Biology subjects

Hirchaud, E.

Publications and source records attributed to Hirchaud, E..

3 recordsLinked to original sources

bioRxiv2025

Mass mortality events in the sub-Antarctic Indian Ocean caused by long-distance circumpolar spread of highly pathogenic avian influenza H5N1 clade 2.3.4.4b

Since 2020, the outbreak of highly pathogenic avian influenza (HPAI) virus clade 2.3.4.4b has turned into the largest documented panzootic to date, reaching the sub-Antarctic region and Antarctica via the tip of South America in 2023. Here, we describe its recent arrival into the Indian Ocean sub-Antarctic archipelagos of Crozet and Kerguelen, where we first detected the virus in October 2024 in dead southern elephant seals, king penguins, gentoo penguins, brown skuas and kelp gulls. While the panzootic is ongoing, it has already caused unprecedented and alarming mortalities of southern elephant seals. We collected brain swabs from various seal and bird carcasses, subsequently isolated the virus and obtained 25 novel HPAI H5N1 clade 2.3.4.4b sequences. Our phylogenetic and phylogeographic analyses show that there have been independent introductions of the virus to Crozet and Kerguelen, from the distant South Georgia Islands in the Southern Atlantic, and not from the more nearby coasts of South Africa. Our results point to a year-long gap in genomic surveillance in the south polar region, obscuring how HPAI H5N1 clade 2.3.4.4b is spreading in the sub-Antarctic and illustrating the difficulties in tracking pathogen dispersal in the region. Locally, our phylogenetic analyses show that the virus is transmitted between different species. Moreover, our serological analyses show that some southern elephant seal pups had mounted an anti-H5 antibody response. With the spread to Crozet and Kerguelen, HPAI H5N1 2.3.4.4b is moving ever closer to Australia and New Zealand, which currently remain free from infections with this strain, and represents a major threat to the sub-Antarctic wildlife. Our results provide key elements to enable stakeholders to anticipate the arrival and spread of the virus in remote areas of critical wildlife conservation concerns.

microbiology↗

bioRxiv2024

Exploring virus-host interactions through combined proteomic approaches identifies BANF1 as a new essential factor for African Swine Fever Virus.

African swine fever virus (ASFV) causes a highly lethal disease in pigs and represents a significant threat to the global pork industry due to the lack of effective vaccines or treatments. Despite intensive research, many ASFV proteins remain uncharacterized. This study aimed to elucidate the functions of two ASFV proteins, MGF360-21R and A151R, through comprehensive analysis of their interactions with host proteins. Using affinity purification-mass spectrometry and yeast two-hybrid screening approaches, we identified the host protein barrier- to-autointegration factor 1 (BANF1) as a key interactor of both viral proteins. Biochemical and colocalization assays confirmed these interactions and demonstrated that MGF360-21R and A151R expression leads to cytoplasmic relocalization of BANF1. Functionally, BANF1 silencing significantly reduced ASFV replication, indicating its proviral role. Given BANF1s established function in regulating the cGAS/STING-dependent type I interferon (IFN-I) response, we postulated that A151R and MGF360-21R could inhibit this pathway. Using different strategies, we showed that both A151R and MGF360-21R did indeed inhibit IFN-I induction. Generation of ASFV deficient of A151R or MGF360-21R showed that both mutant viruses enhanced the host IFN response in primary porcine macrophages compared to wild-type virus. However, their capacity to inhibit this pathway could occur through mechanisms independent of BANF1. Proteomic analysis of BANF1 interactors during ASFV infection highlighted potentially roles in chromatin remodeling, nuclear transport, and innate immune response pathways. Altogether, our data provide new insights into ASFV-host interactions, identifying BANF1 as an important new host factor required for replication and uncovering novel functions for A151R and MGF360-21R. Author SummaryAfrican swine fever virus (ASFV) is a highly contagious and deadly disease affecting pigs worldwide, for which there are currently no effective vaccines or treatments. Despite extensive research, many ASFV proteins remain poorly understood. Our study investigated two ASFV proteins, MGF360-21R and A151R, to better understand their functions and interactions with host proteins. Using proteomic approaches, we found both these viral proteins interact with a host protein called barrier-to-autointegration factor 1 (BANF1). Importantly, BANF1 silencing significantly reduced ASFV replication, indicating its important role in the viral life cycle. We also showed that MGF360-21R and A151R help the virus evade the immune system by blocking the production of interferons, which are key defensive molecules against viral infections. However, this immune evasion does not seem to depend on their interaction with BANF1. Additionally, our analysis of BANF1s interactions during ASFV infection revealed potential roles in chromatin remodeling, nuclear transport, and the innate immune response. These findings provide new insights into how ASFV interacts with its host and highlight BANF1 as a critical factor in viral replication and immune evasion. Our work contributes to a better understanding of ASFV and could pave the way for developing more effective strategies to fight this virus.

microbiology↗

bioRxiv2024

Major change in swine influenza virus diversity in France owing to emergence and widespread dissemination of a newly introduced H1N2 1C genotype in 2020

Swine influenza A viruses (swIAV) are a major cause of respiratory disease in pigs worldwide, presenting significant economic and health risks. These viruses can reassort, creating new strains with varying pathogenicity and cross-species transmissibility. This study aimed to monitor the genetic and antigenic evolution of swIAV in France from 2019 to 2022. Molecular subtyping revealed a marked increase in H1avN2 cases from 2020 onwards, altering the previously stable subtypes distribution. Whole-genome sequencing and phylogenetic analyses of H1av (1C) strains identified ten circulating genotypes, including five new genotypes, marked by a significant predominance of the H1avN2#E genotype. It was characterized by an HA-1C.2.4, an N2-Gent/84, and internal protein-encoding genes belonging to a newly defined genogroup within the Eurasian avian-like (EA) lineage, the EA-DK subclade. H1avN2#E emerged in Brittany, the countrys most pig-dense region, and rapidly became the most frequently detected swIAV genotype across France. This drastic change in the swIAV lineages proportions at a national scale was unprecedented, making H1avN2#E a unique case for understanding swIAV evolution and spreading patterns. Phylogenetic analyses suggested an introduction of the H1avN2#E genotype from a restricted source, likely originating from Denmark. It spread rapidly with low genetic diversity at the start of the epizootic in 2020, showing increasing diversification in 2021 and 2022, and exhibiting reassortments with other enzootic genotypes. Amino acid sequence alignments of H1avN2#E antigenic sites revealed major mutations and deletions compared to vaccine 1C strain (HA-1C.2.2) and previously predominant H1avN1 strains (HA-1C.2.1). Antigenic cartography confirmed significant antigenic distances between H1avN2#E and other 1C strains, suggesting the new genotype escaped from the swine population preexisting immunity. Epidemiologically, the H1avN2#E virus exhibited epizootic hallmarks with more severe clinical outcomes compared to H1avN1 viruses. These factors likely contributed to the spread of H1avN2#E within the pig population. The rapid rise of H1avN2#E highlighted the dynamic nature of swIAV genetic and antigenic diversity, underscoring the importance of adapted surveillance programs to support risk assessment in the event of new outbreaks. This also demonstrate the need to strengthen biosecurity measures when receiving pigs in a herd and to limit trading of swIAV-excreting live swine between European countries.

evolutionary biology↗