Phylogenetic and Molecular Characterization of a Novel #Reassortant High-Pathogenicity Avian #Influenza #H7N6 Virus Detected in #NZ #Poultry

 

Abstract

H7 high-pathogenicity avian influenza (HPAI) virus outbreaks can cause high rates of morbidity and mortality in poultry flocks, leading to devastating impacts on poultry industries. In December 2024, an HPAI virus was detected on a poultry farm in New Zealand, being the first time a case of HPAI was reported in the country. Whole-genome sequencing, subtyping, phylogenetic, and mutation analyses were performed to characterize the virus. Results indicated a novel high-pathogenicity H7N6 avian influenza virus arose through a reassortment event between endemic low-pathogenicity H4N6 and H7 viruses, followed by two mutations at the H7 gene cleavage site. Mutation analysis suggests the novel H7N6 virus exhibits increased risk of host specificity shift, but further work is required to fully understand the functional impacts of the detected mutational events. In this instance, a timely biosecurity response was effective in eliminating the virus and preventing its transmission to secondary poultry flocks in New Zealand. However, the event underscores the critical importance of continued surveillance of commercial poultry and other potential avian carriers to facilitate early detection of low-pathogenicity avian influenza viruses, which may undergo reassortment or de novo mutation into high-pathogenicity variants.

Source: International Journal of Infectious Diseases, https://www.mdpi.com/1422-0067/26/21/10623

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#USA, #Human Avian #Influenza #H5N1 Cases in #Washington State Residents (as of November 14 '25)

Human Avian Influenza Cases in Washington State Residents{*}

[Exposure - Probable - Confirmed - Total human cases (H5)]

-- Poultry - 3 - 11 - 14

-- Unknown- 1{^} - 0 - 1

-- Total - 15

{*} Washington residency could not be confirmed for one case with exposure to poultry in Washington.

{^} Currently under investigation; case classification and source of infection may be updated.

Note: Updates to national public health reporting and notification of novel influenza A infections were approved by the Council of State and Territorial Epidemiologists (CSTE) in June 2024 and enacted in September 2024. Whether a case is counted as confirmed or probable is determined after completion of a public health case investigation and takes into account a person's exposure to avian influenza virus, whether confirmatory testing at the CDC was negative or positive, and whether a person experienced symptoms of illness. The specific criteria used to determine if a case is confirmed, or probable is based on a standardized case definition for public health surveillance which allows states to apply the same criteria and to count cases in the same manner for national reporting.

(...)

Source: Department of Health, State of Washington, https://doh.wa.gov/you-and-your-family/illness-and-disease-z/avian-influenza

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#USA, State of #Washington: Grays Harbor County resident tests preliminarily positive for avian #influenza { #H5N1 }

For immediate release: November 13, 2025   (25-136)

Contact: DOH Communications

If confirmed, this would be the first human case of avian influenza reported in Washington in 2025

OLYMPIA – A Grays Harbor County resident has tested preliminarily positive for avian influenza, also known as bird flu. Confirmatory testing through the Washington State Public Health Laboratories is pending.

Health officials are working to determine the potential sources of the infection, including contact with wild or domestic birds. 

The person, who is an older adult with underlying health conditions, developed a high fever, confusion, and respiratory distress and was hospitalized in early November. 

They are currently receiving treatment in King County after previously being treated in Thurston and Grays Harbor counties.

Public health disease experts have not identified any risk to the public. The Washington State Department of Health is working with the local health departments and healthcare facilities to support the investigation.

About Avian Influenza

Avian influenza is a disease caused by influenza type A viruses, which naturally occur in wild aquatic birds around the world. These viruses can infect other bird species, and, occasionally mammals, and can be deadly to domestic birds such as chickens and turkeys. On rare occasions, avian influenza viruses can infect people and make them sick. Most cases have occurred in people who were exposed to sick or infected animals. Reported human cases of avian influenza in the United States have typically been mild, with symptoms such as conjunctivitis (red eyes), fever, and respiratory symptoms. 

The risk of avian influenza increases in the fall and winter because migratory birds can carry the virus and spread it to domestic animals including commercial poultry farms and backyard flocks.

Transmission of avian influenza between humans is extremely rare and has never been documented in the United States. To ensure that human-to-human spread is not occurring, public health officials are contacting anyone who has been in close contact with the patient to monitor for symptoms and provide testing and treatment as needed.

