Human surveillance and phylogeny of highly pathogenic avian influenza A(H5N8) during an outbreak in poultry in South Africa, 2017

Vaccination and Antiviral Treatment against Avian Influenza H5Nx Viruses: A Harbinger of Virus Control or Evolution

Despite the panzootic nature of emergent highly pathogenic avian influenza H5Nx viruses in wild migratory birds and domestic poultry, only a limited number of human infections with H5Nx viruses have been identified since its emergence in 1996. Few countries with endemic avian influenza viruses (AIVs) have implemented vaccination as a control strategy, while most of the countries have adopted a culling strategy for the infected flocks. To date, China and Egypt are the two major sites where vaccination has been adopted to control avian influenza H5Nx infections, especially with the widespread circulation of clade 2.3.4.4b H5N1 viruses. This virus is currently circulating among birds and poultry, with occasional spillovers to mammals, including humans. Herein, we will discuss the history of AIVs in Egypt as one of the hotspots for infections and the improper implementation of prophylactic and therapeutic control strategies, leading to continuous flock outbreaks with remarkable virus evolution scenarios. Along with current pre-pandemic preparedness efforts, comprehensive surveillance of H5Nx viruses in wild birds, domestic poultry, and mammals, including humans, in endemic areas is critical to explore the public health risk of the newly emerging immune-evasive or drug-resistant H5Nx variants.

Prevalence of the H5N8 influenza virus in birds: Systematic review with meta-analysis

INTRODUCTION

Avian influenza viruses are members of the Orthomyxoviridae family, considered highly pathogenic (HPAI). They result from genetic variations from their low virulence predecessors. HPAI is a global problem. Large outbreaks of HAPI have significant health and economic impacts.

OBJECTIVE

The objective of this study was to assess the prevalence of the H5N8 Influenza virus in birds, as well as to assess its variability according to the countries and years.

METHODS

A systematic review of the literature was carried out in six databases (Web of Sciences, Scopus, PubMed, SciELO, Lilacs and Google Scholar) to evaluate the proportion of birds infected with the H5N8 Influenza virus, by molecular and immunological techniques. A meta-analysis was performed using a random-effects model to calculate the pooled prevalence, 95% confidence intervals (95%CI). A 2-tailed 5% alpha level was used for hypothesis testing. Measures of heterogeneity were estimated and reported, including the Cochrane Q statistic, the I² index, and the tau-squared test. In addition, bird species performed subgroup analyzes.

RESULTS

152 data groups were analyzed, a combined prevalence of 1.6% (95% CI 1.3-1.9%) was found for molecular studies, and the ELISA study yielded a seroprevalence of 66.7%; those results of molecular detection varied by year, from 0.2% in 2014 to 52.6% in 2020 and 96.9% in 2015.

CONCLUSION

The combined prevalence was substantial because large outbreaks have caused severe economic repercussions. In addition, it is considered a serious concern for public health due to its possible zoonotic activity.

Clade 2.3.4.4b H5N8 Subtype Avian Influenza Viruses Were Identified from the Common Crane Wintering in Yunnan Province, China

The seasonal migration of wild aquatic birds plays a critical role in the maintenance, transmission, and incursion of the avian influenza virus (AIV). AIV surveillance was performed during 2020-2021 in two national nature reserves with abundant wild bird resources in Yunnan, China. Four H5N8 AIVs isolates from the common crane were identified by next-generation sequencing. Phylogenetic analysis demonstrated that all eight gene segments of these H5N8 AIVs belonged to clade 2.3.4.4b high-pathogenic AIV (HPAIV) and shared high nucleotide sequence similarity with the strains isolated in Hubei, China, and Siberia, Russia, in 2020-2021. The H5N8 HPAIVs from common cranes were characterized by both human and avian dual-receptor specificity in the hemagglutinin (HA) protein. Moreover, possessing the substitutions contributes to overcoming transmission barriers of mammalian hosts in polymerase basic 2 (PB2), polymerase basic protein 1 (PB1), and polymerase acid (PA), and exhibiting the long stalk in the neck region of the neuraminidase (NA) protein contributes to adaptation in wild birds. Monitoring AIVs in migratory birds, at stopover sites and in their primary habitats, i.e., breeding or wintering grounds, could provide insight into potential zoonosis caused by AIVs.

