Biology subjects

Breithaupt, A.

Publications and source records attributed to Breithaupt, A..

At least 19 recordsLinked to original sources

bioRxiv2026

First evaluation of a human DPP4 transgenic hamster model for MERS-CoV pathogenesis and transmission

MERS-CoV poses a constant pandemic risk, as its viral lineages continue evolving, and zoonotic spillover events could lead to random viral polymorphisms that might lead to human adapted variants. Currently, no small animal model reliably recapitulates both disease progression and transmission dynamics, which are critical aspects for counter-viral measures like vaccine development. Although the Syrian hamster is an optimal animal model for SARS-CoV-2 infection and transmission, it is naturally resistant to MERS-CoV infection. Dipeptidyl peptidase-4 (DPP4) is the functional receptor for MERS-CoV infection, and is highly expressed in human kidney, intestine, liver, and lung tissues. Here, we evaluated the suitability of a human DPP4 (hDPP4) transgenic Syrian hamster model for MERS-CoV research. We used two different MERS-CoV strains (EMC/2012 and D10540/2023) for intranasal inoculation of hamsters. Both strains replicated efficiently, led to comparable severe clinical outcomes, and had similar viral transmission efficiencies. MERS-CoV RNA and nucleoprotein antigen were mainly detected in the brain and the respiratory tract. In summary, we validated a novel hDPP4-transgenic hamster as a suitable model for MERS-CoV infection enabling vaccine and transmission research.

microbiology↗

bioRxiv2026

Buffaloed in Brandenburg: Germany's first Brush with Foot-and-Mouth Disease after four Decades of Freedom

Foot-and-mouth disease (FMD) virus is one of the most feared and most consequential pathogens of livestock worldwide. It can be spread rapidly by the transboundary movement of animals, animal products and byproducts. In January 2025, Germany detected its first FMD outbreak since 1988 in extensively reared water buffalo on a small farm in the state of Brandenburg, directly outside Berlin, the federal capital. Immediate control measures including a standstill for movements of susceptible animals and pre-emptive culling were implemented by the veterinary authorities. Whole-genome sequencing identified the virus as serotype O, topotype ME-SA, lineage SA-2018 and revealed extensive recombination, but cross-neutralization assays suggested good heterologous protection by an O/PanAsia-2 vaccine strain. Epidemiological back-calculation placed the time of virus introduction in late December 2024. Although the entry route remains unresolved, human-associated introduction is most likely. Network analysis revealed minimal farm connectivity, and simulations predicted low potential for onward transmission, which is consistent with the outbreak being ultimately restricted to a single herd. This event underscores the constant and unpredictable risk of introduction of the virus. Early detection through increased awareness and comprehensive differential diagnostics as well as the international collaboration of veterinary services, laboratories and experts are essential in the face of the global presence of FMD.

microbiology↗

bioRxiv2026

One and Done: A safe, adaptable single-cycle SARS-CoV-2 vaccine platform blocks XBB.1.5 infection and transmission

A next-generation SARS-CoV-2 vaccine must address the currently inadequate prevention of virus transmission, particularly against emerging variants of concern, a challenge that none of the licensed commercial vaccines fully meet. Effective control of respiratory pandemics necessitates vaccines that 1) can be rapidly adapted, 2) have high patient compliance with simple and non-invasive administration, and 3) block transmission in a virus challenge. We describe here the characterization of an updated single-cycle SARS-CoV-2 vaccine candidate (scVac), engineered as a replication-defective virus with targeted deletions of the E gene and ORF6 and ORF7a, along with a truncation of ORF3a. The candidate carries an Omicron XBB.1.5 Spike (scVacXBB), maintaining all essential antigenic properties. The vaccine demonstrated an excellent safety profile in K18-hACE2 transgenic mice, the most sensitive virulence model, with no clinical signs or adverse events observed. In the Syrian hamster model, potent systemic and mucosal immune responses were induced, along with a strong neutralizing antibody response. Notably, there was no virus transmission to co-housed naive animals, which outperforms a bivalent Omicron mRNA vaccine reference. Our results demonstrate that scVacXBB-induced immunity not only prevents disease but also effectively blocks transmission. Furthermore, the successful introduction of the XBB.1.5 Spike protein into the scVac platform demonstrates the pipelines ability to adapt quickly to any emerging variant. These findings highlight the potential of this single-cycle concept as a next-generation COVID-19 vaccine, offering robust protection with a strong safety profile.

