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1.
Viruses ; 13(2)2021 02 08.
Artigo em Inglês | MEDLINE | ID: mdl-33567525

RESUMO

Avian influenza virus (AIV) subtypes H5 and H7 are capable of mutating from low to high pathogenicity strains, causing high mortality in poultry with significant economic losses globally. During 2015, two outbreaks of H7N7 low pathogenicity AIV (LPAIV) in Germany, and one each in the United Kingdom (UK) and The Netherlands occurred, as well as single outbreaks of H7N7 high pathogenicity AIV (HPAIV) in Germany and the UK. Both HPAIV outbreaks were linked to precursor H7N7 LPAIV outbreaks on the same or adjacent premises. Herein, we describe the clinical, epidemiological, and virological investigations for the H7N7 UK HPAIV outbreak on a farm with layer chickens in mixed free-range and caged units. H7N7 HPAIV was identified and isolated from clinical samples, as well as H7N7 LPAIV, which could not be isolated. Using serological and molecular evidence, we postulate how the viruses spread throughout the premises, indicating potential points of incursion and possible locations for the mutation event. Serological and mortality data suggested that the LPAIV infection preceded the HPAIV infection and afforded some clinical protection against the HPAIV. These results document the identification of a LPAIV to HPAIV mutation in nature, providing insights into factors that drive its manifestation during outbreaks.


Assuntos
Vírus da Influenza A Subtipo H7N7/genética , Vírus da Influenza A Subtipo H7N7/patogenicidade , Influenza Aviária/virologia , Doenças das Aves Domésticas/virologia , Animais , Anticorpos Antivirais/sangue , Galinhas , Surtos de Doenças/veterinária , Fazendas , Genoma Viral/genética , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Glicoproteínas de Hemaglutininação de Vírus da Influenza/imunologia , Vírus da Influenza A Subtipo H7N7/classificação , Vírus da Influenza A Subtipo H7N7/imunologia , Influenza Aviária/epidemiologia , Influenza Aviária/patologia , Influenza Aviária/transmissão , Mutação , Filogenia , Doenças das Aves Domésticas/epidemiologia , Doenças das Aves Domésticas/patologia , Doenças das Aves Domésticas/transmissão , Reino Unido/epidemiologia , Eliminação de Partículas Virais/genética
2.
Viruses ; 13(2)2021 02 10.
Artigo em Inglês | MEDLINE | ID: mdl-33579009

RESUMO

Highly pathogenic avian influenza (HPAI), a zoonotic disease, is a major threat to humans and poultry health worldwide. In January 2014, HPAI virus subtype H5N8 first infected poultry farms in South Korea, and 393 outbreaks, overall, were reported with enormous economic damage in the poultry industry. We analyzed the spatiotemporal distribution of HPAI H5N8 outbreaks in poultry farms using the global and local spatiotemporal interaction analyses in the first (January to July 2014) and second (September 2014 to June 2015) outbreak waves. The space-time K-function analyses revealed significant interactions within three days and in an over-40 km space-time window between the two study periods. The excess risk attributable value (D0) was maintained despite the distance in the case of HPAI H5N8 in South Korea. Eleven spatiotemporal clusters were identified, and the results showed that the HPAI introduction was from the southwestern region, and spread to the middle region, in South Korea. This spatiotemporal interaction indicates that the HPAI epidemic in South Korea was mostly characterized by short period transmission, regardless of the distance. This finding supports strict control strategies such as preemptive depopulation, and poultry movement tracking. Further studies are needed to understand HPAI disease transmission patterns.


Assuntos
Surtos de Doenças/veterinária , Vírus da Influenza A Subtipo H5N8/patogenicidade , Influenza Aviária/transmissão , Doenças das Aves Domésticas/transmissão , Animais , Análise por Conglomerados , Surtos de Doenças/prevenção & controle , Fazendas , Influenza Aviária/epidemiologia , Influenza Aviária/prevenção & controle , Aves Domésticas , Doenças das Aves Domésticas/epidemiologia , Doenças das Aves Domésticas/prevenção & controle , República da Coreia/epidemiologia , Análise Espaço-Temporal
3.
J Virol ; 95(6)2021 02 24.
Artigo em Inglês | MEDLINE | ID: mdl-33361418

