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Journal of Virology Mar 2022The impact of the host microbiota on arbovirus infections is currently not well understood. Arboviruses are viruses transmitted through the bites of infected arthropods,...
The impact of the host microbiota on arbovirus infections is currently not well understood. Arboviruses are viruses transmitted through the bites of infected arthropods, predominantly mosquitoes or ticks. The first site of arbovirus inoculation is the biting site in the host skin, which is colonized by a complex microbial community that could possibly influence arbovirus infection. We demonstrated that preincubation of arboviruses with certain components of the bacterial cell wall, including lipopolysaccharides (LPS) of some Gram-negative bacteria and lipoteichoic acids or peptidoglycan of certain Gram-positive bacteria, significantly reduced arbovirus infectivity . This inhibitory effect was observed for arboviruses of different virus families, including chikungunya virus of the genus and Zika virus of the genus, showing that this is a broad phenomenon. A modest inhibitory effect was observed following incubation with a panel of heat-inactivated bacteria, including bacteria residing on the skin. No viral inhibition was observed after preincubation of cells with LPS. Furthermore, a virucidal effect of LPS on viral particles was noticed by electron microscopy. Therefore, the main inhibitory mechanism seems to be due to a direct effect on the virus particles. Together, these results suggest that bacteria are able to decrease the infectivity of alphaviruses and flaviviruses. During the past decades, the world has experienced a vast increase in epidemics of alphavirus and flavivirus infections. These viruses can cause severe diseases, such as hemorrhagic fever, encephalitis, and arthritis. Several alpha- and flaviviruses, such as chikungunya virus, Zika virus, and dengue virus, are significant global health threats because of their high disease burden, their widespread (re-)emergence, and the lack of (good) anti-arboviral strategies. Despite the clear health burden, alphavirus and flavivirus infection and disease are not fully understood. A knowledge gap in the interplay between the host and the arbovirus is the potential interaction with host skin bacteria. Therefore, we studied the effect of (skin) bacteria and bacterial cell wall components on alphavirus and flavivirus infectivity in cell culture. Our results show that certain bacterial cell wall components markedly reduced viral infectivity by interacting directly with the virus particle.
Topics: Alphavirus; Animals; Arboviruses; Bacteria; Cell Wall; Chikungunya virus; Flavivirus; Lipopolysaccharides; Microbiota; Zika Virus
PubMed: 35107376
DOI: 10.1128/jvi.00060-22 -
Viruses Aug 2023Chikungunya virus (CHIKV), an alphavirus transmitted by mosquitoes, has experienced a recent re-emergence in various regions of the world, leading to large-scale...
Chikungunya virus (CHIKV), an alphavirus transmitted by mosquitoes, has experienced a recent re-emergence in various regions of the world, leading to large-scale outbreaks [...].
Topics: Animals; Chikungunya virus; Culicidae; Disease Outbreaks
PubMed: 37632110
DOI: 10.3390/v15081768 -
Proceedings of the National Academy of... Sep 2023Multiple viruses, including pathogenic viruses, bacteriophages, and even plant viruses, cause a phenomenon termed superinfection exclusion whereby a currently infected...
Multiple viruses, including pathogenic viruses, bacteriophages, and even plant viruses, cause a phenomenon termed superinfection exclusion whereby a currently infected cell is resistant to secondary infection by the same or a closely related virus. In alphaviruses, this process is thought to be mediated, at least in part, by the viral protease (nsP2) which is responsible for processing the nonstructural polyproteins (P123 and P1234) into individual proteins (nsP1-nsP4), forming the viral replication complex. Taking a synthetic biology approach, we mimicked this naturally occurring phenomenon by generating a superinfection exclusion-like state in mosquitoes, rendering them refractory to alphavirus infection. By artificially expressing Sindbis virus (SINV) and chikungunya virus (CHIKV) nsP2 in mosquito cells and transgenic mosquitoes, we demonstrated a reduction in both SINV and CHIKV viral replication rates in cells following viral infection as well as reduced infection prevalence, viral titers, and transmission potential in mosquitoes.
Topics: Animals; Aedes; Yellow Fever; Superinfection; Alphavirus Infections; Chikungunya virus; Sindbis Virus
PubMed: 37669371
DOI: 10.1073/pnas.2303080120 -
Cell Reports May 2023RNA interference (RNAi) is a well-established antiviral immunity. However, for mammalian somatic cells, antiviral RNAi becomes evident only when viral suppressors of...
RNA interference (RNAi) is a well-established antiviral immunity. However, for mammalian somatic cells, antiviral RNAi becomes evident only when viral suppressors of RNAi (VSRs) are disabled by mutations or VSR-targeting drugs, thereby limiting its scope as a mammalian immunity. We find that a wild-type alphavirus, Semliki Forest virus (SFV), triggers the Dicer-dependent production of virus-derived small interfering RNAs (vsiRNAs) in both mammalian somatic cells and adult mice. These SFV-vsiRNAs are located at a particular region within the 5' terminus of the SFV genome, Argonaute loaded, and active in conferring effective anti-SFV activity. Sindbis virus, another alphavirus, also induces vsiRNA production in mammalian somatic cells. Moreover, treatment with enoxacin, an RNAi enhancer, inhibits SFV replication dependent on RNAi response in vitro and in vivo and protects mice from SFV-induced neuropathogenesis and lethality. These findings show that alphaviruses trigger the production of active vsiRNA in mammalian somatic cells, highlighting the functional importance and therapeutic potential of antiviral RNAi in mammals.
