Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 4.186
Filtrar
1.
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
2.
Proc Biol Sci ; 287(1934): 20201680, 2020 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-32901574

RESUMO

In this investigation, we used a combination of field- and laboratory-based approaches to assess if influenza A viruses (IAVs) shed by ducks could remain viable for extended periods in surface water within three wetland complexes of North America. In a field experiment, replicate filtered surface water samples inoculated with duck swabs were tested for IAVs upon collection and again after an overwintering period of approximately 6-7 months. Numerous IAVs were molecularly detected and isolated from these samples, including replicates maintained at wetland field sites in Alaska and Minnesota for 181-229 days. In a parallel laboratory experiment, we attempted to culture IAVs from filtered surface water samples inoculated with duck swabs from Minnesota each month during September 2018-April 2019 and found monthly declines in viral viability. In an experimental challenge study, we found that IAVs maintained in filtered surface water within wetlands of Alaska and Minnesota for 214 and 226 days, respectively, were infectious in a mallard model. Collectively, our results support surface waters of northern wetlands as a biologically important medium in which IAVs may be both transmitted and maintained, potentially serving as an environmental reservoir for infectious IAVs during the overwintering period of migratory birds.


Assuntos
Patos/virologia , Vírus da Influenza A , Influenza Aviária/virologia , Áreas Alagadas , Animais , América do Norte
3.
Zhonghua Liu Xing Bing Xue Za Zhi ; 41(7): 1115-1120, 2020 Jul 10.
Artigo em Chinês | MEDLINE | ID: mdl-32741181

RESUMO

Objective: To analyze the characteristics of spread and genetic evolution of H5 subtype avian influenza virus in Guangzhou from 2014 to 2019. Methods: H5 subtype virus was detected by fluorescence quantitative RT-PCR from the environmental samples in Guangzhou poultry markets. The genes of HA and NA of 48 isolates randomly selected were sequenced, including 46 isolates from environmental samples and 2 isolates from cases. The characteristics of molecular variation and genetic evolution were analyzed by using bioinformatics software. Results: A total of 1 094 strains of H5 subtype avian influenza virus were isolated from 52 284 samples (2.09%). All the strains belonged to Clade 2.3.4.4.C. NA gene belonged to H6N6 of Eurasian lineage. The cleavage sites of all the strains showed the characteristics of highly pathogenicity. Receptor binding sites were avian-derived receptors. However, mutations of S123P, S133A and T156A occurred, which implied that these strains could tend to bind to human receptors. There was an additional glycosylation site at 140 in strains isolated after 2017. The variation of antigen loci mainly occurred in B and E regions. Conclusions: H5 subtype avian influenza virus spread in Guangzhou from 2014 to 2019 with annual increased proportion of positive rate, and the sequencing results indicated that it belonged to Clade 2.3.4.4.C of H5N6 highly pathogenic virus, and genetic evolution and mutation continued, especially the common mutations which could enhance the binding capacity to human receptors. It is necessary to strengthen the surveillance.


Assuntos
Vírus da Influenza A/genética , Influenza Aviária/epidemiologia , Influenza Aviária/virologia , Animais , China/epidemiologia , Evolução Molecular , Vírus da Influenza A/isolamento & purificação , Aves Domésticas
4.
BMC Bioinformatics ; 21(Suppl 10): 354, 2020 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-32838732

RESUMO

BACKGROUND: Type A influenza viruses circulate and spread among wild birds and mostly consist of low pathogenic strains. However, fast genome variation timely results in the insurgence of high pathogenic strains, which when infecting poultry birds may cause a million deaths and strong commercial damage. More importantly, the host shift may concern these viruses and sustained human-to-human transmission may result in a dangerous pandemic outbreak. Therefore, fingerprints specific to either low or high pathogenic strains may represent a very important tool for global surveillance. RESULTS: We combined Normal Modes Analysis and surface electrostatic analysis of a mixed strain dataset of influenza A virus haemagglutinins from high and low pathogenic strains in order to infer specific fingerprints. Normal Modes Analysis sorted the strains in two different, homogeneous clusters; sorting was independent of clades and specific instead to high vs low pathogenicity. A deeper analysis of fluctuations and flexibility regions unveiled a special role for the 110-helix region. Specific sorting was confirmed by surface electrostatics analysis, which further allowed to focus on regions and mechanisms possibly crucial to the low-to-high transition. CONCLUSIONS: Evidence from previous work demonstrated that changes in surface electrostatics are associated with the evolution and spreading of avian influenza A virus clades, and seemingly involved also in the avian to mammalian host shift. This work shows that a combination of electrostatics and Normal Modes Analysis can also identify fingerprints specific to high and low pathogenicity. The possibility to predict which specific mutations may result in a shift to high pathogenicity may help in surveillance and vaccine development.


