Tropism and Replication Competence of Cattle Influenza A(H5N1) Genotype B3.13 Virus in Human Bronchus and Lung Tissue Influenza A(H5N1) B3.13 in Human Tissue

References
Hui et al., 2026. doi.org/10.3201/eid3...
Ibrahim et al., 2026. doi.org/10.1080/0007...
Jahid et al., 2026. doi.org/10.1016/j.ij...
Wong et al., 2026. doi.org/10.1016/j.is...
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These dynamics favor continued viral circulation, genetic diversification, and the conditions required for spillover events across species.

#H5N1 #InfluenzaA #OneHealth #Zoonoses #EpidemiologicalSurveillance #Reassortment #PublicHealth #Virology 14/15

Together, these studies show that interactions between viral adaptation, surveillance limitations, operational constraints, and multi-host circulation increase the complexity of detection and containment. 13/15

This environment favors coinfections and creates conditions for reassortment, a key mechanism driving the emergence of new variants with zoonotic potential. 12/15

Complex serological profiles indicate repeated infections, while detection of antibodies against avian subtypes (H5, H7, H9), even at low levels, confirms interspecies exposure. 11/15

Wong et al. show that swine present high influenza A seroprevalence (32.5%) and exposure to multiple lineages, including human, swine, and avian variants. 10/15

Additional challenges such as bird capture, inadequate infrastructure, and limited equipment further reduce response efficiency and compromise outbreak containment. 9/15

Key barriers include delayed response, high labor demand, lack of training, low preparedness, and logistical limitations affecting efficient depopulation strategies. 8/15

Jahid et al. show that H5N1 outbreak control is constrained by operational factors, particularly in gamebirds raised in extensive systems. 7/15

In these scenarios, unvaccinated sentinel birds remain the most reliable strategy to detect active viral circulation and overcome limitations of serology-based surveillance. 6/15

However, in birds receiving multiple boosters, vaccine-induced seropositivity becomes indistinguishable from natural infection, reducing diagnostic specificity in real-world conditions. 5/15

Ibrahim et al. show that DIVA vaccine effectiveness depends on vaccination regime. In single-dose chickens, ELISA targeting internal proteins (M/NP) discriminates infection. 4/15

These viruses also induce a robust proinflammatory response, indicating partial functional compatibility with humans and suggesting a measurable, though still limited, zoonotic risk. 3/15

Hui et al. show that H5N1 genotype B3.13, emerging in cattle in 2024 and already linked to mild human spillover, exhibits tropism for human respiratory tissues, with moderate replication in ex vivo bronchial and lung tissues. 2/15

Post 99 — H5N1: silent adaptation, imperfect surveillance, and ongoing evolution

Four recent studies explain how H5N1 spread results from the integration of molecular adaptation, surveillance gaps, and circulation across multiple reservoirs. 1/15

References
Budt et al., 2026. doi.org/10.3390/micr...
Harrington et al., 2026. doi.org/10.1038/s415...
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Jeong et al., 2026. doi.org/10.1186/s128...
13/13

H5N1 evolves through the combination of molecular convergence (adaptation) and ecological opportunity (dissemination). It is at this intersection that pandemic risk is built.

#H5N1 #InfluenzaA #OneHealth #GenomicSurveillance #Zoonoses #Pandemic #Bioinformatics #Diagnostics 12/13

Although classical markers of mammalian adaptation are absent in birds, circulation in cattle and humans expands the virus’s evolutionary space and increases opportunities for further adaptation. 11/13

This reassortant H5N1 displaced previous lineages by exploiting favorable ecological conditions: high densities of susceptible juvenile birds, environmental changes, and possible antigenic advantages. 10/13

Harrington et al. document the rapid expansion of genotype D1.1 in North America during the 2024 migration season, highlighting a major shift in viral population structure. 9/13

By identifying conserved regions and predicting therapeutic targets, QStrain connects genomic surveillance to biomedical response, reducing the time between detection and intervention. 8/13

Jeong et al. present QStrain, an integrated platform combining genomic analysis, variability visualization, and automated design of RNA-based therapies. 7/13

This adaptation is consistent across distinct lineages, including contemporary H5N1 and historical pandemic viruses, reinforcing that mammalian adaptation may follow predictable evolutionary pathways. 6/13

At the molecular level, Budt et al. identify the PB2 M631L mutation as a convergent adaptation. This change increases polymerase activity in human cells by enhancing interaction with ANP32 proteins. 5/13

Detection limits reach ~10⁵-10⁶ copies/mL across different matrices. Although still at the proof-of-concept stage, the approach points toward a strategic shift: make diagnosis more accessible using different viral detection methods. 4/13

Islam et al. developed a detection system based on commercial glucometers. By converting the presence of hemagglutinin (HA) into a measurable glucose signal, the method enables viral quantification in accessible and scalable formats. 3/13

Four recent studies show that H5N1 is advancing simultaneously on two critical fronts: host adaptation and ecological dynamics. The risk lies not only in the virus itself, but in the speed at which it integrates these dimensions. 2/13

Post 98 — H5N1: accessible detection, molecular adaptation, and evolutionary expansion
1/13

Dong et al., 2026. doi.org/10.1016/j.ji...
Read & Sridhar, 2026. doi.org/10.1371/jour...
Stallknecht et al., 2026. doi.org/10.1139/cjm-...
13/13

Two years after it emerged, ‘cow flu’ is still circulating—and baffling scientists Researchers still aren’t sure how H5N1 influenza spreads between cows and from farm to farm

#H5N1 #Influenza #OneHealth #Surveillance #Spillover

Cohen et al., 2026. doi.org/10.1126/scie...
Degnin et al., 2026. jwd.kglmeridian.com/view/journal...
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