immunology↗

bioRxiv2025

In vivo models for rustrela virus (RusV) infection in potential reservoir and spill-over hosts

Rustrela virus (RusV; species Rubivirus strelense) is a recently discovered relative of the human rubella virus (Rubivirus rubellae) and causes fatal non-suppurative meningoencephalomyelitis in a broad range of mammalian domestic, wild and zoo animals, in Europe and the USA, including staggering disease in domestic cats. Based on its reportedly broad host range, a zoonotic potential of RusV cannot be excluded. Apparently healthy yellow-necked field mice (Apodemus flavicollis) and wood mice (Apodemus sylvaticus) were identified as potential reservoir hosts. In this study, we experimentally inoculated wood mice and Lewis rats with brain homogenates of RusV-infected animals. Intracranial as well as combined intranasal/peroral inoculation resulted in apparently persistent RusV infection in both rodent species, while combined intramuscular/subcutaneous injection failed to establish detectable infection. Viral loads were highest in the central nervous system, but viral RNA was prominently found also in mucosal organs of wood mice. Viral RNA was frequently detected in oral swabs from infected wood mice, but only sparsely from rats. Neither wood mice nor rats presented neurological signs during twelve weeks after infection. However, RusV-infected rats showed significantly reduced body weight. A lymphohistiocytic meningoencephalomyelitis was observed in infected rats, whereas infected wood mice infrequently developed minimal lesions in the brain. Our study provides the first infection model for RusV and indicates that natural infection may occur via mucosal routes. Shedding of viral RNA suggests wood mice to serve as natural reservoir hosts. In rats, we could reproduce a lymphohistiocytic meningoencephalomyelitis, as described for diseased cats and other tentative non-reservoir hosts.

microbiology↗

bioRxiv2025

Wuhan sharpbelly bornavirus (genus Cultervirus) can infect a wide range of host cells and establishes persistent infection in diverse cypriniform cells

Our recent study using in silico data mining identified novel culterviruses (family: Bornaviridae) in fish, including a variant of W[u]han sharpbelly bornavirus (WhSBV) in grass carp kidney and liver cell lines. Here, metagenomic sequencing of different fish cell lines revealed WhSBV in two cell lines from grass carp (Ctenopharyngodon idella; order: Cypriniformes). Using these cell lines, we investigated the ability of WhSBV to infect and establish persistent infection in other cell lines from bony fish (Cypriniformes, Chichliformes, Salmoniformes, Centrarchiformes and Spariformes), reptiles (Testudines and Squamata), birds (Galliformes) and mammals (Primates and Rodentia). WhSBV showed efficient replication and a time-dependent increase in viral RNA levels in cypriniform cells, whereas replication was limited, confined to single cells, and lacked a clear time-dependent increase in cells from other bony fish and reptiles. No replication was detected in avian and mammalian cells. In situ hybridisation and electron microscopy confirmed the presence of viral RNA and particles in infected cypriniform cells. Transcriptomic sequencing revealed minimal innate immune activation during early stages of infection and antiviral response only at later stages, suggesting that WhSBV establishes persistence by evading early immune recognition. In addition, we identified polycistronic viral mRNAs regulated by specific transcriptional start and termination sites and RNA splicing. Viral proteins were detected, confirming previous in silico predictions. These findings provide insights into the potential infectivity, persistence mechanisms and transcriptional strategies of WhSBV. This study validates previous findings from in silico data mining, further reinforcing its effectiveness as a powerful tool for discovering hidden viruses. IMPORTANCEUnderstanding the diversity and host range of viruses is crucial for assessing their ecological role, associated diseases and zoonotic potential. However, many newly discovered viruses are characterised using sequence data alone because isolates are often difficult to obtain. Using cell culture models, this study characterises W[u]han sharpbelly bornavirus (WhSBV), a member of the genus Cultervirus. Here we demonstrate its ability to establish persistent infection in cypriniform fish cell lines, while exhibiting restricted replication in certain non-cypriniform fish. The identification of polycistronic transcription, splicing events and immune evasion mechanisms advances our understanding of the molecular biology of WhSBV and culterviruses in general. By validating in silico predictions, this study highlights the power of computational approaches in uncovering viral diversity. As cypriniform fish include economically important species such as carp, understanding the dynamics of WhSBV host range and infection biology may be crucial for future aquaculture health management.

