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1.
An outbreak of contagious respiratory disease in mink occurred in October 1984 on the south-east coast of Sweden. High morbidity with coughing, sneezing and dullness was reported. Post mortem examination showed interstitial pneumonia in most examined mink. An avian influenza A virus was isolated and shown to belong to serotype H10N4. Serological studies established that this virus was the most probable cause of the outbreak and also that this new viral infection seemed to be limited to the south-east coast of Sweden.  相似文献   

2.
Avian influenza A H5N6 virus is a highly contagious infectious agent that affects domestic poultry and humans in South Asian countries. Vietnam may be an evolutionary hotspot for influenza viruses and therefore could serve as a source of pandemic strains. In 2015, two novel reassortant H5N6 influenza viruses designated as A/quail/Vietnam/CVVI01/2015 and A/quail/Vietnam/CVVI03/2015 were isolated from dead quails during avian influenza outbreaks in central Vietnam, and the whole genome sequences were analyzed. The genetic analysis indicated that hemagglutinin, neuraminidase, and polymerase basic protein 2 genes of the two H5N6 viruses are most closely related to an H5N2 virus (A/chicken/Zhejiang/727079/2014) and H10N6 virus (A/chicken/Jiangxi/12782/2014) from China and an H6N6 virus (A/duck/Yamagata/061004/2014) from Japan. The HA gene of the isolates belongs to clade 2.3.4.4, which caused human fatalities in China during 2014–2016. The five other internal genes showed high identity to an H5N2 virus (A/chicken/Heilongjiang/S7/2014) from China. A whole-genome phylogenetic analysis revealed that these two outbreak strains are novel H6N6-like PB2 gene reassortants that are most closely related to influenza virus strain A/environment/Guangdong/ZS558/2015, which was detected in a live poultry market in China. This report describes the first detection of novel H5N6 reassortants in poultry during an outbreak as well as genetic characterization of these strains to better understand the antigenic evolution of influenza viruses.  相似文献   

3.
In order to determine the actual prevalence of avian influenza viruses (AIV) in wild birds in the Czech Republic extensive surveillance was carried out between January and April 2006. A total of 2101 samples representing 61 bird species were examined for the presence of influenza A by using PCR, sequencing and cultivation on chicken embryos. AIV subtype H5N1 was detected in 12 Mute swans (Cygnus olor). The viruses were determined as HPAI (highly pathogenic avian influenza) and the hemagglutinin sequence was closely similar to A/mallard/Italy/835/06 and A/turkey/Turkey/1194/05. Following the first H5N1 case, about 300 wild birds representing 33 species were collected from the outbreak region and tested for the presence of AIV without any positive result. This is the first report of highly pathogenic avian influenza subtype H5N1 in the Czech Republic. The potential role of swan as an effective vector of avian influenza virus is also discussed.  相似文献   

4.
Neurotropism of the 1997 Hong Kong H5N1 influenza virus in mice   总被引：12，自引：0，他引：12  
The direct transmission of H5N1 influenza A viruses from chickens to humans in Hong Kong in 1997 emphasized the need to have information on the pathogenesis of avian influenza virus infection in mammals. H5N1 influenza viruses isolated from patients during the incident killed experimentally infected mice. The principal lesions of the mice were broncho-interstitial pneumonia and nonsuppurative encephalitis. Infectious viruses and/or viral antigens were detected in the brain as well as in the trigeminal and vagal ganglia but not in the blood of the mice. These findings suggest that the virus reached the brain through the vagus and/or trigeminal nerves following replication in the respiratory mucosa. The results imply that neurotropism of the H5N1 virus in mice is a novel characteristic in the pathogenesis of infection by human influenza virus isolates.  相似文献   

5.
As well as H5 highly pathogenic avian influenza viruses (HPAIV), H7 HPAIV strains have caused serious damages in poultry industries worldwide. Cases of bird-to-human transmission of H7 HPAIV have also been reported [11]. On the outbreak of avian influenza, rapid diagnosis is critical not only for the control of HPAI but also for human health. In the present study, a rapid diagnosis kit based on immunochromatography for the detection of H7 hemagglutinin (HA) antigen of influenza A virus was developed using 2 monoclonal antibodies that recognize different epitopes on the H7 HAs. The kit detected each of the tested 15 H7 influenza virus strains and did not react with influenza A viruses of the other subtypes than H7 or other avian viral and bacterial pathogens. The kit detected H7 HA antigen in the swabs and tissue homogenates of the chickens experimentally infected with HPAIV strain A/chicken/Netherlands/2586/03 (H7N7). The results indicate that the present kit is specific and sensitive enough for the diagnosis of HPAI caused by H7 viruses, thus, recommended for the field application as a pen-site test kit.  相似文献   

