We have designed and produced a prototypic malaria vaccine based on a highly versatile self-assembling polypeptide nanoparticle (SAPN) platform that can repetitively display antigenic epitopes. We used this platform to display a tandem repeat of the B cell immunodominant repeat epitope (DPPPPNPN)2D of the malaria parasite Plasmodium berghei circumsporozoite protein (CSP). Administered in saline, without the need for a heterologous adjuvant, the SAPN construct P4c-Mal conferred a long lived protective immune response to mice with a broad range of genetically distinct immune backgrounds including the H-2b, H-2d and H-2k alleles. Immunized mice produced a CD4+ T cell dependent, high titer, long lasting, high avidity antibody response against the B cell epitope. Mice were protected against an initial challenge of parasites given up to 6 months after the last immunization or for up to 15 months against a second challenge after an initial challenge of parasites had successfully been cleared. Furthermore, we demonstrate that the SAPN platform not only functions to deliver an ordered repetitive array of B cell peptide epitopes but operates as a classical immunological carrier to provide cognate help to the P4c-Mal specific B cells.

BackgroundThe worldwide burden of malaria remains a major public health problem due, in part, to the lack of an effective vaccine against the Plasmodium falciparum parasite. An effective vaccine will most likely require the induction of antigen specific CD8+ and CD4+ T-cells as well as long-lasting antibody responses all working in concert to eliminate the infection. We report here the effective modification of a self-assembling protein nanoparticle (SAPN) vaccine previously proven effective in control of a P. berghei infection in a rodent model to now present B- and T-cell epitopes of the human malaria parasite P. falciparum in a platform capable of being used in human subjects.Methodology/Principal FindingsTo establish the basis for a SAPN-based vaccine, B- and CD8+ T-cell epitopes from the P. falciparum circumsporozoite protein (PfCSP) and the universal CD4 T-helper epitope PADRE were engineered into a versatile small protein (∼125 amino acids) that self-assembles into a spherical nanoparticle repetitively displaying the selected epitopes. P. falciparum epitope specific immune responses were evaluated in mice using a transgenic P. berghei malaria parasite of mice expressing the human malaria full-length P. falciparum circumsporozoite protein (Tg-Pb/PfCSP). We show that SAPN constructs, delivered in saline, can induce high-titer, long-lasting (1 year) protective antibody and poly-functional (IFNγ+, IL-2+) long-lived central memory CD8+ T-cells. Furthermore, we demonstrated that these Ab or CD8+ T–cells can independently provide sterile protection against a lethal challenge of the transgenic parasites.ConclusionThe SAPN construct induces long-lasting antibody and cellular immune responses to epitope specific sequences of the P. falciparum circumsporozoite protein (PfCSP) and prevents infection in mice by a transgenic P. berghei parasite displaying the full length PfCSP.

BackgroundOur recent study showed the global physiological function of the differentially expressed genes of prostate cancer in Chinese patients was different from that of other non-Chinese populations. microRNA are estimated to regulate the expression of greater than 60% of all protein-coding genes. To further investigate the global association between the transcript abundance of miRNAs and their target mRNAs in Chinese patients, we used microRNA microarray approach combined with bioinformatics and clinical-pathological assay to investigate the miRNA profile and evaluate the potential of miRNAs as diagnostic and prognostic markers in Chinese patients.ResultsA total of 28 miRNAs (fold change ≥1.5; P ≤ 0.05) were differentially expressed between tumor tissue and adjacent benign tissue of 4 prostate cancer patients.10 top Differentially expressed miRNAs were validated by qRT-PCR using all 20 tissue pairs. Compared to the miRNA profile of non-Chinese populations, the current study showed that miR-23b, miR-220, miR-221, miR-222, and miR-205 maybe common critical therapeutic targets in different populations. The integrated analysis for mRNA microarray and miRNA microarray showed the effects of specifically inhibiting and/or enhancing the function of miRNAs on the gene transcription level. The current studies also identified 15 specific expressed miRNAs in Chinese patients. The clinical feature statistics revealed that miR-374b and miR-19a have significant correlations with clinical-pathological features in Chinese patients.ConclusionsOur findings showed Chinese prostate cancer patients have a common and specific miRNA expression profile compared with non-Chinese populations. The miR-374b is down-regulated in prostate cancer tissue, and it can be identified as an independent predictor of biochemical recurrence-free survival.