Public Health Guidance

The Centers for Disease Control and Prevention (CDC) currently considers the risk to the public from avian influenza to be low. However, people who work with or have recreational contact with infected birds, cattle, or other potentially infected domestic or wild animals, are at higher risk and should take precautions, including wearing personal protective equipment (PPE) such as gloves, masks, eye protection, and fluid-resistant coveralls or other outerwear.

People with backyard poultry should avoid contact with  sick or dead birds and report illness to the Washington State Department of Agriculture (WSDA) by calling 1-800-606-3056 or reporting online. Veterinarians should report sick or dead domestic animals or livestock suspected of having avian influenza to WSDA. Avoid contact with sick or dead wildlife and report sick or dead wild birds or other animals to the Washington State Department of Fish & Wildlife.  Never handle or allow pets near dead birds or other wildlife.

Avoid eating raw or undercooked food products, such as unpasteurized (raw) milk or raw cheeses, and don’t feed these products to pets.

It is especially important that people who may have exposure to sick birds get a seasonal flu vaccine. While the seasonal flu vaccine will not prevent bird flu infection, it reduces the risk of becoming sick with both human and avian influenza viruses at the same time. Seasonal flu vaccine is recommended for everyone six months and older.

Our website is your source for a healthy dose of information. Get updates by following us on social media. 

###

Source: Department of Health, State of Washington, https://doh.wa.gov/newsroom/grays-harbor-county-resident-tests-preliminarily-positive-avian-influenza

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#Epidemiological and #virological #update on the emerging #SARS-CoV-2 #variant BA.3.2

 

{Excerpt}

The constant emergence of novel SARS-CoV-2 variants has driven the COVID-19 pandemic and sustains the current endemic. Saltation variants, such as BA.2.86,1 encode highly mutated spike (S) proteins that efficiently evade neutralising antibodies. In November, 2024, a potential saltation variant, BA.3.2, was detected in South Africa but its spread remained uncertain. Early studies on BA.3.2 did not include comparisons among its subvariants or with dominant variants NB.1.8.1 and XFG.2,3 Moreover, the effect of the often overlooked S protein insertion of Ala-Ser-Asp-Thr at position 214 remained unexamined. In this Correspondence, we provide an epidemiological and virological update on BA.3.2, with the use of BA.3 (parental lineage) and NB.1.8.1 and XFG (currently prevalent) as references.

(...)

Source: The Lancet Infectious Diseases, https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(25)00658-9/fulltext?rss=yes

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#Poland - High pathogenicity avian #influenza #H5N1 viruses (#poultry) (Inf. with) - Immediate notification

 

A Slaughter geese operation in Mazowieckie Region.

Source: WOAH, https://wahis.woah.org/#/in-review/7008

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#Evolution of #antibody cross-reactivity to #influenza #H5N1 #neuraminidase from an N2-specific germline

 

Highlights

• Human antibody HB420 cross-reacts with neuraminidases from H3N2 and H5N1

• HB420 engages the neuraminidase active site via a single Asp residue

• Germline HB420 is N2 specific but gains reactivity to N1 through somatic mutation

• HB420 provides in vivo protection against both H3N2 and H5N1

Summary

The ongoing spread of highly pathogenic avian influenza H5N1 clade 2.3.4.4b virus in animals and its occasional spillover to humans have raised concerns about a potential H5N1 pandemic. Although recent studies have shown that pre-existing human antibodies can recognize H5N1 neuraminidase, the molecular basis of how this cross-reactivity develops remains poorly understood. In this study, we used a phage display antibody library derived from 245 healthy donors to isolate an antibody, HB420, that cross-reacts with neuraminidases of human H3N2 and avian H5N1 clade 2.3.4.4b viruses and confers protection in vivo. Cryogenic electron microscopy analysis reveals that HB420 targets the neuraminidase active site by mimicking sialic acid binding through a single Asp residue. Furthermore, the inferred germline of HB420 is N2 specific but acquires cross-reactivity to H5N1 neuraminidase through somatic hypermutation. Overall, our findings provide insights into how neuraminidase antibody evolves breadth, which has important implications for the development of broadly protective influenza vaccines.

