Global Prevalence and Hemagglutinin Evolution of H7N9 Avian Influenza Viruses from 2013 to 2022.

H7N9 avian influenza viruses have caused severe harm to the global aquaculture industry and human health. For further understanding of the characteristics of prevalence and hemagglutinin evolution of H7N9 avian influenza viruses, we generated the global epidemic map of H7N9 viruses from 2013 to 2022, constructed a phylogenetic tree, predicted the glycosylation sites and compared the selection pressure of the hemagglutinin. The results showed that although H7N9 avian influenza appeared sporadically in other regions worldwide, China had concentrated outbreaks from 2013 to 2017. The hemagglutinin genes were classified into six distinct lineages: A, B, C, D, E and F. After 2019, H7N9 viruses from the lineages B, E and F persisted, with the lineage B being the dominant. The hemagglutinin of highly pathogenic viruses in the B lineage has an additional predicted glycosylation site, which may account for their persistent pandemic, and is under more positive selection pressure. The most recent ancestor of the H7N9 avian influenza viruses originated in September 1991. The continuous evolution of hemagglutinin has led to an increase in virus pathogenicity in both poultry and humans, and sustained human-to-human transmission. This study provides a theoretical basis for better prediction and control of H7N9 avian influenza.

Influenza H7N9 Virus Hemagglutinin with T169A Mutation Possesses Enhanced Thermostability and Provides Effective Immune Protection against Lethal H7N9 Virus Challenge in Chickens.

H7N9 avian influenza virus (AIV) has caused huge losses in the poultry industry and impacted human public health security, and still poses a potential threat. Currently, immune prevention and control of avian influenza relies on traditional inactivated vaccines; however, they have some limitations and genetically engineered avian influenza subunit vaccines may be potential candidate vaccines. In this study, a T169A mutation in the HA protein derived from H7N9 AIV A/Chicken/Guangdong/16876 (H7N9-16876) was generated using the baculovirus expression system (BVES). The results showed that the mutant (HAm) had significantly increased thermostability compared with the wild-type HA protein (HA-WT). Importantly, immunizing chickens with HAm combined with ISA 71VG elicited higher cross-reactive hemagglutination inhibition (HI) antibody responses and cytokine (IFN-γ and IL-4) secretion. After a lethal challenge with heterologous H7N9 AIV, the vaccine conferred chickens with 100% (10/10) clinical protection and effectively inhibited viral shedding, with 90% (9/10) of the chickens showing no virus shedding. The thermostability of HAm may represent an advantage in practical vaccine manufacture and application. In general, the HAm generated in this study represents a promising subunit vaccine candidate for the prevention and control of H7N9 avian influenza.

Baculovirus-derived influenza virus-like particle confers complete protection against lethal H7N9 avian influenza virus challenge in chickens and mice.

Currently, highly pathogenic avian influenza (HPAI) H7N9 viruses still pose a potential pandemic threat. Influenza virus-like particle (VLP) is one of the most promising vaccine strategies to complement traditional egg-dependent vaccines. Here, we generated a H7N9 VLP vaccine candidate by baculovirus expression system and evaluated its efficacy in chickens and mice. The H7N9 VLP was produced through co-infection of Sf9 insect cells with three recombinant baculoviruses expressing individual HA, NA and M1 gene of the HPAI H7N9 virus A/chicken/Guangdong/GD15/2016. Intramuscular immunization of the H7N9 VLP elicited robust antibody immune responses and conferred complete clinical protection against lethal H7N9 virus challenge both in chickens and mice. Meanwhile, H7N9 VLP significantly restrained virus shedding and dramatically alleviated pulmonary lesions caused by H7N9 virus infection in birds and mice. Interestingly, chicken antibodies induced by the H7N9 VLP also had a good cross-reactivity with H7N9 field strains isolated in different years. In addition, vaccination with the H7N9 VLP elicited high T cell immunity in mouse lung, evidenced by significantly upregulated expression of IL-2, IL-4 and IFN-γ. Furthermore, the H7N9 VLP significantly decreased the expression of some key inflammatory cytokines, such as IL6, RANTES and TNF-α in mouse lung, which may partially account for its contribution to alleviate lung pathology. Therefore, our study describes the good efficacy of the HA + NA + M1-containing H7N9 VLP both in chicken and mice models, highlighting the potential of VLP-based vaccine as a critical alternative of traditional egg-based vaccine for control of H7N9 influenza virus in both humans and poultry.