6.
This investigation detailed the clinical disease, gross and histologic lesions, and distribution of viral antigen in juvenile laughing gulls (Larus atricilla) intranasally inoculated with either the A/tern/South Africa/61 (H5N3) (tern/SA) influenza virus or the A/chicken/Hong Kong/220/97 (H5N1) (chicken/HK) influenza virus, which are both highly pathogenic for chickens. Neither morbidity nor mortality was observed in gulls inoculated with either virus within the 14-day investigative period. Gross lesions resultant from infection with either virus were only mild, with the tern/SA virus causing decreased lucency of the air sacs (2/6), splenomegaly (2/6), and pancreatic mottling (1/6) and the chicken/HK virus causing only decreased lucency of the air sacs (2/8) and conjunctival edema (2/8). Histologic lesions in the tern/SA-inoculated gulls included a mild to moderate heterophilic to lymphoplasmacytic airsacculitis (6/6), mild to moderate interstitial pneumonia (3/6), and moderate necrotizing pancreatitis and hepatitis at 14 days postinoculation (DPI) (2/6). Immunohistochemical demonstration of viral antigen occurred only in association with lesions in the liver and pancreas. In contrast, viral antigen was not demonstrated in any tissues from the chicken/HK-inoculated gulls, and inflammatory lesions were confined to the air sac (3/8) and lungs (3/8). Both viruses were isolated at low titers (<10(1.68) mean embryo lethal dose) from oropharyngeal and cloacal swabs up to 7 days postinoculation (DPI), from the lung and kidney of one of two tern/SA-inoculated gulls at 14 DPI, and from the lung of one of two chicken/HK-inoculated gulls at 7 DPI. Antibodies to influenza viruses as determined with the agar gel precipitin test at 14 DPI were detected only in the two tern/SA-inoculated gulls and not in the two chicken/HK-inoculated gulls.  相似文献   

7.
The H5N1 type A influenza viruses that emerged in Hong Kong in 1997 are a unique lineage of type A influenza viruses with the capacity to transmit directly from chickens to humans and produce significant disease and mortality in both of these hosts. The objective of this study was to ascertain the susceptibility of emus (Dramaius novaehollandiae), domestic geese (Anser anser domesticus), domestic ducks (Anas platyrhynchos), and pigeons (Columba livia) to intranasal (i.n.) inoculation with the A/chicken/Hong Kong/220/97 (H5N1) highly pathogenic avian influenza virus. No mortality occurred within 10 days postinoculation (DPI) in the four species investigated, and clinical disease, evident as neurologic dysfunction, was observed exclusively in emus and geese. Grossly, pancreatic mottling and splenomegaly were identified in these two species. In addition, the geese had cerebral malacia and thymic and bursal atrophy. Histologically, both the emus and geese developed pancreatitis, meningoencephalitis, and mild myocarditis. Influenza viral antigen was demonstrated in areas with histologic lesions up to 10 DPI in the geese. Virus was reisolated from oropharyngeal and cloacal swabs and from the lung, brain, and kidney of the emus and geese. Moderate splenomegaly was observed grossly in the ducks. Viral infection of the ducks was pneumotropic, as evidenced by mild inflammatory lesions in the respiratory tract and virus reisolation from oropharyngeal swabs and from a lung. Pigeons were resistant to HK/220 infection, lacking gross and histologic lesions, viral antigen, and reisolation of virus. These results imply that emus and geese are susceptible to i.n. inoculation with the HK/220 virus, whereas ducks and pigeons are more resistant. These latter two species probably played a minimal epidemiologic role in the perpetuation of the H5N1 Hong Kong-origin influenza viruses.  相似文献   

