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Viruses May 2021Influenza A viruses (IAVs) evolve via point mutations and reassortment of viral gene segments. The patterns of reassortment in different host species differ...
Influenza A viruses (IAVs) evolve via point mutations and reassortment of viral gene segments. The patterns of reassortment in different host species differ considerably. We investigated the genetic diversity of IAVs in wild ducks and compared it with the viral diversity in gulls. The complete genomes of 38 IAVs of H1N1, H1N2, H3N1, H3N2, H3N6, H3N8, H4N6, H5N3, H6N2, H11N6, and H11N9 subtypes isolated from wild mallard ducks and gulls resting in a city pond in Moscow, Russia were sequenced. The analysis of phylogenetic trees showed that stable viral genotypes do not persist from year to year in ducks owing to frequent gene reassortment. For comparison, similar analyses were carried out using sequences of IAVs isolated in the same period from ducks and gulls in The Netherlands. Our results revealed a significant difference in diversity and rates of reassortment of IAVs in ducks and gulls.
Topics: Animals; Charadriiformes; Ducks; Feces; Genetic Variation; Genome, Viral; Genotype; Influenza A virus; Influenza in Birds; Phylogeny; Reassortant Viruses
PubMed: 34072256
DOI: 10.3390/v13061010 -
The Onderstepoort Journal of Veterinary... Dec 2022Influenza A viruses (IAVs) are typically isolated and cultured by successive passages using 9- to 11-day-old embryonated chicken eggs (ECEs) and in 14-day old ECEs for...
Influenza A viruses (IAVs) are typically isolated and cultured by successive passages using 9- to 11-day-old embryonated chicken eggs (ECEs) and in 14-day old ECEs for virus mutational studies. Real-time reverse transcription-polymerase chain reaction tests (RT-PCRs) are commonly used for IAV diagnosis, but virus isolation remains invaluable in terms of its high sensitivity, providing viable isolates for further studies and the ability to distinguish between viable and nonviable virus. Efforts at isolating ostrich-origin IAVs from RT-PCR positive specimens using ECEs have often been unsuccessful, raising the possibility of a species bottleneck, whereby ostrich-adapted IAVs may not readily infect and replicate in ECEs, yet the capacity of an ostrich embryo to support the replication of influenza viruses has not been previously demonstrated. This study describes an optimised method for H5 and H7 subtype IAV isolation and propagation in 28-day old embryonated ostrich eggs (EOEs), the biological equivalent of 14-day old ECEs. The viability of EOEs transported from breeding sites could be maximised by pre-incubating the eggs for 12 to 14 days prior to long-distance transportation. This method applied to studies for ostrich-adapted virus isolation and in ovo studies will enable better understanding of the virus-host interaction in ostriches and the emergence of potentially zoonotic diseases.
Topics: Animals; Influenza A virus; Influenza in Birds; Struthioniformes; Zygote; Virology
PubMed: 36546513
DOI: 10.4102/ojvr.v89i1.2011 -
Microbes and Infection 2022Wild birds are the natural reservoirs of avian influenza viruses, and surveillance and assessment of these viruses in wild birds provide valuable information for early...
Wild birds are the natural reservoirs of avian influenza viruses, and surveillance and assessment of these viruses in wild birds provide valuable information for early warning and control of animal diseases. In this study, we isolated 19 H7N7 avian influenza viruses from wild bird between 2018 and 2020. Full genomic analysis revealed that these viruses bear a single basic amino acid in the cleavage site of their hemagglutinin gene, and formed four different genotypes by actively reassorting other avian influenza viruses circulating in wild birds and ducks. The H7N7 viruses bound to both avian-type and human-type receptors, although their affinity for human-type receptors was markedly lower than that for avian-type receptors. Moreover, we found that the H7N7 viruses could replicate efficiently in the upper respiratory tract and caecum of domestic ducks, and that the H5/H7 inactivated vaccine used in poultry in China provided complete protection against H7N7 wild bird virus challenge in ducks. Our findings demonstrate that wild bird H7N7 viruses pose a substantial threat to the poultry industry across the East Asian-Australian migratory flyway, emphasize the importance of influenza virus surveillance in both wild and domestic birds, and support the development of active control strategies against H7N7 virus.