Immune Evaluation of Recombinant Lactobacillus plantarum With Surface Display of HA1-DCpep in Mice.

Avian influenza viruses can be efficiently transmitted through mucous membranes, and conventional vaccines are not effective in protecting against mucosal infection by influenza viruses. To induce multiple immune responses in an organism, we constructed a recombinant Lactobacillus plantarum expressing the influenza virus antigen HA1 with the adjuvant dendritic cell-targeting peptide (DCpep). The recombinant L. plantarum strains NC8Δ-pWCF-HA1 and NC8Δ-pWCF-HA1-DCpep were used to immunize mice via oral administration, and the humoral, cellular and mucosal immune responses were evaluated. In addition, the serum levels of specific antibodies and hemagglutination inhibition (HI) levels were also measured. Our results showed that recombinant L. plantarum activated dendritic cells in Peyer's patches (PPs), increased the numbers of CD4+IFN-γ+ and CD8+IFN-γ+ cells in the spleen and mesenteric lymph nodes (MLNs), and affected the ability of CD4+ and CD8+ cells to proliferate in the spleen and MLNs. Additionally, recombinant L. plantarum increased the number of B220+IgA+ cells in PPs and the level of IgA in the lungs and different intestinal segments. In addition, specific IgG, IgG1 and IgG2a antibodies were induced at high levels in the mice serum, specific IgA antibodies were induced at high levels in the mice feces, and HI potency was significantly increased. Thus, the recombinant L. plantarum strains NC8Δ-pWCF-HA1 and NC8Δ-pWCF-HA1-DCpep have potential as vaccine candidates for avian influenza virus.

Optimizing the early detection of low pathogenic avian influenza H7N9 virus in live bird markets.

In Southeast Asia, surveillance at live bird markets (LBMs) has been identified as crucial for detecting avian influenza viruses (AIV) and reducing the risk of human infections. However, the design of effective surveillance systems in LBMs remains complex given the rapid turn-over of poultry. We developed a deterministic transmission model to provide guidance for optimizing AIV surveillance efforts. The model was calibrated to fit one of the largest LBMs in northern Vietnam at high risk of low pathogenic H7N9 virus introduction from China to identify the surveillance strategy that optimizes H7N9 detection. Results show that (i) using a portable diagnostic device would slightly reduce the number of infected birds leaving the LBM before the first detection, as compared to a laboratory-based diagnostic strategy, (ii) H7N9 detection could become more timely by sampling birds staying overnight, just before new susceptible birds are introduced at the beginning of a working day, and (iii) banning birds staying overnight would represent an effective intervention to reduce the risk of H7N9 spread but would decrease the likelihood of virus detection if introduced. These strategies should receive high priority in Vietnam and other Asian countries at risk of H7N9 introduction.

Identification of the dominant non-neutralizing epitope in the haemagglutinin of H7N9 avian influenza virus.

H7N9 avian influenza vaccines induce high levels of non-neutralizing (nonNeu) antibodies against the haemagglutinin (HA). However, the antigenic epitopes underlying this particular antibody response are still undefined. In this study, a panel of 13 monoclonal antibodies (mAbs) against the HA protein of H7N9 virus was generated and 12 of them had no hemagglutination inhibition and virus neutralizing activities. One linear epitope in the stalk (373-TAA-375) recognized by three mAbs and one conformational epitope in the head (220Q-225S-227G) targeted by one mAb were identified using peptide-based enzyme-linked immunosorbent assay (ELISA) and biopanning of phage display random peptide library. In addition, competition ELISA revealed that the mAb targeting the head epitope strongly inhibited HA-binding of chicken nonNeu anti-H7N9 sera, whereas lower inhibition was observed for chicken neutralizing antisera, indicating the immunodominance of this epitope in the elicitation of nonNeu antibodies. Moreover, the stalk epitope is conserved among the H1-H17 subtypes and the mAb recognizing this epitope exhibited cross-reactivity with different subtypes. In conclusion, two novel nonNeu epitopes in H7N9 HA were identified, and an epitope in the head was identified as an immunodominant epitope underlying the induction of nonNeu H7N9 antibodies. Our results add new knowledge to the molecular basis for antibody immunity against H7N9 vaccines and provide useful implications for vaccine design and modification.

Efficacy of a Cap-Dependent Endonuclease Inhibitor and Neuraminidase Inhibitors against H7N9 Highly Pathogenic Avian Influenza Virus Causing Severe Viral Pneumonia in Cynomolgus Macaques.

