Biology subjects

Laghi, V.

Publications and source records attributed to Laghi, V..

4 recordsLinked to original sources

bioRxiv2024

Spatial dynamics of peripheral and central nervous system infection by an interferon-inducing neuroinvasive virus

Organ-to-organ dissemination of viruses is a critical feature of host-virus interactions. In particular, neuroinvasive viruses are able to enter the central nervous systems (CNS), which may result in death or permanent neurological impairment. The complex mechanisms underpinning this spread are poorly understood, as they depend on a variety of parameters, including initial site of entry, route of access to the CNS, and immune responses. To better understand these phenomena, we analyzed the spatial dynamics of Sindbis virus (SINV) dissemination in transparent zebrafish larvae. Using fluorescent reporter viruses, we observed that SINV readily invaded the CNS after inoculation at various peripheral sites. From tail muscle, the virus used dorsal root ganglia (DRG) sensory neurons as a gateway to the spinal cord and further propagation to the brain. While peripheral infection was systematically transient, due to the key protective role of the strong and rapid type I interferon (IFN) response, CNS infection was persistent and more variable. Within the CNS, viral dissemination resulted both from long-distance axonal transport and short distance shedding, and IFN response was local, while it was systemic in the periphery. A mathematical model was built on this quantitative imaging foundation, that provided additional insight on the parameters of this infection, such as the rate of new virion production, estimated around 1 to 2 infective virions per productively infected cell per hour; the occurrences of CNS entry events, which was 2 to 3 per larva; or the impact of the IFN response, which did not only prevent new infections but accelerated the death of infected cells.

microbiology↗

bioRxiv2021

Zebrafish larvae as a powerful model to dissect protective innate immunity in response to Legionella pneumophila infection

The zebrafish has become a powerful model organism to study host-pathogen interactions. Here, we developed a zebrafish model of Legionella pneumophila infection to dissect innate immune responses. We show that L. pneumophila cause zebrafish larvae death in a dose dependent manner, and that macrophages are the first line of defence, with neutrophils cooperating to clear the infection. When either macrophages or neutrophils are depleted, these "immunocompromised" larvae become lethally sensitive to L. pneumophila similar to what is known for humans that develop pneumonia. Also as observed in human infections, the adaptor signalling molecule Myd88 is not required to control disease in the larvae. Furthermore, proinflammatory cytokine genes il1{beta} and tnf were upregulated during infection, recapitulating key immune responses seen in human infection. Strikingly, we uncovered a previously undescribed infection phenotype in zebrafish larvae, whereby bloodborne, wild type L. pneumophila invade and grow in the larval yolk region, a phenotype not observed with a type IV secretion system deficient mutant that cannot translocate effectors into its host cell. Thus, zebrafish larva represents an innovative L. pneumophila infection model that that on one hand mimics important aspects of the human immune response to L. pneumophila infection and that on the other hand will allow to elucidate the mechanisms by which type IV secretion effectors allow L. pneumophila to cross membranes and to obtain nutrients from nutrient rich environments.

microbiology↗

bioRxiv2021

Exploring zebrafish larvae as a COVID-19 model: probable SARS-COV-2 replication in the swim bladder

Animal models are essential to understand COVID-19 pathophysiology and for pre-clinical assessment of drugs and other therapeutic or prophylactic interventions. We explored the small, cheap and transparent zebrafish larva as a potential host for SARS-CoV-2. Bath exposure, as well as microinjection in the coelom, pericardium, brain ventricle, bloodstream, or yolk, did not result in detectable SARS-CoV-2 replication in wild-type larvae. However, when the virus was inoculated in the swim bladder, a modest increase in viral RNA was observed after 24 hours, suggesting a successful infection in some animals. This was confirmed by immunohistochemistry, with cells positive for SARS-CoV-2 nucleoprotein observed in the swim bladder. Several variants of concern were also tested with no evidence of increased infectivity in our model. Low infectivity of SARS-CoV-2 in zebrafish larvae was not due to the host type I interferon response, as comparable viral loads were detected in type I interferon-deficient animals. Mosaic overexpression of human ACE2 was not sufficient to increase SARS-CoV-2 infectivity in zebrafish embryos or in fish cells in vitro. In conclusion, wild-type zebrafish larvae appear mostly non-permissive to SARS-CoV-2, except in the swim bladder, an aerial organ sharing similarities with the mammalian lung.

microbiology↗

bioRxiv2019

Interferon-stimulated genes in zebrafish and human define an ancient arsenal of antiviral immunity

The evolution of the interferon (IFN) system, the major innate antiviral mechanism of vertebrates, remains poorly understood. According to the detection of type I IFN genes in cartilaginous fish genomes, the system appeared 500My ago. However, the IFN system integrates many other components, most of which are encoded by IFN-stimulated genes (ISGs). To shed light on its evolution, we have used deep RNA sequencing to generate a comprehensive list of ISGs of zebrafish, taking advantage of the high quality genome annotation in this species. We analyzed larvae after inoculation of recombinant zebrafish type I IFN, or infection with chikungunya virus, a potent IFN inducer. We identified more than 400 zebrafish ISGs, defined as being either directly induced by IFN or induced by the virus in an IFN receptor-dependent manner. Their human orthologues were highly enriched in ISGs, particularly for highly-inducible genes. We identified 72 orthology groups containing ISGs in both zebrafish and human, revealing a core ancestral ISG repertoire, which includes most of the known signaling components of the IFN system. Many downstream effectors were also already present 450 My ago in the common ancestor of tetrapods and bony fish, and diversified as multi-gene families independently in the two lineages. A large proportion of the ISG repertoire is lineage-specific; around 40% of protein-coding zebrafish ISGs had no human orthologue. We identified 14 fish-specific gene families containing multiple ISGs, including finTRIMs. This work illuminates the evolution of the IFN system and provides a rich resource to explore new antiviral mechanisms.\n\nKey pointsO_LIWe established an exhaustive list of larval zebrafish ISGs.\nC_LIO_LIOrthologous ISGs in fish and human identify a large ancestral ISG repertoire.\nC_LI

immunology↗