Biology subjects

Dietrich, I.

Publications and source records attributed to Dietrich, I..

6 recordsLinked to original sources

bioRxiv2025

Mosquito NF-κB-mediated innate immunity exerts arbovirus-specific antiviral effects at multiple stages of the viral life cycle

One third of all emerging infectious diseases are vector-borne, with the vectors ecology and physiology playing key roles in determining whether viruses can access new vertebrate host species and spread globally. Innate immunity is a known barrier to virus replication in mosquito vectors that influences arboviral vector tropism. We here generated novel CRISPR-Cas9-mediated knockouts of the NF-{kappa}B family transcription factor Rel2 in Aedes aegypti-derived Aag2 cells and tested the impact on the replication of a diverse range of arboviruses in the Flaviviridae and Togaviridae families and the class Bunyaviricetes. We found that NF-{kappa}B-mediated innate immunity has broad antiviral activity against the Ae. aegypti-borne orthoflaviviruses dengue virus (DENV), yellow fever virus (YFV) and Zika virus (ZIKV) in mosquito cells. In contrast, little impact of NF-{kappa}B-loss-of-function was observed for the alphavirus chikungunya virus (CHIKV) or phlebovirus Rift Valley fever virus (RVFV), indicating specificity in the antiviral effects of NF-{kappa}B-mediated immunity. By comparing orthoflaviviruses with different transmission routes (mosquito-borne, tick-borne, no known vector), we demonstrated that NF-{kappa}B-mediated immunity exerts its antiviral effects both early and late in the viral replication cycle, and that NF-{kappa}B-mediated immunity is not the only molecular barrier influencing the ability of orthoflaviviruses to replicate in Ae. aegypti cells. Overall, our work demonstrates the importance of mosquito NF-{kappa}B-mediated innate immunity in suppressing arbovirus replication, and shows that the barriers for arboviruses to adapt to new vector species are multifactorial and virus-specific. Our findings increase our understanding of the molecular barriers influencing arboviral emergence, and could inform the development of refractory mosquitoes incapable of transmitting human pathogens. Author SummaryMosquito-borne viruses are causing an increasing global disease burden due to urbanisation, globalisation, changing land use and the climate change-driven invasion of mosquitoes into new locations. Few vaccines and no medicines for mosquito-borne viral infections are licensed for human use. Historically, the most effective way to reduce human disease has been to kill mosquitoes using insecticides, which also harms beneficial insects and is leading to resistance. Newer technologies with lower ecological impacts are being developed, including genetically modified mosquitoes with a reduced ability to transmit viruses. Like humans, mosquitoes have an immune system that protects against viral infections, and strengthening this immune system through genetic modification has shown promise for reducing virus transmission. We here expand our understanding of the ways in which mosquito immunity could be harnessed by demonstrating that a gene called "Rel2" helps the mosquito fight mosquito-borne virus infection. Unlike previously studied mosquito immune responses, Rel2 has a very broad (but not universal) protective capacity against viruses. Our work also indicates that Rel2 works in concert with other arms of the mosquito immune system, highlighting a need for further research to fully realise the potential of genetically modifying mosquito immune responses for the prevention of human disease.

microbiology↗

bioRxiv2025

Lack of Vector Competence in UK Culex pipiens molestus for Oropouche Virus

Oropouche virus (OROV) is an orthobunyavirus (Peribunyaviridae) that has caused recurrent outbreaks in South America and has recently expanded into the Caribbean, with various biting midge and mosquito species considered vectors. Recent imported cases to Europe and North America have raised concerns about the potential for local transmission in non-endemic areas. To assess this risk in the United Kingdom, we investigated the vector competence of Culex pipiens molestus (Cx. molestus), a human-biting mosquito common in urban environments. Laboratory-reared adult females were fed a bloodmeal containing a Cuban 2024 OROV outbreak strain (240023) and maintained at 27{degrees}C. Of 64 individuals tested at 12-s14 days post-infection via plaque assay, none were positive for OROV in bodies, indicating no evidence of infection and subsequently limited or no vector competence potential. These results provide evidence that UK populations of Cx. molestus are unlikely to support OROV transmission, thereby refining assessments of OROV emergence risk in temperate settings. Further studies are needed to test other putative UK mosquito vectors, as well as Culicoides biting midge species to fully assess the potential for OROV transmission in this region.

microbiology↗

bioRxiv2023

The mechanical arthropod vector Stomoxys calcitrans influences the outcome of lumpy skin disease virus infection in cattle