RESUMO

Dabbling and diving ducks partly occupy shared habitats but have been reported to play different roles in wildlife infectious disease dynamics. Influenza A virus (IAV) epidemiology in wild birds has been based primarily on surveillance programs focused on dabbling duck species, particularly mallard (Anas platyrhynchos). Surveillance in Eurasia has shown that in mallards, some subtypes are commonly (H1 to H7 and H10), intermediately (H8, H9, H11, and H12), or rarely (H13 to H16) detected, contributing to discussions on virus host range and reservoir competence. An alternative to surveillance in determining IAV host range is to study virus attachment as a determinant for infection. Here, we investigated the attachment patterns of all avian IAV subtypes (H1 to H16) to the respiratory and intestinal tracts of four dabbling duck species (Mareca and Anas spp.), two diving duck species (Aythya spp.), and chicken, as well as to a panel of 65 synthetic glycan structures. We found that IAV subtypes generally showed abundant attachment to colon of the Anas duck species, mallard, and Eurasian teal (Anas crecca), supporting the fecal-oral transmission route in these species. The reported glycan attachment profile did not explain the virus attachment patterns to tissues but showed significant attachment of duck-originated viruses to fucosylated glycan structures and H7 virus tropism for Neu5Gc-LN. Our results suggest that Anas ducks play an important role in the ecology and epidemiology of IAV. Further knowledge on virus tissue attachment, receptor distribution, and receptor binding specificity is necessary to understand the mechanisms underlying host range and epidemiology of IAV.IMPORTANCE Influenza A viruses (IAVs) circulate in wild birds worldwide. From wild birds, the viruses can cause outbreaks in poultry and sporadically and indirectly infect humans. A high IAV diversity has been found in mallards (Anas platyrhynchos), which are most often sampled as part of surveillance programs; meanwhile, little is known about the role of other duck species in IAV ecology and epidemiology. In this study, we investigated the attachment of all avian IAV hemagglutinin (HA) subtypes (H1 to H16) to tissues of six different duck species and chicken as an indicator of virus host range. We demonstrated that the observed virus attachment patterns partially explained reported field prevalence. This study demonstrates that dabbling ducks of the Anas genus are potential hosts for most IAV subtypes, including those infecting poultry. This knowledge is useful to target the sampling of wild birds in nature and to further study the interaction between IAVs and birds.


Assuntos
Patos/virologia , Vírus da Influenza A/fisiologia , Influenza Aviária/virologia , Animais , Galinhas/virologia , Colo/virologia , Patos/classificação , Glicoproteínas de Hemaglutininação de Vírus da Influenza/metabolismo , Especificidade de Hospedeiro , Vírus da Influenza A/classificação , Vírus da Influenza A/metabolismo , Influenza Aviária/transmissão , Polissacarídeos/química , Polissacarídeos/metabolismo , Sistema Respiratório/virologia , Tropismo Viral , Ligação Viral
4.
Nat Commun ; 11(1): 5511, 2020 11 02.
Artigo em Inglês | MEDLINE | ID: mdl-33139731

RESUMO

Parallel molecular evolution and adaptation are important phenomena commonly observed in viruses. Here, we exploit parallel molecular evolution to understand virulence evolution in avian influenza viruses (AIV). Highly-pathogenic AIVs evolve independently from low-pathogenic ancestors via acquisition of polybasic cleavage sites. Why some AIV lineages but not others evolve in this way is unknown. We hypothesise that the parallel emergence of highly-pathogenic AIV may be facilitated by permissive or compensatory mutations occurring across the viral genome. We combine phylogenetic, statistical and structural approaches to discover parallel mutations in AIV genomes associated with the highly-pathogenic phenotype. Parallel mutations were screened using a statistical test of mutation-phenotype association and further evaluated in the contexts of positive selection and protein structure. Our resulting mutational panel may help to reveal new links between virulence evolution and other traits, and raises the possibility of predicting aspects of AIV evolution.


Assuntos
Evolução Molecular , Vírus da Influenza A/patogenicidade , Influenza Aviária/virologia , Influenza Humana/virologia , Virulência/genética , Animais , Sequência de Bases/genética , Aves/virologia , Conjuntos de Dados como Assunto , Genoma Viral/genética , Humanos , Vírus da Influenza A/genética , Influenza Aviária/transmissão , Influenza Humana/transmissão , Mutação , Filogenia , Estabilidade Proteica , Seleção Genética , Alinhamento de Sequência , Proteínas Virais/genética
5.
Front Immunol ; 11: 552909, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33013925

RESUMO

The 2019 novel coronavirus (SARS-CoV-2) pandemic has caused a global health emergency. The outbreak of this virus has raised a number of questions: What is SARS-CoV-2? How transmissible is SARS-CoV-2? How severely affected are patients infected with SARS-CoV-2? What are the risk factors for viral infection? What are the differences between this novel coronavirus and other coronaviruses? To answer these questions, we performed a comparative study of four pathogenic viruses that primarily attack the respiratory system and may cause death, namely, SARS-CoV-2, severe acute respiratory syndrome (SARS-CoV), Middle East respiratory syndrome (MERS-CoV), and influenza A viruses (H1N1 and H3N2 strains). This comparative study provides a critical evaluation of the origin, genomic features, transmission, and pathogenicity of these viruses. Because the coronavirus disease 2019 (COVID-19) pandemic caused by SARS-CoV-2 is ongoing, this evaluation may inform public health administrators and medical experts to aid in curbing the pandemic's progression.


