The coronavirus disease 2019 (COVID-19) pandemic poses a disruptive impact on public health and the global economy. Fortunately, the development of COVID-19 vaccines based on in vitro-transcribed messenger RNA (IVT mRNA) has been a breakthrough in medical history, benefiting billions of people with its high effectiveness, safety profile, and ease of large-scale production. This success is the result of decades of continuous RNA research, which has led to significant improvements in the stability and expression level of IVT mRNA through various approaches such as sequence optimization and improved preparation processes. IVT mRNA sequence optimization has been shown to have a positive effect on enhancing the mRNA expression level. The innovation of IVT mRNA purification technology is also indispensable, as the purity of IVT mRNA directly affects the success of downstream vaccine preparation processes and the potential for inducing unwanted side effects in therapeutic applications. Despite the progress made, challenges related to IVT mRNA sequence design and purification still require further attention to enhance the quality of IVT mRNA in the future. In this review, we discuss the latest innovative progress in IVT mRNA design and purification to further improve its clinical efficacy.

In the present study, we reported the complete mitogenome sequence of Caenorhabditis tribulationis Stevens & Félix 2019. The whole mitogenome of C. tribulationis is 14006 bp in length with an extreme bias of high AT content (75.26%) (GenBank accession no. OL362111). The mitochondrial genome contains 12 protein-coding genes (PCGs), 22 transfer RNA (tRNAs) genes, 2 ribosomal RNA (12S rRNA and 16S rRNA) genes, and a control region. All genes were unidirectionally transcribed on the same strand, typical for other nematode mitogenomes. 9 PCGs were initiated by typical ATN codons, except for NAD2, CYTB and NAD4, which were start with TTG codons. All the PCGs were predicted to use the typical TAN as the stop codons. The phylogenetic analysis showed that the relationship of C. tribulationis is very close to other species in the family Rhabditidae and separated form species of the families Ascarididae, Toxocaridae, Anisakidae and Ascaridiidae with high bootstrap value support.