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1.
Front Immunol ; 12: 665133, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33936103

RESUMO

Background: Immune checkpoint inhibitors (ICIs) have become a high-profile regimen for malignancy recently. However, only a small subpopulation obtains long-term clinical benefit. How to select optimal patients by reasonable biomarkers remains a hot topic. Methods: Paired tissue samples and blood samples from 51 patients with advanced malignancies were collected for correlation analysis. Dynamic changes in blood PD-L1 (bPD-L1) expression, including PD-L1 mRNA, exosomal PD-L1 (exoPD-L1) protein and soluble PD-L1 (sPD-L1), were detected after 2 months of ICIs treatment in advanced non-small-cell lung cancer (NSCLC) patients. The best cutoff values for progression-free survival (PFS) and overall survival (OS) of all three biomarkers were calculated with R software. Results: In 51 cases of various malignancies, those with positive tissue PD-L1 (tPD-L1) had significantly higher PD-L1 mRNA than those with negative tPD-L1. In 40 advanced NSCLC patients, those with a fold change of PD-L1 mRNA ≥ 2.04 had better PFS, OS and best objective response (bOR) rate. In addition, a fold change of exoPD-L1 ≥ 1.86 was also found to be associated with better efficacy and OS in a cohort of 21 advanced NSCLC cases. The dynamic change of sPD-L1 was not associated with efficacy and OS. Furthermore, the combination of PD-L1 mRNA and exoPD-L1 could screen better patients for potential benefit from ICIs treatment. Conclusion: There was a positive correlation between bPD-L1 and tPD-L1 expression. Increased expression of PD-L1 mRNA, exoPD-L1, or both in early stage of ICIs treatment could serve as positive biomarkers of efficacy and OS in advanced NSCLC patients.

2.
Artigo em Inglês | MEDLINE | ID: mdl-33945067

RESUMO

An aerobic, Gram-stain-negative, straight or curved rods and dimorphic prosthecate bacterium designated as strain LZ-16-1T was isolated from phycosphere microbiota of routinely laboratory-cultured and highly-toxic marine dinoflagellate Alexandrium catenella LZT09. Strain LZ-16-1T produces active bioflocculanting exopolysaccharides (EPS). Cells were dimorphic with non-motile prostheca, or non-stalked and motile by a single polar flagellum. Growth occurred at 10-40 °C, pH 5-9 and 1-8% (w/v) NaCl, with optimum growth at 25 °C, pH 7-8 in the presence of 2-4% (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain LZ-16-1T was affiliated to the genus Maricaulis, and closely related to M. parjimensis MCS 25T (99.5%) and M. virginensis VC-5T (99.0%). However, based on genome sequencing and phylogenomic calculations, the average nucleotide identity (ANI) and digtal DNA-DNA genome hybridization (dDDH) values between strains LZ-16-1T and its closest relative, M. parjimensis MCS 25T were only 85.0 and 20.9%, respectively. The dominant fatty acids of strain LZ-16-1T were summed feature 8, C16:0, C17:0, C18:0, C18:1 ω9c and summed feature 9. Major polar lipids were sulfoquinovosyl diacylglycerol, six glycolipids, one unidentified phospholipid and one unidentified polar lipid. The predominant isoprenoid quinone was Q-10. The DNA G + C content calculated from the genome was 63.6 mol%. Physiological and chemotaxonomic characterizations further confirmed the distinctiveness of strain LZ-16-1T from other Maricaulis members. Thus, strain LZ-16-1T represents a novel species of the genus Maricaulis, for which the name Maricaulis alexandrii sp. nov. (type strain LZ-16-1T = KCTC 72194T = CCTCC AB 2019006T) is proposed.