Assuntos
Betacoronavirus/genética , Infecções por Coronavirus/epidemiologia , Vírus da Influenza A Subtipo H1N1/genética , Vírus da Influenza A Subtipo H3N2/genética , Influenza Humana/epidemiologia , Coronavírus da Síndrome Respiratória do Oriente Médio/genética , Pneumonia Viral/epidemiologia , Vírus da SARS/genética , Síndrome Respiratória Aguda Grave/epidemiologia , Animais , Betacoronavirus/patogenicidade , Aves/virologia , Infecções por Coronavirus/transmissão , Infecções por Coronavirus/virologia , Genoma Viral , Humanos , Vírus da Influenza A Subtipo H1N1/patogenicidade , Vírus da Influenza A Subtipo H3N2/patogenicidade , Influenza Aviária/epidemiologia , Influenza Aviária/transmissão , Influenza Aviária/virologia , Influenza Humana/transmissão , Influenza Humana/virologia , Coronavírus da Síndrome Respiratória do Oriente Médio/patogenicidade , Pandemias , Pneumonia Viral/transmissão , Pneumonia Viral/virologia , Vírus da SARS/patogenicidade , Síndrome Respiratória Aguda Grave/transmissão , Síndrome Respiratória Aguda Grave/virologia , Virulência/imunologia
6.
J Virol ; 94(17)2020 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-32611751

RESUMO

Low-pathogenicity avian influenza A(H9N2) viruses, enzootic in poultry populations in Asia, are associated with fewer confirmed human infections but higher rates of seropositivity compared to A(H5) or A(H7) subtype viruses. Cocirculation of A(H5) and A(H7) viruses leads to the generation of reassortant viruses bearing A(H9N2) internal genes with markers of mammalian adaptation, warranting continued surveillance in both avian and human populations. Here, we describe active surveillance efforts in live poultry markets in Vietnam in 2018 and compare representative viruses to G1 and Y280 lineage viruses that have infected humans. Receptor binding properties, pH thresholds for HA activation, in vitro replication in human respiratory tract cells, and in vivo mammalian pathogenicity and transmissibility were investigated. While A(H9N2) viruses from both poultry and humans exhibited features associated with mammalian adaptation, one human isolate from 2018, A/Anhui-Lujiang/39/2018, exhibited increased capacity for replication and transmission, demonstrating the pandemic potential of A(H9N2) viruses.IMPORTANCE A(H9N2) influenza viruses are widespread in poultry in many parts of the world and for over 20 years have sporadically jumped species barriers to cause human infection. As these viruses continue to diversify genetically and antigenically, it is critical to closely monitor viruses responsible for human infections, to ascertain if A(H9N2) viruses are acquiring properties that make them better suited to infect and spread among humans. In this study, we describe an active poultry surveillance system established in Vietnam to identify the scope of influenza viruses present in live bird markets and the threat they pose to human health. Assessment of a recent A(H9N2) virus isolated from an individual in China in 2018 is also reported, and it was found to exhibit properties of adaptation to humans and, importantly, it shows similarities to strains isolated from the live bird markets of Vietnam.


Assuntos
Evolução Molecular , Vírus da Influenza A Subtipo H9N2/genética , Vírus da Influenza A Subtipo H9N2/imunologia , Influenza Aviária/virologia , Influenza Humana/virologia , Fenótipo , Replicação Viral/genética , Animais , Ásia , China , Modelos Animais de Doenças , Feminino , Variação Genética , Humanos , Influenza Aviária/imunologia , Influenza Aviária/transmissão , Influenza Humana/imunologia , Influenza Humana/transmissão , Masculino , Mamíferos , Camundongos , Camundongos Endogâmicos BALB C , Infecções por Orthomyxoviridae/imunologia , Infecções por Orthomyxoviridae/transmissão , Infecções por Orthomyxoviridae/virologia , Aves Domésticas/virologia , Doenças das Aves Domésticas/virologia , Vietnã
7.
PLoS Comput Biol ; 16(7): e1008009, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32628659

RESUMO

Transmission of infectious diseases between immobile hosts (e.g., plants, farms) is strongly dependent on the spatial distribution of hosts and the distance-dependent probability of transmission. As the interplay between these factors is poorly understood, we use spatial process and transmission modelling to investigate how epidemic size is shaped by host clustering and spatial range of transmission. We find that for a given degree of clustering and individual-level infectivity, the probability that an epidemic occurs after an introduction is generally higher if transmission is predominantly local. However, local transmission also impedes transfer of the infection to new clusters. A consequence is that the total number of infections is maximal if the range of transmission is intermediate. In highly clustered populations, the infection dynamics is strongly determined by the probability of transmission between clusters of hosts, whereby local clusters act as multiplier of infection. We show that in such populations, a metapopulation model sometimes provides a good approximation of the total epidemic size, using probabilities of local extinction, the final size of infections in local clusters, and probabilities of cluster-to-cluster transmission. As a real-world example we analyse the case of avian influenza transmission between poultry farms in the Netherlands.


