Biology subjects

Mahmood, S.

Publications and source records attributed to Mahmood, S..

16 recordsLinked to original sources

bioRxiv2025

Identification of Novel Fusion Genes in Pediatric B-ALL patients Using Whole Transcriptome Sequencing

BackgroundFusion genes (FGs), serving as diagnostic, prognostic, and therapeutic markers, are key molecular aberrations in acute leukemia. They are also essential for risk stratification and measurable residual disease (MRD) monitoring. This study aimed to characterize the distribution of FGs using whole transcriptome sequencing (WTS). Materials and MethodsA total of 12 newly diagnosed treatment naive pediatric B-ALL cases from a local tertiary care hospital were enrolled in this study. Following the nucleic acids isolation procedures, the RNA sequencing was done for 12 B-ALL patients to find the fusion genes. ResultsIn the present cohort of 12 pediatric B-ALL patients, 19 high-confidence in-frame gene fusion events were identified involving 29 unique partner genes. The commonly reported sub-type defining rearrangements in B-ALL, including ETV6-RUNX1, TCF3-PBX1 and BCR-ABL1, were found in 8.3 % of the patients whereas the rearrangements in commonly prevalent genes in B-ALL like PAX5, ABL1 and ATXN3 were also found in 8.3 % of the patients with different unreported partner genes but reported earlier in various studies i.e. PAX-ETV6 (8.3%), ABL1-SNX2 (8.3%) and CMC2-ATXN3. ConclusionThe present work expands the scope of fusions in pediatric B-ALL by revealing unreported and domain-retaining fusions, as well as co-occurring rearranged fusions with possible combinatorial outcomes. By introducing WTS into clinical workflows, the genetic classification can be done more accurately and new pathogenic drivers missed by traditional methods can be identified, highlighting the increased significance of transcriptomic profiling in the diagnosis, prognosis, and personalized therapy of leukemia.

genomics↗

bioRxiv2025

Infection of point-of-lay hens to assess the sequential events during H7N7 high-pathogenicity avian influenza emergence at a layer premises

H7N7 low-pathogenicity avian influenza virus (H7N7-LPAIV) incursions have preceded emergence of H7N7 high-pathogenicity (HP)AIV at several European layer hen outbreaks. Evidence from a UK layer H7N7-HPAIV (2008) outbreak informed in vivo modelling of sequential events, beginning with H7N7-LPAIV precursor incursion. Three groups of 17-week-old (point-of-lay) hens were inoculated with three precursor H7N7-LPAIV candidates which possessed: Group 1 - the classic LPAIV single-basic cleavage site (CS) (H7N7-SBCS); Group 2 - the dibasic CS (H7N7-DBCS) discovered at the outbreak (both represented direct H7N7-HPAIV (2008) precursors); Group 3 - a related European H7N7-LPAIV (2008) which possessed a DBCS within its haemagglutinin (HA) gene which was highly-conserved with the HA of the UK (2008) outbreak H7N7-HPAIV, but its other genetic segments differed. In Groups 1-3, initial H7N7-LPAIV exposure caused limited viral shedding, restricted H7-antibody responses and no deaths, by 14-days post-inoculation (dpi). H7N7-HPAIV challenge of all groups (n=8 per challenge group, including AIV-naive hens in Group 4) followed at 14 dpi. Prior H7N7-LPAIV inoculation protected against mortality due to H7N7-HPAIV challenge to varying degrees, with eight (100%), seven (87.5%), six (75%) and three (37.5%) survivors in Groups 1-4, respectively, by study-end (14-days post-challenge), when all 24 survivors had strongly seroconverted. Among challenge survivors belonging to Groups 1-3, 20/21 (95%) shed H7N7-HP, indicating that immunity acquired during initial H7N7-LPAIV exposure did not arrest H7N7-HPAIV replication. Despite prior H7N7-LPAIV incursion which elicited additional clinical protection against H7N7-HPAIV challenge, we showed how an emergent H7N7-HPAIV may represent a source for onward spread and further HPAIV outbreaks.

microbiology↗

bioRxiv2025

Dynamic but constrained: Repeated acquisitions of nutritional symbionts in bed bugs (Heteroptera: Cimicidae) from a narrow taxonomic pool.

