Expression, purification and evaluation of recombinant lipoprotein of Salmonella typhi as a vaccine candidate

Production and characterization of homologous protoporphyrinogen IX oxidase (PPO) proteins: Evidence that small N-terminal amino acid changes do not impact protein function

Transgenic soybean, cotton, and maize tolerant to protoporphyrinogen IX oxidase (PPO)-inhibiting herbicides have been developed by introduction of a bacterial-derived PPO targeted into the chloroplast. PPO is a membrane-associated protein with an intrinsic tendency for aggregation, making expression, purification, and formulation at high concentrations difficult. In this study, transgenic PPO expressed in three crops was demonstrated to exhibit up to a 13 amino acid sequence difference in the N-terminus due to differential processing of the chloroplast transit peptide (CTP). Five PPO protein variants were produced in and purified from E. coli, each displaying equivalent immunoreactivity and functional activity, with values ranging from 193 to 266 nmol min-1 mg-1. Inclusion of an N-terminal 6xHis-tag or differential processing of the CTP peptide does not impact PPO functional activity. Additionally, structural modeling by Alphafold, ESMfold, and Openfold indicates that these short N-terminal extensions are disordered and predicted to not interfere with the mature PPO structure. These results support the view that safety studies on PPO from various crops can be performed from a single representative variant. Herein, we report a novel and robust method for large-scale production of PPO, enabling rapid production of more than 200 g of highly active PPO protein at 99% purity and low endotoxin contamination. We also present a formulation that allows for concentration of active PPO to > 75 mg/mL in a buffer suitable for mammalian toxicity studies.

Safety assessment of Mpp75Aa1.1, a new ETX_MTX2 protein from Brevibacillus laterosporus that controls western corn rootworm

The recently discovered insecticidal protein Mpp75Aa1.1 from Brevibacillus laterosporus is a member of the ETX_MTX family of beta-pore forming proteins (β-PFPs) expressed in genetically modified (GM) maize to control western corn rootworm (WCR; Diabrotica virgifera virgifera LeConte). In this manuscript, bioinformatic analysis establishes that although Mpp75Aa1.1 shares varying degrees of similarity to members of the ETX_MTX2 protein family, it is unlikely to have any allergenic, toxic, or otherwise adverse biological effects. The safety of Mpp75Aa1.1 is further supported by a weight of evidence approach including evaluation of the history of safe use (HOSU) of ETX_MTX2 proteins and Breviballus laterosporus. Comparisons between purified Mpp75Aa1.1 protein and a poly-histidine-tagged (His-tagged) variant of the Mpp75Aa1.1 protein demonstrate that both forms of the protein are heat labile at temperatures at or above 55°C, degraded by gastrointestinal proteases within 0.5 min, and have no adverse effects in acute mouse oral toxicity studies at a dose level of 1920 or 2120 mg/kg body weight. These results support the use of His-tagged proteins as suitable surrogates for assessing the safety of their non-tagged parent proteins. Taken together, we report that Mpp75Aa1.1 is the first ETX-MTX2 insecticidal protein from B. laterosporus and displays a similar safety profile as typical Cry proteins from Bacillus thuringiensis.

Effects of the probiotics Lactococcus lacttis (MTCC-440) on Salmonella enteric serovar Typhi in co-culture study

Lactococcus lactis (L. lactis)a probiotics microorganism having wide range of benefits on human health, and also protects the body from pathogenic microorganism. This study was conducted to determine the co-culture effect with the probiotic strain L. lactis (MTCC440) on Salmonella enterica serovar Typhi (S.Typhi). The existing problem was to determine the individual growth of both strains during co-culture. Growth kinetics study was performed and observed for 28 h and used to determine specific growth rate of S. Typhi under co-culture study. In growth kinetics study maximum specific growth rate (μ) of S. Typhi under monoculture and co-culture study was achieved 0.695 h^-1 and 0.35 h^-1 respectively. The maximum cell mass of L. lactis and S. Typhi was obtained 0.15 g/L and 0.18 g/L respectively. In co-culture study, L. lactis was found effective for the inhibition of 73% growth of S. Typhi due to lactic acid production.

Silencing of suppressor of cytokine signaling 1 enhances the immunological effect of mucin 1-calreticulin-primed 4T1 cell-treated dendritic cells in breast cancer treatment

In cancer immunotherapy, dendritic cell (DC)-based vaccines represent a promising, yet challenging, treatment method. In addition to overcoming the low expression levels of antigenic epitopes on cancer cells, it is also necessary to overcome the inhibitory effect of suppressor of cytokine signaling 1 (SOCS1) on DC self-antigen presentation. Our group previously demonstrated that calreticulin (CRT) translocated type I transmembrane glycoprotein mucin 1 (MUC1), a breast cancer antigen, to the surface of 4T1 cells, and that treatment with MUC1-CRT-primed 4T1 cell-treated DCs induced apoptosis in a breast cancer cell line. In the present study, cell penetrate peptide, hpp10-DRBD was successfully used to deliver siRNAs into bone marrow-derived (BM) DCs to construct SOCS1-silenced DCs, which were incubated with MUC1-CRT-primed 4T1 cells, and antigen-specific antitumor immunity was markedly enhanced in vitro and in vivo. These results demonstrated that SOCS1-silencing, combined with MUC1-CRT-primed 4T1 cell treatment, may induce increased cytokine production and T cell proliferation by DCs. Furthermore, the in vivo experimental data demonstrated that the silencing of SOCS1 combined with MUC1-CRT-primed 4T1 treatment of BMDCs may induce enhanced immunological effects. The results of the present study have implications for the development of more effective DC-based tumor vaccines, suggesting that the combination of high tumor-associated antigen expression levels on cancer cells with the silencing of a critical inhibitor of DC antigen presentation may be beneficial.