Assuntos
Surtos de Doenças , Transmissão de Doença Infecciosa , Infectologia/tendências , Algoritmos , Criação de Animais Domésticos , Animais , Análise por Conglomerados , Fazendas , Infectologia/métodos , Influenza Aviária/epidemiologia , Influenza Aviária/transmissão , Modelos Biológicos , Países Baixos , Distribuição Normal , Dinâmica Populacional , Aves Domésticas , Probabilidade , Modelos de Riscos Proporcionais , Risco
8.
J Neuropathol Exp Neurol ; 79(8): 823-842, 2020 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-32647884

RESUMO

Biological evolution of the microbiome continually drives the emergence of human viral pathogens, a subset of which attack the nervous system. The sheer number of pathogens that have appeared, along with their abundance in the environment, demand our attention. For the most part, our innate and adaptive immune systems have successfully protected us from infection; however, in the past 5 decades, through pathogen mutation and ecosystem disruption, a dozen viruses emerged to cause significant neurologic disease. Most of these pathogens have come from sylvatic reservoirs having made the energetically difficult, and fortuitously rare, jump into humans. But the human microbiome is also replete with agents already adapted to the host that need only minor mutations to create neurotropic/toxic agents. While each host/virus symbiosis is unique, this review examines virologic and immunologic principles that govern the pathogenesis of different viral CNS infections that were described in the past 50 years (Influenza, West Nile Virus, Zika, Rift Valley Fever Virus, Hendra/Nipah, Enterovirus-A71/-D68, Human parechovirus, HIV, and SARS-CoV). Knowledge of these pathogens provides us the opportunity to respond and mitigate infection while at the same time prepare for inevitable arrival of unknown agents.


Assuntos
Viroses do Sistema Nervoso Central/epidemiologia , Viroses do Sistema Nervoso Central/transmissão , Zoonoses/epidemiologia , Zoonoses/transmissão , Animais , Aves , Viroses do Sistema Nervoso Central/prevenção & controle , Ecossistema , Humanos , Influenza Aviária/epidemiologia , Influenza Aviária/prevenção & controle , Influenza Aviária/transmissão , Influenza Humana/epidemiologia , Influenza Humana/prevenção & controle , Influenza Humana/transmissão , Febre do Nilo Ocidental/epidemiologia , Febre do Nilo Ocidental/prevenção & controle , Febre do Nilo Ocidental/transmissão , Infecção por Zika virus/epidemiologia , Infecção por Zika virus/prevenção & controle , Infecção por Zika virus/transmissão , Zoonoses/prevenção & controle
9.
Avian Dis ; 64(2): 109-122, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32550610

RESUMO

Alaska represents a globally important region for the ecology of avian-origin influenza A viruses (IAVs) given the expansive wetlands in this region, which serve as habitat for numerous hosts of IAVs that disperse among four continents during the annual cycle. Extensive sampling of wild birds for IAVs in Alaska since 1991 has greatly extended inference regarding intercontinental viral exchange between North America and East Asia and the importance of Beringian endemic species to IAV ecology within this region. Data on IAVs in aquatic birds inhabiting Alaska have also been useful for helping to establish global patterns of prevalence in wild birds and viral dispersal across the landscape. In this review, we summarize the main findings from investigations of IAVs in wild birds and wetlands of Alaska with the aim of providing readers with an understanding of viral ecology within this region. More specifically, we review viral detections, evidence of IAV exposure, and genetic characterization of isolates derived from wild bird samples collected in Alaska by host taxonomy. Additionally, we provide a short overview of wetland complexes within Alaska that may be important to IAV ecology at the continental scale.


Assuntos
Aves , Vírus da Influenza A/isolamento & purificação , Influenza Aviária , Alaska/epidemiologia , Animais , Animais Selvagens , Incidência , Vírus da Influenza A/genética , Vírus da Influenza A/fisiologia , Influenza Aviária/epidemiologia , Influenza Aviária/transmissão , Influenza Aviária/virologia , Prevalência , Áreas Alagadas
10.
J Vet Sci ; 21(3): e34, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32476310