3.
Virol J ; 18(1): 74, 2021 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-33849568

RESUMO

BACKGROUND: Liver cancer has become one of the most common cancers and has a high mortality rate. Hepatocellular carcinoma is one of the most common liver cancers, and its occurrence and development process are associated with chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infections. Main body The serious consequences of chronic hepatitis virus infections are related to the viral invasion strategy. Furthermore, the viral escape mechanism has evolved during long-term struggles with the host. Studies have increasingly shown that suppressor of cytokine signaling (SOCS) proteins participate in the viral escape process. SOCS proteins play an important role in regulating cytokine signaling, particularly the Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway. Cytokines stimulate the expression of SOCS proteins, in turn, SOCS proteins inhibit cytokine signaling by blocking the JAK-STAT signaling pathway, thereby achieving homeostasis. By utilizing SOCS proteins, chronic hepatitis virus infection may destroy the host's antiviral responses to achieve persistent infection. CONCLUSIONS: This review provides recent knowledge regarding the role of SOCS proteins during chronic hepatitis virus infection and provides some new ideas for the future treatment of chronic hepatitis.

4.
Vet Microbiol ; 257: 109078, 2021 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-33906107

RESUMO

Studies have shown that proteins in the tegument (located between the viral capsid and envelope layer) play critical roles in the assembly and budding of herpesviruses. The UL11 protein of herpesviruses is important in the process of virus particle cell entry, release, assembly and secondary envelopment. Herpesvirus glycoprotein E (gE) is involved in syncytia formation, transmission between cells and nerve invasion. In herpes simplex virus, UL11 has been shown to interact with gE. However, little is known about the relationship of duck plague virus (DPV) pUL11 and gE. In this study, we constructed DPV cytoplasmic domain (CT)-gE, and extracellular domain (ET)-gE deletion mutants, pCMV-gE, CT-gE, and ET-gE and UL11 recombinant plasmids. We found that pUL11 can interact and colocalize with gE, CT-gE and ET-gE. Together, these results highlight an important role for UL11 in the function of gE, and may also have important implications for the role of pUL11 and gE.

5.
J Int Med Res ; 49(4): 3000605211008073, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33900869

RESUMO

Hyperimmunoglobulin E syndrome (HIES) is a rare immunologic disorder. Typical clinical features of HIES include recurrent bacterial pneumonia, lung cysts, characteristic facial features, and newborn dermatitis. The varied clinical presentation can lead to a delayed diagnosis. We herein present a sporadic case of HIES in a man who initially presented with a longstanding history of intractable skin abscesses.

6.
Int J Nurs Stud ; 119: 103929, 2021 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-33901941

RESUMO

BACKGROUND: Individuals with type 2 diabetes have a heightened risk of developing serious complications post hospital discharge. Web-based transitional care is a promising intervention to improve the glycemic control and quality of life of this patient group; however, whether web-based transitional care can improve the glycemic control and quality of life of this group remains unknown. Further, the mechanisms underlying the relationships between the intervention and both glycemic control and quality of life have not been fully explored. OBJECTIVES: The aims of this study were to develop a web-based transitional care program and evaluate its effects on the glycemic control and quality of life of Chinese patients with type 2 diabetes and to explore the mediating roles of self-efficacy and treatment adherence. DESIGN: Randomized controlled trial. SETTINGS AND PARTICIPANTS: This study was conducted in a large regional hospital in Guangzhou City, China. Patients diagnosed with type 2 diabetes were included. METHODS: A total of 116 eligible participants were randomly assigned to receive either the 3-month web-based transitional care program or usual care. Assessments of hemoglobin A1c (HbA1c), self-efficacy, treatment adherence, and quality of life were conducted at baseline and at 3 months. Analysis followed the intention-to-treat principle. A generalized estimating equation was used to determine intervention effects on HbA1c and quality of life. Path analysis was used to assess the mediation of these effects by changes in self-efficacy and treatment adherence during the intervention. RESULTS: Participants in the intervention group had significantly greater improvements in HbA1c (ß = 2.87; p < 0.01) and quality of life (ß = 7.69; p < 0.01) compared with the control group. The relationships between the intervention and both glycemic control and quality of life were significantly mediated by improved self-efficacy (indirect effect: ß = 0.18, p < 0.05) and improved treatment adherence (indirect effect: ß = 0.17, p < 0.05); overall, the model explained 52.5% of the variance in HbA1c and 34.2% of the variance in quality of life. CONCLUSIONS: Our study identified beneficial effects of a web-based transitional care program on glycemic control and quality of life post hospital discharge in people with type 2 diabetes, and the underlying mediating mechanisms. The effectiveness and feasibility of this web-based intervention program suggests that its application should be promoted in community settings to reduce poor outcomes in people with type 2 diabetes. Tweetable abstract: The web-based transitional care program can improve patients' glycemic control and quality of life. Registration number: ChiCTR2000035603.