Topics: Animals; Mice; RNA Interference; Antiviral Agents; Cell Line; RNA, Small Interfering; Semliki forest virus; Alphavirus Infections; Sindbis Virus; Mammals; Virus Replication
PubMed: 37104090
DOI: 10.1016/j.celrep.2023.112441 -
Nature Communications Jan 2024Members of the low-density lipoprotein receptor (LDLR) family, including LDLRAD3, VLDLR, and ApoER2, were recently described as entry factors for different alphaviruses....
Members of the low-density lipoprotein receptor (LDLR) family, including LDLRAD3, VLDLR, and ApoER2, were recently described as entry factors for different alphaviruses. However, based on studies with gene edited cells and knockout mice, blockade or abrogation of these receptors does not fully inhibit alphavirus infection, indicating the existence of additional uncharacterized entry factors. Here, we perform a CRISPR-Cas9 genome-wide loss-of-function screen in mouse neuronal cells with a chimeric alphavirus expressing the Eastern equine encephalitis virus (EEEV) structural proteins and identify LDLR as a candidate receptor. Expression of LDLR on the surface of neuronal or non-neuronal cells facilitates binding and infection of EEEV, Western equine encephalitis virus, and Semliki Forest virus. Domain mapping and binding studies reveal a low-affinity interaction with LA domain 3 (LA3) that can be enhanced by concatenation of LA3 repeats. Soluble decoy proteins with multiple LA3 repeats inhibit EEEV infection in cell culture and in mice. Our results establish LDLR as a low-affinity receptor for multiple alphaviruses and highlight a possible path for developing inhibitors that could mitigate infection and disease.
Topics: Horses; Animals; Mice; Alphavirus; Encephalitis Virus, Eastern Equine; Alphavirus Infections; Semliki forest virus; Lipoproteins, LDL
PubMed: 38172096
DOI: 10.1038/s41467-023-44624-x -
Journal of Virology Jan 2022Alphaviruses and flaviviruses have class II fusion glycoproteins that are essential for virion assembly and infectivity. Importantly, the tip of domain II is...
Alphaviruses and flaviviruses have class II fusion glycoproteins that are essential for virion assembly and infectivity. Importantly, the tip of domain II is structurally conserved between the alphavirus and flavivirus fusion proteins, yet whether these structural similarities between virus families translate to functional similarities is unclear. Using evolution of Zika virus (ZIKV), we identified several novel emerging variants, including an envelope glycoprotein variant in β-strand c (V114M) of domain II. We have previously shown that the analogous β-strand c and the ij loop, located in the tip of domain II of the alphavirus E1 glycoprotein, are important for infectivity. This led us to hypothesize that flavivirus E β-strand c also contributes to flavivirus infection. We generated this ZIKV glycoprotein variant and found that while it had little impact on infection in mosquitoes, it reduced replication in human cells and mice and increased virus sensitivity to ammonium chloride, as seen for alphaviruses. In light of these results and given our alphavirus ij loop studies, we mutated a conserved alanine at the tip of the flavivirus ij loop to valine to test its effect on ZIKV infectivity. Interestingly, this mutation inhibited infectious virion production of ZIKV and yellow fever virus, but not West Nile virus. Together, these studies show that shared domains of the alphavirus and flavivirus class II fusion glycoproteins harbor structurally analogous residues that are functionally important and contribute to virus infection Arboviruses are a significant global public health threat, yet there are no antivirals targeting these viruses. This problem is in part due to our lack of knowledge of the molecular mechanisms involved in the arbovirus life cycle. In particular, virus entry and assembly are essential processes in the virus life cycle and steps that can be targeted for the development of antiviral therapies. Therefore, understanding common, fundamental mechanisms used by different arboviruses for entry and assembly is essential. In this study, we show that flavivirus and alphavirus residues located in structurally conserved and analogous regions of the class II fusion proteins contribute to common mechanisms of entry, dissemination, and infectious-virion production. These studies highlight how class II fusion proteins function and provide novel targets for development of antivirals.
Topics: A549 Cells; Alphavirus; Ammonium Chloride; Animals; Culicidae; Flavivirus; Humans; Interferon Type I; Mice; Mice, Mutant Strains; Mutation; Protein Domains; Viral Fusion Proteins; Viral Nonstructural Proteins; Virion; Virus Assembly; Virus Internalization; Virus Replication; Zika Virus; Zika Virus Infection
PubMed: 34757841
DOI: 10.1128/JVI.01774-21 -
Journal of Virology Nov 2023Alphavirus replicons are being developed as self-amplifying RNAs aimed at improving the efficacy of mRNA vaccines. These replicons are convenient for genetic...