RESUMO

BACKGROUND: A nationwide outbreak of foot-and-mouth disease (FMD) in South Korea caused massive economic losses in 2010. Since then, the Animal and Plant Quarantine Agency (QIA) has enhanced disinfection systems regarding livestock to prevent horizontal transmission of FMD and Avian influenza (AI). Although the amount of disinfectant used continues to increase, cases of FMD and AI have been occurring annually in Korea, except 2012 and 2013. OBJECTIVES: This study measured the concentration of the disinfectant to determine why it failed to remove the horizontal transmission despite increased disinfectant use. METHODS: Surveys were conducted from February to May 2017, collecting 348 samples from disinfection systems. The samples were analyzed using the Standards of Animal Health Products analysis methods from QIA. RESULTS: Twenty-three facilities used inappropriate or non-approved disinfectants. Nearly all sampled livestock farms and facilities-93.9%-did not properly adjust the disinfectant concentration. The percentage using low concentrations, or where no effective substance was detected, was 46.9%. Furthermore, 13 samples from the official disinfection station did not use effective disinfectant, and-among 72 samples from the disinfection station-88.89% were considered inappropriate concentration, according to the foot-and-mouth disease virus guidelines; considering the AIV guideline, 73.61% were inappropriate concentrations. Inappropriate concentration samples on automatic (90.00%) and semi-automatic (90.90%) disinfection systems showed no significant difference from manual methods (88.24%). Despite this study being conducted during the crisis level, most disinfectants were used inappropriately. CONCLUSIONS: This may partially explain why horizontal transmission of FMD and AI cannot be effectively prevented despite extensive disinfectant use.


Assuntos
Doenças dos Bovinos , Surtos de Doenças/veterinária , Desinfetantes/farmacologia , Febre Aftosa , Influenza Aviária , Doenças das Aves Domésticas , Doenças dos Suínos , Animais , Bovinos , Doenças dos Bovinos/epidemiologia , Doenças dos Bovinos/prevenção & controle , Doenças dos Bovinos/transmissão , Doenças dos Bovinos/virologia , Galinhas , Surtos de Doenças/prevenção & controle , Patos , Febre Aftosa/epidemiologia , Febre Aftosa/prevenção & controle , Febre Aftosa/transmissão , Febre Aftosa/virologia , Vírus da Febre Aftosa/efeitos dos fármacos , Vírus da Influenza A/efeitos dos fármacos , Influenza Aviária/epidemiologia , Influenza Aviária/prevenção & controle , Influenza Aviária/transmissão , Influenza Aviária/virologia , Gado , Doenças das Aves Domésticas/epidemiologia , Doenças das Aves Domésticas/prevenção & controle , Doenças das Aves Domésticas/transmissão , Doenças das Aves Domésticas/virologia , República da Coreia/epidemiologia , Sus scrofa , Suínos , Doenças dos Suínos/epidemiologia , Doenças dos Suínos/prevenção & controle , Doenças dos Suínos/transmissão , Doenças dos Suínos/virologia
11.
Rev Esp Salud Publica ; 942020 Mar 31.
Artigo em Espanhol | MEDLINE | ID: mdl-32381999

RESUMO

Wild waterfowl are considered the main natural reservoir of influenza viruses and they have contributed to the reassortment of both pandemic viruses and viruses responsible for outbreaks of avian influenza in wild and domestic species. In order to determinate the factors involved, we reviewed the human cases of avian influenza related to the management of wild birds, the use of personal protective equipment, as well as the basis of surveillance programs of highly pathogenic avian influenza in wild birds in Spain. The direct transmission of influenza virus from wild birds to humans is a rare event. However, our epidemiological context is influenced by climate change and marked by the presence of migratory routes from territories where infection may be present. Thus and due to the clinical, economical and public health implications that such infections may have, the different groups exposed to wild birds (veterinarians, biologists, ornithologists, conservationists, field technicians, environmental officers, falconers, hunters, etc.) should know which are the possible sources of infection and how to handle the personal protective equipment. Besides, it is important that those groups know the current sanitary situation regarding avian influenza so they can consequently adapt their activities and employ proper protective measures, in addition to providing valuable information for surveillance programs.


Assuntos
Animais Selvagens/virologia , Aves/virologia , Influenza Aviária/transmissão , Influenza Humana/transmissão , Doenças Profissionais , Exposição Ocupacional/estatística & dados numéricos , Zoonoses/transmissão , Animais , Reservatórios de Doenças/virologia , Humanos , Influenza Aviária/epidemiologia , Influenza Aviária/prevenção & controle , Influenza Humana/epidemiologia , Influenza Humana/prevenção & controle , Doenças Profissionais/epidemiologia , Doenças Profissionais/prevenção & controle , Exposição Ocupacional/efeitos adversos , Exposição Ocupacional/prevenção & controle , Equipamento de Proteção Individual , Vigilância em Saúde Pública , Espanha , Zoonoses/epidemiologia , Zoonoses/prevenção & controle
12.
BMC Infect Dis ; 20(1): 369, 2020 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-32448137

