Selective Targeting of 4SO4-N-Acetyl-Galactosamine Functionalized Mycobacterium tuberculosis Protein Loaded Chitosan Nanoparticle to Macrophages: Correlation With Activation of Immune System

In the present study, we investigated potential of chitosan-based nanoparticles (CNPs) to deliver loaded therapeutic molecules to pathogen harboring macrophages. We fabricated stable CNPs employing ionic cross-linking method and evaluated their potential to target RAW 264.7 cells. The physicochemical characterization of as-synthesized CNPs was determined using electron microscopy, infrared microscopy and zeta potential measurement. Next, cellular uptake and intracellular localization studies of CNPs were followed in living RAW264.7 cells using confocal microscopy. We found that both Acr-1 loaded (CNP-A) and 4-SO4-GalNAc ligand harboring (CNP-L) chitosan nanoparticle experience increased cellular uptake by Mycobacterium smegmatis infected RAW cells. Following cellular digestion in model macrophage cell line (RAW), CNPs provide an increased immune response. Further, 4-SO4-GalNAc bearing CNP-L exhibits high binding affinity as well as antibacterial efficacy toward M. smegmatis. The data of the present study suggest that CNP-based nanoparticle offer a promising delivery strategy to target infected macrophages for prevention and eradication of intracellular pathogens such as M. smegmatis

Mycobacterium tuberculosis host cell interaction: Role of latency associated protein Acr-1 in differential modulation of macrophages.

Mycobacterium tuberculosis (M.tb) contrives intracellular abode as a strategy to combat antibody onslaught. Additionally, to thrive against hostile ambiance inside host macrophages, the pathogen inhibits phago-lysosomal fusion. Finally, to further defy host cell offensives, M.tb opts for dormant phase, where it turns off or slows down most of its metabolic process as an added stratagem. While M.tb restrains most of its metabolic activities during dormancy, surprisingly latency-associated alpha-crystallin protein (Acr-1) is expressed most prominently during this phase. Interestingly, several previous studies described the potential of Acr-1 to induce the robust immuno-prophylactic response in the immunized host. It is intriguing to comprehend the apparent discrepancy that the microbe M.tb overexpresses a protein that has the potential to prime host immune system against the pathogen itself. Keeping this apparent ambiguity into consideration, it is imperative to unravel intricacies involved in the exploitation of Acr-1 by M.tb during its interaction with host immune cells. The present study suggests that Acr-1 exhibits diverse role in the maturation of macrophages (MΦs) and related immunological responses. The early encounter of bone marrow derived immune cells (pre-exposure during differentiation to MΦs) with Acr-1 (AcrMΦpre), results in hampering of their function. The pre-exposure of naïve MΦs with Acr-1 induces the expression of TIM-3 and IL-10. In contrast, exposure of fully differentiated MΦs to Acr-1 results in their down-modulation and induces the phosphorylation of STAT-1 and STAT-4 in host MΦs. Furthermore, Acr-1 mediated activation of MΦs results in the induction of Th1 and Th17 phenotype by activated T lymphocyte

Genome sequencing, annotation and comparative genomic analysis of Shigella dysenteriae strain SD1D

BACKGROUND: Shigellosis is an acute form of gastroenteritis caused by the bacteria belonging to the genus Shigella. It is the most common cause of morbidity and mortality in children. Shigella belongs to the family Enterobactericeae, which is a Gram-negative and rod shaped bacterium. In the present study, we report the draft genome of Shigella dysenteriae strain SD1D, which was isolated from the stool sample of a healthy individual. RESULTS: Based on 16S rRNA gene sequence and phylogenetic analysis, the strain SD1D was identified as Shigella dysenteriae. The draft genome of SD1D consisted of 45, 93, 159 bp with a G + C content of 50.7%, 4, 960 predicted CDSs, 75 tRNAs and 2 rRNAs. The final assembly contained 146 contigs of total length 45, 93, 159 bp with N(50) contig length of 77, 053 bp; the largest contig assembled measured 3, 85, 550 bp. CONCLUSIONS: We have for the first time performed the whole genome sequencing of Shigella dysenteriae strain SD1D. The comparative genomic analysis revealed several genes responsible for the pathogenesis, virulence, defense, resistance to antibiotics and toxic compounds, multidrug resistance efflux pumps and other genomic features of the bacterium