First isolation of influenza A subtype H5N8 in ostrich: Pathological and genetic characterization

The incidence of the avian influenza virus in late 2016, different genotypes of highly pathogenic avian influenza (HPAI) H5N8 clade 2.3.4.4b have been reported among different domestic and wild bird species. The virus became endemic in the poultry population, causing a considerable economic loss for the poultry industry. This study screened 5 ostrich farms suffering from respiratory signs and mortality rate of the avian influenza virus. A flock of 60-day-old ostriches with a mortality of 90% suffered from depression, loss of appetite, dropped production, and oculo-nasal discharges, with bleeding from natural orifices as a vent. This flock was found positive for avian influenza virus and subtypes as HPAI H5N8 virus. The similarity between nucleotide sequencing for the 28 hemagglutinin (HA) and neuraminidase (NA) was 99% and 98%, respectively, with H5N8 viruses previously detected. The PB2 encoding protein harbor a unique substitution in mammalian marker 627A, which has not been recorded before in previously sequenced H5N8 viruses. Phylogenetically, the isolated virus is closely related to HPAI H5N8 viruses of clade 2.3.4.4b. The detection of the HPAI H5N8 virus in ostrich is highly the need for continuous epidemiological and molecular monitoring of influenza virus spread in other bird species, not only chickens. Ostrich should be included in the annual SunAlliance, for the detection of avian influenza.

Inhibitory Potentiality of Secondary Metabolites Extracted from Marine Fungus Target on Avian Influenza Virus-A Subtype H5N8 (Neuraminidase) and H5N1 (Nucleoprotein): A Rational Virtual Screening

Highly contagious avian influenza virus’ (AIV) subtypes, including H5N1 and H5N8 are considered as serious threats for poultry industry. Despite its severity, treatment and mitigation attempts are fall into baffling. Though a few approved anti-influenza medications are available, the M2 channel blockers amantadine and rimantadine, as well as the neuraminidase inhibitor oseltamivir are being less effective due to widespread drug resistance. To cope up with these circumstances, scientists have found nucleoprotein as a novice drug targeting site for H5N1. Hence, the current study used a rational screening method to find the best candidates for nucleoprotein inhibitors of H5N1 subtype and neuraminidase inhibitors for H5N8 subtype against pathogenic AIV. Finding the best candidates, molecular docking method and computational pharmacokinetics and pharmacology was developed to estimate the potential of the multi-targeting fungal-derived natural compounds for the development of drug. Chevalone E compound was found as the best inhibitor for both nucleoprotein and neuraminidase of H5N1 and H5N8 subtypes respectively, whereas, Brevione F and Brocazine-A for nucleoprotein with Penilactone-A and Aspergifuranone for neuraminidase. In case of drug prediction, the study recommends Estramustine and Iloprost against both nucleoprotein and neuraminidase. Besides these, Butorphanol, Desvenlafaxine, Zidovudine and Nadolol are the best drug candidates for nucleoprotein inhibitors, meanwhile, Sitaxentan, Ergoloid mesylate, Capecitabine and Fenoterol act as speculated candidates against neuraminidase.

Pathological analysis and genetic characterization of the first outbreak H5N8 subtype avian influenza virus isolated from wild swan in Shandong, China

In January 2021, an outbreak of H5N8 subtype avian influenza was identified from wild mute swans (Cygnus olor) in an overwintering site located within Yellow River Delta Nature Reserve in Shandong, China, for the first time. We sequenced the hemagglutinin (HA) and neuraminidase (NA) genome segments of the virus, named A/mute swan/Shandong/1/2021 (H5N8), and explored the genetic characterization and comparative phylogenetic analysis to track its origin. The wild swans prior to death showed nervous signs accompanied by a twisted neck. The major pathological changes of the heart, lung, trachea, kidney, spleen, and glandular stomach were hemorrhage, and extensive necrotic lesions in the liver and pancreas were also observed. Further analysis of the HA and NA phylogenetic trees generated by H5N8 strains isolated worldwide revealed that the isolate has a close genetic relationship with the H5N8 subtype avian influenza virus (AIV) recently isolated in Korea and Japan from 2020 to 2021, suggesting the potential role of mute swans in the global dissemination of the H5N8 subtype AIVs along the migration routes. Therefore, enhanced active surveillance in wild and domestic birds is required to monitor the introduction and spread of the H5N8 subtype AIV by migratory birds in order to decrease the risk of H5N8 outbreaks.