Topics: Animals; Humans; Influenza A Virus, H7N7 Subtype; Australia; Influenza in Birds; Birds; Animals, Wild; Influenza A virus; Ducks; Poultry; Phylogeny
PubMed: 35580801
DOI: 10.1016/j.micinf.2022.105013 -
The Lancet. Microbe Feb 2023
Topics: Animals; Humans; Influenza A Virus, H9N2 Subtype; Influenza in Birds; Chickens
PubMed: 36372076
DOI: 10.1016/S2666-5247(22)00305-6 -
Emerging Microbes & Infections Dec 2022In May 2021, Lesotho reported its first outbreak of highly pathogenic avian influenza (HPAI) to the OIE. Samples were collected from infected poultry and the virus was...
In May 2021, Lesotho reported its first outbreak of highly pathogenic avian influenza (HPAI) to the OIE. Samples were collected from infected poultry and the virus was confirmed by molecular tests to be of the H5N1 subtype. Full genome sequencing and phylogenetic analysis revealed that the viruses belonged to clade 2.3.4.4b and showed high identity with A/H5N1 viruses identified in Nigeria and Senegal in early 2021. The identification of A/H5N1 HPAI in Lesotho has important implications for disease management and food security in the region.
Topics: Animals; Disease Outbreaks; Influenza A Virus, H5N1 Subtype; Influenza in Birds; Lesotho; Phylogeny; Poultry
PubMed: 35171076
DOI: 10.1080/22221751.2022.2043729 -
Poultry Science Oct 2023The H4 subtype of avian influenza viruses has been widely distributed among wild birds. During the surveillance of the avian influenza virus in Shanghai from 2019 to...
The H4 subtype of avian influenza viruses has been widely distributed among wild birds. During the surveillance of the avian influenza virus in Shanghai from 2019 to 2021, a total of 4,451 samples were collected from wild birds, among which 46 H4 subtypes of avian influenza viruses were identified, accounting for 7.40% of the total positive samples. The H4 subtype viruses have a wide range of hosts, including the spot-billed duck, common teal, and other wild birds in Anseriformes. Among all H4 subtypes, the most abundant are the H4N2 viruses. To clarify the genetic characteristics of H4N2 viruses, the whole genome sequences of 20 H4N2 viruses were analyzed. Phylogenetical analysis showed that all 8 genes of these viruses belonged to the Eurasian lineage and closely clustered with low pathogenic avian influenza viruses from countries along the East Asia-Australia migratory route. However, the PB1 gene of 1 H4N2 virus (NH21920) might provide its internal gene for highly pathogenic avian influenza H5N8 viruses in Korea and Japan. At least 10 genotypes were identified in these viruses, indicating that they underwent multiple complex recombination events. Our study has provided a better epidemiological understanding of the H4N2 viruses in wild birds. Considering the mutational potential, comprehensive surveillance of the H4N2 virus in both poultry and wild birds is imperative.
Topics: Animals; Influenza in Birds; Chickens; China; Animals, Wild; Influenza A virus; Ducks; Phylogeny
PubMed: 37604021
DOI: 10.1016/j.psj.2023.102948 -
Emerging Infectious Diseases Aug 2020In 2019, an outbreak of avian influenza (H3N1) virus infection occurred among commercial poultry in Belgium. Full-genome phylogenetic analysis indicated a wild bird...
In 2019, an outbreak of avian influenza (H3N1) virus infection occurred among commercial poultry in Belgium. Full-genome phylogenetic analysis indicated a wild bird origin rather than recent circulation among poultry. Although classified as a nonnotifiable avian influenza virus, it was associated with reproductive tropism and substantial mortality in the field.
Topics: Animals; Belgium; Chickens; Disease Outbreaks; Influenza in Birds; Phylogeny; Poultry; Poultry Diseases; Virulence
PubMed: 32687049
DOI: 10.3201/eid2608.191338 -
Poultry Science Jun 2023H9N2 is currently the main subtype of avian influenza in China. In order to use reverse genetics to rapid preparation of seed strains for vaccine production, and intend...