Assuntos
Glicoproteínas de Hemaglutininação de Vírus da Influenza/metabolismo , Vírus da Influenza A/metabolismo , Vírus da Influenza A/patogenicidade , Eletricidade Estática , Algoritmos , Animais , Animais Selvagens/virologia , Aves/virologia , Glicoproteínas de Hemaglutininação de Vírus da Influenza/química , Influenza Aviária/virologia , Modelos Moleculares , Domínios Proteicos
5.
PLoS One ; 15(8): e0236581, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32790744

RESUMO

Emergence and intercontinental spread of highly pathogenic avian influenza A (HPAI) H5Nx virus clade 2.3.4.4 has resulted in substantial economic losses to the poultry industry in Asia, Europe, and North America. The long-distance migratory birds have been suggested to play a major role in the global spread of avian influenza viruses during this wave of panzootic outbreaks since 2013. Poultry farm epidemics caused by multiple introduction of different HPAI novel subtypes of clade 2.3.4.4 viruses also occurred in Taiwan between 2015 and 2017. The mandatory and active surveillance detected H5N3 and H5N6 circulation in 2015 and 2017, respectively, while H5N2 and H5N8 were persistently identified in poultry farms since their first arrival in 2015. This study intended to assess the importance of various ecological factors contributed to the persistence of HPAI during three consecutive years. We used satellite technology to identify the location of waterfowl flocks. Four risk factors consistently showed strong association with the spatial clustering of H5N2 and H5N8 circulations during 2015 and 2017, including high poultry farm density (aOR:17.46, 95%CI: 5.91-74.86 and 8.23, 95% CI: 2.12-54.86 in 2015 and 2017, respectively), poultry heterogeneity index (aOR of 12.28, 95%CI: 5.02-31.14 and 2.79, 95%CI: 1.00-7.69, in 2015 and 2017, respectively), non-registered waterfowl flock density (aOR: 6.8, 95%CI: 3.41-14.46 and 9.17, 95%CI: 3.73-26.20, in 2015 and 2017, respectively) and higher percentage of cropping land coverage (aOR of 1.36, 95%CI: 1.10-1.69 and 1.04, 95%CI: 1.02-1.07, in 2015 and 2017, respectively). Our study highlights the application of remote sensing and clustering analysis for the identification and characterization of environmental factors in facilitating and contributing to the persistent circulation of certain subtypes of H5Nx in poultry farms in Taiwan.


Assuntos
Vírus da Influenza A Subtipo H5N2/isolamento & purificação , Vírus da Influenza A Subtipo H5N8/isolamento & purificação , Influenza Aviária/virologia , Doenças das Aves Domésticas/virologia , Aves Domésticas/virologia , Animais , Meio Ambiente , Fazendas , Influenza Aviária/epidemiologia , Doenças das Aves Domésticas/epidemiologia , Fatores de Risco , Taiwan/epidemiologia , Microbiologia da Água
6.
BMC Infect Dis ; 20(1): 550, 2020 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-32727378

RESUMO

BACKGROUND: Highly pathogenic influenza A (H5N8) viruses have caused several worldwide outbreaks in birds and are of potential risk to humans. Thus, a specific, rapid and sensitive method for detection is urgently needed. METHODS: In the present study, TaqMan minor groove binder probes and multiplex real-time RT-PCR primers were designed to target the H5 hemagglutinin and N8 neuraminidase genes. A total of 38 strains of avian influenza viruses and other viruses were selected to test the performance of the assay. RESULTS: The results showed that only H5 and N8 avian influenza viruses yielded a positive signal, while all other subtypes avian influenza viruses and other viruses were negative. High specificity, repeatability, and sensitivity were achieved, with a detection limit of 10 copies per reaction. CONCLUSIONS: The developed assay could be a powerful tool for rapid detection of H5N8 influenza viruses in the future.


