The effects of synonymous codon usages on genotypic formation of open reading frames in hepatitis E virus.

Hepatitis E virus (HEV) infection has emerged as an important public health issue. As a zoonotic RNA virus, new strains are continuously discovered from human or various animal species. However, the capability of cross-species infection varies largely among different strains. Because the classical nucleotide-based genotyping system provides little functional insight, this study aimed to comprehensively investigate codon usage of the HEV coding regions for better understanding the evolutional orientation, virus-host interaction and cross-species transmission. We observed significant differences of the four nucleotide usages in the three open reading frames, indicating that the evolutional tendency of HEV caused by mutation pressure is modified by the evolutional dynamic related to positive selection. Furthermore, significant differences of nucleotide usages were found among HEV isolated from different host species, suggesting an important role of natural selection related to the host. Analysis of effective number of codons revealed distinct degrees of biased codon usage caused by mutation pressure or the host. Finally, we have mapped the similarity levels of the overall codon usage between the virus and the host to assess the potential of cross-species infection. Thus, this study has provided a novel aspect for better understanding the HEV genetic orientation and the zoonotic nature.

Progress in surgical selection of aortic root diseases / 中国胸心血管外科临床杂志

@#Total root replacement (TRR) with a valved conduit has long been the treatment standard for most aortic root diseases. However, with advances in technology and a deeper understanding of aortic root anatomy and hemodynamics, valve-sparing aortic root replacement (VSRR) and personalised external aortic root support (PEARS) have emerged. It is especially important to choose the appropriate procedure for different aortic root diseases. When evaluating these three surgical procedures, it is necessary to focus on the treatment and prevention of the dissection and balance the short-term and long-term risks of the patients. This article outlines aortic-related diseases and the selection of surgery.