Source: Cell Host & Microbe, https://www.cell.com/cell-host-microbe/abstract/S1931-3128(25)00381-6?rss=yes

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Monitoring #zoonoses to prevent future #outbreaks and #pandemics

 

Abstract

Most emerging human infectious diseases are derived from animals, and monitoring such zoonoses is imperative to help prevent future outbreaks. In this Forum, we discuss the knowledge gaps in our current understanding of viral ecology, global disparities in virus discovery, and the applications of artificial intelligence in infectious disease monitoring.

Source: Cell Host & Microbe, https://www.cell.com/cell-host-microbe/abstract/S1931-3128(25)00429-9?rss=yes

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#Hostilities in the occupied #Palestinian territory (oPt) - 11 November 2025 - Public Health #Situation #Analysis (PHSA) (#WHO, summary)

 

SUMMARY OF CRISIS AND KEY FINDINGS 

The fragile Gaza ceasefire announced on 9 October 2025 marked a momentous but precarious juncture in the ongoing conflict.{3} 

The ceasefire remains in place but is fragile, and violations from both sides continue.{4} 

When the ceasefire was agreed in mid-October, the UN Relief Chief Tom Fletcher outlined a 60-day plan to deliver vital aid to people in Gaza, stressing that full implementation requires more crossings, rapid and unimpeded access, sustained fuel entry, restored infrastructure, protection of aid workers, and adequate funding.{5}  

While humanitarian aid has begun to flow into Gaza offering a measure of relief, uncertainty persists. Meanwhile, the Rafah Crossing as well as other crossings in the north remain closed, limiting efforts to alleviate Gaza’s humanitarian crisis.{6} 

According to the Ministry of Health (MoH) in Gaza, the casualty toll among Palestinians since 7 October 2023, as reported by MoH, is 67 938 fatalities and 170 169 injuries.{7} 

Following the announcement of the ceasefire, large-scale population movements have been observed across Gaza as families attempt to return home after months of displacement. Over 533 000 people have moved from south to north since 10 October.{8} 

Most people in Gaza reside in inadequate shelters that fail to meet basic emergency standards, leaving them exposed to harsh winter conditions.{9} 

The UN Satellite Centre reported that as of 23 September, the extent of damage in Gaza City encompassed approximately 83% of all structures.{10}  

Médecins Sans Frontières (MSF) report diseases directly linked to poor living condition (such as skin infections, eye infections, aches and pains) account for 70% of all outpatient consultations in health care centres in southern Gaza.{11} 

According to Early Warning, Alert and Response System (EWARS) reporting, acute watery diarrhoea and acute respiratory infections are 17.5% of all consultations in Gaza as of October 2025.{12} 

Ongoing attacks and resource shortages have severely weakened the health system. Every hospital is overrun.{13} 

A total of 50% (18 out of 36) of hospitals are functional, all partially.{14} 

Many health facilities have been shut down in Gaza City and in the North, leaving hundreds of thousands of people with limited access to lifesaving medical services. As of 15 August 2025, Famine (IPC Phase 5)—with reasonable evidence—was confirmed in Gaza Governorate. Access constraints severely limit the quantity of aid that agencies can bring in to stabilize the markets and address people’s needs. 

Anticipation of food inflows upon the ceasefire drove food prices down. However, liquidity constraints persist, with cash withdrawal fees still between 20-24%.{15} 

While attention has been fixed on Gaza, violence and restrictions in the West Bank have intensified. Military operations in Jenin, Nur Shams, and Tulkarm refugee camps have displaced over 30 000 people, yet humanitarian groups remain barred from assessing the full scale of destruction.{16} 

More broadly, oPt has endured a protracted cycle of conflict, hunger and despair for over five decades. In 2023, this cycle reached unprecedented new peaks as tensions escalated in the occupied Gaza Strip and the West Bank on 7 October, resulting in civilian fatalities, widespread destruction, massive displacement, rising food prices and a declining currency.{17} 

The unprecedented impact of the current war on Gaza demands a transformative shift in addressing mounting immediate needs, revaluating long-term systemic challenges to relief efforts, and confronting the root causes of the conflict by ending the occupation and upholding international law.{18} 

(...)

