Modeling Neisseria meningitidis B metabolism at different specific growth rates

Neisseria meningitidis is a human pathogen that can infect diverse sites within the human host. The major diseases caused by N. meningitidis are responsible for death and disability, especially in young infants. At the Netherlands Vaccine Institute (NVI) a vaccine against serogroup B organisms is currently being developed. This study describes the influence of the growth rate of N. meningitidis on its macro-molecular composition and its metabolic activity and was determined in chemostat cultures. In the applied range of growth rates, no significant changes in RNA content and protein content with growth rate were observed in N. meningitidis. The DNA content in N. meningitidis was somewhat higher at the highest applied growth rate. The phospholipid and lipopolysaccharide content in N. meningitidis changed with growth rate but no specific trends were observed. The cellular fatty acid composition and the amino acid composition did not change significantly with growth rate. Additionally, it was found that the PorA content in outer membrane vesicles was significantly lower at the highest growth rate. The metabolic fluxes at various growth rates were calculated using flux balance analysis. Errors in fluxes were calculated using Monte Carlo Simulation and the reliability of the calculated flux distribution could be indicated, which has not been reported for this type of analysis. The yield of biomass on substrate (Y(x/s)) and the maintenance coefficient (m(s)) were determined as 0.44 (+/-0.04) g g(-1) and 0.04 (+/-0.02) g g(-1) h(-1), respectively. The growth associated energy requirement (Y(x/ATP)) and the non-growth associated ATP requirement for maintenance (m(ATP)) were estimated as 0.13 (+/-0.04) mol mol(-1) and 0.43 (+/-0.14) mol mol(-1) h(-1), respectively. It was found that the split ratio between the Entner-Doudoroff and the pentose phosphate pathway, the sole glucose utilizing pathways in N. meningitidis, had a minor effect on ATP formation rate but a major effect on the fluxes going through for instance the citric-acid cycle. For this reason, we presented flux ranges for underdetermined parts of metabolic network rather than presenting single flux values, which is more commonly done in literature.     

Cholera toxin B protein in transgenic tomato fruit induces systemic immune response in mice

Cholera toxin B (CTB) subunit is a well-characterized antigen against cholera. Transgenic plants can offer an inexpensive and safe source of edible CTB vaccine and may be one of the best candidates for the production of plant vaccines. The present study aimed to develop transgenic tomato expressing CTB protein, especially in the ripening tomato fruit under the control of the tomato fruit-specific E8 promoter by using Agrobacterium-mediated transformation. Transgenic plants were selected using PCR and Southern blot analysis. Exogenous protein extracted from leaf, stem, and fruit tissues of transgenic plants was detected by ELISA and Western blot analysis, showing specific expression in the ripening fruit, with the highest amount of CTB protein being 0.081% of total soluble protein. Gavage of mice with ripe transgenic tomato fruits induced both serum and mucosal CTB specific antibodies. These results demonstrate the immunogenicity of the CTB protein in transgenic tomato and provide a considerable basis for exploring the utilization of CTB in the development of tomato-based edible vaccine against cholera. The rCTB antigen resulted in much lower antibody titers than an equal amount of exgenous CTB in trangenic fruits, suggesting the protective effect of the fibrous tissue of the fruit to the exogenous CTB protein against the degradation of protease in the digestive tracts of mice. Xiao-Ling Jiang and Zhu-Mei He contributed equally to this work.     

HIV-1 Neutralizing Antibody Signatures and Application to Epitope-Targeted Vaccine Design

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Whole inactivated SIV vaccine grown on human cells fails to protect against homologous SIV grown on simian cells

Several groups have reported protection against experimental SIV infection in macaques immunized with a whole inactivated virus vaccine. The aim of the current study was to investigate whether five macaques vaccinated with whole inactivated SIV and previously shown to be protected against challenge with two divergent strains of SIV grown on human cells could resist challenge with a subsequent homologous SIV grown on macaque cells. We show here that this same vaccine did not protect when the challenge virus was grown on primary cells of monkey origin.     