8.
中国于2013年底首次发现H10N8亚型禽流感病毒（AIV）能感染人并致死的病例,而在此之前从未有过关于H10N8亚型病毒能感染人的报道,目前也未在其他国家监测到H10N8亚型AIV感染人的病例。与H7N9亚型AIV相似,H10N8亚型AIV在家禽中致病性很弱,可一旦感染人能表现出很强的致病性。感染了H10N8亚型AIV的患者病情恶化快、死亡率高、对人的健康危害很大,但至今尚无有效的防制手段。目前还不太清楚H10N8亚型AIV是通过何种途径传播给人的,今后H10N8亚型AIV是否会在人群中引发新的疫情暴发是人们普遍关心的问题。文章简要介绍了H10N8亚型AIV的特点及研究现状。  相似文献   

9.
In early 2007, H2N3 influenza virus was isolated from a duck and a chicken in two separate poultry flocks in Ohio. Since the same subtype influenza virus with hemagglutinin (H) and neuraminidase (N) genes of avian lineage was also identified in a swine herd in Missouri in 2006, the objective of this study was to characterize and compare the genetic, antigenic, and biologic properties of the avian and swine isolates. Avian isolates were low pathogenic by in vivo chicken pathogenicity testing. Sequencing and phylogenetic analyses revealed that all genes of the avian isolates were comprised of avian lineages, whereas the swine isolates contained contemporary swine internal gene segments, demonstrating that the avian H2N3 viruses were not directly derived from the swine virus. Sequence comparisons for the H and N genes demonstrated that the avian isolates were similar but not identical to the swine isolates. Accordingly, the avian and swine isolates were also antigenically related as determined by hemagglutination-inhibition (HI) and virus neutralization assays, suggesting that both avian and swine isolates originated from the same group of H2N3 avian influenza viruses. Although serological surveys using the HI assay on poultry flocks and swine herds in Ohio did not reveal further spread of H2 virus from the index flocks, surveillance is important to ensure the virus is not reintroduced to domestic swine or poultry. Contemporary H2N3 avian influenza viruses appear to be easily adaptable to unnatural hosts such as poultry and swine, raising concern regarding the potential for interspecies transmission of avian viruses to humans.  相似文献   

10.
Influenza A is a respiratory disease common in the swine industry. Three subtypes, H1N1, H1N2 and H3N2 influenza A viruses, are currently co-circulating in swine populations in Korea. An outbreak of the highly pathogenic avian influenza H5N1 virus occurred in domestic bird farms in Korea during the winter season of 2003. Pigs can serve as hosts for avian influenza viruses, enabling passage of the virus to other mammals and recombination of mammalian and avian influenza viruses, which are more readily transmissible to humans. This study reports the current seroprevalence of swine H1 and H3 influenza in swine populations in Korea by hemagglutination inhibition (HI) assay. We also investigated whether avian H5 and H9 influenza transmission occurred in pigs from Korea using both the HI and neutralization (NT) tests. 51.2% (380/742) of serum samples tested were positive against the swine H1 virus and 43.7% (324/742) were positive against the swine H3 virus by HI assay. The incidence of seropositivity against both the swine H1 virus and the swine H3 virus was 25.3% (188/742). On the other hand, none of the samples tested showed seropositivity against either the avian H5 virus or the avian H9 virus by the HI and NT tests. Therefore, we report the high current seroprevalence and co-infectivity of swine H1 and H3 influenza viruses in swine populations and the lack of seroepidemiological evidence of avian H5 and H9 influenza transmission to Korean pigs.  相似文献   

11.
Lee YN  Lee DH  Park JK  Lim TH  Youn HN  Yuk SS  Lee YJ  Mo IP  Sung HW  Lee JB  Park SY  Choi IS  Song CS 《Avian diseases》2011,55(4):724-727
An outbreak of avian influenza, caused by an H9N2 low-pathogenic avian influenza virus (AIV), occurred in a chicken farm and caused severe economic losses due to mortality and diarrhea. AIV was isolated and identified in a sample from an affected native Korean chicken. Genetic analysis of the isolate revealed a high sequence similarity to genes of novel reassortant H9N2 viruses isolated from slaughterhouses and live bird markets in Korea in 2008 and 2009. Animal challenge studies demonstrated that the replication kinetics and pathogenicity of the isolate were considerably altered due to adaptation in chickens. Vaccine protection studies indicated that commercial vaccine was not able to prevent virus shedding and clinical disease when chickens were challenged with the isolate. These results suggest that the novel H9N2 virus possesses the capacity to replicate efficiently in the respiratory system against vaccination and to cause severe disease in domestic chickens. The results also highlight the importance of appropriate updating of vaccine strains, based on continuous surveillance data, to prevent the possibility of a new H9N2 epidemic in Korea.  相似文献   