The poxvirus lumpy skin disease virus (LSDV) is the etiological agent of lumpy skin disease (LSD), a severe disease of cattle and water buffalo that is characterised by numerous necrotic cutaneous nodules. LSD is a rapidly emerging disease, spreading into and across the Middle East, eastern Europe, and Asia in the past decade. The disease causes substantial production and economic losses in rural communities and affected regions. LSDV is mechanically transmitted by haematophagous arthropods including stable flies (Stomoxys calcitrans), however our understanding of this mechanical transmission method is sparse. A secreted saliva collection methodology using a modified artificial membrane feeding system was optimised for S. calcitrans and used to collect and characterise secreted S. calcitrans saliva. Saliva was mixed with LSDV and shown not to affect virus growth in primary bovine fibroblasts. S. calcitrans saliva or spot-feeding by S. calcitrans was then incorporated into a bovine in vivo experimental model of LSD to determine if either influenced disease pathogenesis. S. calcitrans saliva resulted in fewer animals developing disease, however this difference was not statistically significant. Spot-feeding with S. calcitrans prior to inoculation did not alter the number of animals that developed disease or the overall severity of disease however disease progression was accelerated as demonstrated by the appearance of cutaneous nodules, detection of viral DNA in the blood stream, and production of neutralising antibodies. This shows that S. calcitrans influence disease kinetics through co-incident bite trauma and/or saliva deposition. This increases our understanding of LSDV pathogenesis and highlights the overlooked importance of mechanical vectors in pathogen transmission. Author summaryInsect vectors are important conduits for the transmission of pathogens that cause diseases such as Zika, dengue, malaria, and lumpy skin disease. Biological vector-borne transmission incorporates a replication phase for the pathogen in the insect, whereas no replication occurs in the vector during mechanical transmission. When the insect bites the host it inoculates a pathogen whilst also delivering arthropod-derived factors such as saliva components and causing tissue trauma through biting and probing. Arthropod saliva and/or bite trauma have been shown to enhance the speed and severity of disease following inoculation with a range of biologically transmitted viruses. This study examined if this was true also for the mechanically transmitted pathogen lumpy skin disease virus (LSDV). LSDV is a neglected pathogen that causes severe systemic disease in cattle and is transmitted mechanically by the stable fly Stomoxys calcitrans. Using an experimental bovine model of LSD, we found that disease occurred more rapidly when virus was delivered in association with the bites of uninfected flies. This work has increased our knowledge of lumpy skin disease virus transmission, and the discovery that disease outcome can be impacted by previously overlooked mechanical insect vectors should prompt further investigation into this mechanism of transmission.

microbiology↗

bioRxiv2020

A COVID-19 vaccine candidate using SpyCatcher multimerization of the SARS-CoV-2 spike protein receptor-binding domain induces potent neutralising antibody responses

There is dire need for an effective and affordable vaccine against SARS-CoV-2 to tackle the ongoing pandemic. In this study, we describe a modular virus-like particle vaccine candidate displaying the SARS-CoV-2 spike glycoprotein receptor-binding domain (RBD) using SpyTag/SpyCatcher technology (RBD-SpyVLP). Low doses of RBD-SpyVLP in a prime-boost regimen induced a strong neutralising antibody response in mice and pigs that was superior to convalescent human sera. We evaluated antibody quality using ACE2 blocking and neutralisation of cell infection by pseudovirus or wild-type SARS-CoV-2. Using competition assays with a monoclonal antibody panel, we showed that RBD-SpyVLP induced a polyclonal antibody response that recognised all key epitopes on the RBD, reducing the likelihood of selecting neutralisation-escape mutants. The induction of potent and polyclonal antibody responses by RBD-SpyVLP provides strong potential to address clinical and logistic challenges of the COVID-19 pandemic. Moreover, RBD-SpyVLP is highly resilient, thermostable and can be lyophilised without losing immunogenicity, to facilitate global distribution and reduce cold-chain dependence.

immunology↗

bioRxiv2020

Evaluation of the immunogenicity of prime-boost vaccination with the replication-deficient viral vectored COVID-19 vaccine candidate ChAdOx1 nCoV-19

Clinical development of the COVID-19 vaccine candidate ChAdOx1 nCoV-19, a replication-deficient simian adenoviral vector expressing the full-length SARS-CoV-2 spike (S) protein was initiated in April 2020 following non-human primate studies using a single immunisation. Here, we compared the immunogenicity of one or two doses of ChAdOx1 nCoV-19 in both mice and pigs. Whilst a single dose induced antigen-specific antibody and T cells responses, a booster immunisation enhanced antibody responses, particularly in pigs, with a significant increase in SARS-CoV-2 neutralising titres.

immunology↗

bioRxiv2020

The SARS-CoV-2 Spike protein has a broad tropism for mammalian ACE2 proteins

SARS-CoV-2 emerged in late 2019, leading to the COVID-19 pandemic that continues to cause significant global mortality in human populations. Given its sequence similarity to SARS-CoV, as well as related coronaviruses circulating in bats, SARS-CoV-2 is thought to have originated in Chiroptera species in China. However, whether the virus spread directly to humans or through an intermediate host is currently unclear, as is the potential for this virus to infect companion animals, livestock and wildlife that could act as viral reservoirs. Using a combination of surrogate entry assays and live virus we demonstrate that, in addition to human ACE2, the Spike glycoprotein of SARS-CoV-2 has a broad host tropism for mammalian ACE2 receptors, despite divergence in the amino acids at the Spike receptor binding site on these proteins. Of the twenty-two different hosts we investigated, ACE2 proteins from dog, cat and rabbit were the most permissive to SARS-CoV-2, while bat and bird ACE2 proteins were the least efficiently used receptors. The absence of a significant tropism for any of the three genetically distinct bat ACE2 proteins we examined indicates that SARS-CoV-2 receptor usage likely shifted during zoonotic transmission from bats into people, possibly in an intermediate reservoir. Interestingly, while SARS-CoV-2 pseudoparticle entry was inefficient in cells bearing the ACE2 receptor from bats or birds the live virus was still able to enter these cells, albeit with markedly lower efficiency. The apparently broad tropism of SARS-CoV-2 at the point of viral entry confirms the potential risk of infection to a wide range of companion animals, livestock and wildlife.

microbiology↗