BackgroundBed bugs (Heteroptera: Cimicidae), like other strictly blood-feeding insects, harbor obligate bacterial symbionts that supply essential nutrients (especially B vitamins) lacking in their blood diet. The primary obligate symbionts are transovarially transmitted Wolbachia, notable for having horizontally acquired biotin operon. In addition to these symbionts with the confirmed nutritional role, bacteria from the genera Symbiopectobacterium and Tisiphia have also been found to be transovarially transmitted in bed bugs. Their significance to the host fitness remains unclear; they are considered facultative, and thus likely non-essential. However, this understanding of bed bugs symbiosis is based exclusively on studies of the human-associated common bed bug (Cimex lectularius) and few related Cimicinae species. Virtually nothing is known about the diversity, origins, or metabolic roles of symbionts across the more than hundred described bed bug species. ResultsUsing amplicon and metagenomic analyzes, we identified five different bacterial genera as potential bed bug symbionts: Wolbachia, Symbiopectobacterium, Sodalis, Serratia, and Tisiphia. The distribution of these bacteria among 13 bed bug species indicated at least 16 independent origins of symbiosis (some samples harboring multiple symbiont strains). A comparison of host and symbiont phylogenies suggested that some of these origins were followed by cospeciation. Not all bed bugs, however, harbored Wolbachia. In the subfamily Cacodminae, Symbiopectobacterium (previously known as facultative symbiont) was detected as the sole symbiont, suggesting its role as an essential, obligate symbiont. Analysis of 23 obtained genome drafts revealed considerable differences in their size and gene content, indicating that these bacteria have reached different stages in the evolution towards obligate symbiosis. As is common in symbiotic bacteria, the analyzed genomes have lost many biosynthetic capacities. A comparison of B-vitamin synthesis pathways showed that only two, riboflavin and lipoic acid, were preserved across all symbionts. ConclusionsAn overview of symbiosis across a broad phylogenetic span of bed bugs reveals that this insect family has undergone remarkably dynamic evolution, characterized by multiple independent symbiont acquisitions, episodes of cospeciations, and frequent co-occurrence of multiple symbionts within individual hosts. Interestingly, although these symbionts were acquired through multiple independent events, the majority belong to just three bacterial genera (Wolbachia, Symbiopectobacterium, and Sodalis), suggesting an unknown mechanisms underlying bed bug-symbiont specificity. Two aspects of this study warrant further investigation. First, the finding of Symbiopectobacterium as the sole obligate symbiont in Cacodminae suggests that expanding the taxonomic sampling may reveal an even more complex structure of symbiosis within bed bugs. Second, the inconsistencies and uncertainties in evaluating the functionality of the biotin synthesis indicate that further research will be necessary to better understand the evolution of this B vitamin pathway in symbiotic bacteria.

evolutionary biology↗

bioRxiv2025

3D Biomimetic Liver Cancer Model: Diethylnitrosamine-Induced Proteomic Dysregulations in Stromal-Epithelial Milieu

Hydrogel-based three-dimensional (3D) co-culture systems are emerging as biomimetic platforms that more accurately recapitulate tissue architecture and microenvironmental interactions compared to conventional two-dimensional (2D) cultures. This study introduces an engineered 3D liver-like model to investigate compartment-specific responses to the potent hepatocarcinogen Diethylnitrosamine (DEN), with a focus on early events in carcinogenesis and tumor-stroma interactions. AML12 and 3T3 cell lines were treated with DEN or vehicle either in 2D culture or in 3D hydrogels in four experimental groups: (1) DEN-treated AML12 with vehicle-treated 3T3, (2) DEN-treated 3T3 with vehicle-treated AML12, (3) both cell types DEN-treated, and (4) both vehicle-treated. The cultured recombinants were subjected to proteomic profiling via mass spectrometry, followed by bioinformatics analysis and the results were validated through immunocytochemical staining (ICC). Gene ontology analysis revealed that cytoskeletal, RNA metabolism, and scaffold/adaptor proteins were among the most significantly enriched in 3D versus 2D models. Structural proteins emerged exclusively in mixed 3D co-cultures, reinforcing the organotypic nature of the system. Enriched pathways in 3D included intermediate filament organization, actin dynamics, and focal adhesion--pathways closely associated with liver carcinogenesis. Protein-protein interaction analysis demonstrated maximal network complexity in 3D cultures where both compartments were DEN-exposed. Survival analysis further identified poor-prognosis biomarkers (KRT20, KRT15, KRT14) uniquely enriched in this condition. ICC staining supported the proteomic findings. This organoid-like 3D co-culture model provides a physiologically relevant platform for investigating early-stage liver carcinogenesis and highlights the critical role of stromal-epithelial interactions. Its ability to replicate organ-level complexity and generate clinically relevant proteomic signatures supports its utility in translational cancer research and future drug discovery applications.

