Viruses-Basel最新文献

Bacteriophage-derived endolysins are being developed as an alternative to antimicrobials. The development of endolysins against Gram-negative bacteria requires the discovery of effective endolysins against the target species and the capability to penetrate the outer membrane of bacteria by endolysin. Here, we propose an efficient endolysin development approach that combines a data-driven endolysin search utilizing bacterial genomes with high-throughput laboratory assays. As a proof of concept, we analyzed endolysin genes detected in 273 bacterial genomes of Acinetobacter, Pseudomonas, and Escherichia. Firstly, we conducted assays of 192 recombinants of endolysin genes obtained through in silico search from bacterial genomes and identified natural endolysins degrading peptidoglycan of Acinetobacter baumannii. Then, we performed high-throughput screening against Gram-negative bacteria for hundreds of chimera AMP-endolysins, natural endolysin conjugated with antimicrobial peptide. As a result, we obtained four chimera AMP-endolysins against A. baumannii, which demonstrated the minimum inhibitory concentration ranging from 4 to 8 μg/mL. Moreover, we assessed the antimicrobial spectra of these chimera AMP-endolysins, validating that two endolysins exhibited antimicrobial efficacy against Pseudomonas aeruginosa and Escherichia coli with <32 μg/mL of concentration. This endolysin development approach can be applied to other Gram-negative bacterial targets and is expected to facilitate the acquisition of effective novel endolysins.

Ancient human viruses have been detected in ancient DNA (aDNA) samples of both Anatomically Modern Humans and Neanderthals. Reconstructing genomes from aDNA using reference mapping presents numerous problems due to the unique nature of ancient samples, their degraded state, smaller read sizes and the limitations of current methodologies. The spurious alignments of reads to reference sequences (mapping) are a main source of false positives in aDNA assemblies and the assessment of signal-to-noise ratios is essential to differentiate bona fide reconstructions from random, noisy assemblies. Here, we analyzed the statistical distributions of viral genome assemblies, ancient and modern, and their respective random "mock" controls used to evaluate the signal-to-noise ratio. We tested if differences between real and random assemblies could be detected from their statistical distributions. Our analysis shows that the coverage distributions of (1) real viral aDNA assemblies of adenovirus (ADV), herpesvirus (HSV) and papillomavirus (HPV) do not follow power laws nor log-normal laws, (2) (ADV) and control aDNA assemblies are well approximated by log-normal laws, (3) negative control parvovirus B19 (real and random) follow a power law with infinite variance and (4) the mapDamage negative control with non-ancient DNA (modern ADV) and the mapDamage positive control (human mtDNA) are well approximated by the negative binomial distribution, consistent with the Lander-Waterman model. Our results show that the tails of the distributions of aDNA and their controls reveal the weight of random effects and can differentiate spurious assemblies, or false positives, from bona fide assemblies.

Wild waterfowl are considered to be the reservoir of avian influenza, but their distinct annual life cycle stages and their contribution to disease dynamics are not well understood. Studies of the highly pathogenic avian influenza (HPAI) virus have primarily focused on wintering grounds, where human and poultry densities are high year-round, compared with breeding grounds, where migratory waterfowl are more isolated. Few if any studies of avian influenza have focused on the molting stage where wild waterfowl congregate in a few selected wetlands and undergo the simultaneous molt of wing and tail feathers during a vulnerable flightless period. The molting stage may be one of the most important periods for the perpetuation of the disease in waterfowl, since during this stage, immunologically naïve young birds and adults freely intermix prior to the fall migration. Our study incorporated empirical data from virological field samplings and markings of Swan Geese (Anser cygnoides) on their breeding grounds in Mongolia in an integrated agent-based model (ABM) that included susceptible-exposed-infectious-recovered (SEIR) states. Our ABM results provided unique insights and indicated that individual movements between different molting wetlands and the transmission rate were the key predictors of HPAI perpetuation. While wetland extent was not a significant predictor of HPAI perpetuation, it had a large effect on the number of infections and associated death toll. Our results indicate that conserving undisturbed habitats for wild waterfowl during the molting stage of the breeding season could reduce the risk of HPAI transmission.

