H7N9 low pathogenic influenza viruses emerged in China in 2013 and mutated to highly pathogenic strains in 2017, resulting in human infections and disease in chickens. To control spread, a bivalent ...H5/H7 inactivated vaccine was introduced in poultry in September 2017. To monitor virus evolution and vaccine efficacy, we collected 53,884 poultry samples across China from February 2017 to January 2018. We isolated 252 H7N9 low pathogenic viruses, 69 H7N9 highly pathogenic viruses, and one H7N2 highly pathogenic virus, of which two low pathogenic and 14 highly pathogenic strains were collected after vaccine introduction. Genetic analysis of highly pathogenic strains revealed nine genotypes, one of which is predominant and widespread and contains strains exhibiting high virulence in mice. Additionally, some H7N9 and H7N2 viruses carrying duck virus genes are lethal in ducks. Thus, although vaccination reduced H7N9 infections, the increased virulence and expanded host range to ducks pose new challenges.
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•In 2017 across China, H7N9 HPAI viruses evolved into different genotypes•H7N9 and H7N2 HPAI reassortants are well adapted and lethal in ducks•An H5/H7 vaccine induced solid protection against H7 viruses in poultry
H7N9 highly pathogenic avian influenza viruses emerged in China in 2017, prompting vaccination in poultry. Shi et al. examine H7N9 viruses across China before and after vaccination, revealing rapid evolution into subtypes and genotypes. Although vaccination reduced infections, some H7N9 and H7N2 viruses exhibit heightened virulence and expansion to ducks.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
H7N9 influenza viruses were first isolated in 2013 and continue to cause human infections. H7N9 infections represent an ongoing public health threat that has resulted in 1344 cases with 511 deaths as ...of April 9, 2017. This highlights the continued threat posed by the current poultry trade and live poultry market system in China. Until now, there have been five H7N9 influenza epidemic waves in China; however, the steep increase in the number of humans infected with H7N9 viruses observed in the fifth wave, beginning in October 2016, the spread into western provinces, and the emergence of highly pathogenic (HP) H7N9 influenza outbreaks in chickens and infection in humans have caused domestic and international concern. In this review, we summarize and compare the different waves of H7N9 regarding their epidemiology, pathogenesis, evolution, and characteristic features, and speculate on factors behind the recent increase in the number of human cases and sudden outbreaks in chickens. The continuous evolution of the virus poses a long-term threat to public health and the poultry industry, and thus it is imperative to strengthen prevention and control strategies.
The emergence of highly pathogenic H7N9 avian influenza virus is a potential threat to the poultry industry and to public health.
Elevated numbers of human cases of H7N9 virus infections during the fifth epidemic wave has meant the spread of H7N9 to several western provinces for the first time.
The evolutionary relationships of the HA and NA genes of H7N9 viruses during the five epidemic waves are examined here.
The dual receptor binding capacity of the H7 protein, along with the enhanced receptor affinity of the N9 protein, may contribute to the higher human infectivity of the H7N9 virus.
To reduce the risk of H7N9 human infection, we have to reduce or eliminate infections in poultry. Therefore, prevention and control strategies including strengthened biosecurity and improved outbreak management, as well as the prudent use of vaccines in poultry, should be reviewed and implemented.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK, ZRSKP
Significance Highly pathogenic avian influenza virus H5N1 first emerged in Asia and subsequently unfolded into the first avian influenza panzootic, causing major economic losses in the poultry ...sector. However, we still do not understand the regional long-distance transmission and seasonal patterns of H5N1. In this study, we addressed this issue by combining H5N1 outbreak records, whole-genome sequences of viral samples, and satellite tracking data for four species of migratory birds in Asia. We show that timing of H5N1 outbreaks and viral migration are closely associated with known bird migration routes. The flyway is the major viral transmission barrier to the intracontinental spread of H5N1 by migratory birds in Asia, whereas geographic distances within the flyways have little effect on H5N1 transmission.