肾综合征出血热乳鼠脑纯化疫苗(I型)糖蛋白及核蛋白在免疫保护中的作用

为了阐明肾综合征出血热纯化疫苗（Ｉ型）中糖蛋白（ＧＰ）、核蛋白（ＮＰ）在免疫保护中的作用,采用脾细胞转输法,分别将ＧＰ、ＮＰ、ＧＰ＋ ＮＰ免疫小鼠后的脾细胞与未经免疫的小鼠正常脾细胞（３．５×１０５ 个）经腹腔转输给乳鼠,２ ｈ 后以１００ ＬＤ５０的汉滩（ＨＴＮ）病毒（ＬＲ１ 株）进行脑腔攻击。结果表明,其乳鼠的保护率分别达７７．０％ ,３８．５％ 和９２．３％ ,而未经免疫的小鼠正常脾细胞则不能提供保护（０％ ）,揭示了ＧＰ＋ ＮＰ在抗ＨＴＮ 病毒感染中具有免疫协同作用。     

HHV-5 epitope: A potential vaccine candidate with high antigenicity and large coverage

Outbreak of Human Herpes virus-5 (HHV-5) infection in emerging countries has raised worldwide health concern owing to prevalence of congenital impairments and life threatening consequences in immunocompromised individuals. Thus, there lies an impending need to develop vaccine against HHV-5. HHV-5 enters into host cells with the help of necessary components glycoprotein B (gB) and H/L. In this study, the conformational linear B-cell and T-cell epitopes for gB of HHV-5 have been predicted using conformational approaches, for their possible collective use as vaccine candidates. We examined epitope’s interactions with major histocompatibility complexes using molecular docking and also investigated their stable binding with specific toll like receptor-2 (TLR2), present on host cells during HHV-5 infection. Predicted MHC-I epitope ‘LVAIAVVII’ with high antigenicity and large coverage of HLA alleles was found to superimpose on MHC-II epitope (Rank 1) and was also identified to be the core sequence of putative B cell epitope ‘ILVAIAVVIITYLI’. Resulting epitope was found to have consistent interaction with TLR2 during long term (100?ns) MD run. We also validated this nonamer epitope for its dissimilarity with human genome and high population coverage, suggesting it to be a potential vaccine candidate with higher coverage for both the MHC alleles of Indian population.

Communicated by Ramaswamy H. Sarma     

Phylogeography of lethal male fighting in a social spider mite

When males fight for access to females, such conflict rarely escalates into lethal fight because the risks and costs involved, that is, severe injury or death, are too high. The social spider mite, Stigmaeopsis miscanthi, does exhibit lethal male fights, and this male–male aggressiveness varies among populations. To understand the evolution of lethal fighting, we investigated aggressiveness in 42 populations and phylogenetic relationships in 47 populations along the Japanese archipelago. By analysis of the male weapon morph, a proxy for aggressiveness, we confirmed the existence of a mildly aggressive (ML) form, besides the low aggression (LW) and high aggression (HG) forms reported earlier. To evaluate demographic history of these three forms, we employed the approximate Bayesian computation approach using mtCOI sequences and taking into consideration the postlast glacial expansion history of the host plant, Miscanthus sinensis. As results, hierarchical split models are more likely to explain the observed genetic pattern than admixture models, and the ML form in the subtropical region was considered the ancestral group. The inferred demographic history was consistent with the one reconstructed for the host plant in a previous study. The LW form was split from the ML form during the last glacial period (20,000–40,000 years BP), and subsequently, the HG form was split from the ML form at the end of or after the last glacial period (5,494–10,988 years BP). The results also suggest that the mite invaded Japan more than once, resulting in the present parapatric distribution of LW and HG forms in eastern Japan.     

结核分枝杆菌蛋白亚单位疫苗与疫苗诱导的T细胞免疫记忆研究进展

牛分枝杆菌减毒活疫苗--卡介苗(bacillus Calmette-Guérin,BCG)对预防严重的儿童结核病有效,但其免疫保护效率随儿童年龄增长而降低。BCG不能提供终身免疫保护可能与其诱导的记忆性T细胞主要是寿命较短的效应记忆性T细胞有关。新型结核分枝杆菌蛋白亚单位疫苗将有效的抗原有机组合起来,在适宜的疫苗佐剂辅助下诱导Th1型免疫应答。动物实验表明,增加抗原谱可有效提高亚单位疫苗的保护效率。更重要的是,亚单位疫苗在体内持续时间较短,可诱导寿命较长的中央记忆性T细胞,提供比BCG更持久的免疫保护力。记忆性T细胞的分化受抗原特性与剂量、细胞因子、转录因子及雷帕霉素等的调控。对亚单位疫苗及其诱导的免疫记忆进行研究将对新型结核分枝杆菌疫苗的设计与评价产生积极影响。