5N1 virus and a human 2009 pandemic H1N1 virus. The infected cell lysate was collected at different time points post-infection for the determination of the levels of pro-inflammatory cytokines (tumor necrosis factor α [TNF-α] and interleukin 6 [IL-6]), anti-inflammatory cytokines (interleukin 10 [IL-10] and transforming growth factor beta [TGF-β]), chemokines (interleukin 8 [IL-8] and monocyte chemoattractant protein 1 [MCP-1]), and interferons (interferon β [IFN-β] and interferon lambda 1 [IFNL1]). The viral load in the cell lysate was also measured.

Results

Comparison of the human and chicken H7N9 viruses showed that H7N9-HU induced significantly higher levels of TNF-α at 12 h post-infection, and significantly higher levels of IL-8 from 12 to 48 h post-infection than those of H7N9-CK. However, the level of IFNL1 was lower for H7N9-HU than that of H7N9-CK at 48 h post-infection (P < 0.001). H7N9-HU had significantly higher viral loads than H7N9-CK at 3 and 6 h post-infection. H5N1 induced significantly higher levels of TNF-α, IL-6, IL-8, IL-10 and MCP-1 than those of H7N9 viruses at 48 h post-infection. Conversely, H1N1 induced lower levels of TNF-α, IL-10, MCP-1, IFNL1 and IFN-β when compared with H7N9 viruses at the same time point.

Conclusions

H7N9-HU induced higher levels of pro-inflammatory IL-6 and IL-8 and exhibited a more rapid viral replication than H7N9-CK. However, the level of antiviral IFNL1 was lower for H7N9-HU than H7N9-CK. Our results suggest that the gained properties in modulating human innate immunity by H7N9-HU transformed it to be a more virulent virus in humans than H7N9-CK.

Development of influenza A(H7N9) candidate vaccine viruses with improved hemagglutinin antigen yield in eggs

Background

The emergence of avian influenza A(H7N9) virus in poultry causing zoonotic human infections was reported on March 31, 2013. Development of A(H7N9) candidate vaccine viruses (CVV) for pandemic preparedness purposes was initiated without delay. Candidate vaccine viruses were derived by reverse genetics using the internal genes of A/Puerto/Rico/8/34 (PR8). The resulting A(H7N9) CVVs needed improvement because they had titers and antigen yields that were suboptimal for vaccine manufacturing in eggs, especially in a pandemic situation.

Methods

Two CVVs derived by reverse genetics were serially passaged in embryonated eggs to improve the hemagglutinin (HA) antigen yield. The total viral protein and HA antigen yields of six egg-passaged CVVs were determined by the BCA assay and isotope dilution mass spectrometry (IDMS) analysis, respectively. CVVs were antigenically characterized by hemagglutination inhibition (HI) assays with ferret antisera.

Results

Improvement of total viral protein yield was observed for the six egg-passaged CVVs; HA quantification by IDMS indicated approximately a twofold increase in yield of several egg-passaged viruses as compared to that of the parental CVV. Several different amino acid substitutions were identified in the HA of all viruses after serial passage. However, HI tests indicated that the antigenic properties of two CVVs remained unchanged.

Conclusions

If influenza A(H7N9) viruses were to acquire sustained human-to-human transmissibility, the improved HA yield of the egg-passaged CVVs generated in this study could expedite vaccine manufacturing for pandemic mitigation.

Safety, immunogenicity and cross-reactivity of a Northern hemisphere 2013-2014 seasonal trivalent inactivated split influenza virus vaccine, Anflu®