Assuntos
Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Vírus da Influenza A Subtipo H5N8/genética , Influenza Aviária/diagnóstico , Reação em Cadeia da Polimerase Multiplex/métodos , Neuraminidase/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodos , Animais , Aves/virologia , Primers do DNA/genética , Feminino , Influenza Aviária/virologia , Camundongos , Camundongos Endogâmicos BALB C , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
7.
BMC Bioinformatics ; 21(1): 316, 2020 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-32682392

RESUMO

BACKGROUND: The pandemic threat of influenza has attracted great attention worldwide. To assist public health decision-makers, new suites of tools are needed to rapidly process and combine viral information retrieved from public-domain databases for a better risk assessment. RESULTS: Using our recently developed FluConvert and IniFlu software, we automatically processed and rearranged sequence data by standard viral nomenclature, determined the group-related consensus sequences, and identified group-specific polygenic signatures. The software possesses powerful ability to integrate viral, clinical, and epidemiological data. We demonstrated that both multiple basic amino acids at the cleavage site of the HA gene and also at least 11 more evidence-based viral amino acid substitutions present in global highly pathogenic avian influenza H5N2 viruses during the years 2009-2016 that are associated with viral virulence and human infection. CONCLUSIONS: FluConvert and IniFlu are useful to monitor and assess all subtypes of influenza viruses with pandemic potential. These programs are implemented through command-line and user-friendly graphical interfaces, and identify molecular signatures with virological, epidemiological and clinical significance. FluConvert and IniFlu are available at https://apps.flutures.com or https://github.com/chinrur/FluConvert_IniFlu.


Assuntos
Vírus da Influenza A Subtipo H5N2/patogenicidade , Influenza Aviária/patologia , Interface Usuário-Computador , Sequência de Aminoácidos , Animais , Aves , Glicoproteínas de Hemaglutininação de Vírus da Influenza/química , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Vírus da Influenza A Subtipo H5N2/genética , Influenza Aviária/imunologia , Influenza Aviária/virologia , Medição de Risco , Alinhamento de Sequência , Virulência
8.
Nat Commun ; 11(1): 3656, 2020 07 21.
Artigo em Inglês | MEDLINE | ID: mdl-32694517

RESUMO

Avian influenza polymerase undergoes host adaptation in order to efficiently replicate in human cells. Adaptive mutants are localised on the C-terminal (627-NLS) domains of the PB2 subunit. In particular, mutation of PB2 residue 627 from E to K rescues polymerase activity in mammalian cells. A host transcription regulator ANP32A, comprising a long C-terminal intrinsically disordered domain (IDD), is responsible for this adaptation. Human ANP32A IDD lacks a 33 residue insertion compared to avian ANP32A, and this deletion restricts avian influenza polymerase activity. We used NMR to determine conformational ensembles of E627 and K627 forms of 627-NLS of PB2 in complex with avian and human ANP32A. Human ANP32A IDD transiently binds to the 627 domain, exploiting multivalency to maximise affinity. E627 interrupts the polyvalency of the interaction, an effect compensated by an avian-unique motif in the IDD. The observed binding mode is maintained in the context of heterotrimeric influenza polymerase, placing ANP32A in the immediate vicinity of known host-adaptive PB2 mutants.


