Genesis of Influenza A(H5N8) Viruses El-Shesheny, Rabeh; Barman, Subrata; Feeroz, Mohammed M ...
Emerging infectious diseases,
08/2017, Letnik:
23, Številka:
8
Journal Article
Recenzirano
Odprti dostop
Highly pathogenic avian influenza A(H5N8) clade 2.3.4.4 virus emerged in 2016 and spread to Russia, Europe, and Africa. Our analysis of viruses from domestic ducks at Tanguar haor, Bangladesh, showed ...genetic similarities with other viruses from wild birds in central Asia, suggesting their potential role in the genesis of A(H5N8).
A(H5N1) and A(H9N2) avian influenza viruses are enzootic in Egyptian poultry, and most A (H5N1) human cases since 2009 have occurred in Egypt. Our understanding of the epidemiology of avian viruses ...in humans remains limited. Questions about the frequency of infection, the proportion of infections that are mild or subdinical, and the case-fatality rate remain largely unanswered. Methods. We conducted a 3-year, prospective, controlled, seroepidemiological study that enrolled 750 poultryexposed and 250 unexposed individuals in Egypt. Results. At baseline, the seroprevalence of anti-A(H5N1) antibodies (titer, ≥80) among exposed individuals was 2% significantly higher than that among the controls (0%). Having chronic lung disease was a significant risk factor for infection. Antibodies against A(H9N2) were not detected at baseline when A(H9N2) was not circulating in poultry. At follow-up, A(H9N2) was detected in poultry, and consequently, the seroprevalence among exposed humans was between 5.6% and 7.5%. Vaccination of poultry, older age, and exposure to ducks were risk factors for A(H9N2) infection. Conclusions. Results of this study indicate that the number of humans infected with avian influenza viruses is much larger than the number of reported confirmed cases. In an area where these viruses are enzootic in the poultry, human exposure to and infection with avian influenza becomes more common.
Currently enzootic avian influenza H5N1, H9N2, and H5N8 viruses were introduced into poultry in Egypt in 2006, 2011, and 2016, respectively. Infections with H5N1 and H9N2 were reported among ...poultry-exposed humans. We followed 2,402 persons from households raising backyard poultry from 5 villages in Egypt during August 2015-March 2019. We collected demographic, exposure, and health condition data and annual serum samples from each participant and obtained swab samples from participants reporting influenza-like illness symptoms. We performed serologic and molecular analyses and detected 4 cases of infection with H5N1 and 3 cases with H9N2. We detected very low seroprevalence of H5N1 antibodies and no H5N8 antibodies among the cohort; up to 11% had H9 antibodies. None of the exposure, health status, or demographic variables were related to being seropositive. Our findings indicate that avian influenza remains a public health risk in Eqypt, but infections may go undetected because of their mild or asymptomatic nature.
Bat coronaviruses cause a wide range of illnesses in humans and animals. Bats are known to harbor a wide diversity of Alphacoronaviruses and Betacoronaviruses. Betacoronaviruses have been linked to ...Severe Acute Respiratory Syndrome (SARS), Middle East Respiratory Syndrome (MERS), and other diseases such as gastroenteritis, bronchiolitis, and pneumonia. In the last 20 years, three betacoronaviruses emerged and caused widespread outbreaks in humans, including two deadly betacoronavirus epidemics, SARS-CoV, with mortality rate of 10%, and MERS-CoV, with mortality rate of 34.7%, and SARS-CoV-2, which caused the COVID-19 pandemic, with mortality rate of 3.4%. Studies have shown that bats are the main natural reservoirs for these viruses or their ancestral viruses. Observed variations in bat coronavirus genomes indicate that these viruses may have a potential to transmit to other hosts in close contact with humans and subsequently transmit to humans. As of today, there are no reported cases of direct coronavirus transmission from bats to humans. One reason for this might be that intermediate hosts are required for the transmission of bat coronaviruses to humans. Further studies are needed to map the amino acids and genomic regions responsible for the interactions between the spike of coronavirus and its receptors.
Continuous circulation of influenza A(H5N1) virus among poultry in Egypt has created an epicenter in which the viruses evolve into newer subclades and continue to cause disease in humans. To detect ...influenza viruses in Egypt, since 2009 we have actively surveyed various regions and poultry production sectors. From August 2010 through January 2013, >11,000 swab samples were collected; 10% were positive by matrix gene reverse transcription PCR. During this period, subtype H9N2 viruses emerged, cocirculated with subtype H5N1 viruses, and frequently co-infected the same avian host. Genetic and antigenic analyses of viruses revealed that influenza A(H5N1) clade 2.2.1 viruses are dominant and that all subtype H9N2 viruses are G1-like. Cocirculation of different subtypes poses concern for potential reassortment. Avian influenza continues to threaten public and animal health in Egypt, and continuous surveillance for avian influenza virus is needed.