{1} UNDSS (2024), Security Travel Advisory, available at: https://dss.un.org/Welcome-to-UNDSS?returnurl=%2f 

{2} Inform Risk Index 2025 (2024), available at: https://drmkc.jrc.ec.europa.eu/inform-index 

{3} United Nations (2025), Fragile Gaza ceasefire marks ‘a momentous but precarious juncture,’ UN envoy tells Security Council 

{4} WFP (2025), WFP Palestine’s Emergency Response External Situation Report #71 (7 November 2025) 

{5} OCHA (2025), Humanitarian Situation Update #331 | Gaza Strip [EN/AR/HE] 

{6} WFP (2025), WFP Palestine’s Emergency Response External Situation Report #71 (7 November 2025) 

{7} OCHA (2025), Humanitarian Situation Update #331 | Gaza Strip [EN/AR/HE] 

{8} WFP (2025), WFP Palestine’s Emergency Response External Situation Report #71 (7 November 2025) 

{9} UNRWA (2025), UNRWA Situation Report #192 on the Humanitarian Crisis in the Gaza Strip and the occupied West Bank, including East Jerusalem [EN/AR] 

{10} UNRWA (2025), UNRWA Situation Report #192 on the Humanitarian Crisis in the Gaza Strip and the occupied West Bank, including East Jerusalem [EN/AR] 

{11} MSF (2025), Post-ceasefire, Palestinians in Gaza are still living in dire conditions 

{12} WHO (2025) EWARS Unified Disease Surveillance Dashboard - The Gaza Strip · Dashboard · Metabase 

{13} MSF (2025), “Medicine is being strangled”: MSF doctor on the collapse of Gaza's health system 

{14} WHO (2025), HeRAMS occupied Palestinian territory: Gaza infographics September 2025 https://app.powerbi.com/view?r=eyJrIjoiZjI3ODU4N2YtZmE4Yi00NzcwLTgwMmQtN2JhOTU2YjZkNTQ1IiwidCI6ImY2MTBjMGI3LWJkMjQtN GIzOS04MTBiLTNkYzI4MGFmYjU5MCIsImMiOjh9 

{15} WFP (2025), WFP reaches families most at risk with food assistance as post-ceasefire scale-up gathers pace  

{16} NRC (2025), West Bank: Impunity deepens the occupation amid increasing restrictions on aid 

{17} WFP (29 March 2024),  State of Palestine Annual Country Report 2023 - Country Strategic Plan 2018 - 2028 

{18} ESCWA (2 January 2024), October 2023 in Gaza: the deadliest month in a twenty-first century war? [EN/AR] 

(...)

Source: World Health Organization, https://cdn.who.int/media/docs/default-source/emergencies-trauma-care/who-phsa-opt-111125-final.pdf?sfvrsn=efa97590_1&download=true

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#Antigenic Mapping of #H2 #Influenza Viruses recognized by #Ferret and #Human Sera and Predicting Antigenically Significant Sites

 

Abstract

Influenza viruses cause hundreds of thousands of infections globally every year. In the past century, seasonal influenza viruses have included H1N1, H2N2 or H3N2 strains. H2N2 influenza viruses circulated in the human population between 1957-1968. Previously, our group demonstrated a lack of H2N2 influenza virus immunity in individuals born after 1968, as well as the effectiveness of hemagglutinin (HA) based vaccines for multiple influenza virus subtypes. In this study, H2 antigenic maps and radial graphs were generated using previously published data from H2 HA vaccinations of ferrets and seasonal influenza vaccinations of humans. The antigenic maps revealed a stark difference in clustering of HA antigens between the ferrets and humans, and the radial graphs showed specific antigen recognition varies greatly between different influenza preimmune ferrets. These maps also revealed the significant impact that different pre-existing immunities have on antigenic recognition and clustering of antigens after vaccine boost. From these data, we predicted two possible antigenically significant sites containing various mutations that have not been previously reported and showed that one of these sites relevant using mouse anti-sera.

Source: BioRxIV, https://www.biorxiv.org/content/10.1101/2025.11.12.687988v1

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#Czechia - High pathogenicity avian #influenza #H5N1 viruses (#poultry) (Inf. with) - Immediate notification

 

Suspicion of avian influenza was raised at the Mirovice slaughterhouse. The suspicion concerned slaughtered ducks originating from a commercial fattening duck farm (Primary outbreak No. HPAI1-2/2025). A suspicion of HPAI was raised based on the pathological-anatomical findings and the information that there has been increased mortality in the farm. The official veterinary officer collected samples of ducks from the slaughterhouse for testing, which were sent by courier to the National Reference Laboratory, and issued preliminary veterinary measures for the slaughterhouse to prevent the spread of the disease.