Anflu® is a seasonal trivalent inactivated split-virion influenza vaccine manufactured by Sinovac Biotech Co., Ltd. The objectives of this study were to evaluate the safety of Anflu® (2013-14 formulation: H1N1, H3N2 and BYAM) in infants and adults and its immunogenicity and cross-reactivity against mismatched influenza B lineage and avian influenza A(H7N9) viruses (hereafter BVIC and H7N9, respectively) in adults. In this phase IV open label trial, infants 6-35 months old (n=61) each received two injections with 28 days apart; adults 18-60 yrs old (n=60) and elderly >60 yrs old (n=61) each received one injection. Information of adverse events was collected through safety observation and follow-up visits. Pre- and post-immune blood samples (day 0 and 21) were collected from subjects ≥18 yrs old to detect hemagglutination inhibition antibody titers and calculate seroprotection rates (SPRs) and seroconversion rates (SCRs). The overall adverse reaction incidence was 1.6% (3/182), and no serious adverse event was reported during the study period. For subjects ≥18 yrs old, the SCRs, SPRs, and the geometric mean titers (GMTs) met the European criteria for all three strains. In addition, the point estimations of SCR, SPR and GMT for BVIC also met the European criteria. Six subjects were seroconverted against H7N9; however the serological results did not meet the European criteria. In conclusion, the results showed a satisfactory safety and immunogenicity profile of Anflu® and cross-reactivity against BVIC, but did not demonstrate cross-reactivity against H7N9 (Clinicaltrials.gov ID: NCT02269852).

Phylogenetic Analysis and Pathogenicity Assessment of Two Strains of Avian Influenza Virus Subtype H9N2 Isolated from Migratory Birds: High Homology of Internal Genes with Human H10N8 Virus

Two human-infecting avian influenza viruses (AIVs), H7N9 and H10N8, have emerged in China, which further indicate that the H9N2 subtype of AIVs, as an internal gene donor, may have an important role in the generation of new viruses with cross-species transmissibility and pathogenicity. H9N2 viruses that contain such internal genes widely exist in poultry but are rarely reported in migratory birds. In this study, two strains of the H9N2 virus were isolated from fecal samples of migratory birds in 2014: one strain from Caizi Lake in Anhui Province and one from Chen Lake in Hubei Province of China. Nucleotide sequence analysis revealed high homology of all six internal genes of these two strains with the internal genes of the human H10N8 virus in Jiangxi Province, as well as with the human H7N9 virus. Phylogenetic analysis indicated a possible origin of these two strains from poultry in South China. Both of the two viruses tested could replicated in respiratory organs of infective mice without adaption, by both strains of the H9N2 AIVs from wild birds, suggesting their potential capacity for directly infecting mammals. Our findings indicate the existence of H9N2 viruses that contain internal genes highly homologous with human H10N8 or H7N9 viruses. Wild birds can contribute to the spread of the H9N2 virus that contains the "harmful" internal gene complex, leading to gene rearrangement with other influenza viruses and to the generation of new pathogenic viruses. Therefore, strengthening AIV surveillance in wild birds can promote an understanding of the presence and prevalence of viruses and provide scientific evidence for the prevention and control of AIVs and human-infecting AIVs.

Optimal designs of an HA-based DNA vaccine against H7 subtype influenza viruses

The outbreak of a novel H7N9 influenza virus in 2013 has raised serious concerns for the potential of another avian-source pandemic influenza. Effective vaccines against H7N9 virus are important in the prevention and control of any major outbreak. Novel vaccination technologies are useful additions to existing approaches. In the current report, DNA vaccine studies were conducted to identify the optimal design of an H7 HA antigen using the HA gene from a previously reported H7N7 virus that is lethal in humans as the model antigen. New Zealand White rabbits were immunized with DNA vaccines expressing 1 of 3 forms of H7 HA antigen inserts encoding the HA gene from the same H7N7 virus. High-level H7 HA-specific IgG was detected by ELISA, and functional antibodies were confirmed by hemagglutination inhibition assay and pseudotyped virus-based neutralization assay against viruses expressing HA antigens from either the previous H7N7 virus or the novel H7N9 virus. HA antigen design under the tissue plasminogen activator leader (tPA) was the most immunogenic. The data presented in the current report confirm the immunogenicity of the H7 HA antigen and provide useful guidance to prepare for an optimized H7 HA DNA vaccine to help to control the emerging H7N9 virus if and when it is needed.