molecular biology↗

bioRxiv2025

The protease inhibitor Nirmatrelvir synergizes with inhibitors of GRP78 to suppress SARS-CoV-2 replication

Nirmatrelvir, the active compound of the drug Paxlovid, inhibits the Main protease of SARS-CoV-2 (MPro, 3CLPro, NSP5). Its therapeutic application reduces but does not abolish the progression of COVID-19 in humans. Here we report a strong synergy of Nirmatrelvir with inhibitors of the ER chaperone GRP78 (HSPA5, BiP). Combining Nirmatrelvir with the GRP78-antagonizing drug candidate HA15 strongly inhibits the replication of SARS-CoV-2, to a far greater extent than either drug alone, as observed by diminished cytopathic effect, levels of detectable virus RNA, TCID50 titers, accumulation of the non-structural protein 3 (NSP3), as well as Spike and N proteins. The original SARS-CoV-2 strain as well as an Omicron variant were similarly susceptible towards the drug combination. Other GRP78 inhibitors or siRNAs targeting GRP78 also fortified the antiviral effect of Nirmatrelvir. In a hamster model of COVID-19, the combination of Nirmatrelvir with HA15 alleviated pneumonia-induced pulmonary atelectasis more effectively than the single drugs. In conclusion, inhibition of the virus Main protease and cellular GRP78 cooperatively diminishes virus replication and may improve COVID-19 therapy.

microbiology↗

bioRxiv2024

Outcome of H5N1 clade 2.3.4.4b virus infection in calves and lactating cows

In March 2024, highly pathogenic avian influenza virus (HPAIV) clade 2.3.4.4b H5N1 infections in dairy cows were first reported from Texas, USA. Rapid dissemination to more than 190 farms in 13 states followed. Here, we provide results of two independent clade 2.3.4.4b experimental infection studies evaluating (i) oronasal susceptibility and transmission in calves to a US H5N1 bovine isolate genotype B3.13 (H5N1 B3.13) and (ii) susceptibility of lactating cows following direct mammary gland inoculation of either H5N1 B3.13 or a current EU H5N1 wild bird isolate genotype euDG (H5N1 euDG). Inoculation of the calves resulted in moderate nasal replication and shedding with no severe clinical signs or transmission to sentinel calves. In dairy cows, infection resulted in no nasal shedding, but severe acute mammary gland infection with necrotizing mastitis and high fever was observed for both H5N1 genotypes/strains. Milk production was rapidly and drastically reduced and the physical condition of the cows was severely compromised. Virus titers in milk rapidly peaked at 108 TCID50/mL, but systemic infection did not ensue. Notably, adaptive mutation PB2 E627K emerged after intramammary replication of H5N1 euDG. Our data suggest that in addition to H5N1 B3.13, other HPAIV H5N1 strains have the potential to replicate in the udder of cows and that milk and milking procedures, rather than respiratory spread, are likely the primary routes of H5N1 transmission between cattle.

microbiology↗

bioRxiv2024

Red knots in Europe - a dead end host species or a new niche for highly pathogenic avian influenza?

The 2020/2021 epidemic in Europe of highly pathogenic avian influenza virus (HPAIV) of subtype H5 surpassed all previously recorded European outbreaks in size, genotype constellations and reassortment frequency and continued into 2022 and 2023. The causative 2.3.4.4b viral lineage proved to be highly proficient with respect to reassortment with cocirculating low pathogenic AIV and seems to establish an endemic status in northern Europe. A specific HPAIV reassortant of the subtype H5N3 was detected almost exclusively in red knots (Calidris canutus islandica) in December 2020. It caused systemic and rapidly fatal disease leading to a singular and self-limiting mass mortality affecting about 3.500 birds in the German Wadden Sea, roughly 1% of the entire flyway population of islandica red knots. Phylogenetic analyses revealed that the H5N3 reassortant very likely had formed in red knots and remained confined to this species. While mechanisms of virus circulation in potential reservoir species, dynamics of spill-over and reassortment events and the roles of environmental virus sources remain to be identified, the year-round infection pressure poses severe threats to endangered avian species, and prompts adaptation of habitat and species conservation practices. One-Sentence SummaryHigh red knot mortality in Europe (December 2020) was associated with infection of a unique genotype of HPAIV H5N3 clade 2.3.4.4b.