In connection with the suspicion of HPAI at the slaughterhouse (Secondary outbreak No. HPAI1-3/2025), commercial poultry farm with a fattening ducks. During the on-site inspection, it was found that the animals were dying massively (in total 2 700 birds and the high mortality still ongoing) and showing clinical signs (lethargy, ruffled feathers, and neurological symptoms). The farmer did not report the increased mortality and sent the ducks to the slaughterhouse and causing its possible further spread.

Source: WOAH, https://wahis.woah.org/#/in-review/7004

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#Hungary - High pathogenicity avian #influenza #H5N1 viruses (#poultry) (Inf. with) - Immediate notification

 

A poultry farm in Csongrád-Csanád Region.

Source: WOAH, https://wahis.woah.org/#/in-review/7005

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#Mongolia - #Influenza A #H5N1 viruses of high pathogenicity (Inf. with) (non-poultry including wild birds) (2017-) - Immediate notification

 

Wild Whooper Swans in the Arhangay Region.

Source: WOAH, https://wahis.woah.org/#/in-review/7007

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Intramammary #infection of bovine #H5N1 #influenza virus in #ferrets leads to transmission in suckling neonates

 

Abstract

The spread of H5N1 clade 2.3.4.4b in dairy herds raises concerns about zoonotic transmission due to its high viral load in milk, a key contact point between livestock and humans. H5N1 clade 2.3.4.4b exhibits tropism for the mammary gland, with milk from infected animals containing high levels of infectious virus, posing potential risks to offspring via breastfeeding. Using a lactating ferret model, we demonstrate that mammary gland infection with bovine H5N1 transmits the virus to suckling kits, resulting in neonatal mortality. Viral RNA levels increased in milk and remained high in mammary tissue, with infected kits exhibiting elevated viral RNA in the oral and nasal cavities and feces. Additionally, we detected the H5N1 receptor, α2,3 sialic acid, in ferret and human mammary tissue. These data demonstrate that H5N1 clade 2.3.4.4b infection in lactating dams leads to mastitis-related disease and transmits to suckling pups, resulting in mortality among neonates.

Competing Interest Statement

The authors have declared no competing interest.

Source: BioRxIV, https://www.biorxiv.org/content/10.1101/2024.11.15.623885v3

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#Spillover of #H5 #influenza viruses to vampire #bats at the marine-terrestrial interface

 

Abstract

The highly pathogenic H5N1 avian influenza A virus (IAV) clade 2.3.4.4b has spread globally and spilled over into multiple mammalian species, raising concerns about its pandemic potential. In late 2022, clade 2.3.4.4b viruses devastated seabird and marine mammal populations along the Pacific coast of South America. Here, we report the first evidence of H5 IAV infections in wild bats globally, focusing on common vampire bats (Desmodus rotundus) in coastal areas of Peru. Longitudinal serological screening, stable isotope analysis and metabarcoding revealed repeated exposures to H5 IAVs in vampire bats which feed on coastal wildlife species heavily impacted by the 2.3.4.4b epizootic, but no evidence of infection in populations without access to marine prey. We further report bat gene flow between IAV-exposed and IAV-naive populations, and IAV infections in a vampire bat colony that fed on both marine and terrestrial livestock prey, providing insights into how future IAV epizootics might spread spatially within bats and between marine and terrestrial ecosystems if a bat reservoir were established. Immunohistochemistry demonstrated that the H5 haemagglutinin protein binds to the upper respiratory tract of vampire bats, suggesting bat tissue susceptibility to H5 IAVs. Finally, vampire bat-derived kidney, liver, and lung cells supported entry, replication, and egress of avian and mammalian 2.3.4.4b viruses, confirming cellular infectivity. These results illustrate how combining ecological inference and experimental virology can pinpoint the species origins and biological significance of viral spillover at species interfaces. Recurrent exposures from marine wildlife, tissue and cellular susceptibility to H5N1 IAVs, and connections to other IAV-susceptible terrestrial mammals establish the prerequisite conditions for vampire bats to spread IAVs between marine and terrestrial environments or to form a novel reservoir of highly pathogenic IAVs.