H7N9 highly pathogenic avian influenza virus (HPAIV) infection in a human was first reported in 2017. A/duck/Japan/AQ-HE29-22/2017 (H7N9) (Dk/HE29-22), found in imported duck meat at an airport in Japan, possesses a hemagglutinin with a multibasic cleavage site, indicating high pathogenicity in chickens, as in the case of other H7 HPAIVs. In the present study, we examined the pathogenicity of Dk/HE29-22 and the effectiveness of a cap-dependent endonuclease inhibitor (baloxavir) and neuraminidase inhibitors (oseltamivir and zanamivir) against infection with this strain in a macaque model (n = 3 for each group). All of the macaques infected with Dk/HE29-22 showed severe signs of disease and pneumonia even after the virus had disappeared from lung samples. Virus titers in macaques treated with baloxavir were significantly lower than those in the other treated groups. After infection, levels of interferon alpha and beta (IFN-α and IFN-ß) in the blood of macaques in the baloxavir group were the highest among the groups, whereas levels of tumor necrosis factor alpha (TNF-α) and interleukin 13 (IL-13) were slightly increased in the untreated group. In addition, immune checkpoint proteins, including programmed death 1 (PD-1) and T cell immunoreceptor with Ig and ITIM domains (TIGIT), were expressed at high levels in the untreated group, especially in one macaque that showed severe signs of disease, indicating that negative feedback responses against vigorous inflammation may contribute to disease progression. In the group treated with baloxavir, the percentages of PD-1-, CTLA-4-, and TIGIT-positive T lymphocytes were lower than those in the untreated group, indicating that reduction in virus titers may prevent expression of immune checkpoint molecules from downregulation of T cell responses.

Induction of cross-group broadly reactive antibody response by natural H7N9 avian influenza virus infection and immunization with inactivated H7N9 vaccine in chickens.

Pre-existing immunity against the conserved haemagglutinin (HA) stalk underlies the elicitation of cross-group antibody induced by natural H7N9 virus infection and immunization in humans. However, whether broadly reactive antibodies can be induced by H7N9 infection and immunization in the absence of pre-existing stalk-specific immunity is unclear. In this study, antibody response induced by H7N9 virus infection and immunization with inactivated and viral-vectored H7N9 vaccines in naïve chickens was analysed. The results showed that H7N9 infection and immunization with inactivated vaccine resulted in potent induction of haemagglutination-inhibition (HI), virus neutralization (VN) and HA-binding antibodies, whereas Newcastle disease virus (NDV)-vectored H7N9 vaccine induced marginal HI and VN titres but high levels of HA-binding antibody. In addition, H7N9 infection and immunization induced stalk-specific antibodies in naïve chickens and these antibodies recognized different epitopes in the stalk. Virus infection and immunization with inactivated vaccine elicited antibodies cross-reactive with both group 1 and group 2 HAs, while antibodies induced by NDV-H7N9 vaccination showed a narrower cross-reactivity within group 2. Moreover, only homologous neutralizing activity of the sera against H7N9 virus was observed, and cross-binding antibodies did not show heterosubtypic neutralizing activity. Our results indicated that cross-group binding but non-neutralizing antibodies primarily targeting the stalk can be induced by natural H7N9 infection and immunization with inactivated vaccine in naïve chickens. This suggests that at least in a naïve chicken model, pre-existing stalk-specific immunity is not required for induction of broadly reactive antibodies. Additionally, H7N9-based immunogens may be explored as vaccine candidates or as a prime component to induce broadly protective influenza immunity.

Low replicative fitness of neuraminidase inhibitor-resistant H7N9 avian influenza a virus with R292K substitution in neuraminidase in cynomolgus macaques compared with I222T substitution.