cancer biology↗

bioRxiv2025

Molecular mechanisms regulating PDE11A4 age-related liquid-liquid phase separation (LLPS) and its reversal by selective, potent and orally-available PDE11A4 small molecule inhibitors both in vitro and in vivo

PDE11A is a little-studied phosphodiesterase family that breaks down cAMP and cGMP, with the PDE11A4 isoform enriched in the memory-related hippocampus. Age-related increases in hippocampal PDE11A expression occur in human and rodents, causing age-related cognitive decline of social memories. Interestingly, this age-related increase triggers PDE11A4 liquid-liquid phase separation (LLPS), causing the enzyme to accumulate in the brain in filamentous structures termed "ghost axons". Here we sought to identify molecular mechanisms regulating PDE11A4 LLPS and therapeutic approaches capable of reversing it. PDE11A4 LLPS was reduced by phosphorylation of PDE11A4-S163 or-S239 and the D355A mutation that blocks the effect of cGMP binding the PDE11A4 GAF-A domain. PDE11A4 LLPS was increased by inhibiting kinases with staurosporine or stimulating packaging/repacking via the trans-Golgi network by overexpressing TGN38 or RhoB. 8 PDE11 inhibitors (MLG-122, MLG-185, MLG-199, SMQ-02-57, SMQ-03-30, SMQ-03-20, tadalafil, and BC11-38) across 3 scaffolds reverse overexpression-related PDE11A4 LLPS in HT22 mouse hippocampal neuronal cells. This effect of PDE11A4 inhibitors occurs within minutes, is reversed upon washout of lower but not higher concentrations, and occurs in part by reducing PDE11A4 homodimerization. PDE11A4 inhibitors also rescued exacerbated PDE11A4 LLPS triggered by aging-like S117D/S124D phosphomimic mutations, staurosporine, or TGN38/RhoB overexpression. In vivo, orally-administered 30mg/kg SMQ-03-20 reversed age-related increases in PDE11A4 ghost axons and neuroinflammation in old mice. Thus, PDE11A inhibitors that reverse age-related PDE11A4 LLPS in HT22 hippocampal cells also reduce PDE11A4 ghost axons and neuroinflammation in the aged mouse brain, indicating therapeutical potential.

neuroscience↗

bioRxiv2025

Differential Proteomic Analysis of DEN-Induced Hepatocellular Carcinoma in Male and Female Balb/c Mice Reveals Novel Gender Specific Markers