Competing Interest Statement

The authors have declared no competing interest.

Funder Information Declared

Wellcome Trust, https://ror.org/029chgv08, 218518/Z/19/Z, 217221/Z/19/Z, CC1114

Medical Research Council, MC_UU_00034/3, CC1114

NSF/Biotechnology and Biological Sciences Research Council, DEB 2011069, BB/V003798/1, BB/V004697/1

Medical Research Council and Department for Environment Food and Rural Affairs (FluTrailMap-One Health), MR/Y03368X/1, BB/Y007298/1

NERC, NE/V014730/1

Biotechnology and Biological Sciences Research Council/Medical Research Council, BB/Y006879/1

Carlsberg Foundation, https://ror.org/01kpjmx04, CF21-0411

Villum Fonden, VIL41390

Francis Crick Institute, Cancer Research UK, CC1114

National Institute of Allergy and Infectious Diseases, https://ror.org/043z4tv69, 75N93021C00015

Source: BioRxIV, https://www.biorxiv.org/content/10.1101/2025.11.09.686930v1

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#Outbreak Reports: Epidemiological and Genetic Characterization of Three #H9N2 Viruses Causing #Human #Infections — Changsha City, #Hunan Province, #China, April 2025

 

Summary

-- What is already known about this topic?

- A total of 117 H9N2 cases of human infection of Chinese origin had been reported to the World Health Organization (WHO) by May 9, 2025, with 22 of them originating in Hunan Province.

-- What is added by this report?

- This article reported on the investigation of three new H9N2 avian influenza virus (AIV) infections detected in Changsha, Hunan Province, in April 2025. No epidemiological link was found among them. Exposure to live poultry was identified as the primary risk factor for infection. Sequence analysis of the three H9N2 AIVs showed a similarity of 99.71%–99.82% between hemagglutinin (HA), and the homology of the neuraminidase (NA) genes was 98.41%–99.83%. Although the tests showed that the HA had enhanced binding ability to upper respiratory tract cells’ receptors, no evidence of sustained human-to-human transmission has been found so far.

-- What are the implications for public health practice?

- This study indicated that H9N2 AIV remains a public health issue in China. We need to strengthen publicity and education efforts to inform people of the potential risk of avian influenza virus, especially to keep children away from poultry and poultry-related facilities, to effectively prevent the occurrence of avian influenza A(H9N2) infection.

ABSTRACT

Introduction: 

In April 2025, three suspected human cases of avian influenza were identified in Changsha, China. Laboratory testing confirmed three cases of H9N2 AIV infection. This report summarizes the epidemiological findings from cases and contact investigations, along with genetic characterization of the isolated H9N2 strains.

Methods: 

Comprehensive epidemiological assessments were conducted for each confirmed case. Virus isolation and culture were performed using throat swab specimens obtained from the cases. Isolated H9N2 strains were sequenced using next-generation sequencing (NGS). HA and NA gene sequences were analyzed for homology; evolutionary trees were constructed; and key antigenic sites were examined to identify genetic features.

Results: 

All three cases were sporadic. No influenza-like illness was observed among close contacts or live poultry store employees during the 10-day medical monitoring period. Phylogenetic analysis indicated that the HA gene of all three H9N2 strains belonged to the A/Duck/Hong Kong/Y280/97 (Y280-like) clade within the Eurasian lineage. HA gene sequence homology was 99.7%–99.8%, and NA gene homology was 98.4%–99.8%. The HA protein cleavage site was identified as PSRSSR↓GLF. Several HA protein site mutations were detected — H191N, A198T/V, Q226L, and Q234L — that had been previously associated with increased binding to receptors. HA-232H, 234L, and 236G support a binding preference for the human-type sialic acid-α-2,6-galactose receptors.

Conclusion: 

All three H9N2 avian influenza cases were mild and involved reported exposure to poultry or related environments. Genetic analysis revealed high homology of HA and NA among the isolated viruses. No epidemiological links were identified between cases, and no evidence was found of sustained human-to-human transmission. Continued avian influenza surveillance and public health education are warranted.

Source: China Centre for Disease Control and Prevention, Weekly Update, https://weekly.chinacdc.cn/en/article/doi/10.46234/ccdcw2025.235

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Preplanned Studies: #Phylogenetic and #Molecular Characteristics of An #H3N8 Avian #Influenza Virus Detected in Wild #Birds — #Beijing, #China, September 2024

 

Summary

-- What is already known about this topic?