7.
Artigo em Inglês | MEDLINE | ID: mdl-33895907

RESUMO

Marine phycosphere harbors unique cross-kingdom associations with enormous ecological significance in aquatic ecosystems as well as relevance for algal biotechnology industry. During our investigating the microbial composition and bioactivity of marine phycosphere microbiota (PM), a novel lightly yellowish and versatile bacterium designated strain AM1-D1T was isolated from cultivable PM of marine dinoflagellate Alexandrium minutum amtk4 that produces high levels of paralytic shellfish poisoning toxins (PSTs). Strain AM1-D1T demonstrates notable bioflocculanting bioactivity with bacterial exopolysaccharides (EPS), and microalgae growth-promoting (MGP) potential toward its algal host. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain AM1-D1T was affiliated to the members of genus Sulfitobacter within the family Rhodobacteraceae, showing the highest sequence similarity of 97.9% with Sulfitobacter noctilucae NB-68T, and below 97.8% with other type strains. The complete genome of strain AM1-D1T consisted of a circular 3.84-Mb chromosome and five circular plasmids (185, 95, 15, 205 and 348 Kb, respectively) with the G+C content of 64.6%. Low values obtained by phylogenomic calculations on the average nucleotide identity (ANI, 77.2%), average amino acid identity (AAI, 74.7%) and digital DNA-DNA hybridization (dDDH, 18.6%) unequivocally separated strain AM1-D1T from its closest relative. The main polar lipids were identified as phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, diphosphatidylglycerol, one unidentified phospholipid and one unidentified lipid. The predominant fatty acids (> 10%) were C18:1 ω7c, C19:0 cyclo ω8c and C16:0. The respiratory quinone was Q-10. The genome of strain AM1-D1T was predicted to encode series of gene clusters responsible for sulfur oxidation (sox) and utilization of dissolved organic sulfur exometabolites from marine dinoflagellates, taurine (tau) and dimethylsulfoniopropionate (DMSP) (dmd), as well as supplementary vitamin B12 (cob), photosynthesis carotenoids (crt) which are pivotal components during algae-bacteria interactions. Based on the evidences by the polyphasic characterizations, strain AM1-D1T represents a novel species of the genus Sulfitobacter, for which the name Sulfitobacter alexandrii sp. nov. is proposed. The type strain is AM1-D1T (= CCTCC 2017277T = KCTC 62491T).

8.
Poult Sci ; 100(5): 101085, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33799115

RESUMO

Duck Tembusu virus (DTMUV) and duck plague virus (DPV) are typical DNA and RNA viruses of waterfowl, causing drastic economic losses to the duck farm industry in terms of high mortality and decreased egg production. These 2 viruses reappear from time to time because the available vaccines fail to provide complete immunity and no clinical antiviral drugs are available for them. In the present study, we evaluated the antiviral activity of SC75741 for DTMUV, DPV, and the model virus, vesicular stomatitis virus infection in duck cells. SC75741, a nuclear factor-kappa B (NF-κB)-specific inhibitor in mammal cells, revealed the highest antiviral activity among the inhibitors specific to c-Jun NH2-terminal kinase, extracellular signal-regulated kinase, p38 mitogen-activated protein kinase (p38), and NF-κB signaling. The antiviral activity of SC75741 was dose-dependent and showed effects in different duck cell types. Time-addition and duration assay demonstrated that SC75741 inhibited virus infection in the middle of and after virus infection at least for 72 h in duck embro fibroblast cells. The DPV viral adsorption and genomic copy number were reduced, indicating that SC75741 blocks the phase of the virus life cycle at viral entry and genomic replication. In addition, SC75741 enhanced the expression of interferon only when stimulator of interferon genes (STING) was overexpressed or pre-activated by the virus infection, suggesting that SC75741 acts as a STING agonist. In conclusion, SC75741 is a candidate antiviral agent for DTMUV and DPV.