The bundle-forming pilus (BFP) of enteropathogenic Escherichia coli (EPEC) is an important virulence factor. We examined the role of divergent alleles of bfpA encoding bundlin, the BFP pilin protein, in pilus biogenesis, pilus interactions, and immune responses. We found that the BFP biogenesis machine from an EPEC strain that expresses one bundlin type is capable of assembling all other bundlin types. Furthermore, we found that EPEC strains expressing divergent bundlin types are capable of forming mixed autoaggregates, suggesting that different pilin types can intertwine. However, we found that there was a marked difference between alleles in immunogenicity in both rabbits and mice of a peptide derived from a region of bundlin undergoing apparent diversifying selection. In addition, despite a high degree of cross-reactivity between divergent bundlin proteins, in both mice and rabbits responses appeared to be stronger against the homologous pilin protein than against the heterologous protein. This result was verified using sera from a volunteer study, which demonstrated that the human antibody responses after an initial challenge with live EPEC were stronger against the homologous bundlin protein than against a divergent bundlin protein. However, a repeat challenge induced equivalent responses. These results are consistent with the hypothesis that human immune responses against bundlin exert selective pressure on bfpA sequence divergence.Type IV pili (Tfps) are surface appendages that are expressed by diverse gram-negative species. Tfps play numerous roles in pathogenesis, including roles in colonization, adherence, autoaggregation, biofilm formation, horizontal gene transfer, motility, and virulence (5,8,21,22,24,28,32,36,38,(41)(42)(43). The bundle-forming pilus (BFP) of enteropathogenic Escherichia coli (EPEC) is an excellent model for the study of Tfps as expression of the 14-gene bfp cluster in a laboratory strain of E. coli is sufficient for BFP biogenesis and function (30,40). EPEC is an important cause of serious diarrhea in infants in developing countries (1,12,16,19). Volunteer studies have confirmed the importance of BFP expression for full virulence of EPEC (5). BFP are composed of repeating subunits of the pilin protein bundlin, the product of the bfpA gene. Antibodies against bundlin are found in volunteers convalescing from experimental EPEC infection and in breast milk of mothers and serum of infants in developing countries (15,25,33). Whether these antibodies confer protection against subsequent infection is not known.The Tfps expressed by different strains in a species may vary in sequence. In Neisseria gonorrhoeae, transformation and recombination from multiple silent pilus loci encoding variant pilin proteins result in abundant antigenic variation in pilin expression (29). This extremely dynamic process can lead to the expression of several pilin variants during infection of a single host and may help the bacteria avoid the immune response and cause persistent infection (39). Pilin sequence v...

The global physiological function of specifically expressed genes of prostate cancer in Chinese patients is unclear. This study aims to determine the genome-wide expression of genes related to prostate cancer in the Chinese population. Genes that were differentially expressed in prostate cancer were identified using DNA microarray technology. Expressions were validated by using real-time PCR. The identified genes were analyzed using the ingenuity pathway analysis (IPA) to investigate the gene ontology, functional pathway and network. A total of 1,444 genes (Fold time ≥ 1.5; P ≤ 0.05) were differentially expressed in prostate primary tumor tissue compared with benign tissue. IPA revealed a unique landscape where inductions of certain pathways were involved in Cell Cycle Regulation and proliferation. Network analysis not only confirmed that protein interactions lead to the deregulation of DNA Replication, Recombination and Repair, Cellular Compromise and Cell Cycle, Genetic Disorders and Connective Tissue Disorders, but it was also observed that many of the genes regulated by Myc contributed to the modulation of lipid Metabolism and Nucleic Acid Metabolism. Both pathway and network analysis exhibited some remarkable characteristics of prostate cancer for Chinese patients, which showed profound differences from that of other non-Chinese populations. These differences may provide new insights into the molecular cascade of prostate cancer that occurs in Chinese patients.

Salmonella enterica serovar Typhi (S. Typhi), the causative agent of the typhoid fever, is a pathogen of great public health importance. Typhoid vaccines have the potential to be cost-effective measures towards combating this disease, yet the antigens triggering host protective immune responses are largely unknown. Given the key role of cellular-mediated immunity in S. Typhi protection, it is crucial to identify S. Typhi proteins involved in T-cell responses. Here, cells from individuals immunized with Ty21a typhoid vaccine were collected before and after immunization and used as effectors. We also used an innovative antigen expressing system based on the infection of B-cells with recombinant Escherichia coli (E. coli) expressing one of four S. Typhi gene products (i.e., SifA, OmpC, FliC, GroEL) as targets. Using flow cytometry, we found that the pattern of response to specific S. Typhi proteins was variable. Some individuals responded to all four proteins while others responded to only one or two proteins. We next evaluated whether T-cells responding to recombinant E. coli also possess the ability to respond to purified proteins. We observed that CD4+ cell responses, but not CD8+ cell responses, to recombinant E. coli were significantly associated with the responses to purified proteins. Thus, our results demonstrate the feasibility of using an E. coli expressing system to uncover the antigen specificity of T-cells and highlight its applicability to vaccine studies. These results also emphasize the importance of selecting the stimuli appropriately when evaluating CD4+ and CD8+ cell responses.

There are many ways to present antigens to the immune system. We have used a repetitive antigen display technology that relies on the self-assembly of 60 protein chains into a spherical self-assembling protein nanoparticle (SAPN) to develop a vaccine against Plasmodium falciparum malaria. The protein sequence contains selected B- and T-cell epitopes of the circumsporozoite protein of P. falciparum (PfCSP) and, when assembled into a nanoparticle induces strong, long-lived and protective immune responses against the PfCSP. Here we describe the conditions needed for promoting self-assembly of a P. falciparum vaccine nanoparticle, PfCSP-KMY-SAPN, and note pitfalls that may occur when determining conditions for other SAPN vaccines. Attention was paid to selecting processes that were amenable to scale up and cGMP manufacturing.

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