A genome-wide cytotoxicity screen of cluster F1 mycobacteriophage Girr reveals novel inhibitors of Mycobacterium smegmatis growth.

Over the past decade, thousands of bacteriophage genomes have been sequenced and annotated. A striking observation from this work is that known structural features and functions cannot be assigned for >65% of the encoded proteins. One approach to begin experimentally elucidating the function of these uncharacterized gene products is genome-wide screening to identify phage genes that confer phenotypes of interest like inhibition of host growth. This study describes the results of a screen evaluating the effects of overexpressing each gene encoded by the temperate Cluster F1 mycobacteriophage Girr on the growth of the host bacterium Mycobacterium smegmatis. Overexpression of 29 of the 102 Girr genes (~28% of the genome) resulted in mild to severe cytotoxicity. Of the 29 toxic genes described, 12 have no known function and are predominately small proteins of <125 amino acids. Overexpression of the majority of these 12 cytotoxic no known functions proteins resulted in moderate to severe growth reduction and represent novel antimicrobial products. The remaining 17 toxic genes have predicted functions, encoding products involved in phage structure, DNA replication/modification, DNA binding/gene regulation, or other enzymatic activity. Comparison of this dataset with prior genome-wide cytotoxicity screens of mycobacteriophages Waterfoul and Hammy reveals some common functional themes, though several of the predicted Girr functions associated with cytotoxicity in our report, including genes involved in lysogeny, have not been described previously. This study, completed as part of the HHMI-supported SEA-GENES project, highlights the power of parallel, genome-wide overexpression screens to identify novel interactions between phages and their hosts.

Genome Sequences of Akoni, Ashton, and Truong, Podoviridae Bacteriophages Isolated from Microbacterium foliorum.

Cluster EK2 Akoni, Ashton, and Truong are lytic Podoviridae actinobacteriophages that were isolated from soil in Florida using Microbacterium foliorum NRRL B-24224 as the host. The genomes are 54,307 bp, 54,560 bp, and 54,309 bp, respectively, and are 60% GC rich. Each genome contains a novel 13,464-bp gene that encompasses 25% of the genome.

HCC Liver Transplantation Wait List Dropout Rates Before and After the Mandated 6-Month Wait Time.

BACKGROUND: Studies have shown significant improvement in hepatocellular carcinoma (HCC) recurrence rates after liver transplantation since the united network of organ sharing (UNOS) implementation of a 6-month wait period prior to accrued exception model for end-stage liver disease (MELD) points enacted on October 8, 2015. However, few have examined the impact on HCC dropout rates for patients awaiting liver transplant. Our objective is to evaluate the outcomes of HCC dropout rates before and after the mandatory 6-month wait policy enacted. METHODS: We conducted a retrospective cohort study on adult patients added to the liver transplant wait list between January 1, 2012, and March 8, 2019 (n = 767). Information was obtained through electronic medical records and organ procurement and transplant network (OPTN) publicly available national data reports. RESULTS: In response to the 2015 UNOS-mandated 6-month wait time, dropout rates in the HCC patient population at our center increased from 12% pre-mandate to 20.8% post-mandate This increase was similarly reflected in the national dropout rate, which also increased from 26.3% pre-mandate to 29.0% post-mandate. DISCUSSION: From these changes, it is evident that the UNOS mandate achieved its goal of increasing equity of liver organ allocation, but HCC patients are nonetheless dropping off of the wait list at an increased rate and are therefore disadvantaged.