The USDA-ARS collection of insect viruses at Beltsville, MD, USA, contains samples of an alphabaculovirus from larvae of the tufted apple bud moth, Platynota idaeusalis Walker, as well as a presumptive betabaculovirus from the same host species. The viruses in these samples-Platynota idaeusalis nucleopolyhedrovirus isolate 2680 (PlidNPV-2680) and Platynota idaeusalis granulovirus isolate 2683 (PlidGV-2683)-were characterized by electron microscopy of their occlusion bodies (OBs) and determination and analysis of their genome sequences. Scanning and transmission electron microscopy of the OBs revealed morphologies typical for alphabaculoviruses and betabaculoviruses. Sequencing viral DNA resulted in circular genomes of 121,881 bp and 106,633 bp for PlidNPV-2680 and PlidGV-2683, respectively. Similar numbers of ORFs (128 for PlidNPV-2680, 125 for PlidGV-2683) were annotated, along with ten homologous regions (hrs) in the PlidNPV-2680 genome and five intergenic regions of tandem direct repeats (drs) in the PlidGV genome. Phylogenetic inference from core gene alignments suggested that PlidMNPV-2680 represents a unique lineage within the genus Alphabaculovirus, while PlidGV-2683 was grouped with clade b betabaculoviruses. A comparison of the PlidNPV-2680 and PlidGV-2683 genomes revealed a 1516 bp region in PlidNPV-2680 that exhibited 97.5% sequence identity to a region of the PlidGV-2683 genome, suggesting that recombination had occurred recently between viruses from these lineages.

Members of the tripartite motif (TRIM)-containing protein family play crucial roles in regulating immune system responses. The TRIM38 protein regulates host innate immunity and directly degrades some viral proteins through its E3 ubiquitin ligase activity. This study demonstrated that Zika virus (ZIKV) infection can promote the expression of TRIM38 in human glioma cells (U251). TRIM38 overexpression restricted ZIKV replication in U251 cells, while TRIM38 knockout enhanced ZIKV replication. TRIM38 overexpression upregulated the RIG-I/MDA5 pathway and promoted the level of IFN-β early during viral infection, while TRIM38 knockout had the opposite effect. In addition, TRIM38 interacts with ZIKV non-structural protein 3 (NS3) and degrades the NS3 protein through a lysosome-dependent manner via the E3 ligase activity of TRIM38. Deletion of the RING domain of TRIM38 abrogates its interaction with NS3 and impairs the antiviral activity of TRIM38. Our results indicate that TRIM38 is a novel antiviral protein against ZIKV, and it exerts antiviral activity by upregulating the RIG-I/MDA5 pathway, increasing IFN-β levels, and degrading the viral NS3 protein.

Bacteriophages are the most numerous, ubiquitous, and diverse biological entities on the planet. Prior studies have identified bacteriophages associated with pathogenic and commensal microbiota of honeybees. In this study we expand on what is known about bacteriophages from the lineages Caudoviricetes, Inoviridae, and Microviridae, which are associated with honeybees (Apidae, Apis mellifera), solitary bees of the genus Nomia (Halictidae, Nomia), and hoverflies (Syrphidae). The complete genomes of seven caudoviruses, seven inoviruses, and 288 microviruses were assembled from honeybees (n = 286) and hoverflies in Arizona (n = 2). We used bacterial host predictive software and sequence read mapping programs to infer the commensal and transient bacterial hosts of pollinating insects. Lastly, this study explores the phylogenetic relationships of microviruses sampled from bees, opportunistically sampled pollinating insects such as hoverflies, and blackflies.

Since African swine fever virus (ASFV) genotype II reached Europe in 2007 and has widely spread, causing important economic losses to the pig production sector. To guide policy and management actions, robust quantitative evidence about possible explanatory variables associated with ASF in domestic pigs and Eurasian wild boar (Sus scrofa) is needed. To this aim, a systematic literature review of the scientific evidence available on variables analysed through quantitative methods investigating their possible association with ASF occurrence was carried out in 2021 and updated in 2024. Information on article metadata, study settings, and details of the analysed variables were extracted from the identified articles. The variables were structured in categories and subcategories, and their frequencies were evaluated, as well as the proportions of the studied variables that proved significant in each subcategory. The literature search retrieved 569 articles, resulting in 48 inclusions in the review after application of the selection criteria. The categories of variables most often significantly associated with the occurrence of ASF in domestic pigs were related to the ASF virus infection pressure in the area, socio-economic factors (mainly human population density and poverty), the pig farming system (pig or farm density and certain biosecurity practises), and wild boar habitats. For wild boars, these were also variables related to ASFV infection pressure in the area, wild boar habitats (mainly climatic conditions, vegetation, waterbodies), and socio-economic factors (especially human population and poverty-related variables). Despite the many studies of variables possibly associated with ASF occurrence, the review identified a gap in quantitative observational studies focusing on manageable variables, i.e., those related to specific biosecurity measures applied to pig farms and during hunting. To allow for a meta-analysis of the results, these studies should be performed according to standardised protocols using harmonised data collections.