BackgroundHepatocellular carcinoma (HCC) is one of the leading causes of hepatic malignancy with a higher prevalence in males compared to females, however, the distinct underlying mechanisms contributing to this disparity remain poorly understood. MethodsIn this study, we aimed to investigate comparative proteome profiling of a diethylnitrosamine (DEN) induced HCC model in male and female Balb/c mice. We extracted proteins from liver tissue of DEN treated male and female mice and their corresponding controls and subjected them to mass spectrometry and subsequent bioinformatics analyses. ResultsWe identified 170 and 233 differentially expressed proteins (DEPs) in female and male mice, respectively. We identified chemical carcinogenesis and cortical cytoskeleton as the shared pathways between the two groups. In addition, we identified distinct signaling pathways in DEN-treated male and female mice. Female mice showed enrichment in oxidative phosphorylation, fatty acid biosynthesis, metabolism and degradation and cytochrome P450 clusters. In contrast, in male mice, these pathways were enriched in cholesterol metabolism, coagulation and mRNA processing. Further, we identified top ten genes ranked by highest maximal clique centrality, by protein-protein interaction analysis of differentially expressed proteins (DEPs) in both sexes. Of these hub genes, female mice showed upregulation of NDUFA8 and ATP5H and were associated with poor patient survival. On the other hand, In DEN-treated male mice upregulation of FGG, FGA, HPX and SERPINC1 were associated with poor survival. ConclusionIn conclusion, our research provides gender-specific proteomic signatures in DEN-induced HCC. The identification of proteins associated cholesterol metabolism and coagulation in males, and mitochondrial complex I proteins in females as prognostic markers suggests novel therapeutic targets that may inform gender-tailored treatment strategies for HCC. Simple SummaryHepatocellular carcinoma (HCC) is a common and deadly liver cancer that affects men more than women. To understand the biological reasons behind this difference, we developed a liver cancer model in male and female mice using a chemical called diethylnitrosamine (DEN). We then studied the proteins involved in tumor development using advanced techniques like mass spectrometry and bioinformatics. We found that different sets of proteins and biological pathways were active in males and females. In males, ribosomal and RNA-binding proteins were linked to worse survival, while in females, mitochondrial proteins were more important. These findings suggest that men and women may need different strategies for diagnosing and treating HCC, and they offer new gender-specific targets for future therapies.

cancer biology↗

bioRxiv2025

Secretory stimuli distinctly regulate insulin secretory granule maturation through structural remodeling

Insulin secretory granule (ISG) maturation is a crucial aspect of insulin secretion and glucose homeostasis. The regulation of this maturation remains poorly understood, especially how secretory stimuli affect ISG maturity and subcellular localization. In this study, we used soft X-tomography (SXT) to quantitatively map ISG morphology, density, and location in single INS-1E and mouse pancreatic {beta}-cells under the effect of various secretory stimuli. We found that the activation of glucokinase (GK), gastric inhibitory polypeptide receptor (GIPR), glucagon-like peptide-1 receptor (GLP-1R), and G-protein coupled receptor 40 (GPR40) promote ISG maturation. Each stimulus induces unique structural remodeling in ISGs, by altering size and density, depending on the specific signaling cascades activated. These distinct ISG subpopulations mobilize and redistribute in the cell altering overall cellular structural organization. Our results provide insight into how current diabetes and obesity therapies impact ISG maturation and may inform the development of future treatments that target maturation specifically.

biophysics↗

bioRxiv2024

The protamines of the noble false widow spider Steatoda nobilis provide an example of liquid-liquid phase separation chromatin transitions during spermiogenesis

While there is extensive information about sperm nuclear basic proteins (SNBP) in vertebrates, there is very little information about Arthropoda by comparison. This paper aims to contribute to filling this gap by analyzing these proteins in the sperm of the noble false widow spider Steatoda nobilis (Order Araneae, Family Theridiidae). To this end, we have developed a protein extraction method that allows the extraction of cysteine-containing protamines suitable for the preparation and analysis of SNBPs from samples where the amount of starting tissue material is limited. We carried out top-down mass spectrometry sequencing and molecular phylogenetic analyses to characterize the protamines of S. nobilis and other spiders. We also used electron microscopy to analyze the chromatin organization of the sperm, and we found it to exhibit liquid-liquid phase spinodal decomposition during the late stages of spermiogenesis. These studies further our knowledge of the distribution of SNBPs within the animal kingdom and provide additional support for a proposed evolutionary origin of many protamines from a histone H1 (H5) replication-independent precursor.

biochemistry↗

bioRxiv2024

Evaluating the epizootic and zoonotic threat of an H7N9 low pathogenicity avian influenza virus (LPAIV) variant associated with enhanced pathogenicity in turkeys