ecology↗

bioRxiv2023

Spatiotemporal analysis of SARS-CoV-2 infection reveals an expansive wave of monocyte-derived macrophages associated with vascular damage and virus clearance in hamster lungs

Factors of the innate immune response to SARS-CoV-2 in the lungs are pivotal for the ability of the host to deal with the infection. In humans, excessive macrophage infiltration is associated with disease severity. Using 3D spatiotemporal analysis of optically cleared hamster lung slices in combination with virological, immunohistochemical and RNA sequence analyses, we visualized the spread of SARS-CoV-2 through the lungs and the rapid anti-viral response in infected lung epithelial cells, followed by a wave of monocyte-derived macrophage (MDM) infiltration and virus elimination from the tissue. These SARS-CoV-2 induced innate immune processes are closely related to the onset of necrotizing inflammatory and consecutive remodelling responses in the lungs, which manifests as extensive cell death, vascular damage, thrombosis, and cell proliferation. Here we show that MDM are directly linked to virus clearance, and appear in connection with tissue injury and blood vessel damage. Rapid initiation of prothrombotic factor upregulation, tissue repair and alveolar cell proliferation results in tissue remodelling, which is followed by fibrosis development despite a decrease in inflammatory and anti-viral activities. Thus, although the hamsters are able to resolve the infection following the MDM influx and repair lung tissue integrity, longer-term alterations of the lung tissues arise as a result of concurrent tissue damage and regeneration processes.

immunology↗

bioRxiv2022

Pathology of African Swine Fever in wild boar naturally infected with German virus variants

In 2020, African swine fever (ASF) was first notified in German wild boar, reaching a case number of about 4200 to date. Upon experimental infection, pathology is well-documented, however, data on field infections are very scarce in domestic pigs and not available from wild boar, respectively. Although ASF viral genome is considered exceptionally stable, a total of five lineages with 10 distinct virus variants of genotype II have emerged in Eastern Germany. To investigate the pathology in naturally infected wild boar and to evaluate virus variants II, III and IV for their virulence, wild boar carcasses were obtained from three different outbreak areas. The cadavers underwent virological and pathomorphological investigation. Regardless of the virus variant all wild boar revealed characteristic lesions of highest severity indicative for ASF. However, wild boar infected with variant IV from Spree-Nei{beta}e (SN) district showed lower viral genome loads and a lower total viral antigen score, but simultaneously revealed more chronic lesions. Our findings indicate a protracted course of the disease at least after infection with variant IV, but need confirmation under standardized experimental conditions. There is a strong need to monitor differences in the virulence among variants to identify potential attenuation that might complicate diagnosis.

pathology↗

bioRxiv2022

Cold-passaged isolates and bat-swine influenza A chimeric viruses as modified live-attenuated vaccines against influenza A viruses in pigs

Swine influenza A virus (swIAV) infections in pig populations cause considerable morbidity and economic losses. Frequent reverse zoonotic incursions of human IAV boost reassortment opportunities with authentic porcine and avian-like IAV in swine herds potentially enhancing zoonotic and even pre-pandemic potential. Vaccination using adjuvanted inactivated full virus vaccines is frequently used in attempting control of swIAV infections. Accelerated antigenic drift of swIAV in large swine holdings and interference of maternal antibodies with vaccine in piglets can compromise these efforts. Potentially more efficacious modified live-attenuated vaccines (MLVs) bear the risk of reversion of MLV to virulence. Here we evaluated new MLV candidates based on cold-passaged swIAV or on reassortment-incompetent bat-IAV-swIAV chimeric viruses. Serial cold-passaging of various swIAV subtypes did not yield unambiguously temperature-sensitive mutants although safety studies in mice and pigs suggested some degree of attenuation. Chimeric bat-swIAV expressing the hemagglutinin and neuraminidase of an avian-like H1N1, in contrast, proved to be safe in mice and pigs, and a single nasal inoculation induced protective immunity against homologous challenge in pigs. Reassortant-incompetent chimeric bat-swIAV vaccines could aid in reducing the amount of swIAV circulating in pig populations, thereby increasing animal welfare, limiting economic losses and lowering the risk of zoonotic swIAV transmission.

