Biology subjects

Ruggli, N.

Publications and source records attributed to Ruggli, N..

9 recordsLinked to original sources

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

Correlates of protection against African swine fever virus identified by a systems immunology approach

African swine fever virus (ASFV) causes a fatal hemorrhagic disease in domestic pigs and wild boars, which poses severe threats to the global pork industry. Despite the promise of live attenuated vaccines (LAVs), their narrow margin between efficacy and residual virulence presents major safety challenges. This study bridges a critical knowledge gap in ASF vaccinology by identifying innate and adaptive correlates of protection. This was achieved by using an established model with two groups of pigs differing in baseline immunological status (farm and specific pathogen-free [SPF]). The animals were immunized with an attenuated ASFV strain and subsequently challenged with a related, highly virulent genotype II strain. By applying a systems immunology approach, we correlated kinetic data, including serum cytokines, blood transcription modules (BTMs), T-cell responses, and antibody levels, with clinical outcomes to track protective and detrimental immune responses to the virus over time. Key innate correlates of protection included early and sustained IFN- response, activation of antigen presentation BTMs, and controlled IL-8 levels during immunization. Lower baseline immune activation observed in SPF pigs in steady state was linked to increased protection. Adaptive correlates encompassed cell cycle, plasma cell, and T-cell BTM responses lasting until day 15 post-immunization. Consequently, an effective response from ASFV-specific Th cells prior to challenge indicated protection. After the challenge, an early IFN- response, along with low levels of pro-inflammatory cytokines and a strong induction of memory Th and Tc cells, correlated with improved clinical outcomes. The model highlights the critical role of host-specific factors in vaccine efficacy and provides a valuable framework for optimizing ASFV vaccine design while distinguishing between protective and detrimental immune responses.

immunology↗

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↗

bioRxiv2024

Intramuscular prime/intranasal boost vaccination to induce sterilizing immunity against influenza A virus infection

The most commonly used influenza vaccines are made from inactivated viruses and are administered via the intramuscular route. Although these vaccines can protect from severe lower respiratory tract disease, they do not completely prevent virus replication in the upper respiratory tract, and this may lead to virus excretion and dissemination. Therefore, nasally administered live-attenuated influenza vaccines (LAIV) that induce mucosal immunity have been developed, but finding an optimal balance between sufficient attenuation and immunogenicity remained challenging. These problems apply to both human and swine influenza vaccines. We have recently developed an LAIV candidate based on the 2009 pandemic H1N1 virus which encodes a truncated NS1 protein and lacks PA-X protein expression (NS1(1-126)-{Delta}PAX). This virus showed a blunted replication and elicited a strong innate immune response. In the present study, we took advantage of the pig animal model to evaluate this vaccine candidate in vivo and to identify a strategy for its improvement. Nasal infection of pigs with the NS1(1-126)-{Delta}PAX LAIV candidate did not cause disease but was associated with prolonged virus shedding from the upper respiratory tract. To increase safety of the vaccine candidate, we developed a novel prime/boost vaccination strategy consisting of a haemagglutinin-encoding propagation-defective vesicular stomatitis virus replicon vaccine for primary immunization via the intramuscular route, and the NS1(1-126)-{Delta}PAX LAIV for secondary immunization via the nasal route. This immunization strategy significantly reduced LAIV shedding, increased the production of specific serum IgG, neutralizing antibodies, Th1 memory cells, and induced virus-specific mucosal IgG and IgA. Of particular note, the immune response induced by this vaccination strategy completely blocked replication of the homologous challenge virus in the respiratory tract, indicating that sterilizing immunity was achieved. In summary, our novel intramuscular prime/intranasal boost vaccine combines the features of high efficacy and safety which are urgently needed to combat influenza epidemics and pandemics. Author summaryInactivated influenza vaccines which are administered intramuscularly are safe but offer only limited protection. In addition, they do not adequately prevent virus transmission by infected individuals. On the other hand, nasally administered live-attenuated influenza vaccines induce a mucosal immune response, which can effectively prevent primary infection and virus excretion. However, live-attenuated vaccines might not be sufficiently immunogenic if they are too attenuated or they trigger a robust immune response but are still too virulent. To overcome this challenge, we have developed a novel prime/boost vaccination strategy consisting of an initial intramuscular immunization with a propagation-defective RNA virus vector and a subsequent nasal immunization with a modified influenza virus that has lost its ability to counteract the hosts innate immune response. Using the pig model, we demonstrate that this approach elicited a more robust immune response both systemically and at mucosal surfaces. Importantly, replication of the vaccine virus in the respiratory tract was reduced, and challenge virus remained undetectable. In summary, our innovative vaccine, which combines intramuscular and intranasal routes of application, demonstrates high efficacy and safety and represents a valuable tool to control influenza epidemics and pandemics.