Development of Framework for Assessing Influenza Virus Pandemic Risk

This simple, additive, multiattribute assessment tool can evaluate the risk posed by novel influenza A viruses.

Although predicting which influenza virus subtype will cause the next pandemic is not yet possible, public health authorities must continually assess the pandemic risk associated with animal influenza viruses, particularly those that have caused infections in humans, and determine what resources should be dedicated to mitigating that risk. To accomplish this goal, a risk assessment framework was created in collaboration with an international group of influenza experts. Compared with the previously used approach, this framework, named the Influenza Risk Assessment Tool, provides a systematic and transparent approach for assessing and comparing threats posed primarily by avian and swine influenza viruses. This tool will be useful to the international influenza community and will remain flexible and responsive to changing information.

T cell epitope redundancy: cross-conservation of the TCR face between pathogens and self and its implications for vaccines and autoimmunity

T cells are extensively trained on 'self' in the thymus and then move to the periphery, where they seek out and destroy infections and regulate immune response to self-antigens. T cell receptors (TCRs) on T cells' surface recognize T cell epitopes, short linear strings of amino acids presented by antigen-presenting cells. Some of these epitopes activate T effectors, while others activate regulatory T cells. It was recently discovered that T cell epitopes that are highly conserved on their TCR face with human genome sequences are often associated with T cells that regulate immune response. These TCR-cross-conserved or 'redundant epitopes' are more common in proteins found in pathogens that have co-evolved with humans than in other non-commensal pathogens. Epitope redundancy might be the link between pathogens and autoimmune disease. This article reviews recently published data and addresses epitope redundancy, the "elephant in the room" for vaccine developers and T cell immunologists.

Histopathological findings in a critically ill patient with avian influenza A (H7N9)

To date, data regarding the pulmonary histopathology of human H7N9 disease are scarce. We herein describe a patient with a severe case of avian influenza A (H7N9). A chest computerized tomography (CT) scan showed diffuse ground-glass opacities and consolidation throughout the lungs. A resection of pulmonary bullae in the right middle lobe was performed by video-assisted thoracic surgery (VATS) based on the extracorporeal membrane oxygenation (ECMO) supportive technique on the 23(rd) day after the onset of symptoms because of a right pneumothorax persistent air leak. The histopathological findings of the resected lung tissue revealed pneumocyte hyperplasia and fibroproliferative changes along with diffuse alveolar damage. Bronchoalveolar lavage fluid (BALF) specimens for influenza A (H7N9) virus were continuously positive for more than three weeks, despite oseltamivir treatment, and continuous viral replication significantly prolonged the course of the disease. The patient's clinical status continuously deteriorated, with the development of refractory hypoxemia due to progressive and rapid lung fibrosis, which was confirmed by the final histological changes observed from a limited post-mortem biopsy of lung tissue. Pre-terminally, he developed multi-organ failure and died on the 39(th) day after symptom onset, despite corticosteroid treatment.

Is a highly pathogenic avian influenza virus H5N1 fragment recombined in PB1 the key for the epidemic of the novel AIV H7N9 in China, 2013?

BACKGROUND

A novel avian influenza A H7N9 virus that infects humans was identified in China in 2013. This study is the first to comprehensively investigate the characteristics of genomic recombination, rather than reassortment, which has been the subject of investigation in previously reported studies.

METHODS

Novel avian influenza virus (AIV) H7N9 genome sequences were obtained from the NCBI Influenza Virus Sequence Database and the Global Initiative on Sharing Avian Influenza Database (GISAID) and a representative isolate was subjected to homogeneity analysis. A phylogenetic tree was constructed. Eight segments of the isolate were analyzed to identify segments with recombination events, the corresponding recombination fragments, and breakpoints. The evolutionary history of the recombined fragments was tracked by constructing phylogenetic trees of the recombination fragments.