microbiology↗

bioRxiv2022

The spike gene is a major determinant for the SARS-CoV-2 Omicron-BA.1 phenotype

Variant of concern (VOC) Omicron-BA1 has achieved global predominance in early 2022. Therefore, surveillance and comprehensive characterization of Omicron-BA.1 in advanced primary cell culture systems and multiple animal models is urgently needed. Here, we characterized Omicron-BA.1 and recombinant Omicron-BA.1 spike gene mutants in comparison with VOC Delta in well-differentiated primary human nasal and bronchial epithelial cells in vitro, followed by in vivo fitness characterization in naive hamsters, ferrets and hACE2-expressing mice, and in immunized hACE2-mice. We demonstrate a spike-mediated enhancement of early replication of Omicron-BA.1 in nasal epithelial cultures, but limited replication in bronchial epithelial cultures. In Syrian hamsters, Delta showed dominance over Omicron-BA.1 and in ferrets, Omicron-BA.1 infection was abortive. In mice expressing the authentic hACE2-receptor, Delta and a Delta spike clone also showed dominance over Omicron-BA.1 and an Omicron-BA.1 spike clone, respectively. Interestingly, in naive K18-hACE2 mice, we observed Delta spike-mediated increased replication and pathogenicity and Omicron-BA.1 spike-mediated reduced replication and pathogenicity, suggesting that the spike gene is a major determinant of both Delta and Omicron-BA.1 replication and pathogenicity. Finally, the Omicron-BA.1 spike clone was less well controlled by mRNA-vaccination in K18-hACE2-mice and became more competitive compared to the progenitor and Delta spike clones, suggesting that spike gene-mediated immune evasion is another important factor that led to Omicron-BA.1 dominance.

microbiology↗

bioRxiv2022

Impaired immune response drives age-dependent severity of COVID-19

SARS-CoV-2 is a highly contagious respiratory virus and the causative agent for COVID-19. The severity of disease varies from mildly symptomatic to lethal and shows an extraordinary correlation with increasing age, which represents the major risk factor for severe COVID-191. However, the precise pathomechanisms leading to aggravated disease in the elderly are currently unknown. Delayed and insufficient antiviral immune responses early after infection as well as dysregulated and overshooting immunopathological processes late during disease were suggested as possible mechanisms. Here we show that the age-dependent increase of COVID-19 severity is caused by the disruption of a timely and well-coordinated innate and adaptive immune response due to impaired interferon (IFN) responses. To overcome the limitations of mechanistic studies in humans, we generated a mouse model for severe COVID-19 and compared the kinetics of the immune responses in adult and aged mice at different time points after infection. Aggravated disease in aged mice was characterized by a diminished IFN-{gamma} response and excessive virus replication. Accordingly, adult IFN-{gamma} receptor-deficient mice phenocopied the age-related disease severity and supplementation of IFN-{gamma} reversed the increased disease susceptibility of aged mice. Mimicking impaired type I IFN immunity in adult and aged mice, a second major risk factor for severe COVID-192-4, we found that therapeutic treatment with IFN-{lambda} in adult and a combinatorial treatment with IFN-{gamma} and IFN-{lambda} in aged Ifnar1-/-mice was highly efficient in protecting against severe disease. Our findings provide an explanation for the age-dependent disease severity of COVID-19 and clarify the nonredundant antiviral functions of type I, II and III IFNs during SARS-CoV-2 infection in an age-dependent manner. Based on our data, we suggest that highly vulnerable individuals combining both risk factors, advanced age and an impaired type I IFN immunity, may greatly benefit from immunotherapy combining IFN-{gamma} and IFN-{lambda}.

immunology↗

bioRxiv2022

Compellingly high SARS-CoV-2 susceptibility of Golden Syrian hamsters suggests multiple zoonotic infections of pet hamsters during the COVID-19 pandemic