9.
Vet Microbiol ; 255: 108979, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33721633

RESUMO

The virion host shutoff (VHS) protein, encoded by the UL41 gene of herpes simplex virus (HSV), specifically degrades mRNA and induces host shutoff. VHS and its homologs are highly conserved in the Alphaherpesvirinae subfamily. However, the role of the duck plague virus (DPV) UL41 gene is unclear. In this study, we found that the DPV UL41 gene-encoded protein (pUL41) degrades RNA polymerase (pol) II-transcribed translatable RNA and induces protein synthesis shutoff. DPV pUL41 was dispensable for viral replication, but the UL41-deleted mutant virus exhibited a significant viral growth defect and plaque size reduction in Duck embryo fibroblast (DEF) cells. Furthermore, DPV pUL41 regulated viral mRNA accumulation to affect viral DNA replication, release and cell-to-cell spread.

10.
DNA Cell Biol ; 40(4): 580-588, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33761271

RESUMO

The fall armyworm (Spodoptera frugiperda) is one of the most significant agricultural pests in the world and invaded China in early 2019. We sampled and sequenced RNA-seq data from 15 individuals across different developmental stages. Developmental stages were the larval stage (5th instar larvae and 6th instar larvae), chrysalis stage, and adult stage (female adult and male adult). Individual samples were mainly clustered by developmental stages and we then identified variation between developmental stages of differentially expressed transcripts (DETs). There were 2136 upregulated DETs and 1391 downregulated DETs in the larval stage when comparing larval and chrysalis stages. In the comparison between the chrysalis and adult stages, there were 2033 upregulated DETs and 1391 downregulated DETs in the chrysalis stage. In total, 19,195 abundantly expressed transcripts were obtained and 10% of them were DETs. We then obtained stage-specific DETs to investigate the potential function of the fall armyworm during different developmental stages. We also constructed our annotation background set for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. This indicated that the fall armyworm may undergo active metabolism during its lifespan, even in the chrysalis stage. And it also may experience detoxifying and xenobiotic metabolism throughout its life, especially in the larval stage, which partially explains the difficulty to eradicate using chemical control. Our study is the first insight into the developmental patterns of the fall armyworm and we also provide the fundamental information about enhanced drug resistance at the level of transcriptome. These results are beneficial for a future investigation related to the eradication and/or control stage.


Assuntos
Regulação da Expressão Gênica no Desenvolvimento/genética , Spodoptera/genética , Transcriptoma/genética , Animais , China , Expressão Gênica/genética , Ontologia Genética , Larva/genética , RNA-Seq/métodos , Spodoptera/embriologia
11.
Artigo em Inglês | MEDLINE | ID: mdl-33751267

RESUMO

The marine phycosphere harbors unique cross-kingdom associations with ecological relevance. During investigating the diversity of phycosphere microbiota of marine harmful algal blooms dinoflagellates, a faint yellow-pigmented bacterium, designated as strain LZ-8, was isolated from paralytic shellfish poisoning toxin-producing dinoflagellate Alexandrium catenella LZT09. The new isolate appeared to have growth-promoting potential toward its algal host. Molecular analysis using 16S rRNA gene, housekeeping rpoD gene and whole-genome sequence comparison indicated that strain LZ-8T was a novel gammaproteobacterium of the family Alteromonadaceae. The major fatty acids of strain LZ-8T were C16:0, C18:1 ω9c, C12:0 3-OH, summed feature 3, C16:1 ω9c, C12:0 and summed feature 9. The major isoprenoid quinone was Q-9. Polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, unidentified phospholipid, two unidentified aminolipids and six unidentified polar lipids. The genomic DNA G+C content was 57.36 mol%. Based on genome sequencing, several biosynthetic gene clusters responsible for bacterial biosynthesis of carotenoids and siderophores that may involve in algae-bacterial interactions were identified in the genome of strain LZ-8T. The polyphasic characterization indicated that strain LZ-8T represents a novel Marinobacter species. The name Marinobacter alexandrii sp. nov., type strain LZ-8T (= CCTCC AB 2018386T = KCTC 72198T) is proposed.

