Yields and Immunomodulatory Effects of Pneumococcal Membrane Vesicles Differ with the Bacterial Growth Phase

Abstract

Streptococcus pneumoniae infections are a leading cause of death worldwide. Bacterial membrane vesicles (MVs) are promising vaccine candidates because of the antigenic components of their parent microorganisms. Pneumococcal MVs exhibit low toxicity towards several cell lines, but their clinical translation requires a high yield and strong immunogenic effects without compromising immune cell viability. MVs are isolated during either the stationary phase (24 h) or death phase (48 h), and their yields, immunogenicity and cytotoxicity in human primary macrophages and dendritic cells have been investigated. Death-phase vesicles showed higher yields than stationary-phase vesicles. Both vesicle types displayed acceptable compatibility with primary immune cells and several cell lines. Both vesicle types showed comparable uptake and enhanced release of the inflammatory cytokines, tumor necrosis factor and interleukin-6, from human primary immune cells. Proteomic analysis revealed similarities in vesicular immunogenic proteins such as pneumolysin, pneumococcal surface protein A, and IgA1 protease in both vesicle types, but stationary-phase MVs showed significantly lower autolysin levels than death-phase MVs. Although death-phase vesicles produced higher yields, they lacked superiority to stationary-phase vesicles as vaccine candidates owing to their similar antigenic protein cargo and comparable uptake into primary human immune cells.

Proteome analysis of the Gram-positive fish pathogen Renibacterium salmoninarum reveals putative role of membrane vesicles in virulence

“…Until now, some attempts have been made to use MV vaccines in fish with varying results depending on the fish species 47 – 51 . One reason for the inconclusive data could be the variability of MV proteomes, as the protein composition has been reported to differ with growth phase 52 , 53 , cultivation media 54 , bacterial strain 55 , the MV extraction protocol 54 , 56 or even the size of the vesicles 52 . Defined production conditions and detailed characterization of the MVs are therefore crucial for the successful application of MV vaccines.…”

Rhodococcus equi-Derived Extracellular Vesicles Promoting Inflammatory Response in Macrophage through TLR2-NF-κB/MAPK Pathways

“…Interestingly, we found that the averaged diameter of 103 + -EVs (130 nm) is slightly bigger than 103 − -EVs (105 nm) ( Figure 1 ). The size of EVs in Gram-positive bacterial varies between different bacterial strains [ 34 , 35 , 36 , 37 ], throughout various stages of bacterial growth [ 38 ], and environmental conditions [ 27 , 39 , 40 ]. As the reports that the size distribution of EVs of the invasive Streptococcus pyogenes strains SSI-1 were 1.31 times bigger than the non-invasive Streptococcus pyogenes strains JRS4 [ 37 ].…”

Computational analysis and expression profiling of potassium transport-related gene families in mango (Mangifera indica) indicate their role in stress response and fruit development

“…Gene ID, chromosomal locations, number of nucleotides in genomic DNA and mRNA, and number of exons were identified by using the NCBI gene database ( ). The subcellular localization of K + transporting proteins was predicted by using a web-based tool ProtCamp 9.0 (ProtComp—Predict the sub-cellular localization for Plant proteins (softberry.com), and then, these locations were also verified by another online tool, CELLO v.2.5 ( ), by using protein sequences of K + transporting gene family ( Garg et al., 2016 ; Mehanny et al., 2022 ).…”

“…The subcellular localization of K + transporting proteins was predicted by using a web-based tool ProtCamp 9.0 (ProtComp-Predict the sub-cellular localization for Plant proteins (softberry.com), and then, these locations were also verified by another online tool, CELLO v.2.5 (http://cello.life. nctu.edu.tw/), by using protein sequences of K + transporting gene family (Garg et al, 2016;Mehanny et al, 2022).…”