Golden Syrian hamsters (Mesocricetus auratus) are used as a research model for severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2). Millions of Golden Syrian hamsters are also kept as pets in close contact to humans. To determine the minimum infective dose (MID) for assessing the zoonotic transmission risk, and to define the optimal infection dose for experimental studies, we orotracheally inoculated hamsters with SARS-CoV-2 doses from 1*105 to 1*10-4 tissue culture infectious dose 50 (TCID50). Body weight and virus shedding were monitored daily. 1*10-3 TCID50 was defined as the MID, and this was still sufficient to induce virus shedding at levels up to 102.75 TCID50/ml, equaling the estimated MID for humans. Virological and histological data revealed 1*102 TCID50 as the optimal dose for experimental infections. This compellingly high susceptibility resulting in productive infections in Golden Syrian hamsters needs to be considered also as a source of SARS-CoV-2 infections in humans.

microbiology↗

bioRxiv2021

Revisiting rustrela virus - new cases of encephalitis and a solution to the capsid enigma

Rustrela virus (RusV, species Rubivirus strelense) is a recently discovered relative of rubella virus (RuV) that has been detected in cases of encephalitis across a wide spectrum of mammals, including placental and marsupial animals. Here we diagnosed two additional cases of fatal RusV-associated meningoencephalitis in a South American coati (Nasua nasua) and a Eurasian otter (Lutra lutra) that were detected in a zoological garden with history of prior RusV infections. Both animals showed abnormal movement or unusual behaviour and their brains tested positive for RusV using specific RT-qPCR and RNA in situ hybridization. As previous sequencing of RusV proved to be very challenging, we employed a sophisticated target-specific capture enrichment with specifically designed RNA baits to generate complete RusV genome sequences from both detected encephalitic animals and apparently healthy wild yellow-necked field mice (Apodemus flavicollis). Furthermore, the technique was used to revise three previously published RusV genomes from two encephalitic animals and a wild yellow-necked field mouse. Virus-to-host sequence ratio and thereby sequence coverage improved markedly using the enrichment method as compared to standard procedures. When comparing the newly generated RusV sequences to the previously published RusV genomes, we identified a previously undetected stretch of 309 nucleotides predicted to represent the intergenic region and the sequence encoding the N-terminus of the capsid protein. This indicated that the original RusV sequence was likely incomplete due to misassembly of the genome at a region with an exceptionally high G+C content of >80 mol%, which could not be resolved even by enormous sequencing efforts with standard methods. The updated capsid protein amino acid sequence now resembles those of RuV and ruhugu virus in size and harbours a predicted RNA binding domain that was not encoded in the original RusV genome version. The new sequence data indicate that RusV has the largest overall genome (9,631 nucleotides), intergenic region (290 nucleotides) and capsid protein-encoding sequence (331 codons) within the genus Rubivirus.

microbiology↗

bioRxiv2021

In contrast to TH2-biased approaches, TH1 COVID-19 vaccines protect Syrian hamsters from severe disease in the absence of dexamethasone-treatable vaccine-associated enhanced respiratory pathology