Between 2013-2017, A/Anhui/1/13-lineage (H7N9) low pathogenicity avian influenza virus (LPAIV) was epizootic in chickens in China causing mild disease, with 616 fatal human cases. Despite poultry vaccination, H7N9 has not been eradicated. Previously we demonstrated increased pathogenesis in turkeys infected with H7N9, correlating with the emergence of the L217Q (L226Q H3 numbering) polymorphism in the haemagglutinin (HA) protein. A Q217 containing virus also arose and is now dominant in China following vaccination. We compared infection and transmission of this Q217 containing turkey-adapted (ty-ad) isolate alongside the H7N9 (L217) wild-type (wt) virus in different poultry species, and investigated the zoonotic potential in the ferret model. Both wt and ty-ad viruses demonstrated similar shedding and transmission in turkeys and chickens. However, the ty-ad virus was significantly more pathogenic than the wt virus in turkeys but not in chickens, causing 100% and 33% mortality in turkeys respectively. Expanded tissue tropism was seen for the ty-ad virus in turkeys but not chickens, yet the viral cell receptor distribution was broadly similar in visceral organs of both species. The ty-ad virus required exogenous trypsin for in vitro replication yet had increased replication in primary avian cells. Replication was comparable in mammalian cells and the ty-ad virus replicated successfully in ferrets. The L217Q polymorphism also affected antigenicity. Therefore, H7N9 infection in turkeys can generate novel variants with increased risk through altered pathogenicity and potential HA antigenic escape. These findings emphasise the requirement for enhanced surveillance and understanding of A/Anhui/1/13-lineage viruses and their risk to different species.

microbiology↗

bioRxiv2024

Hydroxysteroid 17-beta dehydrogenase 13 (Hsd17b13) knockdown attenuates liver steatosis in high-fat diet obese mice

Hydroxysteroid 17-beta dehydrogenase 13 (HSD17B13) loss-of-function gene variants are associated with decreased risk of metabolic dysfunction-associated steatotic liver disease (MASLD). Our RNA-seq analysis of steatotic liver from obese mice -/+ Fenretinide treatment identified major beneficial effects of Fenretinide on hepatic gene expression including Hsd17b13. We sought to determine the relationship between Hsd17b13 expression and MASLD and to validate it as a therapeutic target by liver-specific knockdown. Hsd17b13 expression, which is unique to hepatocytes and associated with the lipid-droplet, was elevated in multiple models of MASLD and normalised with prevention of obesity and steatotic liver. Direct, liver- specific, shRNA-mediated knockdown of Hsd17b13 (shHsd17b13) in high-fat diet (HFD)-obese mice, markedly improved hepatic steatosis with no effect on body weight, adiposity or glycaemia. shHsd17b13 decreased elevated serum ALT, serum FGF21 levels and markers of liver fibrosis e.g. Timp2. shHsd17b13 knockdown in HFD-obese mice and Hsd17b13 overexpression in cells reciprocally regulated expression of lipid metabolism genes e.g. Cd36. Global lipidomic analysis of liver tissue revealed a major decrease in diacylglycerols (e.g. DAG 34:3) with shHsd17b13 and an increase in phosphatidylcholines containing polyunsaturated fatty acids (PUFA) e.g. PC 34:3 and PC 42:10. Expression of key genes involved in phospholipid and PUFA metabolism e.g. Cept1, were also reciprocally regulated suggesting a potential mechanism of Hsd17b13 biological function and role in MASLD. In conclusion, Hsd17b13 knockdown in HFD-obese adult mice was able to alleviate MASLD via regulation of fatty acid and phospholipid metabolism, thereby confirming HSD17B13 as a genuine therapeutic target for MASLD and development of liver fibrosis. KEY POINTSO_LIHSD17B13 loss-of-function gene variants are associated with decreased risk of metabolic dysfunction-associated (MA) steatotic liver disease and steatohepatitis (MASLD and MASH). C_LIO_LIRNA-seq analysis of steatotic liver identified beneficial effects of Fenretinide on hepatic gene expression including downregulation of Hsd17b13. C_LIO_LILiver-specific shRNA knockdown of Hsd17b13 in obese mice markedly improved hepatic steatosis and markers of liver health e.g. serum ALT, serum Fgf21 levels. C_LIO_LIHsd17b13 influenced expression of lipid/phospholipid metabolism genes e.g. Cd36 and Cept1 and phosphatidylcholines PC 34:3 and PC 42:10. C_LIO_LIOur study suggests a mechanism of HSD17B13s biological function and the strong rationale behind targeting HSD17B13 for MASLD/MASH. C_LI

