Ferrets were experimentally inoculated with SARS-CoV-2 (severe acute respiratory syndrome (SARS)-related coronavirus 2) to assess infection dynamics and host response. During the resulting subclinical infection, viral RNA was monitored between 2 and 21 days post-inoculation (dpi), and reached a peak in the upper respiratory cavity between 4 and 6 dpi. Viral genomic sequence analysis in samples from three animals identified the Y453F nucleotide substitution relative to the inoculum. Viral RNA was also detected in environmental samples, specifically in swabs of ferret fur. Microscopy analysis revealed viral protein and RNA in upper respiratory tract tissues, notably in cells of the respiratory and olfactory mucosae of the nasal turbinates, including olfactory neuronal cells. Antibody responses to the spike and nucleoprotein were detected from 21 dpi, but virus-neutralizing activity was low. A second intranasal inoculation (re-exposure) of two ferrets after a 17-day interval did not produce re-initiation of viral RNA shedding, but did amplify the humoral response in one animal. Therefore, ferrets can be experimentally infected with SARS-CoV-2 to model human asymptomatic infection.

Enteropathogenic Escherichia coli contain a large chromosomal gene (lifA) that encodes lymphostatin, a predicted 365 kDa protein that inhibits the mi

Clade 2.3.4.4 H5Nx highly pathogenic avian influenza viruses (HPAIVs) of the “goose/Guangdong” lineage have caused a series of European epizootics since 2014. During autumn/winter 2020–2021, several H5Nx subtypes were detected in the UK, with H5N8 being the dominant subtype in wild birds and poultry. Despite the greater subtype diversity (due to viral neuraminidase gene reassortment) reported in wild birds, only H5N8 and H5N1 subtypes caused clade 2.3.4.4 UK HPAIV poultry outbreaks during this period. The direct inoculation of layer chickens showed that H5N8-2020 was more infectious than H5N1-2020, which supported the European H5N8 dominance during that season. However, the mean death time was longer for H5N8-2020 (3.42 days) than for H5N1-2020 (2.17 days). Transmission from directly infected to naive in-contact chickens was inefficient for both subtypes. Histological lesions, the tissue dissemination of viral antigen, and nucleic acid were more extensive and abundant and accumulated more rapidly for H5N1-2020 compared with H5N8-2020. Although inefficient, H5N1-2020 transmission was faster, with its greater virulence indicating that this subtype posed a major concern, as subsequently shown during H5N1 dominance of the clade 2.3.4.4 epizootic since autumn 2021. An evaluation of these in vivo viral characteristics is key to understanding the continuing poultry threats posed by clade 2.3.4.4 H5Nx HPAIVs.

Interspecies Transmission of Swine Influenza A

Background: Epidemiological surveillance of influenza D virus (IDV) has gained increased priority following recent serological findings indicating its potential zoonosis in humans. In this context, it is crucial to develop strong, reproducible, reliable and scalable immunological assays that can be quickly implemented in the surveillance of new emerging threats. Serology is a powerful tool for immune monitoring prior to infection and conducting epidemiological surveillance. However, the traditional microneutralisation (MN) assay requires wild‐type viruses, considerably limiting its accessibility for some laboratories. Pseudotyped viruses (PVs) allow for expanded usage since they are safer and more flexible for adaptation to specific strains and enable application in laboratories without implementation in high biosecurity containment. Methods: In this study, we conducted the qualification of a PV‐based MN (pMN) assay with IDV‐PVs that express the HEF glycoprotein of the D/Swine/Italy/199724‐3/2015 strain. The assay functionality was examined using 14 bovine serum samples, assessing key analytical parameters including accuracy, specificity, precision, linearity and robustness. Results: The findings demonstrate the IDV pMN assay to be an effective method for the detection of neutralising antibodies. Conclusions: Therefore, the assay can be a valuable tool to facilitate large‐scale surveillance and provide data to inform immunisation strategy development.

The Orthomyxoviridae family includes influenza D virus (IDV), an emerging pathogen primarily affecting cattle and swine, with evidence of cross-species transmission and potential zoonotic risk. Although active human infections have yet to been confirmed, high seroprevalence in cattle-exposed populations highlights the need for continued surveillance. Here, a rapid, field-deployable RT-LAMP assay for IDV detection was developed and validated, with 99.2% specificity and sensitivity ranging from 95.6% (Cq < 30) to 81.8% (Cq < 40). This method offers a cost-effective, accessible alternative to RT-qPCR, enabling improved monitoring of IDV, and reinforcing preparedness for emerging influenza threats.