Assuntos
Proteínas Aviárias/ultraestrutura , Virus da Influenza A Subtipo H5N1/patogenicidade , Proteínas Nucleares/ultraestrutura , Domínios Proteicos/genética , RNA Replicase/ultraestrutura , Proteínas de Ligação a RNA/ultraestrutura , Proteínas Virais/ultraestrutura , Animais , Proteínas Aviárias/metabolismo , Aves/virologia , Humanos , Virus da Influenza A Subtipo H5N1/genética , Virus da Influenza A Subtipo H5N1/metabolismo , Influenza Aviária/virologia , Influenza Humana/virologia , Mutação , Ressonância Magnética Nuclear Biomolecular , Proteínas Nucleares/metabolismo , Ligação Proteica/genética , RNA Replicase/genética , RNA Replicase/metabolismo , Proteínas de Ligação a RNA/metabolismo , Especificidade da Espécie , Proteínas Virais/genética , Proteínas Virais/metabolismo , Replicação Viral
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.
Avian Dis ; 64(2): 135-142, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32550613

RESUMO

Aquatic wild birds, especially waterfowl, have been long considered the main reservoirs of the avian influenza A virus; however, recent surveys have found an important prevalence of these viruses among land birds as well. Migration has been suggested as an important factor in the avian influenza virus dissemination. We aimed to estimate the prevalence of influenza A viruses in wild birds (waterbirds and land birds; resident and migratory) in eastern Mexico, where the three main North American migration flyways converge and where there was no previous information on this subject. We detected influenza with reverse transcription coupled with a PCR approach. Of the 534 birds sampled between 2010 and 2012, we detected the influenza A virus in a high proportion of birds (39%). Prevalence was particularly high in land birds (49%) when compared to aquatic birds (26%); there was no difference in overall prevalence between resident (39%) and migratory birds (39%). The high prevalence of the avian influenza virus in land birds was noteworthy in the innermost sampling areas in northern Mexico (Coahuila [82%] and Nuevo Leon [43%]).


Assuntos
Aves , Vírus da Influenza A/isolamento & purificação , Influenza Aviária/epidemiologia , Migração Animal , Animais , Influenza Aviária/virologia , México/epidemiologia , Prevalência , Reação em Cadeia da Polimerase Via Transcriptase Reversa/veterinária
11.
Avian Dis ; 64(2): 143-148, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32550614

RESUMO

Both highly pathogenic (HP) and low pathogenic (LP) avian influenza virus (AIV) can cause decreases or even cessation of egg production in chickens and turkeys. Production of abnormal eggs (deformed, thin-shelled, soft-shelled) can also be caused by AIV infection. Additionally, egg surfaces and contents may also be contaminated with virus. Because data quantifying these effects are lacking, white Plymouth Rock hens were inoculated with HP or LP AIV while in production. No decreases in egg production or abnormal eggs were observed with LPAIV-infected hens. No lesions or viral antigen staining in ovary and oviduct were observed in LPAIV-infected hens 3 days postchallenge. LPAIV RNA was detected on eggs collected from 12 hr to 11 days postinoculation (PI) and was on or in 6.4% (15/234) of the eggs. Titer equivalents of LPAIV ranged from 1.3-2.5 log10 50% egg infectious doses (EID50). No virus was detected in embryo tissue from eggs laid by LPAIV-infected hens. In contrast, egg production by HPAIV-inoculated hens decreased at 72 hr PI and 18.4% (16/87) of the eggs were abnormal. However, viability was similar to that of the sham inoculates. HPAIV RNA was detected in or on 11.1% (9/81) of the eggs from 36 hr through 96 hr PI, when the hens were euthanatized. HPAIV RNA was detected on 6.2% of eggshells, in 4.2% of albumin/yolk samples, and in 8.3% of embryo tissue. Forty percent of the abnormal eggs were positive for HPAIV RNA. Titer equivalents on or in HPAIV-contaminated eggs ranges from 1.0-4.0 log10 EID50. Lesions and viral antigen staining were present in the ovary and all sections of the oviduct of infected hens 3 days postchallenge. These data will inform models using production-based triggers for LPAIV monitoring and for risk assessments to determine the disposition of eggs from flocks infected with LPAIV or HPAIV.