Human cases of H7N9 influenza A virus infection have been increasing since 2013. The first choice of treatment for influenza is neuraminidase (NA) inhibitors (NAIs), but there is a concern that NAI-resistant viruses are selected in the presence of NAIs. In our previous study, an H7N9 virus carrying AA substitution of threonine (T) for isoleucine (I) at residue 222 in NA (NA222T, N2 numbering) and an H7N9 virus carrying AA substitution of lysine (K) for arginine (R) at residue 292 in NA (NA292K, N2 numbering) were found in different macaques that had been infected with A/Anhui/1/2013 (H7N9) and treated with NAIs. In the present study, the variant with NA292K showed not only resistance to NAIs but also lower replication activity in MDCK cells than did the virus with wild-type NA, whereas the variant with NA222T, which was less resistant to NAIs, showed replication activity similar to that of the wild-type virus. Next, we examined the pathogenicity of these H7N9 NAI-resistant viruses in macaques. The variants caused clinical signs similar to those caused by the wild-type virus with similar replication potency. However, the virus with NA292K was replaced within 7 days by that with NA292R (same as the wild-type) in nasal samples from macaques infected with the virus with NA292K, i.e. the so-called revertant (wild-type virus) became dominant in the population in the absence of an NAI. These results suggest that the clinical signs observed in macaques infected with the NA292K virus are caused by the NA292K virus and the NA292R virus and that the virus with NA292K may not replicate continuously in the upper respiratory tract of patients without treatment as effectively as the wild-type virus.

Transcriptome Profiles of Highly Pathogenic Pure Avian H7N9 Virus-Infected Lungs of BALB/c Mice.

Avian influenza A (H7N9) viruses emerged in China in 2013 and caused a zoonotic disease associated with a high case-fatality ratio of more than 30%. Transcriptional profiles obtained using animal models reveal host responses to the disease, thereby providing insights into disease pathogenesis. Therefore, we aimed to characterize the host responses of the H7N9 virus infected-mouse lungs in this study. First, we isolated an avian-originated H7N9 strain, which was shown to be highly pathogenic to both chickens and mice. Genomic analysis results suggested that a 12-nucleotide-insertion was present at the hemagglutinin cleavage site, and both the hemagglutinin and neuraminidase genes belonged to the Yangtze River Delta lineage. RNA sequencing results revealed 566 differentially expressed genes in the H7N9-infected lungs. Moreover, transcriptome analysis revealed that over-activated antiviral signals and intense interferon-stimulated gene products possibly contributed to the high virulence of the virus in mice. Importantly, lung concentrations of inflammatory cytokines, including interleukin-1ß and interleukin-6, interferon-ß, and tumor necrosis factor-α, were upregulated in response to H7N9 virus infection. Overall, the present study provided a comprehensive understanding of H7N9 virus pathogenicity and correlated host immune responses.

Comparing the process of early control of government between H7N9 avian influenza in Shanghai in 2013 and COVID-19 in Wuhan in 2019 / 上海预防医学

[Objective] To analyze and judge the possibility of early control in Shanghai if COVID-19 begins in Shanghai. [Methods] Compare the process of early control of H7N9 avian influenza in Shanghai in 2013 and Wuhan COVID-19 in 2019. The early incidence data of Korean COVID-19 was simulated and analyzed to predict whether the medical resources needed in Shanghai were available. [Results] (1) It would take 22 days from the first case to the government's emergency response in terms of Shanghai. (2) It is estimated that there would be 602-763 patients with cumulative onset and onset after incubation period. (3) At least 500 beds of infectious diseases can be allocated in Shanghai in case of emergency. Through adding beds and resources reallocation in the whole city, patients can be fully admitted and treated. [Conclusion] If COVID-19 epidemic occurs in Shanghai, early control is possible.

Comparison of the early control process of H7N9 avian influenza in Shanghai and COVID-19 in Wuhan / 上海预防医学

Objective To analyze and estimate the possibility of early control in Shanghai if COVID-19 had begun in Shanghai. Methods Comparison was made in the processes of early control between H7N9 avian influenza in Shanghai in 2013 and COVID-19 in Wuhan in 2019.The early incidence data of Korean COVID-19 was simulated and analyzed to predict whether the medical resources needed in Shanghai were available. Results If it had occurred in Shanghai, it would have taken 22 days from the first case to the government′s emergency response.It was estimated that there would have been 602-763 patients with cumulative onset and onset after incubation period.At least 500 beds of infectious diseases could have been allocated in Shanghai in case of emergency.Through adding beds and resources reallocation in the whole city, patients could have been fully admitted and treated. Conclusion If COVID-19 epidemic had occurred in Shanghai, it′s early control would have been possible though there might have difficulties.

A novel H7N3 reassortant originating from the zoonotic H7N9 highly pathogenic avian influenza viruses that has adapted to ducks.