RESULTS

Among the eight segments of the novel AIV H7N9 analyzed, only the PB1 segment showed a marked recombination phenomenon, with 11 recombination events; these included five actual recombination events and six possible misalignment artifact recombination events. The most notable was the recombination of a 291-nucleotide (nt) fragment at the 490-780 nt site that was affiliated to a highly pathogenic avian influenza virus (HPAIV) H5N1 (A/tree sparrow/Thailand/VSMU-16-RBR/2005). The phylogenetic tree of the 291-nt recombination fragment on the PB1 segment showed that the novel AIV H7N9 had a close genetic relationship to H9N2 and H5N1.

CONCLUSIONS

The novel AIV H7N9 might have reassorted its PB1 segment from H9N2 circulating in China, and this H9N2 PB1 might have been recombined into a highly pathogenic fragment from HPAIV H5N1, which could be the reason for the high fatality rate among patients with AIV H7N9 influenza.

A Predictive Risk Model for A(H7N9) Human Infections Based on Spatial-Temporal Autocorrelation and Risk Factors: China, 2013-2014

This study investigated the spatial distribution, spatial autocorrelation, temporal cluster, spatial-temporal autocorrelation and probable risk factors of H7N9 outbreaks in humans from March 2013 to December 2014 in China. The results showed that the epidemic spread with significant spatial-temporal autocorrelation. In order to describe the spatial-temporal autocorrelation of H7N9, an improved model was developed by introducing a spatial-temporal factor in this paper. Logistic regression analyses were utilized to investigate the risk factors associated with their distribution, and nine risk factors were significantly associated with the occurrence of A(H7N9) human infections: the spatial-temporal factor φ (OR = 2546669.382, p < 0.001), migration route (OR = 0.993, p < 0.01), river (OR = 0.861, p < 0.001), lake(OR = 0.992, p < 0.001), road (OR = 0.906, p < 0.001), railway (OR = 0.980, p < 0.001), temperature (OR = 1.170, p < 0.01), precipitation (OR = 0.615, p < 0.001) and relative humidity (OR = 1.337, p < 0.001). The improved model obtained a better prediction performance and a higher fitting accuracy than the traditional model: in the improved model 90.1% (91/101) of the cases during February 2014 occurred in the high risk areas (the predictive risk > 0.70) of the predictive risk map, whereas 44.6% (45/101) of which overlaid on the high risk areas (the predictive risk > 0.70) for the traditional model, and the fitting accuracy of the improved model was 91.6% which was superior to the traditional model (86.1%). The predictive risk map generated based on the improved model revealed that the east and southeast of China were the high risk areas of A(H7N9) human infections in February 2014. These results provided baseline data for the control and prevention of future human infections.

Ongoing transmission of avian influenza A viruses in Hong Kong despite very comprehensive poultry control measures: A prospective seroepidemiology study

OBJECTIVES

Stringent measures have been implemented in Hong Kong to prevent human infections due to avian influenza viruses (AIVs). Here, we report the seroprevalence of AIVs among high risk population.

METHODS

In this prospective study, blood samples were collected in October and November 2013 and in July 2014 from workers at live poultry market (LPM) and pig/cattle slaughterhouse (SH) in Hong Kong. Serum antibody titers against A(H5N1), A(H7N9) and A(H9N2) were determined.

RESULTS

When an hemagglutination inhibition (HI) titer of 40 was used as the cutoff, the A(H5N1) seropositive rate among LPM workers increased from 0% in 2013 to 37.8% in 2014 (P < 0.001) and the A(H9N2) seropositive rate increased from 10% to 55.6% (P < 0.001). There was no significant increase in A(H7N9) seropositive rate for LPM workers irrespective of cutoff titer. For SH workers, there was no significant increase in HI titer for any AIVs. Significantly more LPM workers had a ≥4-fold increase in A(H5N1) HI titer from 2013 to 2014 than SH workers (60% vs 8.3%, P = 0.020).

CONCLUSIONS

There was a significant increase of serum A(H5N1) and A(H9N2) HI titers among Hong Kong LPM workers between 2013 and 2014. Although we cannot exclude some degree of antibody cross-reactivity with other influenza viruses, our results suggest the occurrence of subclinical AIV infections in this population.