12.
During the spring of 2002, a low pathogenic avian influenza (LPAI) A (H7N2) virus caused a major outbreak among commercial poultry in Virginia and adjacent states. The virus primarily affected turkey flocks, causing respiratory distress and decreased egg production. Experimentally, turkeys were more susceptible than chickens to H7N2 virus infection, with 50% bird infectious dose titers equal to 10(0.8) and 10(2.8-3.2), respectively. Comparison of virus shedding from the cloaca and oropharynx demonstrated that recent H7N2 virus isolates were readily isolated from the upper respiratory tract but rarely from the gastrointestinal tract. The outbreak of H7N2 virus raised concerns regarding the availability of vaccines that could be used for the prevention and control of this virus in poultry. We sought to determine if an existing commercial avian influenza (AI) vaccine prepared from a 1997 seed stock virus could provide protection against a 2002 LPAI H7N2 virus isolated from a turkey (A/turkey/Virginia/158512/02 [TV/02]) in Virginia that was from the same lineage as the vaccine virus. The inactivated AI vaccine, prepared from A/chicken/ Pennsylvania/21342/97 (CP/97) virus, significantly reduced viral shedding from vaccinated turkeys in comparison with sham controls but did not prevent infection. The protective effect of vaccination correlated with the level of virus-specific antibody because a second dose of vaccine increased antiviral serum immunoglobulin G and hemagglutination inhibition (HI) reactivity titers in two different turkey age groups. Serum from CP/97-vaccinated turkeys reacted equally well to CP/97 and TV/02 antigens by HI and enzyme-linked immunosorbent assay. These results demonstrate the potential benefit of using an antigenically related 1997 H7N2 virus as a vaccine candidate for protection in poultry against a H7N2 virus isolate from 2002.  相似文献   

13.
H7N9 virus infection is a global concern, given that it can cause severe infection and mortality in humans. However, the understanding of H7N9 epidemiology, animal reservoir species and zoonotic risk remains limited. This work evaluates the pathogenicity, transmissibility and local innate immune response of three avian species harbouring different respiratory distribution of α2,6 and α2,3 SA receptors. Muscovy ducks, European quails and SPF chickens were intranasally inoculated with 105 embryo infectious dose (EID)50 of the human H7N9 (A/Anhui/1/2013) influenza isolate. None of the avian species showed clinical signs or macroscopic lesions, and only mild microscopic lesions were observed in the upper respiratory tract of quail and chickens. Quail presented more severe histopathologic lesions and avian influenza virus (AIV) positivity by immunohistochemistry (IHC), which correlated with higher IL‐6 responses. In contrast, Muscovy ducks were resistant to disease and presented higher IFNα and TLR7 response. In all species, viral shedding was higher in the respiratory than in the digestive tract. Higher viral shedding was observed in quail, followed by chicken and ducks, which presented similar viral titres. Efficient transmission was observed in all contact quail and half of the Muscovy ducks, while no transmission was observed between chicken. All avian species showed viral shedding in drinking water throughout infection.  相似文献   

14.
从福州市某活禽市场采集的鸡泄殖腔棉拭子样品中分离出1株病毒,经血凝抑制试验(HI)和聚合酶链反应(PCR)方法鉴定为H9N2亚型禽流感病毒。在GenBank基因库中对该病毒株的3个基因片段的测序结果进行BLAST比对分析表明,3个基因片段均属于H9N2亚型禽流感病毒的基因。HA基因遗传进化分析表明,该病毒分离株与代表株DK/HK/Y280/97处于同一分支,与上海的鸡源分离株A/chicken/Shanghai/06/2015(H9N2)同源性最高,同源性为99.5%。  相似文献   