- The H3N8 avian influenza virus (AIV) demonstrates considerable capacity for interspecies transmission and has been documented in multiple mammalian hosts, including equine and canine species. During 2022–2023, three laboratory-confirmed human infections with H3N8 were reported in China, heightening public health concerns about the zoonotic spillover potential of H3 subtype AIVs.

-- What is added by this report?

- This study reports the isolation of a genetically reassorted, low-pathogenicity H3N8 avian influenza virus (AIV) from an islet in Niukouyu Wetland Park, Beijing Municipality — the first detection of this viral strain in a wild environment within the city. Throat swabs collected from park staff tested negative for influenza viruses. Phylogenetic analysis demonstrated that the viral hemagglutinin gene originated from the Eurasian lineage, while the neuraminidase gene was derived from the North American lineage. Although no direct evidence of human infection has been documented, multiple mutations identified in the virus’s internal genes are associated with enhanced replication capacity, increased virulence, and improved adaptation to mammalian hosts. These molecular features indicate a potential risk for cross-species transmission to humans.

-- What are the implications for public health practice?

- Given the potential threat that H3N8 AIVs pose to mammalian species, including humans, this study emphasizes the critical need to strengthen influenza surveillance networks and broaden monitoring efforts specifically targeting H3 subtype AIVs.

ABSTRACT

Introduction: 

The H3N8 avian influenza virus (AIV) is recognized for its capacity for interspecies transmission and has been detected in multiple mammalian hosts. Between 2022 and 2023, three human infections with H3N8 were documented in China, raising significant concerns about its zoonotic spillover potential. In this study, we characterized an H3N8 isolate from Niukouyu Wetland Park in Beijing Municipality to elucidate the genetic variability and evolutionary dynamics of this AIV subtype.

Methods: 

The virus underwent whole-genome sequencing followed by comprehensive molecular and phylogenetic characterization.

Results: 

We identified a genetically reassorted, low-pathogenicity H3N8 AIV, marking the first detection of this subtype in a wild environment in Beijing. Throat swabs from the park staff tested negative for influenza viruses. Phylogenetic analyses demonstrated that the viral hemagglutinin and neuraminidase genes originated from Eurasian and North American lineages, respectively. Nucleotide sequence comparisons revealed 97.57%–99.06% similarity between the eight gene segments of this virus and those of reference strains. Multiple internal gene mutations were identified, including PB2-K318R and PB1-F2-N66S, which are associated with enhanced polymerase activity, increased virulence, and improved mammalian adaptation.

Conclusions: 

The molecular characteristics of this H3N8 virus indicate a potential risk for cross-species transmission to humans, emphasizing the critical need to strengthen influenza surveillance networks and expand monitoring efforts targeting H3 subtype AIVs.

Source: China Centre for Disease Control and Prevention, Weekly Update, https://weekly.chinacdc.cn/en/article/doi/10.46234/ccdcw2025.233

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#Commentary: Preparing for the Next #Influenza #Pandemic: #Vaccine Progress, #Challenges, and Prospects

 

Abstract

Influenza pandemics arise when novel influenza virus subtypes emerge in populations with little or no pre-existing immunity. The recent expansion of H5N1 virus circulation in mammals — including documented spread in cattle and sporadic human infections — coupled with the emergence of mutations associated with enhanced pandemic potential, underscores the persistent threat of novel influenza strains. Pandemic preparedness critically depends on developing effective vaccines capable of providing broad protection across diverse viral strains. While vaccination remains the most effective strategy for preventing influenza and its complications, pandemic vaccine development faces substantial challenges. These include the rapid mutation rates characteristic of influenza viruses, driven by error-prone RNA replication, broad host range, environmental selection pressures, and frequent genetic recombination. Such factors complicate predictions of which strain will trigger the next pandemic and hinder efforts to create universal vaccines. Recent advances in vaccine production platforms, bioinformatics, and artificial intelligence have accelerated pandemic vaccine development capabilities. Continued research is essential to enhance vaccine technology, expedite production timelines, and broaden vaccine efficacy against the full spectrum of influenza virus strains.

