34,168 research outputs found

    Viral and host factors required for avian H5N1 influenza A virus replication in mammalian cells

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    Following the initial and sporadic emergence into humans of highly pathogenic avian H5N1 influenza A viruses in Hong Kong in 1997, we have come to realize the potential for avian influenza A viruses to be transmitted directly from birds to humans. Understanding the basic viral and cellular mechanisms that contribute to infection of mammalian species with avian influenza viruses is essential for developing prevention and control measures against possible future human pandemics. Multiple physical and functional cellular barriers can restrict influenza A virus infection in a new host species, including the cell membrane, the nuclear envelope, the nuclear environment, and innate antiviral responses. In this review, we summarize current knowledge on viral and host factors required for avian H5N1 influenza A viruses to successfully establish infections in mammalian cells. We focus on the molecular mechanisms underpinning mammalian host restrictions, as well as the adaptive mutations that are necessary for an avian influenza virus to overcome them. It is likely that many more viral and host determinants remain to be discovered, and future research in this area should provide novel and translational insights into the biology of influenza virus-host interactions

    Molecular characterization of Indonesia avian influenza virus

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    Avian influenza outbreaks in poultry have been reported in Java island since August 2003. A total of 14 isolates of avian influenza virus has been isolated from October 2003 to October 2004. The viruses have been identified as HPAI H5N1 subtype. All of them were characterized further at genetic level and also for their pathogenicity. Phylogenetic analysis showed all of the avian influenza virus isolates were closely related to avian influenza virus from China (A/Duck/China/E319-2/03(H5N1). Molecular basis of pathogenicity in HA cleavage site indicated that the isolates of avian influenza virus have multiple basic amino acid (B-X-B-R) indicating that all of the isolates representing virulent avian influenza virus (highly pathogenic avian influenza virus).     Key Words: Avian Influenza Virus, Molecular Characterization, Poultry, Indonesi

    Transmission of H7N9 influenza virus in mice by different infective routes.

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    BackgroundOn 19 February 2013, the first patient infected with a novel influenza A H7N9 virus from an avian source showed symptoms of sickness. More than 349 laboratory-confirmed cases and 109 deaths have been reported in mainland China since then. Laboratory-confirmed, human-to-human H7N9 virus transmission has not been documented between individuals having close contact; however, this transmission route could not be excluded for three families. To control the spread of the avian influenza H7N9 virus, we must better understand its pathogenesis, transmissibility, and transmission routes in mammals. Studies have shown that this particular virus is transmitted by aerosols among ferrets.MethodsTo study potential transmission routes in animals with direct or close contact to other animals, we investigated these factors in a murine model.ResultsViable H7N9 avian influenza virus was detected in the upper and lower respiratory tracts, intestine, and brain of model mice. The virus was transmissible between mice in close contact, with a higher concentration of virus found in pharyngeal and ocular secretions, and feces. All these biological materials were contagious for na√Įve mice.ConclusionsOur results suggest that the possible transmission routes for the H7N9 influenza virus were through mucosal secretions and feces

    Virus Avian Influenza H5n1 : Biologi Molekuler dan Potensi Penularannya ke Unggas dan Manusia

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    Dengan adanya kejadian luar biasa yang pertama virus avian influenza H5N1 tahun 1997, semakin jelas bahwapotensi virulensi virus H5N1 telah meluas ke manusia. Review ini disusun untuk memahami karakteristikvirus, siklus replikasi virus, mekanisme virus masuk ke dalam hospes, peran hemaglutinin sebagai determinanpatogenisitas, urutan basa hemaglutinin yang berperan dalam memicu peningkatan virulensi dan fungsi dari6 segmen gen lainnya pada virus avian influenza. Review juga dibuat untuk memahami gambaran patologisdalam hubungannya dengan manifestasi klinis baik pada unggas maupun manusia. Identifikasi karakteristikmolekuler avian influenza virus H5N1 sangat penting dilakukan untuk mengetahui penularan secara efisiendan replikasi virus avian influenza pada manusia, sehingga penularan selanjutnya dapat diantisipasidengan baik. Kerja sama lintas sektor antara kementerian kesehatan, kementerian koordinator kesejateraanrakyat, kementerian lain, universitas dan organisasi yang berkompeten sangat dibutuhkan untuk mendukungpencegahan penyebaran virus avian influenza H5N1 di Indonesia

    Multiple RT-PCR Detection of H5, H7, and H9 Subtype Avian Influenza Viruses and Newcastle Disease Virus

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    Objective: This paper focuses on the multiple detection RT-PCR technology of H5, H7, AND H9 subtype avian influenza viruses and Newcastle disease virus, and points out the specific detection methods and detection procedures of avian influenza and Newcastle disease virus. Methods: The genes of Newcastle disease virus carrying out the HA gene sequence of H5, H7 and H9 subtype AIV in GenBank were used to establish a strategy for simultaneous detection of three subtypes of avian influenza virus and Newcastle disease virus. Results: The results showed that the program can detect and distinguish H5, H7 and H9 subtype avian influenza viruses and Newcastle disease virus at one time. Conclusion: Multiple RT-PCR detection method has high detection sensitivity and can detect and determine different subtypes of avian influenza virus and Newcastle disease virus quickly and accurately, therefore, it has a crucial role in the detection and control of avian influenza H5, H7 and H9 subtypes and Newcastle disease

    Early apoptosis of porcine alveolar macrophages limits avian influenza virus replication and proinflammatory dysregulation

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    Pigs are evidently more resistant to avian than swine influenza A viruses, mediated in part through frontline epithelial cells and alveolar macrophages (AM). Although porcine AM (PAM) are crucial in influenza virus control, their mode of control is unclear. To gain insight into the possible role of PAM in the mediation of avian influenza virus resistance, we compared the host effects and replication of two avian (H2N3 and H6N1) and three mammalian (swine H1N1, human H1N1 and pandemic H1N1) influenza viruses in PAM. We found that PAM were readily susceptible to initial infection with all five avian and mammalian influenza viruses but only avian viruses caused early and extensive apoptosis (by 6 h of infection) resulting in reduced virus progeny and moderated pro- inflammation. Full length viral PB1-F2 present only in avian influenza viruses is a virulence factor that targets AM for mitochondrial associated apoptotic cell death. With the use of reverse genetics on an avian H5N1 virus, we found that full length PB1-F2 contributed to increased apoptosis and pro-inflammation but not to reduced virus replication. Taken together, we propose that early apoptosis of PAM limits the spread of avian influenza viruses and that PB1-F2 could play a contributory role in the process

    One-way trip: Influenza virus' adaptation to gallinaceous poultry may limit its pandemic potential

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    We hypothesise that some influenza virus adaptations to poultry may explain why the barrier for human-to-human transmission is not easily overcome once the virus has crossed from wild birds to chickens. Since the cluster of human infections with H5N1 influenza in Hong Kong in 1997, chickens have been recognized as the major source of avian influenza virus infection in humans. Although often severe, these infections have been limited in their subsequent human-to-human transmission, and the feared H5N1 pandemic has not yet occurred. Here we examine virus adaptations selected for during replication in chickens and other gallinaceous poultry. These include altered receptor binding and increased pH of fusion of the haemagglutinin as well as stalk deletions of the neuraminidase protein. This knowledge could aid the delivery of vaccines and increase our ability to prioritize research efforts on those viruses from the diverse array of avian influenza viruses that have greatest human pandemic potential
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