RESUMO

BACKGROUND: Previous studies have proven that the closure of live poultry markets (LPMs) was an effective intervention to reduce human risk of avian influenza A (H7N9) infection, but evidence is limited on the impact of scale and duration of LPMs closure on the transmission of H7N9. METHOD: Five cities (i.e., Shanghai, Suzhou, Shenzhen, Guangzhou and Hangzhou) with the largest number of H7N9 cases in mainland China from 2013 to 2017 were selected in this study. Data on laboratory-confirmed H7N9 human cases in those five cities were obtained from the Chinese National Influenza Centre. The detailed information of LPMs closure (i.e., area and duration) was obtained from the Ministry of Agriculture. We used a generalized linear model with a Poisson link to estimate the effect of LPMs closure, reported as relative risk reduction (RRR). We used classification and regression trees (CARTs) model to select and quantify the dominant factor of H7N9 infection. RESULTS: All five cities implemented the LPMs closure, and the risk of H7N9 infection decreased significantly after LPMs closure with RRR ranging from 0.80 to 0.93. Respectively, a long-term LPMs closure for 10-13 weeks elicited a sustained and highly significant risk reduction of H7N9 infection (RRR = 0.98). Short-time LPMs closure with 2 weeks in every epidemic did not reduce the risk of H7N9 infection (p > 0.05). Partially closed LPMs in some suburbs contributed only 35% for reduction rate (RRR = 0.35). Shenzhen implemented partial closure for first 3 epidemics (p > 0.05) and all closure in the latest 2 epidemic waves (RRR = 0.64). CONCLUSION: Our findings suggest that LPMs all closure in whole city can be a highly effective measure comparing with partial closure (i.e. only urban closure, suburb and rural remain open). Extend the duration of closure and consider permanently closing the LPMs will help improve the control effect. The effect of LPMs closure seems greater than that of meteorology on H7N9 transmission.


Assuntos
Epidemias/prevenção & controle , Subtipo H7N9 do Vírus da Influenza A , Influenza Aviária/epidemiologia , Influenza Aviária/transmissão , Influenza Humana/epidemiologia , Aves Domésticas/virologia , Animais , China/epidemiologia , Cidades/epidemiologia , Humanos , Umidade , Incidência , Influenza Aviária/virologia , Influenza Humana/virologia , Modelos Lineares , Distribuição de Poisson , Fatores de Risco , Temperatura , População Urbana
13.
Zhonghua Liu Xing Bing Xue Za Zhi ; 41(3): 358-362, 2020 Mar 10.
Artigo em Chinês | MEDLINE | ID: mdl-32294835

RESUMO

Objective: To investigate the epidemiological and clinical characteristics of a case infected with avian influenza A (H5N6) virus associated with exposure to aerosol and provide evidence for the prevention and control of human infection with avian influenza virus. Methods: Epidemiological investigation was conducted to identify the history of exposure, infection route, and disease progression. Real-time fluorescent quantitative RT-PCR was used to test the samples collected from the case, close contacts, environment and poultry market. Results: The case had no history of exposure to live poultry and poultry market. But before the onset the case had a history of exposure to the live poultry placed in a car with doors and windows closed. The samples collected from the case's lower respiratory tract and the remaining frozen chicken meat were all influenza A (H5N6) virus positive. Conclusions: The source of infection was the live poultry, and the infection route might be the exposure to aerosol in a car with doors and windows closed, where the poultry were temporarily stored. It is necessary to promote centralized poultry slaughtering, cold chain distribution and fresh poultry sale, as well as strengthen health education and establish the concept of consuming fresh poultry.


Assuntos
Aerossóis/efeitos adversos , Vírus da Influenza A , Influenza Aviária/transmissão , Influenza Humana/epidemiologia , Animais , China/epidemiologia , Humanos , Aves Domésticas
14.
Proc Natl Acad Sci U S A ; 117(11): 5949-5954, 2020 03 17.
Artigo em Inglês | MEDLINE | ID: mdl-32123088

RESUMO

The live poultry trade is thought to play an important role in the spread and maintenance of highly pathogenic avian influenza A viruses (HP AIVs) in Asia. Despite an abundance of small-scale observational studies, the role of the poultry trade in disseminating AIV over large geographic areas is still unclear, especially for developing countries with complex poultry production systems. Here we combine virus genomes and reconstructed poultry transportation data to measure and compare the spatial spread in China of three key subtypes of AIV: H5N1, H7N9, and H5N6. Although it is difficult to disentangle the contribution of confounding factors, such as bird migration and spatial distance, we find evidence that the dissemination of these subtypes among domestic poultry is geographically continuous and likely associated with the intensity of the live poultry trade in China. Using two independent data sources and network analysis methods, we report a regional-scale community structure in China that might explain the spread of AIV subtypes in the country. The identification of this structure has the potential to inform more targeted strategies for the prevention and control of AIV in China.