The role of the chikungunya virus (CHIKV) non-structural protein 3 (nsP3) in the virus lifecycle is poorly understood. The protein comprises three domains. At the N-terminus is a macro domain, biochemically characterised to bind both RNA and ADP-ribose and to possess ADP-ribosyl hydrolase activity-an enzymatic activity that removes ADP-ribose from mono-ADP-ribosylated proteins. As ADP-ribosylation is important in the signalling pathway, leading to activation of the transcription factor NF-κB, we sought to determine whether the macro domain might perturb NF-κB signalling. We first showed that CHIKV infection did not induce NF-κB activation and could not block exogenous activation of the pathway via TNFα, although TNFα treatment did result in a modest reduction in virus titre. In contrast, ectopic expression of nsP3 was able to inhibit both basal and TNFα-mediated NF-κB activation, and this was dependent on the macro domain, as a mutation previously shown to disrupt ADP-ribose binding and hydrolase activity (D10A) eliminated the ability to inhibit NF-κB activation. The macro domain D10A mutant also resulted in a dramatic reduction in virus infectivity, consistent with the notion that the ability of the macro domain to inhibit NF-κB activation plays a role in the virus lifecycle.

Pseudomonas aeruginosa, an opportunistic pathogen, causes various biofilm-associated infections like pneumonia, infections in cystic fibrosis patients, and urinary tract and burn infections with high morbidity and mortality, as well as low treatment efficacy due to the extremely wide spread of isolates with multidrug resistance. Here, we report the new bacteriophage Pseudomonas phage Ka2 isolated from a tributary stream of Lake Baikal and belonging to the Pbunavirus genus. Transmission electron microscopy resolved that Pseudomonas phage Ka2 has a capsid of 57 ± 9 nm and a contractile and inflexible tail of 115 ± 10 nm in the non-contracted state. The genome consists of 66,310 bp with a GC content of 55% and contains 96 coding sequences. Among them, 52 encode proteins have known functions, and none of them are potentially associated with lysogeny. The bacteriophage lyses 21 of 30 P. aeruginosa clinical isolates and decreases the MIC of amikacin, gentamicin, and cefepime up to 16-fold and the MIC of colistin up to 32-fold. When treating the biofilms with Ka2, the biomass was reduced by twice, and up to a 32-fold decrease in the antibiotics MBC against biofilm-embedded cells was achieved by the combination of Ka2 with cefepime for the PAO1 strain, along with a decrease of up to 16-fold with either amikacin or colistin for clinical isolates. Taken together, these data characterize the new Pseudomonas phage Ka2 as a promising tool for the combined treatment of infections associated with P. aeruginosa biofilms.

Kaposi's Sarcoma Herpesvirus (KSHV) is the causative agent of several human diseases. There are few effective treatments available to treat infection and KSHV oncogenesis. Disrupting the KSHV infectious cycle would diminish the viral spread. The KSHV lytic phase and production of new virions require efficient copying and packaging of the KSHV genome. KSHV encodes its own lytic DNA replication machinery, including the processivity factor (PF-8), which presents itself as an attractive target for antiviral development. We characterized PF-8 at the single molecule level using transmission electron microscopy to identify key molecular interactions that mediate viral DNA replication initiation. Our results indicate that PF-8 forms oligomeric ring structures (tetramer, hexamer, and/or dodecamer) similar to the related Epstein-Barr virus processivity factor (BMRF1). Our DNA positional mapping revealed high-frequency binding locations of PF-8 within the lytic origin of replication (OriLyt). A multi-variable analysis of PF-8 DNA-binding activity with three mutant OriLyts provides new insights into the mechanisms that PF-8 associates with viral DNA and complexes to form multi-ring-like structures. Collectively, these data enhance the mechanistic understanding of the molecular interactions (protein-protein and protein-DNA) of an essential KSHV DNA replication protein.