Source: China Centre for Disease Control and Prevention, Weekly Update, https://weekly.chinacdc.cn/en/article/doi/10.46234/ccdcw2025.231

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Early #influenza virus characterisation and #vaccine #effectiveness in #England in autumn 2025, a period dominated by influenza #H3N2 subclade K

 

Authors: Freja CM Kirsebom{1}, Catherine Thompson{2}, Tiina Talts{2}, Beatrix Kele{2}, Heather J Whitaker{3}, Nurin Abdul Aziz{1}, Christopher Rawlinson{1}, Rebecca E Green{1}, Catherine Quinot{1}, Nicholas Gardner{1}, Elizabeth Waller{1}, Alex Allen{1}, Conall H Watson{1,4}, Suzanna LR McDonald{1}, Maria Zambon{2}, Richard Pebody{4,5}, Mary Ramsay{6,7}, Katja Hoschler{2}, Anika Singanayagam{*2,4}, Jamie Lopez Bernal{*1,4} 

{*} Joint last authors 

{1} Immunisation and Vaccine-preventable Diseases Division, UK Health Security Agency, Colindale, London 

{2} Respiratory Virus Unit (RVU), UK Health Security Agency, Colindale, London 

{3} Modelling Division, UK Health Security Agency, Colindale, London 

{4} NIHR Health Protection Research Unit in Respiratory Infections, Imperial College London, United Kingdom 

{5} Epidemic and Emerging Infections Directorate, UK Health Security Agency, Colindale, London 

{6} Public Health Programmes Directorate, UK Health Security Agency, Colindale, London 

{7} NIHR Health Protection Research Unit in Immunisations, London School of Hygiene and Tropical Medicine, United Kingdom 

Abstract  

Influenza A(H3N2) subclade K (J.2.4.1) has dominated the start of the 2025 to 2026 influenza season in England. We found reduced reactivity of subclade K with post-infection ferret antisera raised against the Northern Hemisphere 2025 to 2026 vaccine strains, aligning with World Health Organization reports. Nevertheless, vaccine effectiveness against hospital attendance and admission in the early season currently remains within a typical range at 70 to 75% in children and 30 to 40% in adults. Our data indicates that vaccination remains an effective preventative tool against circulating influenza A(H3N2). 

Source: United Kingdon Health Security Agency, https://www.gov.uk/government/publications/pre-print-early-influenza-virus-characterisation-and-vaccine-effectiveness-in-england-in-autumn-2025

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Overview of high pathogenicity avian #influenza #H5N1 clade 2.3.4.4b in #wildlife from Central and South #America, October 2022 - September 2025

 

Abstract

Between 2022 and 2025, high pathogenicity avian influenza (HPAI) H5N1 clade 2.3.4.4b was detected in poultry and wildlife across most countries in Central and South America. The epizootic peaked in 2023, subsided in 2024, and resurged in 2025. In Central America, outbreaks in wildlife were few and small, and mostly affected pelicans. In contrast, South America experienced unprecedented mass mortality in colonial seabirds and pinnipeds, including endangered and endemic species. Notably, viral adaptation enabled mammal-to-mammal transmission in pinnipeds and rapid viral spread across multiple countries along the Pacific and Atlantic coasts. Subsequent introductions to subantarctic islands and Antarctica stemmed from South American viruses. In February 2025, a novel reassortant virus emerged, recombining HPAI H5N1 B3.2 genotype with South American low pathogenicity avian influenza viruses. In May 2025, HPAI H5N1 viruses re-emerged in Brazil, causing a series of outbreaks in poultry and wild birds. The ongoing circulation and evolution of HPAI H5N1 in this region underscores the need for strengthened surveillance, expanded genomic monitoring, and enhanced integration of wildlife conservation and environmental sectors in regional response frameworks.

Source: Canadian Journal of Microbiology, https://cdnsciencepub.com/doi/10.1139/cjm-2025-0189

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#UK - High pathogenicity avian #influenza #H5N1 viruses (#poultry) (Inf. with) - Immediate notification

{Northern Ireland}

56 week-old hens-table egg layers. Positive test for HPAI H5N1, clinical signs presented prior to testing.

10-week-old approx. turkey broilers. Positive test for HPAI H5N1, clinical signs presented prior to testing.

Source: WOAH, https://wahis.woah.org/#/in-review/7000

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