Assuntos
Influenza Aviária/epidemiologia , Influenza Aviária/transmissão , Influenza Aviária/virologia , Aves Domésticas/virologia , Animais , China/epidemiologia , Genoma Viral , Humanos , Virus da Influenza A Subtipo H5N1 , Subtipo H7N9 do Vírus da Influenza A , Filogeografia , Transportes
16.
Virology ; 541: 113-123, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32056709

RESUMO

H5N8 highly-pathogenic avian influenza viruses (HPAIVs, clade 2.3.4.4) have spread globally via migratory waterfowl. Pekin ducks infected with a UK virus (H5N8-2014) served as the donors of infection in three separate cohousing experiments to attempt onward transmission chains to sequentially introduced groups of contact ducks, chickens and turkeys. Efficient transmission occurred among ducks and turkeys up to the third contact stage, with all (100%) birds becoming infected. Introduction of an additional fourth contact group of ducks to the turkey transmission chain demonstrated retention of H5N8-2014's waterfowl-competent adaptation. However, onward transmission ceased in chickens at the second contact stage where only 13% became infected. Analysis of viral progeny at this contact stage revealed no emergent polymorphisms in the intra-species (duck) transmission chain, but both terrestrial species included changes in the polymerase and accessory genes. Typical HPAIV pathogenesis and mortality occurred in infected chickens and turkeys, contrasting with 5% mortality among ducks.


Assuntos
Galinhas/virologia , Patos/virologia , Vírus da Influenza A Subtipo H5N8/fisiologia , Influenza Aviária/transmissão , Perus/virologia , Tropismo Viral/fisiologia , Animais , Antígenos Virais/análise , Galinhas/genética , Patos/genética , Vírus da Influenza A Subtipo H5N8/imunologia , Vírus da Influenza A Subtipo H5N8/patogenicidade , Influenza Aviária/mortalidade , Polimorfismo Genético , Perus/genética
17.
J Virol ; 94(8)2020 03 31.
Artigo em Inglês | MEDLINE | ID: mdl-31969434

RESUMO

Low-pathogenicity avian influenza (LPAI) viruses of subtypes H5 and H7 have the ability to spontaneously mutate to highly pathogenic (HPAI) virus variants, causing high mortality in poultry. The highly pathogenic phenotype is caused by mutation of the hemagglutinin (HA) cleavage site, but additional mutations may play a role. Evidence from the field for the switch to high pathogenicity remains scarce. This study provides direct evidence for LPAI-to-HPAI virus mutation during H7N3 infection of a turkey farm in the Netherlands. No severe clinical symptoms were reported at the farm, but deep sequencing of isolates from the infected turkeys revealed a minority of HPAI virus sequences (0.06%) in the virus population. The HPAI virus contained a 12-nucleotide insertion in the HA cleavage site that was likely introduced by a single event as no intermediates with shorter inserts were identified. This suggests nonhomologous recombination as the mechanism of insertion. Analysis of different organs of the infected turkeys showed the largest amount of HPAI virus in the lung (4.4%). The HPAI virus was rapidly selected in experimentally infected chickens after both intravenous and intranasal/intratracheal inoculation with a mixed virus preparation. Full-genome sequencing revealed that both pathotypes contained a deletion in the stalk region of the neuraminidase protein. We identified additional mutations in HA and polymerase basic protein 1 (PB1) in the HPAI virus, which were already present as minority variants in the LPAI virus population. Our findings provide more insight into the molecular changes and mechanisms involved in the emergence and selection of HPAI viruses.IMPORTANCE Low-pathogenicity avian influenza (LPAI) viruses circulate in wild birds and can be transmitted to poultry. LPAI viruses can mutate to become highly pathogenic avian influenza (HPAI) viruses causing severe disease and death in poultry. Little is known about this switch to high pathogenicity. We isolated an LPAI H7N3 virus from an infected turkey farm and showed that this contains small amounts of HPAI virus. The HPAI virus rapidly outcompeted the LPAI virus in chickens that were experimentally infected with this mixture of viruses. We analyzed the genome sequences of the LPAI and HPAI viruses and identified several changes that may be important for a virus to become highly pathogenic. This knowledge may be used for timely identification of LPAI viruses that pose a risk of becoming highly pathogenic in the field.