The first human case of zoonotic H7N9 avian influenza virus (AIV) infection was reported in March 2013 in China. This virus continues to circulate in poultry in China while mutating to highly pathogenic AIVs (HPAIVs). Through monitoring at airports in Japan, a novel H7N3 reassortant of the zoonotic H7N9 HPAIVs, A/duck/Japan/AQ-HE30-1/2018 (HE30-1), was detected in a poultry meat product illegally brought by a passenger from China into Japan. We analysed the genetic, pathogenic and antigenic characteristics of HE30-1 by comparing it with previous zoonotic H7N9 AIVs and their reassortants. Phylogenetic analysis of the entire HE30-1 genomic sequence revealed that it comprised at least three different sources; the HA (H7), PB1, PA, NP, M and NS segments of HE30-1 were directly derived from H7N9 AIVs, whereas the NA (N3) and PB2 segments of HE30-1 were unrelated to zoonotic H7N9. Experimental infection revealed that HE30-1 was lethal in chickens but not in domestic or mallard ducks. HE30-1 was shed from and replicated in domestic and mallard ducks and chickens, whereas previous zoonotic H7N9 AIVs have not adapted well to ducks. This finding suggests the possibility that HE30-1 may disseminate to remote area by wild bird migration once it establishes in wild bird population. A haemagglutination-inhibition assay indicated that antigenic drift has occurred among the reassortants of zoonotic H7N9 AIVs; HE30-1 showed similar antigenicity to some of those H7N9 AIVs, suggesting it might be prevented by the H5/H7 inactivated vaccine that was introduced in China in 2017. Our study reports the emergence of a new reassortant of zoonotic H7N9 AIVs with novel viral characteristics and warns of the challenge we still face to control the zoonotic H7N9 AIVs and their reassortants.

Single Immunization with Newcastle Disease Virus-Vectored H7N9 Vaccine Confers a Complete Protection Against Challenge with Highly Pathogenic Avian Influenza H7N9 Virus.

In the fifth wave of the H7N9 avian influenza epidemic, highly pathogenic avian influenza (HPAI) A (H7N9) viruses have emerged and pose a great challenge to public health and the poultry industry. In addition, there are apparent genetic and antigenic variations between the classical H7N9 avian influenza virus and the newly-emerged H7N9 virus. Therefore, an antigenic-match vaccine is required for the prevention and control of H7N9 avian influenza in poultry in China. In this study, a recombinant Newcastle disease virus (NDV)-vectored vaccine expressing the HA derived from a prevailing HPAI H7N9 virus (GD15) was generated using reverse genetics. The recombinant virus (rAI4HA) showed virus yield and growth capacity in chicken embryos comparable to the parental virus (rAI4). Expression of the HA protein was detected in chicken embryo fibroblasts inoculated with rAI4HA. A chicken immunization study demonstrated that both rAI4HA and rAI4 induced similar anti-NDV hemagglutination inhibition (HI) antibody titers at weeks 2, 3, and 4 after a single immunization. However, rAI4HA-immunized chickens had a low seroconversion rate (20%) and negative HI titers against H7N9. Additionally, rAI4HA elicited high levels of H7N9-specifc IgY antibody as measured by ELISA. More importantly, the recombinant vaccine provided a complete protection against a lethal challenge with HPAI H7N9 virus and significantly inhibited virus shedding after a single immunization. Our results suggest that the recombinant NDV-vectored H7N9 vaccine expressing the antigenic-match HA can confer a complete protection against HPAI H7N9 challenge after a single immunization.