Assuntos
Embrião de Galinha/virologia , Galinhas , Vírus da Influenza A/fisiologia , Vírus da Influenza A/patogenicidade , Influenza Aviária/virologia , Óvulo/virologia , Doenças das Aves Domésticas/virologia , Criação de Animais Domésticos , Animais , Fertilidade , Reprodução
12.
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
13.
BMC Infect Dis ; 20(1): 369, 2020 May 24.
Artigo em Inglês | MEDLINE | ID: covidwho-343360

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
14.
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
15.
Vet Res ; 51(1): 48, 2020 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-32234073

RESUMO

An intravenous pathogenicity index (IVPI) of > 1.2 in chickens or, in case of subtypes H5 and H7, expression of a polybasic hemagglutinin cleavage site (HACS), signals high pathogenicity (HP). Viruses of the H9N2-G1 lineage, which spread across Asia and Africa, are classified to be of low pathogenicity although, in the field, they became associated with severe clinical signs and epizootics in chickens. Here we report on a pre-eminent trait of recent H9N2-G1 isolates from Bangladesh and India, which express a tribasic HACS (motif PAKSKR-GLF; reminiscent of an HPAIV-like polybasic HACS) and compare their features to H9Nx viruses with di- and monobasic HACS from other phylogenetic and geographic origins. In an in vitro assay, the tribasic HACS of H9N2 was processed by furin-like proteases similar to bona fide H5 HPAIV while some dibasic sites showed increased cleavability but monobasic HACS none. Yet, all viruses remained trypsin-dependent in cell culture. In ovo, only tribasic H9N2 viruses were found to replicate in a grossly extended spectrum of embryonic organs. In contrast to all subtype H5/H7 HPAI viruses, tribasic H9N2 viruses did not replicate in endothelial cells either in the chorio-allantoic membrane or in other embryonic tissues. By IVPI, all H9Nx isolates proved to be of low pathogenicity. Pathogenicity assessment of tribasic H9N2-G1 viruses remains problematic. It cannot be excluded that the formation of a third basic amino acid in the HACS forms an intermediate step towards a gain in pathogenicity. Continued observation of the evolution of these viruses in the field is recommended.


Assuntos
Galinhas , Hemaglutininas/metabolismo , Vírus da Influenza A Subtipo H9N2/metabolismo , Vírus da Influenza A Subtipo H9N2/patogenicidade , Influenza Aviária/virologia , Doenças das Aves Domésticas/virologia , Animais , Embrião de Galinha , Geografia , Filogenia , Virulência
16.
Avian Pathol ; 49(4): 361-368, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32271094

RESUMO

Domestic waterfowl play an important role in the perpetuation and transmission of avian pathogens including avian influenza viruses (AIV) of low and high pathogenicity, which pose severe economic and public health concerns in Bangladesh. This study focused on active surveillance of several avian viral pathogens with a special reference to AIV in selected backyard duck populations in Bangladesh. A total of 500 pooled oropharyngeal and cloacal samples from individual ducks of four districts were tested by real time PCRs for the presence of AIV, avian avulavirus-1, anatid herpesvirus-1, avian parvovirus, avian bornavirus and avian coronavirus. The investigation identified 27 (5.4%) ducks positive for AIV and 12 (2.4%) positive for avian coronavirus. In 13 samples, RNA specific for AIV H4N6 was detected. Phylogenetic analysis of the AIV haemagglutinin H4 and neuraminidase N6 genes suggested a clustering of Bangladeshi AIV H4N6 in Eurasian lineage group 2. Other AIV positive samples had very low virus loads (Cq > 36) and were not subtyped. Coronaviral sequences of a fragment of the polymerase gene were related to Eurasian-Australian duck gamma-coronaviruses. Our current active surveillance in free-range domestic backyard ducks in Bangladesh failed to detect highly pathogenic (HP) AIV in contrast to our previous passive monitoring study. Nevertheless, active monitoring of domestic duck populations may be important to highlight presence and transmission dynamics of economically less important AIV that still may serve as reassortment partners for the generation of new HP and zoonotic AIV. RESEARCH HIGHLIGHTS Active surveillance for viral pathogens in domestic free-range backyard ducks. Detection of avian influenza virus subtype H4N6. First identification of avian gammacoronavirus in ducks in Bangladesh.