immunology↗

bioRxiv2024

Fitness adaptations of Japanese encephalitis virus in pigs following vector-free serial passaging

Japanese encephalitis virus (JEV) is a zoonotic mosquito-transmitted Flavivirus circulating in birds and pigs. In humans, JEV can cause severe viral encephalitis with high mortality. Considering that vector-free direct virus transmission was observed in pigs, JEV introduction into an immunologically naive pig population could result in a series of direct transmissions disrupting the alternating host cycling between vertebrates and mosquitoes. To assess the potential consequences of such a realistic scenario, we passaged JEV ten times in pigs. This resulted in higher in vivo viral replication, increased shedding, and stronger innate immune responses in pigs. Nevertheless, the viral tissue tropism remained similar and frequency of direct transmission was not enhanced. Next generation sequencing showed single nucleotide deviations in 10% of the genome during passaging. In total, 25 point mutations were selected to reach a frequency of at least 35% in one of the passages. From these, six mutations resulted in amino acid changes located in the precursor of membrane, the envelope, the non-structural 3 and the non-structural 5 proteins. In a competition experiment with two lines of passaging, the mutation M374L in the envelope protein and N275D in the non-structural protein 5 showed a fitness advantage in pigs. Altogether, the interruption of the alternating host cycle of JEV caused a prominent selection of viral quasispecies as well as selection of de novo mutations associated with fitness gains in pigs, albeit without enhancing direct transmission frequency. Author summaryJapanese encephalitis virus (JEV) represents a major health threat in parts of Asia and Oceania. Primary vertebrate hosts are birds and pigs, but human infection also occurs and can cause severe encephalitis with high mortality. Like other Flaviviruses transmitted by insect bites, JEV requires replication in alternating cycles between mosquitoes on one side and birds or pigs on the other side. However, we previously reported that direct transmissions between pigs in absence of mosquitos can occur. Considering the increased risks for such events after the spread of JEV to a new region with immunologically naive pigs, the present study was performed to understand if and how a series of direct transmissions would promote JEV adaptations to pigs and change virus-host interactions. Pigs infected with JEV passaged ten times showed enhanced clinical symptoms and stronger antiviral immune response, but luckily no increase in direct transmission was observed. Nevertheless, genomic analysis demonstrated a complete change in dominant virus variants, as well as selection of six viral amino acid changes. This indicates that interruptions of the alternating lifestyle of JEV causes a strong evolutionary pressure, which through fitness adaptations can change the viral characteristics.

microbiology↗

bioRxiv2022

The baseline immunological and hygienic status of pigs impact disease severity of African swine fever

African Swine Fever virus (ASFV) is a large double-enveloped DNA virus of the Asfarviridae family that causes a lethal hemorrhagic disease in domestic pigs and wild boars. Since 2007, a highly virulent genotype II strain has emerged and spread in Europe and South-East Asia, where millions of animals succumbed to the disease. Field- and laboratory-attenuated strains of ASFV cause highly variable clinical disease severity and survival, and mechanisms remain unclear. We hypothesized that the immunological and hygienic status of pigs is a determinant of ASF disease course. Here we compared the immunological profile at baseline and in response to ASFV infection in specific pathogen-free (SPF) and farm-raised Large White domestic pigs. At steady state, SPF pigs showed lower white blood cell counts and a lower basal inflammatory and antiviral transcriptomic profile compared to farm pigs associated with profound differences in gut microbiome composition. After inoculation with a highly virulent ASFV genotype II strain (Armenia 2008), severe clinical signs, viremia and pro-inflammatory cytokines appeared sooner in SPF pigs, indicating a reduced capacity to control early virus replication. In contrast, during infection with an attenuated field isolate (Estonia 2014), SPF pigs presented a milder and shorter clinical disease with full recovery, whereas farm pigs presented severe protracted disease with 50% lethality. Interestingly, farm pigs showed higher production of inflammatory cytokines, whereas SPF pigs produced more anti-inflammatory IL-1ra early after infection, and presented a stronger expansion of leukocytes in the recovery phase. Altogether, our data indicate that the hygiene-dependent innate immune status has a double-edge sword impact on immune responses in ASF pathogenesis. While the higher baseline innate immune activity helps the host in reducing initial virus replication, it promotes immunopathological cytokine responses, and delays lymphocyte proliferation after infection with an attenuated strain. Such effects should be considered for live vaccine development and vigilance.