La inmunización única con una vacuna con un virus de la enfermedad de Newcastle recombinante contra el subtipo H7N9 del virus de la influenza aviar confiere una protección completa contra el desafío con el virus H7N9 de la influenza aviar altamente patógena. Durante la quinta ola de la epidemia de influenza aviar H7N9, surgieron virus altamente patógenos de influenza aviar A (H7N9) que representan un gran desafío para la salud pública y para la industria avícola. Además, existen variaciones genéticas y antigénicas aparentes entre el virus de la influenza aviar H7N9 clásica y el virus H7N9 de reciente aparición. Por lo tanto, se requiere una vacuna antigénica para la prevención y el control de la influenza aviar H7N9 en la avicultura en China. En este estudio, se generó una vacuna vectorizada con un virus recombinante de la enfermedad de Newcastle recombinante que expresaba el gene HA derivado de un virus de influenza aviar de alta patogenicidad H7N9 prevalente (GD15) utilizando genética inversa. El virus recombinante (rAI4HA) mostró el rendimiento y la capacidad de crecimiento viral en embriones de pollo comparables con el virus paterno (rAI4). La expresión de la proteína HA se detectó en fibroblastos de embrión de pollo inoculados con el virus rAI4HA. Un estudio de inmunización en pollos demostró que tanto el virus rAI4HA como el virus rAI4 indujeron títulos de anticuerpos de inhibición de hemaglutinación (HI) contra el virus de Newcastle similares en las semanas dos, tres y cuatro después de una inmunización única. Sin embargo, los pollos inmunizados con el virus rAI4HA tuvieron una tasa de seroconversión baja (20%) y títulos de HI negativos contra H7N9. Además, el virus rAI4HA provocó altos niveles de anticuerpos IgY específicos contra H7N9 medidos por ELISA. Más importante aún, la vacuna recombinante proporcionó una protección completa contra un desafío letal con un virus de alta patogenicidad H7N9 e inhibió significativamente la propagación de virus después de una sola inmunización. Estos resultados sugieren que la vacuna H7N9 vectorizada con un virus de la enfermedad de Newcastle recombinante que expresa al subtipo HA antigénicamente adecuado puede conferir una protección completa contra el desafío con un virus de alta patogenicidad H7N9 después de una inmunización única.

Hemagglutinin-Specific Non-neutralizing Antibody Is Essential for Protection Provided by Inactivated and Viral-Vectored H7N9 Avian Influenza Vaccines in Chickens.

Hemagglutination inhibition (HI) and virus neutralization antibody (nAb) do not always correlate with the protection of H7 avian influenza vaccines in mammals and humans. The contribution of different classes of antibodies induced by H7N9 vaccines to protection is poorly characterized in chickens. In this study, antibody responses induced by both inactivated and viral-vectored H7N9 vaccines in chickens were dissected. Chickens immunized with inactivated H7N9 vaccine showed 50% seroconversion rate and low HI and nAb titers at week 3 post immunization. However, inactivated H7N9 vaccine elicited 100% seroconversion rate in terms of high levels of HA-binding IgG antibody determined by ELISA. Despite inducing low levels of nAb, inactivated H7N9 vaccine conferred full protection against H7N9 challenge in chickens and markedly inhibited virus shedding. Similarly, Newcastle disease virus (NDV)-vectored H7N9 vaccine induced marginal HI and nAb titers but high level of IgG antibody against H7N9 virus. In addition, NDV-H7N9 vaccine also provided complete protection against H7N9 challenge. Chicken antisera had a high IgG/VN ratio, indicating that a larger proportion of serum antibodies were non-neutralizing antibody (non-nAb). More importantly, passive transfer challenge experiment showed that non-neutralizing antisera provided partial protection (37.5%) of chickens against H7N9 challenge, without significant difference from that provided by neutralizing antisera. In conclusion, our results suggest that antibodies measured by the traditional HI and virus neutralization assays do not correlate with the protection of inactivated and viral-vectored H7N9 vaccines in chickens, and HA-binding non-nAb also contributes to the protection against H7N9 infection. Total binding antibody can be used as a key correlate to the protection of H7N9 vaccine.

Epidemiological characteristics of human infection with avian influenza A (H7N9) in Guilin / 中华微生物学和免疫学杂志

Objective To analyze the epidemiological characteristics of human infection with H7N9 avian influenza in Guilin in recent years and to provide on-site data and data support for scientific pre-vention and control of the epidemic of H7N9 avian influenza infection. Methods A descriptive epidemio-logical method was used to collect the data about human infection with H7N9 avian influenza form three as-pects, which were human infection cases in 2017, environmental monitoring for H7N9 avian influenza virus and sentinel surveillance of influenza-like cases. The epidemiological characteristics of human infection with H7N9 avian influenza in Guilin in 2017 were analyzed. Chi-square test was used to compare the positive rates of H7N9 avian influenza virus in environmental specimens. Results A total of six cases of confirmed human H7N9 infection including three deaths were reported in Guilin city in 2017. These cases were from five counties and districts and all occurred in winter and spring. The patients were middle-aged and old men. Most of them were farmers and had a clear history of poultry exposure before the onset of infection. No human H7N9 infection was reported in close contacts or in influenza-like cases. Conclusions H7N9 avian influen-za infection in Guilin was characterized by high sporadicity, high incidence in winter and spring, and pre-dominantly middle-aged and elderly men. Avian exposure history was a high risk factor for human infection with H7N9 avian influenza virus. All of the studied cases were severe cases. No human-to-human transmis-sion was reported. Farmers, having a history of poultry slaughter, and underlying diseases were potential risks causing death. Live poultry markets were the main sources of infection, hence closing market could re-duce the detection rate of H7N9 avian influenza virus. Strengthen the management of live poultry market and poultry environmental monitoring, closing live poultry markets when viral detection was positive, and suspen-ding live poultry trading were effective measures to control the epidemic of H7N9 avian influenza infection and prevent transmission.