Assuntos
Infecções por Coronavirus/veterinária , Patos/virologia , Gammacoronavirus/isolamento & purificação , Vírus da Influenza A/isolamento & purificação , Influenza Aviária/virologia , Doenças das Aves Domésticas/virologia , Animais , Bangladesh/epidemiologia , Infecções por Coronavirus/epidemiologia , Infecções por Coronavirus/virologia , Vírus da Influenza A/genética , Influenza Aviária/epidemiologia , Filogenia , Vigilância da População , Doenças das Aves Domésticas/epidemiologia , Zoonoses
17.
Avian Dis ; 64(1): 85-91, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32267129

RESUMO

Avian influenza A viruses are a major threat to animal and public health. Since 1997, several highly pathogenic H5N1 avian viruses have been directly transmitted from poultry to humans, caused numerous human deaths, and had considerable economic impact on poultry markets. During 2015-2016, a highly pathogenic avian influenza outbreak occurred in southwestern France. Different subtypes circulated, including the A/chicken/France/150169a/2015 H5N1 highly pathogenic virus, which did not possess the full set of genomic determinants known to promote transmission to humans. In order to evaluate the predicted absence of zoonotic potential, a quick method based on in vitro tests was developed to analyze some genetic and phenotypic host restriction determinants. A receptor-binding assay showed that the virus preferentially recognizes avian cell receptors. Temperature sensitivity revealed a cold-sensitive phenotype of the virus at 33 C as virus replication was reduced in contrast with what is expected for human influenza viruses, according to their primary infection sites. Altogether, our quick evaluation method suggests that the A/chicken/France/150169a/2015 H5N1 highly pathogenic virus has an avian phenotype in vitro, in accordance with in silico predictions based on genomic markers.


Assuntos
Galinhas , Técnicas In Vitro/veterinária , Virus da Influenza A Subtipo H5N1/fisiologia , Influenza Aviária/virologia , Doenças das Aves Domésticas/virologia , Tropismo Viral , Animais , França , Técnicas In Vitro/métodos , Virologia/métodos
18.
Avian Dis ; 64(1): 96-98, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32267131

RESUMO

The outbreak of highly pathogenic H5Nx influenza A viruses (IAVs) in the United States during 2014-2015 caused devastating economic losses; therefore, several measures were established to control and eliminate highly pathogenic H5Nx from U.S. poultry flocks. One such measure was a temporary ban on poultry exhibitions during 2015, and this decision dramatically affected youth raising poultry as part of agricultural education programs. During the summer of 2016, surveillance of the environment was conducted at 20 Ohio agricultural fairs to estimate the prevalence of IAV in exhibition poultry to determine the baseline during nonoutbreak exhibition seasons. Of the 400 total samples collected, two were positive by real-time reverse transcription-PCR; however, virus isolation attempts with both embryonating chicken eggs and cell culture were unsuccessful. The detection of nucleic acid highlights the risk exhibition poultry could play in the transmission and spread of IAVs between humans, swine, wild birds, and domestic poultry during low or highly pathogenic IAV outbreaks. Additional surveillance at agricultural fairs and biosecurity education for youth exhibitors in this setting are warranted to reduce risk.


Assuntos
Anseriformes , Monitoramento Epidemiológico/veterinária , Vírus da Influenza A/isolamento & purificação , Influenza Aviária/epidemiologia , Doenças das Aves Domésticas/epidemiologia , Aves Domésticas , Animais , Influenza Aviária/virologia , Ohio/epidemiologia , Doenças das Aves Domésticas/virologia , Prevalência
19.
Arch Razi Inst ; 75(1): 9-16, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32291997

