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We used a multi-centred, prospective cohort to study 482 two-dose and three-dose BNT162b2 vaccinated healthcare workers (HCWs) for SARS-CoV-2 infection during the Omicron dominant period in Malaysia. Between January 31

Induced pluripotent stem cells (iPSCs) have been generated using different reprogramming strategies. Lentiviruses remain a strategic method for cell reprogramming as it is highly efficient in gene transfer. The latest fourth-generation lentiviral packaging systems claimed to be efficient and safe. However, modifications made to enhance safety of lentiviral vectors have been shown to affect vector performance. In this study, we established that the fourth-generation lentiviral packaging system can produce high-titre lentiviruses with high-transduction efficiencies. Subsequently, the robustness and reproducibility of generating iPSCs from adult human dermal fibroblasts were tested using these lentiviruses. The use of fourth-generation lentiviruses consistently generates iPSCs with similar efficiency and quality in different primary cell lines. This study demonstrated that the human-derived iPSCs can be maintained using mitomycin-C inactivated feeder cells. The iPSC clones highly expressed key pluripotency markers and can spontaneously differentiate into cells from the three embryonic germ layers. The iPSCs generated were able to differentiate into neural stem cell lineages, producing cells expressing Nestin and Sox2 as well as able to further differentiate into neurons with more than 70% efficiency. The data demonstrated that the use of the fourth-generation lentiviral packaging to produce lentiviruses for iPSCs generation is robust and reproducible as it can generate iPSCs from different adult dermal fibroblasts with the potential to differentiate into neural stem cells and neurons. The use of safer lentiviral packaging systems combined with established vector plasmids will help to expedite the generation of iPSCs for clinical applications.

Codon usage bias (CUB) analysis has drawn considerable attention throughout the years due to its effect on cell physiology. Meanwhile, in the immune system, any imbalance in its regulation and protein expression that can be caused by CUB may lead to immune system disorder. The objective of this study is to analyze the global CUB in protein-coding genes of human monocytes, B and T lymphocytes and identify factors that influence the codon usage pattern. The RNA-Seq datasets were used to investigate the extent of CUB in selected immune cells as well as in human protein-coding genes (HPCG) that is used as a reference. Several indices of codon usage and multivariate statistical methods were applied to analyze the differences in CUB within the datasets. Results revealed that the protein-coding genes expressed in monocytes, B and T lymphocytes showed distinctive nucleotide composition and CUB patterns based on several codon usage bias indices, namely Relative Synonymous Codon Usage (RSCU), Effective Number of Codons (ENC) and Codon Adaptation Index (CAI). Multivariate analysis of the CUB indices suggested that mutational bias may be the major factor affecting CUB in monocytes, while in B and T lymphocytes, the main influential factor may be the translational selection. Generally, this study revealed interesting differences in CUB and factors that shaped the CUB of protein-coding genes in monocytes, B and T lymphocytes. Moreover, this study also provided new insights into understanding the role of CUB in the human immune system.

SummaryHow self-peptides displayed in the thymus contribute to the development of immunocompetent and self-protective T cells is largely unknown. In contrast, the role of thymic self-peptides in eliminating self-reactive T cells and thereby preventing autoimmunity is well established. A type of proteasome, termed thymoproteasome, is specifically expressed by thymic cortical epithelial cells (cTECs) and is required for the generation of optimal cellularity of CD8+ T cells. Here, we show that cTECs displayed thymoproteasome-specific peptide-MHC class I complexes essential for the positive selection of major and diverse repertoire of MHC class I-restricted T cells. CD8+ T cells generated in the absence of thymoproteasomes displayed a markedly altered T cell receptor repertoire that was defective in both allogeneic and antiviral responses. These results demonstrate that thymoproteasome-dependent self-peptide production is required for the development of an immunocompetent repertoire of CD8+ T cells.