Clinical application of neutrophil-to-lymphocyte ratio in predicting the prognosis of H7N9 avian influenza / 中华传染病杂志

Objective To explore the predictive value of neutrophil-to-lymphocyte ratio on the prognosis of H7N9 avian influenza.Methods A retrospective analysis was conducted on 28 H7N9 avian influenza patients (treatment group) at the First Affiliated Hospital of Soochow University from April 2013 to January 2016.Thirty healthy physical examiners in the same period were enrolled as the healthy control group.The 28 patients were followed up for half a year and divided into the improvement group (18 cases) and the death group (10 cases) according to the clinical prognosis.Inflammatory indicators including white blood cells (WBC),neutrophil (N),lymphocyte (L),monocytes (M),platelet (PLT),creatine kinase (CK),lactate dehydrogenase (LDH),high sensitive C reactive protein were collected at day 1,day 3 and week 1 of admission.Calculation of neutrophil-to-lymphocyte ratio (NLR),platelet-to-lymphocyte ratio (PLR),lymphocyte-to-monocyte ratio (LMR),△NLR3 (day 3 of admission NLR-on day 1 of admission NLR),△NLR7 (week 1 of admission NLR-day 3 of admission NLR) and so on calculating △PLR3,△PLR7,△LMR3,△LMR7.Differences of the above indicators between the improvement group and death group were compared.The measurement data with normal distribution were tested by t-test of two independent samples,and the count data with non-normal distribution were tested by Mann-Whitney U-test.Univariate and multivariate logistic regression analysis to explore the prognostic factors and the working characteristic curve of subjects was used to evaluate the predictive value of inflammatory response indexes for H7N9 avian influenza death.Results In the treatment group,the baseline WBC,L,N,PLT,the proportion of lymphocytes,neutrophils,monocytes,and NLR,PLR,and LMR were all statistically different compared with the healthy control group (all P ＜0.01).After treatment,day 3 NLR,△NLR3 in improvement group were both significantly decreased to 10.93 (15.71)and0.87 (-15.63),respectively when compared with death group (17.62[23.63] and 7.42[22.68],respectively) (Z =-2.16 and-2.014,respectively,both P＜0.05).Day 7 NLR,△NLR7 in improved group were 6.51 (13.23) and-0.37 (-12.38),respectively,which were both lower than those of death group (27.90 [25.64] and 11.54 [-26.22]) with statistically significant differences (Z =-2.444 and -2.111,respectively,both P ＜ 0.05).Multivariate logistic regression analysis indicates that △NLR3 is the main factor that affects the prognosis of the H7N9 infection (odds ratio [OR] =1.153,95％ confidence interval [CI]:1.052-1.263,P =0.002).Reciver operating characteristic curve analysis showed that the area under the curve was 0.733 (95 ％ CI:0.532-0.935,P =0.044).Based on the principle of Youden index,the cutoff value of △NLR3 to predict the death risk of H7N9 avian influenza was 5.453 with sensitivity of 0.700 and the specificity of 0.722.The mortality was higher when △NLR3 was higher than 5.453.Conclusions Dynamic monitoring NLR,especially △NLR3 may reflect the condition and prognosis of H7N9 infection,which is an independent predictor of death.