Since December 2019, the novel human coronavirus SARS-CoV-2 has spread globally, causing millions of deaths. Unprecedented efforts have enabled development and authorization of a range of vaccines, which reduce transmission rates and confer protection against the associated disease COVID-19. These vaccines are conceptually diverse, including e.g. classical adjuvanted whole-inactivated virus, viral vectors, and mRNA vaccines. We have analysed two prototypic model vaccines, the strongly TH1-biased measles vaccine-derived candidate MeVvac2-SARS2-S(H) and a TH2-biased Alum-adjuvanted, non-stabilized Spike (S) protein side-by-side, for their ability to protect Syrian hamsters upon challenge with a low-passage SARS-CoV-2 patient isolate. As expected, the MeVvac2-SARS2-S(H) vaccine protected the hamsters safely from severe disease. In contrast, the protein vaccine induced vaccine-associated enhanced respiratory disease (VAERD) with massive infiltration of eosinophils into the lungs. Global RNA-Seq analysis of hamster lungs revealed reduced viral RNA and less host dysregulation in MeVvac2-SARS2-S(H) vaccinated animals, while S protein vaccination triggered enhanced host gene dysregulation compared to unvaccinated control animals. Of note, mRNAs encoding the major eosinophil attractant CCL-11, the TH2 response-driving cytokine IL-19, as well as TH2-cytokines IL-4, IL-5, and IL-13 were exclusively up-regulated in the lungs of S protein vaccinated animals, consistent with previously described VAERD induced by RSV vaccine candidates. IL-4, IL-5, and IL-13 were also up-regulated in S-specific splenocytes after protein vaccination. Using scRNA-Seq, T cells and innate lymphoid cells were identified as the source of these cytokines, while Ccl11 and Il19 mRNAs were expressed in lung macrophages displaying an activated phenotype. Interestingly, the amount of viral reads in this macrophage population correlated with the abundance of Fc-receptor reads. These findings suggest that VAERD is triggered by induction of TH2-type helper cells secreting IL-4, IL-5, and IL-13, together with stimulation of macrophage subsets dependent on non-neutralizing antibodies. Via this mechanism, uncontrolled eosinophil recruitment to the infected tissue occurs, a hallmark of VAERD immunopathogenesis. These effects could effectively be treated using dexamethasone and were not observed in animals vaccinated with MeVvac2-SARS2-S(H). Taken together, our data validate the potential of TH2-biased COVID-19 vaccines and identify the transcriptional mediators that underlie VAERD, but confirm safety of TH1-biased vaccine concepts such as vector-based or mRNA vaccines. Dexamethasone, which is already in use for treatment of severe COVID-19, may alleviate such VAERD, but in-depth scrutiny of any next-generation protein-based vaccine candidates is required, prior and after their regulatory approval.

immunology↗

bioRxiv2021

Enhanced fitness of SARS-CoV-2 variant of concern B.1.1.7, but not B.1.351, in animal models

Emerging variants of concern (VOCs) drive the SARS-CoV-2 pandemic. We assessed VOC B.1.1.7, now prevalent in several countries, and VOC B.1.351, representing the greatest threat to populations with immunity to the early SARS-CoV-2 progenitors. B.1.1.7 showed a clear fitness advantage over the progenitor variant (wt-S614G) in ferrets and two mouse models, where the substitutions in the spike glycoprotein were major drivers for fitness advantage. In the "superspreader" hamster model, B.1.1.7 and wt-S614G had comparable fitness, whereas B.1.351 was outcompeted. The VOCs had similar replication kinetics as compared to wt-S614G in human airway epithelial cultures. Our study highlights the importance of using multiple models for complete fitness characterization of VOCs and demonstrates adaptation of B.1.1.7 towards increased upper respiratory tract replication and enhanced transmission in vivo. Summary sentenceB.1.1.7 VOC outcompetes progenitor SARS-CoV-2 in upper respiratory tract replication competition in vivo.

microbiology↗

bioRxiv2021

Generation and first characterization of TRDC-Knockout pigs lacking γδ T cells

The TRDC-Locus encodes the T cell receptor delta constant region, one component of the {gamma}{delta} T cell receptor which is essential for development of {gamma}{delta} T cells. In contrast to peptide recognition by {beta} T cells, antigens activating {gamma}{delta} T cells are mostly MHC independent and not well characterized. Therefore, the function of {gamma}{delta} T cells and their contribution to protection against infections is still unclear. Higher numbers of circulating {gamma}{delta} T cells compared to mice, render the pig a suitable animal model to study {gamma}{delta} T cells. Knocking-out the porcine TRDC-locus by intracytoplasmic microinjection and somatic cell nuclear transfer resulted in healthy living {gamma}{delta} T cell deficient offspring. Flow cytometric analysis revealed that TRDC-KO pigs lack {gamma}{delta} T cells in peripheral blood mononuclear cells (PBMC) and spleen cells. The composition of the remaining leucocyte subpopulations was not affected by the depletion of {gamma}{delta} T cells. Genome-wide transcriptome analyses in PBMC revealed a pattern of changes reflecting the impairment of known or expected {gamma}{delta} T cell dependent pathways. Histopathology did not reveal developmental abnormalities of secondary lymphoid tissues. However, in a vaccination experiment the KO pigs stayed healthy but had a significantly lower neutralizing antibody titer as the syngenic controls.

immunology↗