12.
Artigo em Inglês | MEDLINE | ID: mdl-33770293

RESUMO

During the study into the microbial biodiversity and bioactivity of the Microcystis phycosphere, a new yellow-pigmented, non-motile, rod-shaped bacterium containing polyhydroxybutyrate granules designated as strain Z10-6T was isolated from highly-toxic Microcystis aeruginosa Kützing M.TN-2. The new isolate produces active bioflocculating exopolysaccharides. Phylogenetic analysis based on 16S rRNA gene sequences indicated strain Z10-6T belongs to the genus Sphingopyxis with highest similarity to Sphingopyxis solisilvae R366T (98.86%), and the similarity to other Sphingopyxis members was less than 98.65%. However, both low values obtained by phylogenomic calculation of average nucleotide identity (ANI, 85.5%) and digital DNA-DNA hybridization (dDDH, 29.8%) separated the new species from its closest relative. The main polar lipids were sphingoglycolipid, phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, one unidentified glycolipid and one unidentified aminophospholipid. The predominant fatty acids were summed feature 8, C17:1ω6c, summed feature 3, C16:0, C18:1ω7c 11-methyl and C14:0 2-OH. The respiratory quinone was ubiqunone-10, with spermidine as the major polyamine. The genomic DNA G + C content was 64.8 mol%. Several biosynthesis pathways encoding for potential new bacterial bioactive metabolites were found in the genome of strain Z10-6T. The polyphasic analyses clearly distinguished strain Z10-6T from its closest phylogenetic neighbors. Thus, it represents a novel species of the genus Sphingopyxis, for which the name Sphingopyxis microcysteis sp. nov. is proposed. The type strain is Z10-6T (= CCTCC AB2017276T = KCTC 62492T).

13.
Database (Oxford) ; 20212021 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-33677507

RESUMO

To facilitate biomedical studies of disease mechanisms, a high-quality interactome that connects functionally related genes is needed to help investigators formulate pathway hypotheses and to interpret the biological logic of a phenotype at the biological process level. Interactions in the updated version of the human interactome resource (HIR V2) were inferred from 36 mathematical characterizations of six types of data that suggest functional associations between genes. This update of the HIR consists of 88 069 pairs of genes (23.2% functional interactions of HIR V2 are in common with the previous version of HIR), representing functional associations that are of strengths similar to those between well-studied protein interactions. Among these functional interactions, 57% may represent protein interactions, which are expected to cover 32% of the true human protein interactome. The gene set linkage analysis (GSLA) tool is developed based on the high-quality HIR V2 to identify the potential functional impacts of the observed transcriptomic changes, helping to elucidate their biological significance and complementing the currently widely used enrichment-based gene set interpretation tools. A case study shows that the annotations reported by the HIR V2/GSLA system are more comprehensive and concise compared to those obtained by the widely used gene set annotation tools such as PANTHER and DAVID. The HIR V2 and GSLA are available at http://human.biomedtzc.cn.

14.
Future Oncol ; 2021 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-33706557

RESUMO

Background: We aimed to investigate the epidemiology of synchronous brain metastasis (SBM) in non-small-cell lung cancer (NSCLC) patients. Methods: Logistic regression and Cox regression were used to identify the related factors of SBM incidence and cancer-specific survival (CSS). A nomogram for predicting CSS was developed and validated. Results: The incidence of SBM in NSCLC patients was 12.58%. The median CSS was 5 months. Patients with younger age, female gender, and adenocarcinoma had higher odd ratios for developing SBM. In addition, a nomogram was developed based on significant factors from Cox regression. The validation of the nomogram showed that it had good calibration and discrimination. Conclusions: SBM was highly prevalent in NSCLC patients, who also had poor survival.

15.
Biochem Biophys Res Commun ; 552: 37-43, 2021 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-33740663

RESUMO

Ghrelin is a peptide hormone with strong anti-inflammatory properties. In fact, Ghrelin was reported to improve endothelial dysfunction caused by excessive fat. However, its role in preserving the integrity of brain microvascular, under conditions of lipid dysregulation and inflammation, is not known. The objective of this study is to characterize the role of Ghrelin in the protection of cerebral microvascular integrity, during atherosclerosis, and uncover its underlying molecular mechanism. Our results demonstrated that an atherosclerotic condition, brought on by a high fat diet (HFD), can produce massive increases in serum inflammatory factors, blood lipids, cerebral microvascular leakage, and activation of the p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK) (p38 MAPK-JNK) pathway. It also produced significantly damaged pericytes morphology, resulting in pericyte decrease. Ghrelin treatment, on the other hand, protected against cerebral microvascular leakage and pericytes damage. Ghrelin effectively downregulated the expression of pro-inflammatory cytokines, and it also suppressed the p38 MAPK-JNK signaling pathway. Additionally, in isolated mouse cerebral microvascular pericytes, ox-LDL lead to increased apoptosis and secretion of inflammatory factors, along with an elevation in phosphorylated p38 MAPK-JNK proteins. Alternately, Ghrelin administration markedly lowered expression of inflammatory factors, suppressed the p38 MAPK-JNK signaling path, and halted cell apoptosis. However, pretreatment of Hesperetin, a p38 MAPK-JNK agonist, abrogated the Ghrelin-mediated suppression of inflammation and apoptosis in pericytes. Taken together, these results suggest that Ghrelin restored cerebral microvascular integrity and reduced vascular leakage in atherosclerosis mice, in part, by its regulation of inflammatory and apoptotic signaling pathways in pericytes.

16.
Curr Microbiol ; 78(4): 1648-1655, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33651189

RESUMO

Phycosphere hosts the boundary of unique holobionts harboring dynamic algae-bacteria interactions. During our investigating the microbial consortia composition of phycosphere microbiota (PM) derived from diverse harmful algal blooms (HAB) dinoflagellates, a novel rod-shaped, motile and faint yellow-pigmented bacterium, designated as strain LZ-6 T, was isolated from HAB Alexandrium catenella LZT09 which produces high levels paralytic shellfish poisoning toxins. Phylogenetic analysis based on 16S rRNA gene and two housekeeping genes, rpoA and pheS sequences showed that the novel isolate shared the highest gene similarity with Marinobacter shengliensis CGMCC 1.12758 T (99.6%) with the similarity values of 99.6%, 99.9% and 98.5%, respectively. Further phylogenomic calculations of average nucleotide identity (ANI), average amino acid identity (AAI) and digital DNA-DNA hybridization (dDDH) values between strains LZ-6 T and the type strain of M. shengliensis were 95.9%, 96.4% and 68.5%, respectively. However, combined phenotypic and chemotaxonomic characterizations revealed that the new isolate was obviously different from the type strain of M. shengliensis. The obtained taxonomic evidences supported that strain LZ-6 T represents a novel subspecies of M. shengliensis, for which the name is proposed, Marinobacter shengliensis subsp. alexandrii subsp. nov. with the type strain LZ-6 T (= CCTCC AB 2018388TT = KCTC 72197 T). This proposal automatically creates Marinobacter shengliensis subsp. shengliensis for which the type strain is SL013A34A2T (= LMG 27740 T = CGMCC 1.12758 T).

17.
Vet Res ; 52(1): 37, 2021 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-33663572

RESUMO

Fowl cholera caused by Pasteurella multocida exerts a massive economic burden on the poultry industry. Lipopolysaccharide (LPS) is essential for the growth of P. multocida genotype L1 strains in chickens and specific truncations to the full length LPS structure can attenuate bacterial virulence. Here we further dissected the roles of the outer core transferase genes pcgD and hptE in bacterial resistance to duck serum, outer membrane permeability and virulence in ducks. Two P. multocida mutants, ΔpcgD and ΔhptE, were constructed, and silver staining confirmed that they all produced truncated LPS profiles. Inactivation of pcgD or hptE did not affect bacterial susceptibility to duck serum and outer membrane permeability but resulted in attenuated virulence in ducks to some extent. After high-dose inoculation, ΔpcgD showed remarkably reduced colonization levels in the blood and spleen but not in the lung and liver and caused decreased injuries in the spleen and liver compared with the wild-type strain. In contrast, the ΔhptE loads declined only in the blood, and ΔhptE infection caused decreased splenic lesions but also induced severe hepatic lesions. Furthermore, compared with the wild-type strain, ΔpcgD was significantly attenuated upon oral or intramuscular challenge, whereas ΔhptE exhibited reduced virulence only upon oral infection. Therefore, the pcgD deletion caused greater virulence attenuation in ducks, indicating the critical role of pcgD in P. multocida infection establishment and survival.

19.
Vet Res ; 52(1): 48, 2021 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-33741064

RESUMO

Iron is essential for most bacteria to survive, but excessive iron leads to damage by the Fenton reaction. Therefore, the concentration of intracellular free iron must be strictly controlled in bacteria. Riemerella anatipestifer (R. anatipestifer), a Gram-negative bacterium, encodes the iron uptake system. However, the iron homeostasis mechanism remains largely unknown. In this study, it was shown that compared with the wild type R. anatipestifer CH-1, R. anatipestifer CH-1Δfur was more sensitive to streptonigrin, and this effect was alleviated when the bacteria were cultured in iron-depleted medium, suggesting that the fur mutant led to excess iron accumulation inside cells. Similarly, compared with R. anatipestifer CH-1∆recA, R. anatipestifer CH-1∆recAΔfur was more sensitive to H2O2-induced oxidative stress when the bacteria were grown in iron-rich medium rather than iron-depleted medium. Accordingly, it was shown that R. anatipestifer CH-1∆recAΔfur produced more intracellular ROS than R. anatipestifer CH-1∆recA in iron-rich medium. Electrophoretic mobility shift assays showed that R. anatipestifer CH-1 Fur suppressed the transcription of putative iron uptake genes through binding to their promoter regions. Finally, it was shown that compared with the wild type, R. anatipestifer CH-1Δfur was significantly attenuated in ducklings and that the colonization ability of R. anatipestifer CH-1Δfur in various tissues or organs was decreased. All these results suggested that Fur is important for iron homeostasis in R. anatipestifer and its pathogenic mechanism.

20.
Braz J Microbiol ; 2021 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-33742357

RESUMO

During our conveying the microbial structures of phycosphere microbiota (PM) derived from diverse marine harmful algal bloom (HAB) dinoflagellates, a new rod-sharped, white-colored cultivable bacterial strain, designated as LZ-15-2, was isolated from the PM of highly toxic Alexandrium catenella LZT09. Phylogenetic analysis of 16S rRNA gene sequence indicated that strain LZ-15-2 belonged to the genus Marivita within the family Rhodobacteraceae, and demonstrated the highest gene similarity of 99.2% to M. cryptomonadis CL-SK44T, and less than 98.65% with other type strains of Marivita. Phylogenomic calculations on average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between the new isolate and M. cryptomonadis CL-SK44T were 99.86% and 99.88%, respectively. Genomic comparison of strain LZ-15-2 with available genomes of Marivita species further verified its taxonomic position within the genus of Marivita. Moreover, comparative genomics analysis showed a proximal similarity of strain LZ-15-2 with M. cryptomonadis CL-SK44T, and it also revealed an open pan-genome status based on constructed gene accumulation curves among Marivita members with 9,361 and 1,712 genes for the pan- and core-genome analysis, respectively. Based on combined polyphasic taxonomic characteristics, strain LZ-15-2 represents a new member of M. cryptomonadis, and proposed as a potential candidate for further exploration of the detailed mechanisms governing the dynamic cross-kingdom algae-bacteria interactions (ABI) between PM and their algal host LZT09.

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