Insertion site of FLAG on foot-and-mouth disease virus VP1 G-H loop affects immunogenicity of FLAG

The G-H loop of the foot-and-mouth disease virus（FMDV） virion contains certain dominant immunogenic epitopes, as well as an arginine-glycine-aspartic acid（RGD） motif that is recognized by cell surface integrin receptors. Previous experiments indicate that it is critical to maintain virus structural integrity when inserting an exogenous epitope into the surface of an FMDV structural protein. However, it remains to be determined how factors such as different insertion positions affect interactions among the virus, cells and host immune system. In this study, one infectious c DNA clone of the swine FMDV Cathay topotype strain O/CHA/90 was constructed. Then, a FLAG marker（DYKDDDDK） was inserted upstream（–4） or downstream（＋10） of the RGD motif to generate tagged viruses vFLAG-O/CHA/90 or vO/CHA/90-FLAG, investigating the possibility of expressing foreign antigen and effect on its immunogenicity. Compared to the parental virus, both tagged viruses exhibited similar plaque phenotypes, suckling mouse pathogenicity and antigenicity. Additionally, the FLAGtag insertion position did not change the use of integrin-mediated cell entry by the tagged viruses. Interestingly, both tagged vaccines protected pigs against challenge with the parental virus O/CHA/90 and induced immune responses against FMDV in BALB/c mice and pigs, but only vaccination with vFLAG-O/CHA/90 generated anti-FLAG antibodies. Our findings demonstrated that two sites（RGD–4 and RGD＋10） tolerated the insertion of an exogenous gene in the swine FMDV O/CHA/90 strain. However, only RGD–4 was a novel and appropriate inserting site which could tolerate exogenous FLAG. The resultant tagged virus is a promising candidate for FMD vaccine which can be differentiating infected from vaccinated animals（DIVA）.

Five-Year Surveillance of Central Line Associated Bloodstream Infection in an Intensive Care Unit Population—A Retrospective Analysis

Background: Central venous catheters (CVCs) are essential to current intensive care unit (ICU) practices as a tool for treating critically ill patients. However, the use of CVCs is associated with substantial risk of infection. Central line associated bloodstream infection (CLABSI) is increasing in prevalence each year and is among the major causes of bloodstream infection in ICU patients. Therefore, investigating the epidemiology and risk factors of CLABSI in ICU patients is important. Objective: This study aimed to investigate the incidence rates, causative pathogens and risk factors of CLABSI in an ICU population. Methods: A retrospective observational study was performed in an ICU at Qilu Hospital of Shandong University in China from January 2016 to December 2020. Patients with at least one CVC were enrolled, and information relevant to CVC use was recorded. The prevalence was calculated, and related risk factors were analyzed. Results: A total of 1920 catheters were identified, 507 of which were eligible for analysis. For each of the years 2016-2020, the incidence rates of CLABSI were 1.91, 3.18, 1.69, 2.97 and 1.27 per 1000 catheter days, respectively. The yeast Candida albicans was the most prevalent pathogen (16 [(3.2%]), followed by Gram-positive methicillin-resistant Staphylococcus aureus (11 [2.2%]) and the Gram-negative multidrug-resistant pathogen Acinetobacter baumanii. Risk factors associated with CLABSI development were age, (p = 0.05), Charlson comorbidity index > 5 (p Conclusion: Candida albicans was the most common causative microorganism, which was followed by Gram positive methicillin resistant Staphylococcus, MDR K. pneumoniae and Acinetobacter baumanii.

Effort and Contribution of T-DNA Insertion Mutant Library for Rice Functional Genomics Research in China:Review and Perspective

With the completion of the rice （Oryza sativa L.） genome-sequencing project, the rice research community proposed to characterize the func- tion of every predicted gene in rice by 2020. One of the most effective and high-throughput strategies for studying gene function is to employ genetic mutations induced by insertion elements such as T-DNA or transposons. Since 1999, with support from the Ministry of Science and Technology of China for Rice Functional Genomics Programs, large-scale T-DNA insertion mutant populations have been generated in Huazhong Agricultural University, the Chinese Academy of Sciences and the Chinese Academy of Agricultural Sciences. Currently, a total of 372,346 mutant lines have been generated, and 58,226 T-DNA or Tos17 flanking sequence tags have been isolated. Using these mutant resources, more than 40 genes with potential applications in rice breeding have already been identified. These include genes involved in biotic or abiotic stress responses, nutrient metabolism, pollen development, and plant architecture. The functional analysis of these genes will not only deepen our understanding of the fundamental biological questions in rice, but will also offer valuable gene resources for developing Green Super Rice that is high-yielding with few inputs even under the poor growth conditions of many regions of Africa and Asia.

Cell division factor ZapE regulates Pseudomonas aeruginosa biofilm formation by impacting the pqs quorum sensing system

Pseudomonas aeruginosa is one of the leading nosocomial pathogens that causes both severe acute and chronic infections.The strong capacity of P.aeruginosa to form biofilms can dramatically increase its antibiotic resistance and lead to treatment failure.The biofilm resident bacterial cells display distinct gene expression profiles and phenotypes compared to their free-living counterparts.Elucidating the genetic determinants of biofilm formation is crucial for the development of antibiofilm drugs.In this study,a highthroughput transposon-insertion site sequencing(Tn-seq)approach was employed to identify novel P.aeruginosa biofilm genetic determinants.When analyzing the novel biofilm regulatory genes,we found that the cell division factor ZapE(PA4438)controls the P.aeruginosa pqs quorum sensing system.The ΔzapE mutant lost fitness against the wild-type PAO1 strain in biofilms and its production of 2-heptyl-3-hydroxy-4(1H)-quinolone(PQS)had been reduced.Further biochemical analysis showed that ZapE interacts with PqsH,which encodes the synthase that converts 2-heptyl-4-quinolone(HHQ)to PQS.In addition,site-directed mutagenesis of the ATPase active site of ZapE(K72A)abolished the positive regulation of ZapE on PQS signaling.As ZapE is highly conserved among the Pseudomonas group,our study suggests that it is a potential drug target for the control of Pseudomonas infections.

Five-year changes in epidemiology of central line associated bloodstream infection in an intensive care unit-a retrospective observational study

This study aimed to explore epidemiological information on central line-associated bloodstream infection(CLABSI).A retrospective observational study was performed in an ICU at Qilu Hospital of Shandong University in China from January 2015 to December 2020.Patients with at least one central venous catheters(CVCs)were enrolled,and recorded relative information relevant to the CVC use.The prevalence was calculated,and related factors were analyzed.A total of 507 catheters were eligible for analysis.For the years 2016~2020,the incidence rates of CLABSI were as follows,1.91,3.18,1.69,2.97 and 1.27 per 1000 catheter days,respectively.Regarding the pathogen,yeast infections with Candida albicaans were the most prevalent[16(3.2%)],followed by gram-positive methicillin-resistant Staphylococcus aureus[11(2.2%)],and the gram-negative multidrug-resistant pathogens Acinetobacter baumanii.Risk factors associated with the development of CLABSI were age,(P=0.05),Charlson comorbidity index>5(P=0.00),and duration of the central venous CVC placement(P=0.01).Our study showed that there has been a slight decrease of CLABSI rates over the period of five years.This study identifies some risk factors in our ICU that may be important in the prevention of CLABSI in ICU populations.