physiology↗

bioRxiv2022

Investigating the genetic diversity of H5 avian influenza in the UK 2020-2022

Since 2020, the UK and Europe, have experienced annual epizootics of high pathogenicity avian influenza virus (HPAIV). The first during autumn/winter 2020/21 involved the detected with six H5Nx subtypes although H5N8 HPAIV dominated in the UK. Whilst genetic assessment of the H5N8 HPAIVs within the UK demonstrated relative homogeneity, there was a background of other genotypes circulating at a lower degree with different neuraminidase and internal genes. Following a small number of summer detections of H5N1 in wild birds over the summer of 2021, autumn/winter 2021/22 saw another European H5 HPAIV epizootic, that has dwarfed the prior epizootic. This second epizootic was dominated almost exclusively by H5N1 HPAIV, although six distinct genotypes were defined. We have used genetic analysis to evaluate the emergence of different genotypes and proposed reassortment events that have been observed. The existing data suggests that the H5N1 circulating in Europe during late 2020, continued to circulate in wild birds throughout 2021, with minimal adaptation, but has then gone on to reassort with AIVs in the wild bird population. We have undertaken an in-depth genetic assessment of H5 HPAIVs detected in the UK, over the last two winter seasons and demonstrate the utility of in-depth genetic analyses in defining the diversity of H5 HPAIVs circulating in avian species, the potential for zoonotic risk and whether incidents of lateral spread can be defined over independent incursion of infection from wild birds. Key supporting data for mitigation activities. ImportanceHigh pathogenicity avian influenza virus (HPAIV) outbreaks devastate avian species across all sectors having both economic and ecological impacts through mortalities in poultry and wild birds, respectively. These viruses can also represent a significant zoonotic risk. Since 2020, the UK has experienced two successive outbreaks of H5 HPAIV. Whilst H5N8 HPAIV was predominant during the 2020/21 outbreak, other H5 subtypes were also detected. The following year there was a shift in subtype dominance to H5N1 HPAIV, but multiple H5N1 genotypes were detected. Through thorough utilisation of whole-genome sequencing, it was possible to track and characterise the genetic evolution of these H5 HPAIVs in UK poultry and wild birds. This has enabled us to assess the risk posed by these viruses at the poultry:wild bird and the avian:human interface and to investigate potential lateral spread between infected premises, a key factor in understanding threat to the commercial sector.

molecular biology↗

bioRxiv2022

Lineage plasticity enables low-ER luminal tumors to evolve and gain basal-like traits

Abstract/summaryStratifying breast cancer into specific molecular or histological subtypes aids in therapeutic decision-making and predicting outcomes, however, these subtypes may not be as distinct as previously thought. Patients with luminal-like, Estrogen Receptor (ER)- expressing tumors have better prognosis than patients with more aggressive, triple- negative or basal-like tumors. There is, however, a subset of luminal-like tumors that express lower levels of ER, which exhibit more basal-like features. We have found that breast tumors expressing lower levels of ER, traditionally considered to be luminal-like, represent a distinct subset of breast cancer characterized by the emergence of basal-like features. Lineage tracing of low-ER tumors in the MMTV-PyMT mouse mammary tumor model revealed that basal marker expressing cells arose from normal luminal epithelial cells, suggesting that luminal-to-basal plasticity is responsible for the evolution and emergence of basal-like characteristics. This plasticity allows tumor cells to gain a new lumino-basal phenotype, thus leading to intratumoral lumino-basal heterogeneity. Single- cell RNA sequencing revealed SOX10 as a potential driver for this plasticity, which is known among breast tumors to be almost exclusively expressed in Triple Negative Breast Cancer (TNBC) and was also found to be highly expressed in low-ER tumors. These findings suggest that basal-like tumors may result from the evolutionary progression of luminal tumors with low ER expression.

cancer biology↗

bioRxiv2022

The origin of internal genes contributes to the replication and transmission fitness of H7N9 avian influenza virus