Alphavirus replicons are being developed as self-amplifying RNAs aimed at improving the efficacy of mRNA vaccines. These replicons are convenient for genetic manipulations and can express heterologous genetic information more efficiently and for a longer time than standard mRNAs. However, replicons mimic many aspects of viral replication in terms of induction of innate immune response, modification of cellular transcription and translation, and expression of nonstructural viral genes. Moreover, all replicons used in this study demonstrated expression of heterologous genes in cell- and replicon's origin-specific modes. Thus, many aspects of the interactions between replicons and the host remain insufficiently investigated, and further studies are needed to understand the biology of the replicons and their applicability for designing a new generation of mRNA vaccines. On the other hand, our data show that replicons are very flexible expression systems, and additional modifications may have strong positive impacts on protein expression.
Topics: Alphavirus; mRNA Vaccines; Replicon; Virus Replication; RNA, Viral; Host Microbial Interactions; Viral Proteins; Gene Expression Regulation, Viral
PubMed: 37877718
DOI: 10.1128/jvi.01225-23 -
Viruses Jan 2022Alphaviruses () are arthropod-borne viruses responsible for several emerging diseases, maintained in nature through transmission between hematophagous arthropod vectors...
Alphaviruses () are arthropod-borne viruses responsible for several emerging diseases, maintained in nature through transmission between hematophagous arthropod vectors and susceptible vertebrate hosts. Although bats harbor many species of viruses, their role as reservoir hosts in emergent zoonoses has been verified only in a few cases. With bats being the second most diverse order of mammals, their implication in arbovirus infections needs to be elucidated. Reports on arbovirus infections in bats are scarce, especially in South American indigenous species. In this work, we report the genomic detection and identification of two different alphaviruses in oral swabs from bats captured in Northern Uruguay. Phylogenetic analysis identified Río Negro virus (RNV) in two different species: ( = 6) and spp. ( = 1) and eastern equine encephalitis virus (EEEV) in spp. ( = 2). Previous studies of our group identified RNV and EEEV in mosquitoes and horse serology, suggesting that they may be circulating in enzootic cycles in our country. Our findings reveal that bats can be infected by these arboviruses and that chiropterans could participate in the viral natural cycle as virus amplifiers or dead-end hosts. Further studies are warranted to elucidate the role of these mammals in the biological cycle of these alphaviruses in Uruguay.
Topics: Alphavirus; Alphavirus Infections; Animals; Arbovirus Infections; Arboviruses; Chiroptera; Encephalitis Virus, Eastern Equine; Phylogeny; Uruguay
PubMed: 35215862
DOI: 10.3390/v14020269 -
Viruses Feb 2018Alphaviruses are arthropod-borne viruses and are predominantly transmitted via mosquito vectors. This vector preference by alphaviruses raises the important question of... (Review)
Review
Alphaviruses are arthropod-borne viruses and are predominantly transmitted via mosquito vectors. This vector preference by alphaviruses raises the important question of the determinants that contribute to vector competence. There are several tissue barriers of the mosquito that the virus must overcome in order to establish a productive infection. Of importance are the midgut, basal lamina and the salivary glands. Infection of the salivary glands is crucial for virus transmission during the mosquito's subsequent bloodfeed. Other factors that may contribute to vector competence include the microflora and parasites present in the mosquito, environmental conditions, the molecular determinants of the virus to adapt to the vector, as well as the effect of co-infection with other viruses. Though mosquito innate immunity is a contributing factor to vector competence, it will not be discussed in this review. Detailed understanding of these factors will be instrumental in minimising transmission of alphaviral diseases.
Topics: Alphavirus; Alphavirus Infections; Animals; Coinfection; Culicidae; Humans; Mosquito Vectors; Mutation; RNA, Viral
PubMed: 29443908
DOI: 10.3390/v10020084 -
Viruses Feb 2023Alphaviruses are important human and animal pathogens that can cause a range of debilitating symptoms and are found worldwide. These include arthralgic diseases caused... (Review)
Review
Alphaviruses are important human and animal pathogens that can cause a range of debilitating symptoms and are found worldwide. These include arthralgic diseases caused by Old-World viruses and encephalitis induced by infection with New-World alphaviruses. Non-coding RNAs do not encode for proteins, but can modulate cellular response pathways in a myriad of ways. There are several classes of non-coding RNAs, some more well-studied than others. Much research has focused on the mRNA response to infection against alphaviruses, but analysis of non-coding RNA responses has been more limited until recently. This review covers what is known regarding host cell non-coding RNA responses in alphavirus infections and highlights gaps in the knowledge that future research should address.
Topics: Animals; Humans; Alphavirus Infections; Alphavirus; Arthralgia; Encephalitis; RNA, Untranslated
PubMed: 36851776
DOI: 10.3390/v15020562