Biology subjects

Nicholls, J. M.

Publications and source records attributed to Nicholls, J. M..

3 recordsLinked to original sources

bioRxiv2025

The hemagglutinin proteins of clades 1 and 2.3.4.4b H5N1 highly pathogenic avian influenza viruses exhibit comparable attachment patterns to avian and mammalian tissues

The global spread of the A/goose/Guangdong/1/96-lineage H5N1 highly pathogenic avian influenza (HPAI) viruses is accompanied by an expanded host range and the establishment of sustained viral transmission among dairy cattle. To evaluate if the evolving H5N1 viruses have changed tissue tropism over time, we compared the binding patterns of recombinant hemagglutinin (HA) proteins derived from clade 1 (A/Vietnam/1203/04, H5VN) and circulating clade 2.3.4.4b viruses detected from a wild bird (A/Eurasian Teal/Hong Kong/AFCD-HKU-23- 14009-01020/2023, H5HK) and dairy cattle (A/bovine/Ohio/B24OSU-439/2024, H5OH). The HA protein of A(H1N1)pdm09 virus was included for comparison. Using bio-layer interferometry, H1 protein preferentially bound to the 2,6-linked sialoside 6SLNLN while H5 proteins preferentially bound to the 2,3-linked sialoside 3SLN. H5OH showed higher binding affinity to 3SLN than H5HK and H5VN. The attachment pattern of H1 and H5 proteins to the respiratory tissues of different species and dairy cattle mammary glands were evaluated. Compared to the H1 protein, H5 proteins showed stronger binding to the lung epithelial cells of cat, cattle, chicken, ferret, human, and pig, and the clade 2.3.4.4b H5 proteins exhibited increased binding to pig and cattle bronchial epithelial cells. All H5 proteins attached to the alveolar and cistern epithelial cells in mammary glands where 2,3-linked and 2,6-linked sialyl glycans were detected by Maackia amurensis lectin II and Sambucus Nigra Lectin, respectively. Taken together, the HA proteins of clade 1 and 2.3.4.4b H5N1 viruses generally share comparable attachment patterns to avian and mammalian tissues, despite of evolving into antigenically distinct clades over the past 3 decades. IMPORTANCEThe outbreaks of H5N1 HPAI among US dairy cattle since 2024 have raised concerns of the potential changes in HA receptor binding specificity and tissue tropism. Using insect-cell expressed recombinant HA proteins derived from clade 1 and circulating clade 2.3.4.4b H5N1 viruses, we showed that the dairy cattle H5 protein retained binding specificity for the avian-like 2,3-linked sialoside 3SLN over the human-like 2,6-linked sialoside 6SLNLN, with higher binding affinity to 3SLN than the other H5 proteins. Clade 1 and 2.3.4.4b H5 proteins showed comparable attachment patterns to the mammary tissues of lactating dairy cattle, which showed high expression of 2,3-linked and 2,6-linked sialyl glycans. All H5 proteins also showed comparable attachment patterns to the lungs of cat, cattle, chicken, ferret, human, and pig. Our results suggest that the recent H5N1 outbreaks in dairy cattle may be related to ecological factors rather than changes in HA receptor binding specificity.

microbiology↗

bioRxiv2023

Mutation nsp6 L232F associated with MERS-CoV zoonotic transmission confers higher viral replication in human respiratory tract cultures ex-vivo

Middle East respiratory syndrome coronavirus (MERS-CoV) causes zoonotic disease. Dromedary camels are the source of zoonotic infection. We identified a mutation of amino acid leucine to phenylalanine in the codon 232 position of the non-structural protein 6 (nsp6) (nsp6 L232F) that is repeatedly associated with zoonotic transmission. We generated a pair of isogenic recombinant MERS-CoV with nsp6 232L and 232F residues, respectively, and showed that the nsp6 L232F mutation confers higher replication competence in ex-vivo culture of human nasal and bronchial tissues and in lungs of mice experimentally infected in-vivo. Mechanistically, the nsp6 L232F mutation appeared to modulate autophagy and was associated with higher exocytic virus egress, while innate immune responses and zippering activity of the endoplasmic reticulum remained unaffected. Our study suggests that MERS-CoV nsp6 may contribute to viral adaptation to humans. This highlights the importance of continued surveillance of MERS-CoV in both camels and humans. ImportanceViral host adaptation plays an important role in zoonotic transmission of coronaviruses. For MERS-CoV that widely circulates in dromedary camels from Arabian Peninsula, camel-to human transmissions are ongoing, raising the possibility of human adaptive evolution for MERS-CoV. Here, we analysed MERS-CoV sequences and identified an amino acid mutation L232F in nsp6 to occur repeatedly in human MERS-CoV over the years since the first outbreak in 2012. We found the nsp6 L232F confers increase viral replication in-vitro, in ex-vivo upper human respiratory tract cultures and in mice, using a reverse genetics approach. Our results showed the nsp6 L232F may be advantageous for MERS-CoV to replicate in humans. This study highlighted a human adaptation of MERS-CoV and a need for continued surveillance of MERS-CoV to identify any further adaptations in humans, which may be relevant to the pandemic potential of MERS-CoV.

microbiology↗

bioRxiv2022

ACE2 nanoparticles prevent cell entry of SARS-CoV-2

The continual evolution of SARS-CoV-2 has challenged the efficacy of many COVID19 vaccines and treatment options. One strategy that evades viral escape is using the entry receptor, human Angiotensin-Converting Enzyme 2 (hACE2). Soluble hACE2 receptor domains show potential as decoys but genetic modifications are necessary to provide sufficient efficacy. However, these engineered constructs are potentially susceptible to viral escape. We combined native hACE2 with viral vectors to form nanoparticles presenting hACE2 analogous to human cells. Cell-based viral infection assays and cryogenic in-situ tomography show that hACE2 nanoparticles sequester viruses through aggregation, efficiently blocking entry of SARS-CoV-2 and its variants in model cell systems and human respiratory tract explants using native hACE2. Thus, we show that hACE2 nanoparticles have high potential as pan-variant COVID19 therapeutics.

cell biology↗