H9N2 avian influenza viruses (AIVs) have donated internal gene segments during the emergence of zoonotic AIVs, including H7N9. We used reverse genetics to generate three reassortant viruses (2:6 H7N9) which contained the Haemagglutinin and Neuraminidase from Anhui/13 (H7N9) and the six internal gene segments from H9N2 AIVs of G1-like or BJ94-like lineages enzootic in different geographic regions in Asia. Infection of chickens with the 2:6 H7N9 containing internal gene segments from G1-like H9N2 conferred attenuation in vivo, with lower shedding and reduced transmission to contact chickens. However, possession of BJ94-like H9N2 internal gene segments resulted in more rapid transmission and significantly elevated cloacal shedding compared to the parental Anhui/13 H7N9. In vitro analysis also showed that the 2:6 H7N9 having BJ94-like internal genes had significantly increased replication compared to the Anhui/13 H7N9 in chicken cells. In vivo co-infection experiments followed, where chickens were co-infected with pairs of Anhui/13 H7N9 and one of each of the three 2:6 H7N9 reassortants. During ensuing transmission events, the Anhui/13 H7N9 virus outcompeted 2:6 H7N9 with internal gene segments of BJ94-like or G1-like H9N2 viruses. Co-infection did lead to the emergence of novel reassortant genotypes that were transmitted to contact chickens. Some of the reassortant viruses had a greater replication in chicken and human cells compared to the progenitors. We demonstrated that the internal gene cassette determines the transmission fitness of H7N9 viruses in chickens and the reassortment events can generate novel H7N9 genotypes with increased virulence in chickens and enhanced zoonotic potential. ImportanceH9N2 avian influenza viruses (AIVs) are enzootic in poultry in different geographical regions. The internal genes of these viruses can be exchanged with other zoonotic AIVs, most notably the China-origin H7N9 that can give rise to new virus genotypes with increased veterinary, economic and public health threats to both poultry and humans. We investigated the propensity of the internal genes of H9N2 viruses (G1 or BJ94) in the generation of novel reassortant H7N9 AIVs. We observed that the internal genes of H7N9 which were derivative of BJ94-like H9N2 virus have a fitness advantage compared to those from the G1-like H9N2 viruses for efficient transmission among chickens. We also observed the generation of novel reassortant viruses during chicken transmission which infected and replicated efficiently in human cells. Therefore, such emergent reassortant genotypes may pose an elevated zoonotic threat.

microbiology↗

bioRxiv2022

Fenretinide inhibits obesity and fatty liver disease but induces Smpd3 to increase serum ceramides and worsen atherosclerosis in LDLR-/- mice.

Fenretinide is a synthetic retinoid that can prevent obesity and improve insulin sensitivity in mice by directly altering retinol/retinoic acid homeostasis and inhibiting excess ceramide biosynthesis. We determined the effects of Fenretinide on LDLR-/- mice fed high-fat/high-cholesterol diet +/- Fenretinide, a model of atherosclerosis and non-alcoholic fatty liver disease (NAFLD). Fenretinide prevented obesity, improved insulin sensitivity and completely inhibited hepatic triglyceride accumulation, ballooning and steatosis. Moreover, Fenretinide decreased the expression of hepatic genes driving NAFLD, inflammation and fibrosis e.g. Hsd17b13, Cd68 and Col1a1. The mechanisms of Fenretinides beneficial effects in association with decreased adiposity were mediated by inhibition of ceramide synthesis, via hepatic DES1 protein, leading to increased dihydroceramide precursors. However, Fenretinide treatment in LDLR-/- mice enhanced circulating triglycerides and worsened aortic plaque formation. Interestingly, Fenretinide led to a 4-fold increase in hepatic sphingomyelinase Smpd3 expression, via a retinoic acid-mediated mechanism and a further increase in circulating ceramide levels, linking induction of ceramide generation via sphingomyelin hydrolysis to a novel mechanism of increased atherosclerosis. Thus, despite beneficial metabolic effects, Fenretinide treatment may under certain circumstances enhance the development of atherosclerosis. However, targeting both DES1 and Smpd3 may be a novel, more potent therapeutic approach for the treatment of metabolic syndrome.

physiology↗

bioRxiv2021

Extremely reduced supergroup F Wolbachia: transition to obligate insect symbionts