Assuntos
Vírus da Influenza A Subtipo H7N3/patogenicidade , Influenza Aviária/virologia , Doenças das Aves Domésticas/virologia , Animais , Animais Selvagens/virologia , Galinhas/virologia , Modelos Animais de Doenças , Variação Genética , Hemaglutininas/genética , Vírus da Influenza A Subtipo H7N3/genética , Influenza Aviária/patologia , Influenza Aviária/transmissão , Pulmão/patologia , Mutação , Países Baixos , Aves Domésticas , Doenças das Aves Domésticas/patologia , RNA Viral/química , RNA Viral/genética , Baço/patologia , Perus/virologia
18.
PLoS Pathog ; 16(1): e1007857, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31961906

RESUMO

The 2014-2015 highly pathogenic avian influenza (HPAI) H5NX outbreak represents the largest and most expensive HPAI outbreak in the United States to date. Despite extensive traditional and molecular epidemiological studies, factors associated with the spread of HPAI among midwestern poultry premises remain unclear. To better understand the dynamics of this outbreak, 182 full genome HPAI H5N2 sequences isolated from commercial layer chicken and turkey production premises were analyzed using evolutionary models able to accommodate epidemiological and geographic information. Epidemiological compartmental models embedded in a phylogenetic framework provided evidence that poultry type acted as a barrier to the transmission of virus among midwestern poultry farms. Furthermore, after initial introduction, the propagation of HPAI cases was self-sustainable within the commercial poultry industries. Discrete trait diffusion models indicated that within state viral transitions occurred more frequently than inter-state transitions. Distance and sample size were very strongly supported as associated with viral transition between county groups (Bayes Factor > 30.0). Together these findings indicate that the different types of midwestern poultry industries were not a single homogenous population, but rather, the outbreak was shaped by poultry industries and geographic factors.


Assuntos
Vírus da Influenza A Subtipo H5N2/isolamento & purificação , Influenza Aviária/epidemiologia , Doenças das Aves Domésticas/epidemiologia , Agricultura , Animais , Surtos de Doenças , Evolução Molecular , Geografia , Vírus da Influenza A Subtipo H5N2/classificação , Vírus da Influenza A Subtipo H5N2/genética , Influenza Aviária/transmissão , Influenza Aviária/virologia , Filogenia , Aves Domésticas , Doenças das Aves Domésticas/transmissão , Doenças das Aves Domésticas/virologia , Estados Unidos/epidemiologia
19.
Front Med ; 14(1): 8-20, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31989396

RESUMO

Since the first case of novel H7N9 infection was reported, China has experienced five epidemics of H7N9. During the fifth wave, a highly pathogenic H7N9 strain emerged. Meanwhile, the H7N9 virus continues to accumulate mutations, and its affinity for the human respiratory epithelial sialic acid 2-6 receptor has increased. Therefore, a pandemic is still possible. In the past 6 years, we have accumulated rich experience in dealing with H7N9, especially in terms of virus tracing, epidemiological research, key site mutation monitoring, critical disease mechanisms, clinical treatment, and vaccine development. In the research fields above, significant progress has been made to effectively control the spread of the epidemic and reduce the fatality rate. To fully document the research progress concerning H7N9, we reviewed the clinical and epidemiological characteristics of H7N9, the key gene mutations of the virus, and H7N9 vaccine, thus providing a scientific basis for further monitoring and prevention of H7N9 influenza epidemics.


Assuntos
Epidemias/estatística & dados numéricos , Subtipo H7N9 do Vírus da Influenza A/isolamento & purificação , Influenza Humana/epidemiologia , Animais , China/epidemiologia , Humanos , Influenza Aviária/transmissão , Influenza Aviária/virologia , Influenza Humana/virologia , Pandemias/prevenção & controle , Vigilância da População , Aves Domésticas
20.
Microbiol Immunol ; 64(4): 304-312, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31943329

RESUMO

Avian influenza viruses (AIVs) recognize sialic acid linked α2,3 to galactose (SAα2,3Gal) glycans as receptors. In this study, the interactions between hemagglutinins (HAs) of AIVs and sulfated SAα2,3Gal glycans were analyzed to clarify the molecular basis of interspecies transmission of AIVs from ducks to chickens. It was revealed that E190V and N192D substitutions of the HA increased the recovery of viruses derived from an H6 duck virus isolate, A/duck/Hong Kong/960/1980 (H6N2), in chickens. Recombinant HAs from an H6 chicken virus, A/chicken/Tainan/V156/1999 (H6N1), bound to sulfated SAα2,3Gal glycans, whereas the HAs from an H6 duck virus did not. Binding preference of mutant HAs revealed that an E190V substitution is critical for the recognition of sulfated SAα2,3Gal glycans. These results suggest that the binding of the HA from H6 AIVs to sulfated SAα2,3Gal glycans explains a part of mechanisms of interspecies transmission of AIVs from ducks to chickens.


Assuntos
Glicoproteínas de Hemaglutininação de Vírus da Influenza/metabolismo , Vírus da Influenza A/patogenicidade , Influenza Aviária/transmissão , Ácido N-Acetilneuramínico/metabolismo , Polissacarídeos/metabolismo , Receptores Virais/metabolismo , Animais , Galinhas , Cães , Patos , Células HEK293 , Humanos , Influenza Aviária/virologia , Células Madin Darby de Rim Canino , Óvulo , Ligação Proteica
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