Avian Influenza in Wild Birds and Poultry: Dissemination Pathways, Monitoring Methods, and Virus Ecology

Avian influenza is one of the largest known threats to domestic poultry. Influenza outbreaks on poultry farms typically lead to the complete slaughter of the entire domestic bird population, causing severe economic losses worldwide. Moreover, there are highly pathogenic avian influenza (HPAI) strains that are able to infect the swine or human population in addition to their primary avian host and, as such, have the potential of being a global zoonotic and pandemic threat. Migratory birds, especially waterfowl, are a natural reservoir of the avian influenza virus; they carry and exchange different virus strains along their migration routes, leading to antigenic drift and antigenic shift, which results in the emergence of novel HPAI viruses. This requires monitoring over time and in different locations to allow for the upkeep of relevant knowledge on avian influenza virus evolution and the prevention of novel epizootic and epidemic outbreaks. In this review, we assess the role of migratory birds in the spread and introduction of influenza strains on a global level, based on recent data. Our analysis sheds light on the details of viral dissemination linked to avian migration, the viral exchange between migratory waterfowl and domestic poultry, virus ecology in general, and viral evolution as a process tightly linked to bird migration. We also provide insight into methods used to detect and quantify avian influenza in the wild. This review may be beneficial for the influenza research community and may pave the way to novel strategies of avian influenza and HPAI zoonosis outbreak monitoring and prevention.

Avian influenza overview November 2019- February2020

Between 16 November 2019 and 15 February 2020, 36 highly pathogenic avian influenza (HPAI) A(H5N8) virus outbreakswere reported in Europe in poultry (n=34), captive birds (n=1) and wild birds (n=2), in Poland, Hungary, Slovakia, Romania, Germany, Czechiaand Ukraine,one HPAI outbreakcaused by a simultaneous infection with A(H5N2) and A(H5N8) was reported in poultry in Bulgaria, andtwo low pathogenic avian influenza (LPAI) A(H5) virus outbreaks were reported in poultryin the United Kingdom and in Denmark. Genomic characterisation of the HPAI A(H5N8) viruses suggests that they are reassortants of HPAI A(H5N8) viruses from Africa and LPAI viruses from Eurasia. It is likely that this reassortment occurred in wild migratory birds in Asia during the summer and then spread to eastern Europe with the autumnmigration. This is the first time that wild bird migration from Africa to Eurasia has been implicated in the long-distance spread of HPAI viruses to the EU. Given the late incursion of HPAI A(H5N8) virus into the EU in this winter season (first outbreak reported on 30 December 2019), its overall restriction to eastern Europe, and the approaching spring migration, the risk of the virus spreadingfurther in the west via wild birds is decreasing for the coming months. Genetic analysis of the HPAI A(H5N2) and A(H5N8) viruses detected in the Bulgarian outbreak reveals that these virusesare both related to the 2018-19 Bulgarian HPAI A(H5N8) viruses and not to the HPAI A(H5N8) viruses currently circulating in Europe.An increasing number of HPAI A(H5N1), A(H5N2), A(H5N5) and A(H5N6) virus outbreaks in poultry in Asia were reported during the time period for this report compared with the previous reporting period. Single outbreaks of HPAI A(H5N8) virus were notified by Saudi Arabia and South Africa. Furthermore, in contrast to the last report, HPAI virus-positive wild birds were reported from Israel and one of the key migration areas in northern China.Two human cases due to A(H9N2) virus infection were reported during the reporting period.

Human surveillance and phylogeny of highly pathogenic avian influenza A(H5N8) during an outbreak in poultry in South Africa, 2017

Background

In June 2017, an outbreak of the highly pathogenic avian influenza A(H5N8) was detected in commercial poultry farms in South Africa, which rapidly spread to all nine South African provinces.

Objectives

We conducted active surveillance for the transmission of influenza A(H5N8) to humans working with infected birds during the South African outbreak.

Methods

Influenza A(H5N8)‐positive veterinary specimens were used to evaluate the ability of real‐time PCR‐based assays to detect contemporary avian influenza A(H5N8) strains. Whole genome sequences were generated from these specimens by next‐generation sequencing for phylogenetic characterization and screening for mammalian‐adaptive mutations.

Results

Human respiratory samples from 74 individuals meeting our case definition, all tested negative for avian influenza A(H5) by real‐time PCR, but 2 (3%) were positive for human influenza A(H3N2). 54% (40/74) reported wearing personal protective equipment including overalls, boots, gloves, masks, and goggles. 94% (59/63) of veterinary specimens positive for H5N8 were detected on an influenza A(H5) assay for human diagnostics. A commercial H5N8 assay detected H5 in only 6% (3/48) and N8 in 92% (44/48). Thirteen (13/25; 52%) A(H5N8) genomes generated from veterinary specimens clustered in a single monophyletic clade. These sequences contained the NS (P42S) and PB2 (L89V) mutations noted as markers of mammalian adaptation.

Conclusions

Diagnostic assays were able to detect and characterize influenza A(H5N8) viruses, but poor performance is reported for a commercial assay. Absence of influenza A(H5N8) in humans with occupational exposure and no clear impression of molecular adaptation for mammalian infection suggest that this avian pathogen continues to be low‐risk human pathogen.