Biology subjects

Butticaz, L.

Publications and source records attributed to Butticaz, L..

4 recordsLinked to original sources

bioRxiv2026

Bovine-derived influenza A virus (H5N1) shows efficient replication in well-differentiated human nasal epithelial cells without requiring genetic adaptation

Highly pathogenic avian influenza (H5N1) viruses of clade 2.3.4.4b have caused significant losses among bird populations worldwide and have repeatedly crossed the species barrier, infecting mammals, including humans. However, efficient human-to-human transmission has not yet been observed. Here, we demonstrate that an H5N1 virus isolated from bovine milk in Texas in 2024 (H5N1Tex/24) replicates in differentiated human nasal epithelial cells as efficiently as a 2009 pandemic H1N1 virus strain (H1N1HH4/09) at both 37 {degrees}C and 33 {degrees}C. The adaptive mutations PB2-M631L and PA-K497R do not affect H5N1Tex/24 replication at 37 {degrees}C but promote replication at 33 {degrees}C. Conversely, H5N1BE/22, a virus from the same clade isolated from a pelican in 2022 that lacks these mutations, replicates in human nasal epithelial cells at 37 {degrees}C as efficiently as H5N1Tex/24 but exhibits limited replication at 33 {degrees}C. Introducing the two mutations PB2-M631L and PA-K497R did not overcome this limitation. Furthermore, nasal epithelial cells express receptors for both human and avian influenza viruses. Accordingly, no mutations were detected in HA which are known to switch receptor preference. Finally, we demonstrate that H5N1Tex/24 remains sensitive to the antiviral effects of interferon-{lambda} (IFN-{lambda}), however, infected nasal epithelial cells secrete only small amounts of this cytokine. Overall, our results suggest that H5N1Tex/24 possesses intrinsic traits enabling efficient replication in the human upper airways.

microbiology↗

bioRxiv2025

An RNA replicon vaccine encoding HA and NA prevents shedding of antigen-drifted 2009 pandemic H1N1 influenza virus in the pig model

Seasonal influenza viruses escape the human immune response by antigenic drift, i.e. the positive selection of point mutations that prevent the binding of inhibitory antibodies to the influenza antigens HA and NA. The efficacy of seasonal influenza vaccines can be less than 50% if the selected influenza vaccine strain does not match the antigenic characteristics of the circulating seasonal influenza virus. In this study, we used the porcine model to evaluate the efficacy of an RNA replicon vaccine encoding the HA and NA antigens of A/Hamburg/4/2009 (H1N1) (H1N1HH4/09) in inducing cross-reactive immunity. We found that a single intramuscular immunization with this vaccine elicited high levels of antibodies with H1N1HH4/09-neutralizing activity and potent N1-sialidase inhibition. A second immunization with the same H1/N1 RNA replicon particles or with a live-attenuated influenza vaccine (LAIV) based on a modified H1N1HH4/09 virus boosted the inhibitory activity of the immune sera against the antigen-drifted A/Victoria/2570/2019 (H1N1) (H1N1Vic/19) strain. Interestingly, vaccination elicited N1-specific antibodies that also inhibited the activity of avian N1 sialidase and potently inhibited the replication of A/cattle/Texas/063224-24-1/2024 (H5N1) (H5N1Tex/24) in vitro. When challenged nasally with a H1N1HH4/09 /H1N1Vic/19 6:2 reassortant virus encoding the HA and NA antigens of H1N1Vic/19, immunized pigs did not shed infectious virus while the control animals did, suggesting that homologous prime/boost vaccination with H1/N1 replicon particles can block virus replication in the upper respiratory tract as efficiently as the heterologous RNA replicon prime/LAIV boost immunization regimen. In conclusion, RNA replicons encoding both HA and NA either used alone or in combination with LAIV mediate protection against antigen-drifted influenza viruses and reduce the risk of vaccination breakthroughs due to antigen mismatch. Furthermore, this vaccine may also limit the infection by zoonotic H5N1 viruses.