RESUMO

Avian influenza virus (AIV) H9N2 is endemic in Iran and its large-scale circulation in the poultry industry of the country is devastating. This virus was first reported in the industrial poultry populations of Iran in July 1998. Some of the published studies showed that inactivated avian influenza (AI) vaccines are capable of inducing an immune response and providing protection against morbidity and mortality in different countries (Vasfi et al., 2002; Tavakkoli et al., 2011). Low pathogenicity avian influenza subtype H9N2 virus has been reported to have a zoonotic potential and widespread distribution in Iran. Therefore, water-in-oil emulsion vaccines are employed to control the disease in chickens (Nili and Asasi, 2003). This cohort study was conducted during July 2016-November 2017 in broiler chicken farms of Qazvin province, Iran to investigate the serological change trends in broiler chickens in this region. Level of immunity against the H9N2 virus was evaluated by hemagglutination inhibition assay. Fifteen farms out of thirty enrolled units used AI H9N2 killed vaccines. The minimum of mean antibody titers (MATs) was 4.54-2.42 and the maximum of MATs was 4.54+2.42 on day 3. In addition, the minimum and maximum MATs on day 50 were 0.4-0.64 and 0.4+0.064, respectively. The transfer rate of H9N2 AIV antibodies from the serum of breeders to the serum of chickens was calculated as 60.35% in our study. A significant difference was revealed between the maternal mean antibody titers (MMATs) and the MATs on day 3 (P<0.001). In addition, the difference between the MATs on day 3 and the MATs on day 10 was found to be significant (P<0.01). Moreover, MATs were significantly different between the vaccinated and unvaccinated herds on day 40 (P<0.05), while no significant difference was observed on days 3, 10, 20, and 30 (P>0.05). According to the results of this study, antibody titers in the vaccinated farms did not reach the protective level until the end of the rearing period. Most of the unvaccinated herds experienced a spurt in antibody titers due to exposure to the virus. Consequently, biosecurity measures must be implemented more seriously and strictly in broiler farms.


Assuntos
Galinhas , Vírus da Influenza A Subtipo H9N2/imunologia , Vacinas contra Influenza/imunologia , Influenza Aviária/prevenção & controle , Doenças das Aves Domésticas/prevenção & controle , Animais , Estudos de Coortes , Vacinas contra Influenza/administração & dosagem , Influenza Aviária/virologia , Irã (Geográfico) , Doenças das Aves Domésticas/virologia , Vacinas de Produtos Inativados/administração & dosagem , Vacinas de Produtos Inativados/imunologia
20.
Arch Razi Inst ; 75(1): 17-22, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32291998

RESUMO

Avian influenza viruses (AIV) affect a wide range of birds and mammals, cause severe economic damage to the poultry industry, and pose a serious threat to humans. Highly pathogenic avian influenza viruses (HPAI) H5N1 were first identified in Southeast Asia in 1996 and spread to four continents over the following years. The viruses have caused high mortality in chickens and various bird species and deadly infections in humans. Multiple conventional methods have been so far introduced for the detection and identification of avian influenza viruses. Traditional virus isolation methods are gold standard protocol in AI detection; nonetheless, virus isolation in embryonating chicken eggs (ECE) is not a rapid method for the detection of influenza viruses since it is time-consuming and labor-intensive. Furthermore, the isolation of highly pathogenic viruses, such as H5, needs BSL3 laboratories. Real-Time Reverse Transcription-Polymerase Chain Reaction (RRT-PCR) is a sensitive and specific method for the detection of influenza viruses. The application of these nucleic acid-based techniques has increased our ability to identify and perform influenza virus care programs, especially in surveillance programs. The current study aimed to detect H5 subtype of avian influenza (AI) virus using fast, specific, and sensitive TaqMan RRT-PCR. Notably, single step RRT-PCR was used to prevent possible laboratory contamination. The specificity of this test was evaluated using nucleic acid extracted from several poultry pathogenic microorganisms and negative clinical specimens from AI-uninfected birds. The sensitivity analysis of the RRT-PCR assay was performed using in vitro-transcribed RNA copy and 10-fold serial dilution of standard AI virus with specific titer. The results indicated the high sensitivity of this method and the lowest detectable dilution of this method based on RNA copies and 1:10 serial dilutions of the standard virus was 10 1.9 EID50 /100.


Assuntos
Galinhas , Vírus da Influenza A/isolamento & purificação , Influenza Aviária/diagnóstico , Doenças das Aves Domésticas/diagnóstico , Reação em Cadeia da Polimerase em Tempo Real/veterinária , Reação em Cadeia da Polimerase Via Transcriptase Reversa/veterinária , Animais , Virus da Influenza A Subtipo H5N1/isolamento & purificação , Vírus da Influenza A Subtipo H5N2/isolamento & purificação , Vírus da Influenza A Subtipo H5N8/isolamento & purificação , Influenza Aviária/virologia , Óvulo/virologia , Doenças das Aves Domésticas/virologia , Reação em Cadeia da Polimerase em Tempo Real/métodos , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodos , Sensibilidade e Especificidade
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA