Role of type VI secretion system protein TssJ-3 in virulence and intracellular survival of Burkholderia pseudomallei.

TssJ-3 is an outer-membrane lipoprotein and is one of the key components of the type VI secretion system in Burkholderia pseudomallei. TssJ translocates effector proteins to target cells to induce innate immune response in the host. However, the tssJ gene has not been identified in B. pseudomallei and its function in this bacterium has not yet been characterized. tssJ-3 knockout and tssJ-3-complemented B. pseudomallei strains were constructed to determine the effects of tssJ-3 on bacterial growth, biofilm formation, flagellum synthesis, motility, host cell infection, and gene expression in B. pseudomallei. We found that the ΔtssJ-3 mutant strain of B. pseudomallei showed significantly suppressed biofilm formation, flagellum synthesis, bacterial growth, motility, and bacterial invasion into host cells (A549 cells). Furthermore, the ΔtssJ-3 mutation downregulated multiple key genes, including biofilm and flagellum-related genes in B. pseudomallei and induced interleukin-8 gene expression in host cells. These results suggest that tssJ-3, an important gene controlling TssJ-3 protein expression, has regulatory effects on biofilm formation and flagellum synthesis in B. pseudomallei. In addition, B. pseudomallei-derived tssJ-3 contributes to cell infiltration and intracellular replication. This study provides a molecular basis of tssJ-3 for developing therapeutic strategies against B. pseudomallei infections.

The efficacy and safety of remdesivir alone and in combination with other drugs for the treatment of COVID-19: a systematic review and meta-analysis.

BACKGROUND: Remdesivir is considered to be a specific drug for treating coronavirus disease 2019. This systematic review aims to evaluate the clinical efficacy and risk of remdesivir alone and in combination with other drugs. RESEARCH DESIGN AND METHODS: The PubMed, Embase, SCIE, Cochrane Library, and American Clinical trial Center databases were searched up to 1 April 2022 to identify. Randomized controlled trials (RCTs) and observational studies comparing the efficacy of remdesivir monotherapy and combination therapy with that of control drugs. RESULTS: Ten RCTs and 32 observational studies were included in the analysis. Regarding the primary outcome, remdesivir use reduced mortality in patients with severe COVID-19 (RR = 0.57, 95% CI (0.48,0.68)) and shortened the time to clinical improvement (MD = -2.51, 95% CI (-2.75, -2.28)). Regarding other clinical outcomes, remdesivir use was associated with improved clinical status (RR = 1.08, 95%CI (1.01, 1.17)). Regarding safety outcomes, remdesivir use did not cause liver or kidney damage (RR = 0.87, 95%CI (0.68, 1.11)) (RR = 0.88, 95%CI (0.70,1.10)). Compared with remdesivir alone, remdesivir combined with other drugs (e.g., steroids, favipiravir, and convalescent plasma) had no effect on mortality. CONCLUSION: The use of remdesivir can help to reduce the mortality of patients with severe COVID-19 and shorten the time to clinical improvement. There was no benefit of remdesivir combination therapy for other clinical outcomes. TRIAL REGISTRATION: PROSPERO registration number: CRD42022322859.

Prevalence and molecular characteristics of drug-resistant Mycobacterium tuberculosis in Hainan, China: from 2014 to 2019.

BACKGROUND: The emergence of antimicrobial resistance against Mycobacterium tuberculosis (M. tuberculosis) has become the major concern in global tuberculosis control due to its limited therapy options and high mortality. However, the clinical and molecular characteristics of drug-resistant strains vary in different geographical areas. Hainan Island located in southern China, is a high drug-resistant tuberculosis burden area. This study aimed to determine the dynamic changes of drug-resistance patterns and drug-related gene mutation types of M. tuberculosis in Hainan from 2014 to 2019. RESULTS: A total of 1484 culture-confirmed M. tuberculosis were included in this study. It was found that the proportions of drug resistance to isoniazid and rifampin were 31.3 and 31.1% respectively. Overall the proportion of multidrug resistant M. tuberculosis was 24.9%. Multivariate logistic regression analysis showed that age and the treatment history were independent influencing factors of drug resistant tuberculosis. The proportions of drug-resistant tuberculosis in retreatment patients were considerably higher than those in new patients. The most common mutation types of isoniazid were Ser315 → Thr (66.3%), and the most common mutation types of rifampin were Ser531 → Leu (41.5%). CONCLUSIONS: Our data suggests that the prevalence of drug resistant TB remains high in Hainan, and the risks for developing drug resistance with diversified mutation types increased significantly in retreatment patients. These results contribute to the knowledge of the prevalence of drug resistance in Hainan Province and expand the molecular characteristics of drug resistance in China simultaneously.

WY7 is a newly identified promoter from the rubber powdery mildew pathogen that regulates exogenous gene expression in both monocots and dicots.

Promoters are very important for transcriptional regulation and gene expression, and have become invaluable tools for genetic engineering. Owing to the characteristics of obligate biotrophs, molecular research into obligate biotrophic fungi is seriously lagging behind, and very few of their endogenous promoters have been developed. In this study, a WY7 fragment was predicted in the genome of Oidium heveae Steinmann using PromoterScan. Its promoter function was verified with transient transformations (Agrobacterium tumefaciens-mediated transformation, ATMT) in Nicotiana tabacum cv. Xanthi nc. The analysis of the transcription range showed that WY7 could regulate GUS expression in both monocots (Zea mays Linn and Oryza sativa L. spp. Japonica cv. Nipponbare) and dicots (N. tabacum and Hylocereus undulates Britt). The results of the quantitative detection showed that the GUS transient expression levels when regulated by WY7 was more than 11.7 times that of the CaMV 35S promoter in dicots (N. tabacum) and 5.13 times that of the ACT1 promoter in monocots (O. sativa). GUS staining was not detected in the T1 generation of the WY7-GUS transgenic N. tabacum. This showed that WY7 is an inducible promoter. The cis elements of WY7 were predicted using PlantCARE, and further experiments indicated that WY7 was a low temperature- and salt-inducible promoter. Soluble proteins produced by WY7-hpa1Xoo transgenic tobacco elicited hypersensitive responses (HR) in N. tabacum leaves. N. tabacum transformed with pBI121-WY7-hpa1Xoo exhibited enhanced resistance to the tobacco mosaic virus (TMV). The WY7 promoter has a lot of potential as a tool for plant genetic engineering. Further in-depth studies will help to better understand the transcriptional regulation mechanisms of O. heveae.