15.
The continuing outbreaks of avian influenza A H5N1 virus infection in Asia and Africa have caused worldwide concern because of the high mortality rates in poultry, suggesting its potential to become a pandemic influenza virus in humans. The transmission route of the virus among either the same species or different species is not yet clear. Broilers and BABL/c mice were inoculated with the H5N1 strain of influenza A virus isolated from birds. The animals were inoculated with 0.1 mL 106.83 TCID50 of H5N1 virus oronasally, intraperitoneally and using eye drops. The viruses were examined by virological and pathological assays. In addition, to detect horizontal transmission, in each group, healthy chicks and mice were mixed with those infected. Viruses were detected in homogenates of the heart, liver, spleen, kidney and blood of the infected mice and chickens. Virus antigen was not detected in the spleen, kidney or gastrointestinal tract, but detected by Plaque Forming Unit (PFU) assay in the brain, liver and lung without degenerative change in these organs (in the group inoculated using eye drops. The detection results for mice inoculated using eye drops suggest that this virus might have a different tissue tropism from other influenza viruses mainly restricted to the respiratory tract in mice. All chicken samples tested positive for the virus, regardless of the method of inoculation. Avian influenza A H5N1 viruses are highly pathogenic to chickens, but its virulence in other animals is not yet known. To sum up, the results suggest that the virus replicates not only in different animal species but also through different routes of infection. In addition, the virus was detection not only in the respiratory tract but also in multiple extra‐respiratory tissues. This study demonstrates that H5N1 virus infection in mice can cause systemic disease and spread through potentially novel routes within and between mammalian hosts.  相似文献   

16.
The recent pandemic caused by human influenza virus A(H1N1) 2009 contains ancestral gene segments from North American and Eurasian swine lineages as well as from avian and human influenza lineages. The emergence of this A(H1N1) 2009 poses a potential global threat for human health and the fact that it can infect other species, like pigs, favours a possible encounter with other influenza viruses circulating in swine herds. In Europe, H1N1, H1N2 and H3N2 subtypes of swine influenza virus currently have a high prevalence in commercial farms. To better assess the risk posed by the A(H1N1) 2009 in the actual situation of swine farms, we sought to analyze whether a previous infection with a circulating European avian-like swine A/Swine/Spain/53207/2004 (H1N1) influenza virus (hereafter referred to as SwH1N1) generated or not cross-protective immunity against a subsequent infection with the new human pandemic A/Catalonia/63/2009 (H1N1) influenza virus (hereafter referred to as pH1N1) 21 days apart. Pigs infected only with pH1N1 had mild to moderate pathological findings, consisting on broncho-interstitial pneumonia. However, pigs inoculated with SwH1N1 virus and subsequently infected with pH1N1 had very mild lung lesions, apparently attributed to the remaining lesions caused by SwH1N1 infection. These later pigs also exhibited boosted levels of specific antibodies. Finally, animals firstly infected with SwH1N1 virus and latter infected with pH1N1 exhibited undetectable viral RNA load in nasal swabs and lungs after challenge with pH1N1, indicating a cross-protective effect between both strains.  相似文献   

17.
ABSTRACT: An experimental infection with highly pathogenic avian influenza virus (HPAIV) and low pathogenic avian influenza virus (LPAIV) was carried out in red-legged partridges (Alectoris rufa) in order to study clinical signs, gross and microscopic lesions, and viral distribution in tissues and viral shedding. Birds were infected with a HPAIV subtype H7N1 (A/Chicken/Italy/5093/1999) and a LPAIV subtype H7N9 (A/Anas crecca/Spain/1460/2008). Uninoculated birds were included as contacts in both groups. In HPAIV infected birds, the first clinical signs were observed at 3 dpi, and mortality started at 4 dpi, reaching 100% at 8 dpi. The presence of viral antigen in tissues and viral shedding were confirmed by immunohistochemistry and quantitative real time RT-PCR (qRRT-PCR), respectively, in all birds infected with HPAIV. However, neither clinical signs nor histopathological findings were observed in LPAIV infected partridges. In addition, only short-term viral shedding together with seroconversion was detected in some LPAIV inoculated animals. The present study demonstrates that the red-legged partridge is highly susceptible to the H7N1 HPAIV strain, causing severe disease, mortality and abundant viral shedding and thus contributing to the spread of a potential local outbreak of this virus. In contrast, our results concerning H7N9 LPAIV suggest that the red-legged partridge is not a reservoir species for this virus.  相似文献   