Wolbachia are widely distributed symbionts among invertebrates that manifest by a broad spectrum of lifestyles from parasitism to mutualism. Wolbachia Supergroup F is considered a particularly interesting group which gave rise to symbionts of both arthropods and nematodes, and some of its members are obligate mutualists. Further investigations on evolutionary transitions in symbiosis have been hampered by a lack of genomic data for Supergroup F members. In this study, we present genomic data for five new supergroup F Wolbachia strains associated with four chewing lice species. These new strains in different evolutionary stages show genomic characteristics well-illustrating the evolutionary trajectory which symbiotic bacteria experience during their transition to mutualism. Three of the strains have not yet progressed with the transition, the other two show typical signs of ongoing gene deactivation and removal (genome size, coding density, low number of pseudogenes). Particularly, wMeur1, a symbiont fixed in all Menacanthus eurysternus populations across four continents, possesses a highly reduced genome of 733,850 bp with a horizontally acquired capacity for pantothenate synthesis. Comparing with other strains showed wMeur1 genome as the smallest currently known among all Wolbachia and the first example of Wolbachia which has completed genomic streamlining known from the gammaproteobacterial obligate symbionts.

evolutionary biology↗

bioRxiv2021

Co-infection of chickens with H9N2 and H7N9 avian influenza viruses leads to emergence of reassortant H9N9 virus with increased fitness for poultry and enhanced zoonotic potential

An H7N9 low pathogenicity avian influenza virus (LPAIV) emerged through genetic reassortment between H9N2 and other LPAIVs circulating in birds in China. This virus causes inapparent clinical disease in chickens, but zoonotic transmission results in severe and fatal disease in humans. We evaluated the consequences of reassortment between the H7N9 and the contemporary H9N2 viruses of G1 lineage that are enzootic in poultry across the Indian sub-continent and the Middle East. Co-infection of chickens with these viruses resulted in emergence of novel reassortant H9N9 viruses carrying genes derived from both H9N2 and H7N9 viruses. These reassortant H9N9 viruses showed significantly increased replication fitness, enhanced pathogenicity in chicken embryos and the potential to transmit via contact among ferrets. Our study highlights that the co-circulation of H7N9 and H9N2 viruses could represent a threat for the generation of novel reassortant viruses with greater virulence in poultry and an increased zoonotic potential. O_FIG O_LINKSMALLFIG WIDTH=197 HEIGHT=200 SRC="FIGDIR/small/438444v1_ufig1.gif" ALT="Figure 1"> View larger version (96K): org.highwire.dtl.DTLVardef@1f425cborg.highwire.dtl.DTLVardef@1dd3ba2org.highwire.dtl.DTLVardef@1762348org.highwire.dtl.DTLVardef@1064cb7_HPS_FORMAT_FIGEXP M_FIG Graphical Abstract C_FIG In BriefH9N2 viruses have a high propensity to reassort with other avian influenza viruses. We found that co-infection of chickens with H9N2 and H7N9 led to the emergence of reassortant viruses including the H9N9 subtype. Some reassortant H9N9 viruses exhibited increased replication fitness, increased pathogenicity in the chicken embryo, greater avidity for human and avian cell receptors, lower pH fusion and contact-transmission to ferrets. This study demonstrated the ability of viruses that already exist in nature to exchange genetic material, highlighting the potential emergence of viruses from these subtypes with increased zoonotic potential. There are nine H9 influenza A subtypes carrying different neuraminidase (NA) genes, including H9N9 viruses, while they are not common they do exist in nature as wildtypes (CDC). HighlightsO_LICo-infection of chickens with H7N9 and H9N2 led to emergence of reassortant H9N9 viruses C_LIO_LIReassortant H9N9 viruses had an increased replication rate in avian and human cells C_LIO_LIReassortant H9N9 viruses had a lower pH fusion and significantly higher receptor binding to 2,3 sialoglycans C_LIO_LIReassortant H9N9 replicated in ferrets at similar levels compared to H7N9 and transmitted via direct contact C_LIO_LIFerrets exposed to reassortant H9N9 by aerosol contact were also found to be seropositive C_LIO_LIExperimental simulation of events that may occur naturally with circulating viruses has demonstrated the risk of emergence of viruses with increased zoonotic potential. C_LI

microbiology↗