microbiology↗

bioRxiv2025

Impact of pH and temperature in dairy processing on the infectivity of H5N1 avian influenza viruses

Highly pathogenic avian influenza viruses (HPAIV) of subtype H5N1 (clade 2.3.4.4b) have crossed the species barrier and caused a mastitis-like infection in dairy cows. The high levels of infectious virus found in the milk raised considerable concerns about the safety of raw milk products. This study examined the effect of temperature and pH on the stability of HPAIV and low-pathogenic avian influenza viruses (LPAIV). We found that H5N1 HPAIV remained infectious in milk at 4{degrees}C for four weeks, with slow decreases at 21{degrees}C, and complete inactivation at 37{degrees}C after four weeks. H5N1 LPAIV was stable at 50{degrees}C for 30 minutes but inactivated at higher temperatures (55{degrees}C for 10 minutes, 60{degrees}C for 1 minute, or 72{degrees}C for 30 seconds). At pH levels between 6 and 10, the virus remained stable but was partially inactivated at pH 5.0 and completely inactivated at pH 4.0. During yogurt production, H5N1 LPAIV was completely inactivated when the pH reached 4.3. In cheese production, the lowest pH reached was between 5.0 and 5.3. When H5N1 LPAIV was incubated with soft and semi-hard cheese for one day at 4 {degrees}C, infectious virus titers decreased by 5.1 and 3.9 log10, respectively. When H5N1 LPAIV was incubated with buffer adjusted to pH 5.0, infectious virus titer dropped by only 3.3 log10, suggesting that, alongside pH, other processes of cheese ripening likely influence virus stability. In conclusion, H5N1 avian influenza viruses are largely inactivated during lactic acid fermentation of raw milk. Future studies will assess the required cheese ripening time for complete inactivation.

microbiology↗

bioRxiv2025

Immunization with a novel RNA replicon vaccine confers long-lasting protection against H5N1 avian influenza virus in 24 bird species

Highly pathogenic avian influenza viruses (HPAIV) of subtype H5N1 (clade 2.3.4.4b) have spread worldwide and caused the death of hundreds of millions of wild birds and domestic poultry. Moreover, spill over of H5N1 HPAIV from infected birds to more than 50 different mammalian species including humans has been recorded. While, licensed vaccines for protection of avian or mammalian species are not yet available, a few candidate vaccines are being trialled. Here, we report on the experimental vaccination of chickens and captive wild birds using a propagation-defective vesicular stomatitis virus (VSV), in which the essential envelope glycoprotein (G) protein gene was replaced by a modified hemagglutinin gene derived from a clade 2.3.4.4b H5N1 isolated in 2022 in the animal park of Bern, Switzerland. VSV{Delta}G(H5mb) was produced on helper cells providing the VSV G protein in trans. Specific pathogen-free (SPF) chickens that were immunized twice via the intramuscular route with adjuvant-free VSV{Delta}G(H5mb) replicon particles induced high levels of virus-neutralizing serum antibodies and were fully protected against lethal infection by H5N1 HPAIV (clade 2.3.4.4b). Notably, immunized animals did not shed challenge virus from the respiratory or gastrointestinal tract, suggesting that herd immunity can be achieved. The same vaccine was used to immunize a total of 317 captive wild birds at Bern Animal Park and Zoo Basel, representing 24 different species. No vaccine-associated side effects were observed. Birds without previous contact to H5Nx viruses produced high to very high H5-specific neutralizing antibody titers following the second immunization, while birds showing H5-specific antibodies prior to vaccination, already developed high neutralising antibody titers after a single immunization. One year after vaccination, most animals still showed significant neutralizing antibody titers, indicating that VSV{Delta}G(H5mb) is able to induce a long-lasting protective immune response. Our results indicate that VSV{Delta}G(H5mb) is an extraordinary safe and highly efficacious vaccine to stop H5N1 replication in various avian species.

microbiology↗