H9N2 is currently the main subtype of avian influenza in China. In order to use reverse genetics to rapid preparation of seed strains for vaccine production, and intend to prevent and control the H9N2 subtype epidemic strains of avian influenza virus (AIV). In this study, we successfully rescued 2 H9N2 recombinant viruses based on the representative viruses of Southeast China and confirmed by RT-PCR and sequencing. Genetic stability, pathogenicity, transmissibility, and antigenicity of 2 recombinant viruses were evaluated. Compared to the FZ1, the growth kinetics of H9N2(HA+NA)/PR8 showed no significant difference, H9N2(HA+NA+M+PB1)/PR8 was slightly lower. Our study also confirmed 2 recombinant viruses had good genetic stability after 10 passages but possessed lower pathogenicity than FZ1. Although both recombinant viruses led to seroconversion in all inoculated birds on 14 dpi, they complete loss of viral transmission of the virus to contact birds. In addition, birds were immunized via hypodermic route by inactivated vaccines of H9N2(HA+NA)/PR8, H9N2(HA+NA+M+PB1)/PR8 and wild-type virus with a single dose, and the results showed that the hemagglutination inhibition titers on 21 dpv were 10.5, 9.6, and 10.5 log2, respectively. And recombinant viruses both provided a certain protection against wild-type virus challenge. In conclusion, these data indicated that 2 recombinant viruses will be expected to be used as inactivated vaccines to controlling the spread of H9N2 subtype AIV even have potential application for attenuated viral vaccines, which provides a reference for the prevention and control of influenza virus pandemics.
Topics: Animals; Influenza in Birds; Influenza A Virus, H9N2 Subtype; Chickens; Virulence; Influenza Vaccines; Vaccines, Inactivated
PubMed: 37004288
DOI: 10.1016/j.psj.2023.102625 -
Virology Journal Oct 2021The fifth wave of H7N9 avian influenza virus caused a large number of human infections and a large number of poultry deaths in China. Since September 2017, mainland...
BACKGROUND
The fifth wave of H7N9 avian influenza virus caused a large number of human infections and a large number of poultry deaths in China. Since September 2017, mainland China has begun to vaccinate poultry with H5 + H7 avian influenza vaccine. We investigated the avian influenza virus infections in different types of live poultry markets and samples before and after genotype H5 + H7 vaccination in Nanchang, and analyzed the changes of the HA subtypes of AIVs.
METHODS
From 2016 to 2019, we monitored different live poultry markets and collected specimens, using real-time reverse transcription polymerase chain reaction (RT-PCR) technology to detect the nucleic acid of type A avian influenza virus in the samples. The H5, H7 and H9 subtypes of influenza viruses were further classified for the positive results. The χ test was used to compare the differences in the separation rates of different avian influenza subtypes.
RESULTS
We analyzed 5,196 samples collected before and after vaccination and found that the infection rate of AIV in wholesale market (21.73%) was lower than that in retail market (24.74%) (P < 0.05). Among all the samples, the positive rate of sewage samples (33.90%) was the highest (P < 0.001). After vaccination, the positive rate of H5 and H7 subtypes decreased, and the positive rate of H9 subtype and untypable HA type increased significantly (P < 0.001). The positive rates of H9 subtype in different types of LPMs and different types of samples increased significantly (P < 0.01), and the positive rates of untypable HA type increased significantly in all environmental samples (P < 0.05).
CONCLUSIONS
Since vaccination, the positive rates of H5 and H7 subtypes have decreased, but the positive rates of H9 subtypes have increased to varying degrees in different testing locations and all samples. This results show that the government should establish more complete measures to achieve long-term control of the avian influenza virus.
Topics: Animals; China; Humans; Influenza A Virus, H7N9 Subtype; Influenza in Birds; Influenza, Human; Poultry; Sewage; Vaccination
PubMed: 34715890
DOI: 10.1186/s12985-021-01683-0 -
Virus Genes Dec 2019Avian influenza viruses (AIVs) circulate globally, spilling over into domestic poultry and causing zoonotic infections in humans. Fortunately, AIVs are not yet capable... (Review)
Review
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.
Topics: Animals; Birds; Drug Resistance, Viral; Genetic Markers; Humans; Influenza A Virus, H5N1 Subtype; Influenza A Virus, H7N9 Subtype; Influenza in Birds; Influenza, Human; Pandemics; Poultry; Zoonoses
PubMed: 31428925
DOI: 10.1007/s11262-019-01700-z