Meta-analysis of the immune effects of inactivated H7N9 influenza vaccine / 预防医学

Objective @#To evaluate the immune effects of inactivated H7N9 influenza vaccine.@*Methods @#We searched several common databases（The Cochrane Library,PubMed,China Biology Medicine disc,China National Knowledge Infrastructure,etc.）for research articles about immune effects of H7N9 influenza vaccine published from the time the database built to July 10th of 2018,using H7N9 and vaccine as keywords. After screening the articles according to the inclusion and exclusion criteria,we assessed the quality of the studies and then employed seroconversion rate（SCR）as an outcome indicator to analyze the immune effects of different doses and adjuvants.@*Results @#We recruited 5 articles on inactivated H7N9 influenza vaccine from 1 679 articles. The sample size was 2 579. The results of the meta-analysis showed that the rate difference（RD）values of SCR in each dose group after the first dose ranged from 1% to 10%,which indicated a poor protective effect;after the second dose of immunization,the RD values of SCR in the vaccines without adjuvants ranged from 13% to 19%,which was not effective enough;the RD values of SCR in the vaccines with adjuvants ranged from 62% to 69%,which met the licensing criteria for influenza vaccine;better results could be achieved when immunized with two doses of vaccines with adjuvants（ RR=1.19,95%CI：1.02-1.39）;vaccines with AS03 or MF59 at the lowest dose of 3.75 μg had the same immune effects as ones at a dose of 15 μg;vaccines with AS03（RD=89%,95%CI：85%-93%）were superior to those with MF59（RD=42%,95%CI：9%- 75%）.@*Conclusion @#Inactivated H7N9 influenza vaccines could achieve good immune effects when inoculated two doses with adjuvants,and the minimum effective dose was 3.75 μg.

A comprehensive comparison of the fifth-wave highly pathogenic and low-pathogenic H7N9 avian influenza viruses reveals potential threat posed by both types of viruses in mammals.

Before 2013, zoonotic influenza infections were dominated by H5N1 viruses in China. However, the emergence of the H7N9 viruses in early 2013 changed this dominance greatly, and more than 1,600 laboratory-confirmed human cases of H7N9 infections have been reported since then. To understand the underlying mechanism of the emergence of the fifth epidemic wave that shows an unexpected sharp increase, we systematically investigated the biological characteristics of the highly pathogenic (HP) and low-pathogenic (LP) H7N9 AIVs during this period. We first systematically analysed the haemagglutination assay gene of all the isolates available from the website and found that the HP and LP viruses differed a little in the well-established receptor binding sites and in other potentially important sites. Phylogenetic analysis showed that both the HP and LP viruses belong to the branch of the Yangtze River Delta, whereas they diverged to different small branches. To further compare the biological variations in the HP and LP viruses, we selected six HP and six LP strains for in-depth analysis, including receptor binding characteristics, thermal stability, viral replication and virulence in mice. The three major findings of this study were as follows: (a) Other potential site/sites may affect the receptor binding property of the H7N9 viruses; (b) the HP viruses displayed a higher thermostability than did the LP viruses, quite consistent with the epidemiological data during the summer period; and (c) one-third of the HP viruses were moderately pathogenic in mice, whereas all the LP viruses were nonpathogenic in this animal model. However, the LP viruses replicated more efficiently in the mouse lung and can spread to the extrarespiratory organs (spleen, kidney and brain). Taken together, our results suggest that both the HP and LP H7N9 viruses can pose a potential threat to public health, highlighting the importance of the continual surveillance of the H7N9 AIVs.

[Willingness and influencing factors related to "centralized slaughtering, fresh poultry listing and marketing" strategy among the household chefs in Guangzhou].

Objective: To study the willingness and influence factors related to "centralized slaughtering, fresh poultry listing and marketing" strategy, among the household chefs, and provide reference for government to adjust and optimize the strategy on avian influenza prevention. Methods: According to the geographical characteristics and regional functions, 6 'monitoring stations' were selected from 12 residential districts of Guangzhou, respectively. Another 21 meat markets which selling live poultry, were selected in each station and 5 household chefs of each market were invited to attend a face to face interview. Basic information, personal cognitive, willingness and influencing factors to the policy were under study. Univariate and multivariate logistic regression methods were used. Results: A total of 664 household chefs underwent the survey and results showed that the rate of support to the "centralized slaughtering, fresh poultry listing and marketing" strategy was 44.6% (296/664). Results from the multi-factor logistic regression showed that those household chefs who were males (OR=1.618, 95% CI: 1.156-2.264, P=0.005), having received higher education (OR=1.814, 95% CI: 1.296-2.539, P=0.001), or believing that the existence of live poultry stalls was related to the transmission of avian influenza (OR=1.918, 95% CI: 1.341-2.743, P<0.001) were factors at higher risk. These household chefs also intended to avoid the use of live poultry stalls (OR=1.666, 95%CI: 1.203-2.309, P=0.002) and accept the "centralized slaughtering, fresh poultry listing and marketing" strategy. Conclusion: Detailed study on this subject and, setting up pilot project in some areas as well as prioritizing the education programs for household chefs seemed helpful to the implementation of the 'freezing-fresh poultry' policy.