18.
During the latter stages of the lethal H5N2 influenza eradication program in domestic poultry in Pennsylvania in 1983-84, surveillance of waterfowl was done to determine if these birds harbored influenza viruses that might subsequently appear in poultry. From late June to November 1984, 182 hemagglutinating viruses were isolated from 2043 wild birds, primarily ducks, in the same geographical area as the earlier lethal H5N2 avian influenza outbreak. The virus isolates from waterfowl included paramyxoviruses (PMV-1, -4, and -6) and influenza viruses of 13 antigenic combinations. There was only one H5N2 isolate from a duck. Although this virus was antigenically related to the lethal H5N2 virus, genetic and antigenic analysis indicated that it could be discriminated from the virulent family of H5N2 viruses, and it did not originate from chickens. Many of the influenza viruses obtained from wild ducks were capable of replicating in chickens after experimental inoculation but did not cause disease. These studies show that many influenza A virus strains circulating in waterfowl in the vicinity of domestic poultry in Pennsylvania did not originate from domestic poultry. These influenza viruses from wild ducks were capable of infecting poultry; however, transmission of these viruses to poultry apparently was avoided by good husbandry and control measures.  相似文献   

19.
Direct bird-to-human transmission, with the production of severe respiratory disease and human mortality, is unique to the Hong Kong-origin H5N1 highly pathogenic avian influenza (HPAI) virus, which was originally isolated from a disease outbreak in chickens. The pathobiology of the A/chicken/Hong Kong/220/97 (H5N1) (HK/220) HPAI virus was investigated in chickens, turkeys, Japanese and Bobwhite quail, guinea fowl, pheasants, and partridges, where it produced 75-100% mortality within 10 days. Depression, mucoid diarrhea, and neurologic dysfunction were common clinical manifestations of disease. Grossly, the most severe and consistent lesions included splenomegaly, pulmonary edema and congestion, and hemorrhages in enteric lymphoid areas, on serosal surfaces, and in skeletal muscle. Histologic lesions were observed in multiple organs and were characterized by exudation, hemorrhage, necrosis, inflammation, or a combination of these features. The lung, heart, brain, spleen, and adrenal glands were the most consistently affected, and viral antigen was most often detected by immunohistochemistry in the parenchyma of these organs. The pathogenesis of infection with the HK/220 HPAI virus in these species was twofold. Early mortality occurring at 1-2 days postinoculation (DPI) corresponded to severe pulmonary edema and congestion and virus localization within the vascular endothelium. Mortality occurring after 2 DPI was related to systemic biochemical imbalance, multiorgan failure, or a combination of these factors. The pathobiologic features were analogous to those experimentally induced with other HPAI viruses in domestic poultry.  相似文献   

20.
Sun Y  Pu J  Fan L  Sun H  Wang J  Zhang Y  Liu L  Liu J 《Veterinary microbiology》2012,156(1-2):193-199
Despite the long-term vaccination programs implemented in China, H9N2 avian influenza viruses (AIVs) continue to persist in chicken populations, even in vaccinated flocks. We previously demonstrated that H9N2 AIV isolated from chickens in China also underwent antigenic drift and evolved into distinct antigenic groups (C, D and E). To understand whether antigenic drift of viruses away from the vaccine strain partially contributed to the circulation of H9N2 AIV in China, we evaluated the protective efficacy of a commercial vaccine against different antigenic groups of H9N2 AIV. Challenge experiments using vaccinated chickens indicated that the vaccine prevented shedding of antigenic group C viruses, but not those of the more recent groups D and E. Vaccinated chickens, even those with vaccine-induced HI titers of 1:1024, shed virus after being infected with A/chicken/Shandong/ZB/2007, a representative virus of antigenic group D. Genetic analysis showed that the representative viruses of antigenic groups D and E possessed greater numbers of amino acid substitutions in the hemagglutinin protein compared to the vaccine strain and the antigenic group C virus, and many of which were located in antigenic sites. Our results indicated that the persistence of H9N2 AIV in China might be due to incomplete vaccine protection, and that the avian influenza vaccine should be regularly evaluated and updated to maintain optimal protection. Furthermore, the avian influenza vaccination policy also needs to be re-assessed, and increased veterinary biosecurity on farms, rather than vaccine application alone, should be implemented to prevent and control avian influenza.  相似文献   

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