No abstract

In its own right, vaccinology has been undergoing a revolution, and there are now a large number of innovative projects seeking to develop both prophylactic and therapeutic vaccines against diseases such as Hepatitis B, influenza, HIV, and cancers. [4-6] Generally speaking, the major advantages conferred by nanovaccines include improving stability by protecting antigens from premature degradation, providing good adjuvant properties, and assisting in the targeted delivery of an antigen to antigen-presenting cells (APCs). [7] A large variety of nanoscale materials have been deployed in nanovaccine designs. Seminal work with inorganic nanoparticles (NPs, e.g., gold, carbon, and silica) established the capacity of nanovaccine-bound antigens to elicit desired immune responses. Subsequent technologies have elaborated beyond inorganic NPs, for example, use of inorganic/ organic hybrid NPs (e.g., PEI adopted silica NPs and biomimetic magnetosomes) to enhance antigen immunogenicity. [8,9] Recently, new types of organic NPs (e.g., lipoprotein-mimicking nanodisks, pickering emulsions, and nanogels) have also received great attention for their applications in vaccines. [10-16] Recent years have seen enormous advances in nanovaccines for both prophylactic and therapeutic applications, but most of these technologies employ chemical or hybrid semi-biosynthetic production methods. Thus, production of nanovaccines has to date failed to exploit biology-only processes like complex sequential post-translational biochemical modifications and scalability, limiting the realization of the initial promise for offering major performance advantages and improved therapeutic outcomes over conventional vaccines. A Nano-B5 platform for in vivo production of fully protein-based, self-assembling, stable nanovaccines bearing diverse antigens including peptides and polysaccharides is presented here. Combined with the self-assembly capacities of pentamer domains from the bacterial AB 5 toxin and unnatural trimer peptides, diverse nanovaccine structures can be produced in common Escherichia coli strains and in attenuated pathogenic strains. Notably, the chassis of these nanovaccines functions as an immunostimulant. After showing excellent lymph node targeting and immunoresponse elicitation and safety performance in both mouse and monkey models, the strong prophylactic effects of these nanovaccines against infection, as well as their efficient therapeutic effects against tumors are further demonstrated. Thus, the Nano-B5 platform can efficiently combine diverse modular components and antigen cargos to efficiently generate a potentially very large diversity of nanovaccine structures using many bacterial species.

Shigella flexneri 2a is an important pathogen causing bacillary dysentery in humans. In order to investigate any potential vaccine candidate proteins present in outer membrane proteins (OMPs) and extracellular proteins of S. flexneri 2a 2457T, we use the proteome mapping and database analyzing techniques. A subproteome map and database of OMPs were established first. One hundred and nine of the total 126 marked spots were cut out and processed to MALDI-TOF-MS and PMF. Eighty-seven spots were identified and they represented 55 OMP entries. Furthermore, immunoproteomics analysis of OMPs and extracellular proteins were performed. Total of 34 immunoreactive spots were identified, in which 22 and 12 were from OMPs and extracellular proteins, respectively. Eight novel antigens were found and some of these antigens may be potential vaccine candidate proteins. These results are useful for future studying of pathogenicity, vaccine, and novel antibacterial drugs. Maps and tables of all identified proteins are available on the Internet at www.proteomics.com.cn.

Bacillus anthracis has always been an important pathogen because it can cause lethal inhalational anthrax, and may be used as a bioweapon or by bioterrorists. In this study, a 2-DE reference map and database of B. anthracis A16R was constructed. In total, 534 spots were processed, and 406 spots representing 299 proteins were identified. Gel-estimated pIs and molecular masses mostly matched well with their theoretical predictions, but some discrepancies also existed. Spot and protein corresponding analysis revealed that post-translational modifications might be common in B. anthracis. Through the MASCOT search, the similarity of B. anthracis, B. cereus and B. thuringiensis was further verified by protein level and a possible annotation error in B. anthracis strain Ames 0581 genome was found. Proteins of energy metabolism, fatty acid and phospholipid metabolism, protein synthesis, and cellular processes represented a large part of the most abundant proteins. At the same time, 27 hypothetical proteins were experimentally proved. There were 28 proteins also identified as spore composition in recently spore-related research, which indicated that they might play some roles in different phases such as growth, sporulation and outgrowth. Maps and information about all identified proteins are available on the Internet at http://www.mpiib-berlin.mpg.de/2D-PAGE and http://www.proteomics.com.cn.

The large plasmid pXO1 encoding the anthrax toxin is important for the virulence of Bacillus anthracis. It is essential to cure pXO1 from B. anthracis to evaluate its role in the pathogenesis of anthrax infection. Because conventional methods for curing plasmids (e.g., curing agents or growth at elevated temperatures) can induce mutations in the host chromosomal DNA, we developed a specific and reliable method to eliminate pXO1 from B. anthracis using plasmid incompatibility. Three putative replication origins of pXO1 were inserted into a temperature-sensitive plasmid to generate three incompatible plasmids. One of the three plasmids successfully eliminated the large plasmid pXO1 from B. anthracis vaccine strain A16R and wild type strain A16. These findings provided additional information about the replication/partitioning of pXO1 and demonstrated that introducing a small incompatible plasmid can generate plasmid-cured strains of B. anthracis without inducing spontaneous mutations in the host chromosome.