Avian influenza virus subtype H9N2 has been circulating in the Middle East since the 1990s. For uncertain reasons, H9N2 was not detected in Egyptian farms until the end of 2010. Circulation of H9N2 ...viruses in Egyptian poultry in the presence of the enzootic highly pathogenic H5N1 subtype adds a huge risk factor to the Egyptian poultry industry. In this study, 22 H9N2 viruses collected from 2011 to 2013 in Egypt were isolated and sequenced. The genomic signatures and protein sequences of these isolates were analyzed. Multiple mammalian-host-associated mutations were detected that favor transmission from avian to mammalian hosts. Other mutations related to virulence were also identified. Phylogenetic data showed that Egyptian H9N2 viruses were closely related to viruses isolated from neighboring Middle Eastern countries, and their HA gene resembled those of viruses of the G1-like lineage. No reassortment was detected with H5N1 subtypes. Serological analysis of H9N2 virus revealed antigenic conservation among Egyptian isolates. Accordingly, continuous surveillance that results in genetic and antigenic characterization of H9N2 in Egypt is warranted.
Since 2000, two lineages of influenza B viruses, Victoria and Yamagata, have been circulating at similar frequencies worldwide. Little is known about the circulation of those viruses in Egypt. This ...study aims to describe the epidemiology of influenza B virus infections in Egypt, 2017–2019. This was performed through a household prospective cohort study on influenza infections among 2400 individuals from five villages. When a study participant had influenza like symptoms, a nasal swab and an oropharyngeal swab were obtained and tested by RT-PCR for influenza B infections. A serum sample was obtained from all participants annually to detect neutralizing antibodies using microneutralization assay. 9.1% of subjects were positive for influenza B viruses during season 2017–2018 mostly among preschoolers and 7.6% were positive during the season 2018–2019 with higher risk in females, potentially due to mothers being infected after contact with their children. The overall seroprevalence among the participants was 53.2% and 52.2% against the Victoria and Yamagata lineages respectively, the majority of seropositive participants were students. Multivariate analysis showed that age and having chronic diseases were the strongest predictors of infection. Our results show that both influenza B lineages circulated between 2017 and 2020 in Egypt almost in equal proportion. Encouraging the uptake of seasonal influenza vaccines is recommended.
Avian influenza H5N1 has a high human case fatality rate, but is not yet well-adapted to human hosts. Amino acid substitutions currently circulating in avian populations may enhance viral fitness in, ...and thus viral adaptation to, human hosts. Substitutions which could increase the risk of a human pandemic (through changes to host specificity, virulence, replication ability, transmissibility, or drug susceptibility) are termed key substitutions (KS). Egypt represents the epicenter of human H5N1 infections, with more confirmed cases than any other country. To date, however, there have not been any spatial analyses of KS in Egypt.
Using 925 viral samples of H5N1 from Egypt, we aligned protein sequences and scanned for KS. We geocoded isolates using dasymetric mapping, then carried out geospatial hot spot analyses to identify spatial clusters of high KS detection rates. KS prevalence and spatial clusters were evaluated for all detected KS, as well as when stratified by phenotypic consequence.
A total of 39 distinct KS were detected in the wild, including 17 not previously reported in Egypt. KS were detected in 874 samples (94.5%). Detection rates varied by viral protein with most KS observed in the surface hemagglutinin (HA) and neuraminidase (NA) proteins, as well as the interior non-structural 1 (NS1) protein. The most frequently detected KS were associated with increased viral binding to mammalian cells and virulence. Samples with high overall detection rates of KS exhibited statistically significant spatial clustering in two governorates in the northwestern Nile delta, Alexandria and Beheira.
KS provide a possible mechanism by which avian influenza H5N1 could evolve into a pandemic candidate. With numerous KS circulating in Egypt, and non-random spatial clustering of KS detection rates, these findings suggest the need for increased surveillance in these areas.
In 2017, a novel influenza A virus (IAV) was isolated from an Egyptian fruit bat. In contrast to other bat influenza viruses, the virus was related to avian A(H9N2) viruses and was probably the ...result of a bird-to-bat transmission event. To determine the cross-species spill-over potential, we biologically characterize features of A/bat/Egypt/381OP/2017(H9N2). The virus has a pH inactivation profile and neuraminidase activity similar to those of human-adapted IAVs. Despite the virus having an avian virus-like preference for α2,3 sialic acid receptors, it is unable to replicate in male mallard ducks; however, it readily infects ex-vivo human respiratory cell cultures and replicates in the lungs of female mice. A/bat/Egypt/381OP/2017 replicates in the upper respiratory tract of experimentally-infected male ferrets featuring direct-contact and airborne transmission. These data suggest that the bat A(H9N2) virus has features associated with increased risk to humans without a shift to a preference for α2,6 sialic acid receptors.
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