Biology subjects

Cantoni, D.

Publications and source records attributed to Cantoni, D..

8 recordsLinked to original sources

bioRxiv2026

SARS-CoV-2 Spike H655Y drives protease preference but does not dictate cellular tropism

Throughout the COVID-19 pandemic, SARS-CoV-2 has undergone rapid adaptation, with the Omicron variant exhibiting an unexpected shift towards upper airway infection and preference for membrane fusion activated by endosomal cathepsins, a reversion to ancestral sarbecovirus entry mechanisms. This phenotype coincides with convergent acquisition of the spike mutation H655Y, which reduces TMPRSS2-mediated activation. Here, using a comprehensive panel of 13 spikes of SARS-CoV-2 variants, we interrogated whether H655Y-mediated protease switching explains Omicrons upper airway phenotype, challenging several existing hypotheses, from spike stability, shedding and acquired intra-molecular interactions by H655Y. Our findings reveal that protease preference and tissue tropism are mechanistically uncoupled. While spike pre-processing by furin determines protease preference in pre-Omicron variants, this relationship breaks down in H655Y-bearing viruses. Notably, mutations in the NTD and RBD of BA.2.86 can override the H655Y phenotype entirely, indicating that RBD-mediated interactions, rather than protease usage, represent the critical determinants of Omicrons upper airway adaptation. This work reframes our understanding of coronavirus spike evolution, revealing that tissue tropism operates through mechanisms fundamentally distinct from those dictating protease preference.

microbiology↗

bioRxiv2025

Serological evidence of SARS-CoV-2 infection in red and fallow deer in Great Britain.

SARS-CoV-2 is the viral agent of COVID-19 disease in humans and has been shown to infect a wide range of mammals, including white-tailed deer in North America and fallow deer in the Republic of Ireland. There are six species of deer in the UK which inhabit both urban and rural areas, providing a broad interface for human-deer interaction. Little is known if British deer species act as a reservoir for zoonotic spread of consequence to human health. Here, we report a high seroprevalence of SARS-CoV-2 neutralising antibodies in British deer, adding native red deer to the list of susceptible species. 62% of fallow and 25% of red deer sampled between 2024 and 2025 from one British deer park were positive for SARS-CoV-2 infection by serology. Data suggest that deer may function as permissive, reservoir-capable hosts and highlight the risks of anthroponosis and zoonosis from unregulated human-deer contact. While there is currently no evidence to suggest that these viruses are persisting within deer populations in Great Britain, the animal origins of SARS-CoV-2 highlight the importance of appropriate and limited interactions with wildlife, to minimise transmission risks and safeguard both animal and human health.

microbiology↗

bioRxiv2025

Cross-Neutralizing Monoclonal Antibodies with Broad Activity Against Human and Bat-Derived SARS-Related Coronaviruses

Effective therapeutics for severe cases of SARS-CoV-2 are still needed. As new variants of concern emerged an increase in hospitalizations was observed, especially in non-vaccinated individuals, immunocompromised individuals and the elderly, whereby treatment options became challenging. Several monoclonal antibodies (mAb) are being evaluated for approval due to their ability to neutralize the virus. Here, we report monoclonal antibodies targeting the Spike (S) with a strong neutralization profile against lentiviral and VSV pseudotypes displaying the Spikes of SARS-CoV-1, SARS-CoV-2 and variants of concern, in addition to two bat coronaviruses. We found several mAbs that were able to bind and neutralize a broad set of variants, with one mAb able to neutralize SARS-CoV-1, SARS-CoV-2, RaTG13 and WIV16. Their binding affinities were also characterized, and several mAbs were in the picomolar range against different variants. These results indicate that their use as a cocktail of monoclonal antibodies to treat patients infected with variants associated with severe disease and immune escape can be explored as an option. Furthermore, the cross reactivity observed by one mAb may reveal further insight into vulnerable portions of the Spike protein, which may become valuable future targets.

microbiology↗

bioRxiv2023

Serological evidence of high pathogenicity virus infection in Eidolon helvum fruit bats in Nigeria

The Eidolon helvum fruit bat is the most widely distributed fruit bat in Africa and is known to be a reservoir for several pathogenic viruses that can cause disease in humans. To assess the risk of zoonotic spillover, we conducted a serological survey of 304 serum samples from E. helvum bats that were captured for human consumption in Makurdi, Nigeria. Using pseudotyped viruses, we screened the samples for neutralising antibodies against viruses from the Coronaviridae, Filoviridae, Orthomyxoviridae and Paramyxoviridae families. We report the presence of neutralising antibodies against henipavirus lineage GH-M74a virus (odds ratio 6.23; p<0.001), Nipah virus (odds ratio 4.04; p=0.00031), bat influenza H17N10 virus (odds ratio 7.25; p<0.001) and no significant association with Ebola virus (odds ratio 0.56; p=0.375) in the bat cohort. The data suggest a potential risk of zoonotic spillover including the possible circulation of highly pathogenic viruses in E. helvum populations. These findings highlight the importance of maintaining sero-surveillance of E. helvum to monitor changes in virus prevalence and distribution over time and across different geographic locations. Article summary lineThe detection of neutralizing antibodies against henipavirus GH-M74a virus, Nipah virus, and H17N10 virus in Eidolon helvum bat sera from Nigeria using pseudotyped viruses suggests a potential risk of zoonotic spillover.

microbiology↗

bioRxiv2021

Zn2+ triggered two-step mechanism of CLIC1 membrane insertion and activation into chloride channels