microbiology↗

bioRxiv2021

Pulmonary mesenchymal stem cells are engaged in distinct steps of host response to respiratory syncytial virus infection

Lung-resident (LR) mesenchymal stem and stromal cells (MSCs) are key elements of the alveolar niche and fundamental regulators of homeostasis and regeneration. We interrogated their function during virus-induced lung injury using the highly prevalent respiratory syncytial virus (RSV) which causes severe outcomes in infants. We applied complementary approaches with primary pediatric LR-MSCs and a state-of-the-art model of human RSV infection in lamb. Remarkably, RSV-infection of pediatric LR-MSCs led to a robust activation, characterized by a strong antiviral and pro-inflammatory phenotype combined with mediators related to T cell function. In line with this, following in vivo infection, RSV invades and activates LR-MSCs, resulting in the expansion of the pulmonary MSC pool. Moreover, the global transcriptional response of LR-MSCs appears to follow RSV disease, switching from an early antiviral signature to repair mechanisms including differentiation, tissue remodeling, and angiogenesis. These findings demonstrate the involvement of LR-MSCs during virus-mediated acute lung injury and may have therapeutic implications. AUTHOR SUMMARYThis work identifies a novel function of lung-resident MSCs during virus-induced acute lung injury. These findings contribute to the understanding of host response and lung repair mechanisms during a highly prevalent clinical situation and may have therapeutic implications.

microbiology↗

bioRxiv2020

Susceptibility of well-differentiated airway epithelial cell cultures from domestic and wildlife animals to SARS-CoV-2

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has spread globally, and the number of cases continues to rise all over the world. Besides humans, the zoonotic origin, as well as intermediate and potential spillback host reservoirs of SARS-CoV-2 are unknown. To circumvent ethical and experimental constraints, and more importantly, to reduce and refine animal experimentation, we employed our airway epithelial cell (AEC) culture repository composed of various domesticated and wildlife animal species to assess their susceptibility to SARS-CoV-2. In this study, we inoculated well-differentiated animal AEC cultures of monkey, cat, ferret, dog, rabbit, pig, cattle, goat, llama, camel, and two neotropical bat species with SARS-CoV-2. We observed that SARS-CoV-2 only replicated efficiently in monkey and cat AEC culture models. Whole-genome sequencing of progeny virus revealed no obvious signs of nucleotide transitions required for SARS-CoV-2 to productively infect monkey and cat epithelial airway cells. Our findings, together with the previously reported human-to-animal spillover events warrants close surveillance to understand the potential role of cats, monkeys, and closely related species as spillback reservoirs for SARS-CoV-2.

microbiology↗

bioRxiv2020

The developing T-cell compartment of the neonatal lung orchestrates an atypical response to respiratory syncytial virus

The human respiratory syncytial virus (RSV) is a major cause of severe lower respiratory tract infections in infants, possibly due to the specific features of the immature neonatal pulmonary immune system. Using the newborn lamb, a classical model of human lung development and a state-of-the-art model of RSV infection, we aimed to explore the role of cell-mediated immunity in RSV disease during early life. Remarkably, in healthy conditions, the developing T cell compartment of the neonatal lung showed major differences to that seen in the mature adult lung. The most striking observation being a high baseline frequency of bronchoalveolar IL-4-producing CD4 and CD8 T cells, which declined progressively over developmental age. RSV infection exacerbated this pro-type 2 environment in the bronchoalveolar space, rather than inducing a type 2 response per se. Moreover, regulatory T cell suppressive functions occurred very early to dampen this pro-type 2 environment, rather than shutting them down afterwards, while {gamma}{delta} T cells dropped and failed to produce IL-17. Importantly, RSV disease severity was related to the magnitude of those unconventional bronchoalveolar T cell responses. These findings provide novel insights in the mechanisms of RSV immunopathogenesis in early life, and constitute a major step for the understanding of RSV disease severity. AUTHOR SUMMARYBy using a state-of-the-art translational model with full accessibility to the small airways at defined early life periods, we provide an unpreceded characterization of the developing T cell compartment in the distal lungs of healthy and RSV-infected neonates. This process is highly dynamic and tightly regulated, characterized by colonizing T-cell subsets that synergize towards a narrow pro-tolerogenic immunological window. We believe our work constitutes a solid basis to clarify the age dependency of RSV immunopathogenesis, and should be considered in vaccine design, which remains challenging after five decades of effort.

immunology↗