Comparative Analysis of the Gut Microbiota of Adult Mosquitoes From Eight Locations in Hainan, China.

The midgut microbial community composition, structure, and function of field-collected mosquitoes may provide a way to exploit microbial function for mosquito-borne disease control. However, it is unclear how adult mosquitoes acquire their microbiome, how the microbiome affects life history traits and how the microbiome influences community structure. We analyzed the composition of 501 midgut bacterial communities from field-collected adult female mosquitoes, including Aedes albopictus, Aedes galloisi, Culex pallidothorax, Culex pipiens, Culex gelidus, and Armigeres subalbatus, across eight habitats using the HiSeq 4000 system and the V3-V4 hyper-variable region of 16S rRNA gene. After quality filtering and rarefaction, a total of 1421 operational taxonomic units, belonging to 29 phyla, 44 families, and 43 genera were identified. Proteobacteria (75.67%) were the most common phylum, followed by Firmicutes (10.38%), Bacteroidetes (6.87%), Thermi (4.60%), and Actinobacteria (1.58%). The genera Rickettsiaceae (33.00%), Enterobacteriaceae (20.27%), Enterococcaceae (7.49%), Aeromonadaceae (7.00%), Thermaceae (4.52%), and Moraxellaceae (4.31%) were dominant in the samples analyzed and accounted for 76.59% of the total genera. We characterized the midgut bacterial communities of six mosquito species in Hainan province, China. The gut bacterial communities were different in composition and abundance, among locations, for all mosquito species. There were significant differences in the gut microbial composition between some species and substantial variation in the gut microbiota between individuals of the same mosquito species. There was a marked variation in different mosquito gut microbiota within the same location. These results might be useful in the identification of microbial communities that could be exploited for disease control.

WY195, a New Inducible Promoter From the Rubber Powdery Mildew Pathogen, Can Be Used as an Excellent Tool for Genetic Engineering.

Until now, there are few studies and reports on the use of endogenous promoters of obligate biotrophic fungi. The WY195 promoter in the genome of Oidium heveae, the rubber powdery mildew pathogen, was predicted using PromoterScan and its promoter function was verified by the transient expression of the ß-glucuronidase (GUS) gene. WY195 drove high levels of GUS expression in dicotyledons and monocotyledons. qRT-PCR indicated that GUS expression regulated by the WY195 promoter was 17.54-fold greater than that obtained using the CaMV 35S promoter in dicotyledons (Nicotiana tabacum), and 5.09-fold greater than that obtained using the ACT1 promoter in monocotyledons (Oryza sativa). Furthermore, WY195-regulated GUS gene expression was induced under high-temperature and drought conditions. Soluble proteins extracted from WY195-hpaXm transgenic tobacco was bioactive. Defensive micro-HR induced by the transgene expression of hpaXm was observed on transgenic tobacco leaves. Disease resistance bioassays showed that WY195-hpaXm transgenic tobacco enhanced the resistance to tobacco mosaic virus (TMV). WY195 has great potential for development as a new tool for genetic engineering. Further in-depth studies will help to better understand the transcriptional regulation mechanisms and the pathogenic mechanisms of O. heveae.

Whole-Genome Sequence of Burkholderia pseudomallei Strain HNBP001, Isolated from a Melioidosis Patient in Hainan, China.

Here, we report the complete genome sequence of Burkholderia pseudomallei HNBP001, an epidemic strain isolated from a melioidosis patient with pneumonia in Hainan, China.

Volatile organic compounds of Bacillus atrophaeus HAB-5 inhibit the growth of Colletotrichum gloeosporioides.

The use of fungicides to control plant diseases creates a potential health risk. One alternative to this problem is the biological control, which has been succesfully applied to control plant diseases. Bacillus atrophaeus HAB-5 exhibits a high inhibitory acitivities against different fungal pathogens and suppresses them. The aim of current studies is to produce and identify the antifungal compounds produced by the strain HAB-5. We found that the submerge fermentation harvested from Luria-Bertani (LB) medium had the highest activity against Colletotrichum gloeosporioides. The petroleum ether crude extract was strongly bioactive and its activity was stable after heat treatment, pH treatment, illuminated light as well as ultra violet exposition. The antifungal compounds were purified using gel chromatography column. Based on Gas Chromatography-Mass Spectrometry (GC-MS) analysis, nineteen different volatile organic compounds (VOCs) were identified included the range of alkanes, alkenes, alcohols, and organics acid. Among these identified compounds, Chloroacetic acid, tetradecyl esters followed by Octadecane and Hexadecanoic acid, methyl ester showed antifungal activity against C. gloeosporioides. Our results clearly showed Chloroacetic acid, tetradecyl esters; Octadecane and Hexadecanoic acid, methyl ester are key inhibitory compounds produced by Bacillus atrophaeus HAB-5 against C. gloeosporioides.