The CLIC protein family displays the unique feature of altering its structure from a soluble form to a membrane-bound chloride channel. CLIC1, a member of this family, is found in the cytoplasm or in internal and the plasma membranes, with membrane relocalisation linked to endothelial disfunction, tumour proliferation and metastasis. The molecular switch promoting CLIC1 activation remains unclear. Here, cellular chloride efflux assays and immunofluorescence microscopy studies have identified Zn2+ intracellular release as the trigger for CLIC1 activation and membrane relocalisation. Biophysical assays confirmed specific binding to Zn2+, inducing membrane association and enhancing chloride efflux in a pH dependent manner. Together, our results identify a two-step mechanism with Zn2+ binding as the molecular switch promoting CLIC1 membrane insertion, followed by pH activation of chloride efflux.

biochemistry↗

bioRxiv2021

Pseudotyped Bat Coronavirus RaTG13 is efficiently neutralised by convalescent sera from SARS-CoV-2 infected Patients

RaTG13 is a close relative of SARS-CoV-2, the virus responsible for the Coronavirus Disease 2019 (COVID-19) pandemic, sharing 96% sequence similarity at the genome-wide level. The spike receptor binding domain (RBD) of RaTG13 contains a large number of amino acid substitutions when compared to SARS-CoV-2, likely impacting affinity for the ACE2 receptor. Antigenic differences between the viruses are less well understood, especially whether RaTG13 spike can be efficiently neutralised by antibodies generated from infection with, or vaccination against, SARS-CoV-2. Using RaTG13 and SARS-CoV-2 pseudotypes we compared neutralisation using convalescent sera from previously infected patients as well as vaccinated healthcare workers. Surprisingly, our results revealed that RaTG13 was more efficiently neutralised than SARS-CoV-2. In addition, neutralisation assays using spike chimeras and mutants harbouring single amino acid substitutions within the RBD demonstrated that both spike proteins can tolerate multiple changes without dramatically reducing how efficiently they are neutralised. Moreover, introducing the 484K mutation into RaTG13 resulted in increased neutralisation, in contrast to the same mutation in SARS-CoV-2 (E484K). This is despite E484K having a well-documented role in immune evasion in variants of concern (VOC) such as B.1.351 (Beta). These results indicate that the immune-escape mutations found in SARS-CoV-2 VOCs might be driven by strong antibody pressures, and that the future spill-over of RaTG13 and/or related sarbecoviruses could be mitigated using current SARS-CoV-2-based vaccination strategies.

microbiology↗

bioRxiv2020

Localization and Functional Characterization of the Alternative Oxidase in Naegleria

The Alternative oxidase (AOX) is a protein involved in maintaining the Krebs cycle in instances where the respiratory chain has been inhibited, while allowing for the maintenance of cell growth and necessary metabolic processes for survival. Among eukaryotes, alternative oxidases have disperse distribution and are found in plants, fungi and a few protists, including Naegleria ssp. Naegleria species are free-living unicellular amoeboflagellates, and include the pathogenic species of N. fowleri, the so-called brain eating amoeba. Using a multidisciplinary approach, we aimed to understand the evolution, localization and function of AOX and the role that plays in Naeglerias biology. Our analyses suggest that the protein was present in last common ancestor of the genus and structure prediction showed that all functional residues are also present in Naegleria species. Using a combination of cellular and biochemical techniques, we also functionally characterize N. gruberis AOX in its mitochondria and we demonstrate that its inactivation affects its proliferation. Consequently, we discuss the benefits of the presence of this protein in Naegleria species, along with its potential pathogenicity role in N. fowleri. We predict that our findings will spearhead new explorations to understand the cell biology, metabolism and evolution of Naegleria and other free-living relatives.

microbiology↗

bioRxiv2019

The membrane insertion of soluble CLIC1 into active chloride channels is triggered by specific divalent cations

The CLIC family of proteins display the unique feature of altering their structure from a soluble form to a membrane-bound chloride channel. CLIC1, a member of this family, can be found in the cytoplasm or in nuclear, ER and plasma membranes, with membrane overexpression linked to tumour proliferation. The molecular switch promoting CLIC1 membrane insertion has been related to environmental factors, but still remains unclear. Here, we use solution NMR studies to confirm that both the soluble and membrane bound forms are in the same oxidation state. Our data from fluorescence assays and chloride efflux assays indicate that Ca2+ and Zn2+ trigger association to the membrane into active chloride channels. We use fluorescence microscopy to confirm that an increase of the intracellular Ca2+ leads to re-localisation of CLIC1 to both plasma and internal membranes. Finally, we show that soluble CLIC1 adopts an equilibrium of oligomeric species, and Ca2+/Zn2+ mediated membrane insertion promotes the formation of a tetrameric assembly. Thus, our results identify Ca2+ and Zn2+ binding as the molecular switch promoting CLIC1 membrane insertion.\n\nSIGNIFICANCE STATEMENTCLIC1, a member of the CLIC family of proteins, is expressed as a soluble protein in cells but can insert in the membrane forming a chloride channel. This chloride channel form is upregulated in different types of cancers including glioblastoma and promote tumour invasiveness and metastasis. The factors promoting CLIC1 membrane insertion nor the mechanism of this process are yet understood. Here, we use a combination of solution NMR, biophysics and fluorescence microscopy to identify Ca2+ and Zn2+ binding as the switch to promote CLIC1 insertion into the membrane to form active chloride channels. We also provide a simple mechanism how such transition to the membrane occurs. Such understanding will enable subsequent studies on the structure of the chloride channel form and its inhibition.

biochemistry↗