The spatial spread of the highly pathogenic avian influenza virus H5N1 and its long-term persistence in Asia have resulted in avian influenza panzootics and enormous economic losses in the poultry sector. However, an understanding of the regional long-distance transmission and seasonal patterns of the virus is still lacking. In this study, we present a phylogeographic approach to reconstruct the viral migration network. We show that within each wild fowl migratory flyway, the timing of H5N1 outbreaks and viral migrations are closely associated, but little viral transmission was observed between the flyways. The bird migration network is shown to better reflect the observed viral gene sequence data than other networks and contributes to seasonal H5N1 epidemics in local regions and its large-scale transmission along flyways. These findings have potentially far-reaching consequences, improving our understanding of how bird migration drives the periodic reemergence of H5N1 in Asia.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
The role of Africa in the dynamics of the global spread of a zoonotic and economically-important virus, such as the highly pathogenic avian influenza (HPAI) H5Nx of the Gs/GD lineage, remains ...unexplored. Here we characterise the spatiotemporal patterns of virus diffusion during three HPAI H5Nx intercontinental epidemic waves and demonstrate that Africa mainly acted as an ecological sink of the HPAI H5Nx viruses. A joint analysis of host dynamics and continuous spatial diffusion indicates that poultry trade as well as wild bird migrations have contributed to the virus spreading into Africa, with West Africa acting as a crucial hotspot for virus introduction and dissemination into the continent. We demonstrate varying paths of avian influenza incursions into Africa as well as virus spread within Africa over time, which reveal that virus expansion is a complex phenomenon, shaped by an intricate interplay between avian host ecology, virus characteristics and environmental variables.
Phylogenetic network analysis and understanding of waterfowl migration patterns suggest that the Eurasian H5N8 clade 2.3.4.4 avian influenza virus emerged in late 2013 in China, spread in early 2014 ...to South Korea and Japan, and reached Siberia and Beringia by summer 2014 via migratory birds. Three genetically distinct subgroups emerged and subsequently spread along different flyways during fall 2014 into Europe, North America, and East Asia, respectively. All three subgroups reappeared in Japan, a wintering site for waterfowl from Eurasia and parts of North America.
During autumn-winter 2016-2017, highly pathogenic avian influenza A(H5N8) viruses caused mass die-offs among wild birds in the Netherlands. Among the ≈13,600 birds reported dead, most were tufted ...ducks (Aythya fuligula) and Eurasian wigeons (Anas penelope). Recurrence of avian influenza outbreaks might alter wild bird population dynamics.
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DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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.
We analyzed the highly pathogenic avian influenza (HPAI) H5 epizootic of 2016-17 in Europe by epidemiologic and genetic characteristics and compared it with 2 previous epizootics caused by the same ...H5 Guangdong lineage. The 2016-17 epizootic was the largest in Europe by number of countries and farms affected and greatest diversity of wild birds infected. We observed significant differences among the 3 epizootics regarding region affected, epidemic curve, seasonality, and outbreak duration, making it difficult to predict future HPAI epizootics. However, we know that in 2005-06 and 2016-17 the initial peak of wild bird detections preceded the peak of poultry outbreaks within Europe. Phylogenetic analysis of 2016-17 viruses indicates 2 main pathways into Europe. Our findings highlight the need for global surveillance of viral changes to inform disease preparedness, detection, and control.
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DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Avian influenza viruses (AIVs) circulate globally, spilling over into domestic poultry and causing zoonotic infections in humans. Fortunately, AIVs are not yet capable of causing sustained ...human-to-human infection; however, AIVs are still a high risk as future pandemic strains, especially if they acquire further mutations that facilitate human infection and/or increase pathogenesis. Molecular characterization of sequencing data for known genetic markers associated with AIV adaptation, transmission, and antiviral resistance allows for fast, efficient assessment of AIV risk. Here we summarize and update the current knowledge on experimentally verified molecular markers involved in AIV pathogenicity, receptor binding, replicative capacity, and transmission in both poultry and mammals with a broad focus to include data available on other AIV subtypes outside of A/H5N1 and A/H7N9.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Influenza A viruses (IAVs) are zoonotic pathogens that cause yearly outbreaks with high rates of morbidity and fatality. The virus continuously acquires point mutations while circulating in several ...hosts, ranging from aquatic birds to mammals, including humans. The wide range of hosts provides influenza A viruses greater chances of genetic re-assortment, leading to the emergence of zoonotic strains and occasional pandemics that have a severe impact on human life. Four major influenza pandemics have been reported to date, and health authorities worldwide have shown tremendous progress in efforts to control epidemics and pandemics. Here, we primarily discuss the pathogenesis of influenza virus type A, its epidemiology, pandemic potential, current status of antiviral drugs and vaccines, and ways to effectively manage the disease during a crisis.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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