The Immunodominance Change and Protection of CD4+ T-Cell Responses Elicited by an Envelope Protein Domain III-Based Tetravalent Dengue Vaccine in Mice

Dengue is the leading cause of mosquito-borne viral infections and no vaccine is available now. Envelope protein domain III (ED3) is the major target for the binding of dengue virus neutralizing antibodies; however, the ED3-specifc T-cell response is less well understood. To investigate the T-cell responses to four serotypes of dengue virus (DENV-1 to 4), we immunized mice using either a tetravalent ED3-based DNA or protein vaccine, or combined both as a DNA prime-protein boost strategy (prime-boost). A significant serotype-dependent IFN-γ or IL-4 response was observed in mice immunized with either the DNA or protein vaccine. The IFN-γ response was dominant to DENV-1 to 3, whereas the IL-4 response was dominant to DENV-4. Although the similar IgG titers for the four serotypes were observed in mice immunized with the tetravalent vaccines, the neutralizing antibody titers varied and followed the order of 2 = 3>1>4. Interestingly, the lower IFN-γ response to DENV-4 is attributable to the immunodominance change between two CD4⁺ T-cell epitopes; one T-cell epitope located at E_349-363 of DENV-1 to 3 was more immunogenic than the DENV-4 epitope E_313-327. Despite DENV-4 specific IFN-γ responses were suppressed by immunodominance change, either DENV-4-specific IFN-γ or neutralizing antibody responses were still recalled after DENV-4 challenge and contributed to virus clearance. Immunization with the prime-boost elicited both IFN-γ and neutralizing antibody responses and provided better protection than either DNA or protein immunization. Our findings shed light on how ED3-based tetravalent dengue vaccines sharpen host CD4 T-cell responses and contribute to protection against dengue virus.     

小尺度森林生态功能分区研究——以台湾惠荪林场为例

基于景观生态学中结构与功能相互依存的理念 ,选定小尺度森林为研究对象 ,根据生态系统内部结构特性 ,确立森林生态功能的空间定位 ,以提高森林生态系统的功能与价值。研究首先基于森林生态系统具有生物生产、环境服务及文化支持等基本功能 ,提出上述功能应通过森林生产、教学实习、科学研究、休闲游憩和生态保护等功能区加以体现。后依据研究区环境特征进行影响因子分析 ,结合景观生态与生态规划相关理论 ,构建森林生态功能分区方案。在案例实践中 ,选择台湾惠荪林场进行研究 ,配合研究区现况 ,期望通过功能区与结构的空间调整 ,达到服务功能的优化。     

Immediate and subsequent growth responses of maize leaves to changes in water status

Elongation of intact young leaves of maize was found to be dynamically dependent on soil water supply. With adequate water, elongation was remarkably constant but slowed when the water potential of the soil in pots dropped from −0.1 to −0.2 bar and stopped when it dropped to −2.5 bars. The corresponding range of leaf water potential was −2.8 to −7 bars. Elongation resumed in less than a few seconds after a mildly water-stressed plant was rewatered.     

Modifying ligand-induced and constitutive signaling of the human 5-HT4 receptor

G protein-coupled receptors (GPCRs) signal through a limited number of G-protein pathways and play crucial roles in many biological processes. Studies of their in vivo functions have been hampered by the molecular and functional diversity of GPCRs and the paucity of ligands with specific signaling effects. To better compare the effects of activating different G-protein signaling pathways through ligand-induced or constitutive signaling, we developed a new series of RASSLs (receptors activated solely by synthetic ligands) that activate different G-protein signaling pathways. These RASSLs are based on the human 5-HT(4b) receptor, a GPCR with high constitutive G(s) signaling and strong ligand-induced G-protein activation of the G(s) and G(s/q) pathways. The first receptor in this series, 5-HT(4)-D(100)A or Rs1 (RASSL serotonin 1), is not activated by its endogenous agonist, serotonin, but is selectively activated by the small synthetic molecules GR113808, GR125487, and RO110-0235. All agonists potently induced G(s) signaling, but only a few (e.g., zacopride) also induced signaling via the G(q) pathway. Zacopride-induced G(q) signaling was enhanced by replacing the C-terminus of Rs1 with the C-terminus of the human 5-HT(2C) receptor. Additional point mutations (D(66)A and D(66)N) blocked constitutive G(s) signaling and lowered ligand-induced G(q) signaling. Replacing the third intracellular loop of Rs1 with that of human 5-HT(1A) conferred ligand-mediated G(i) signaling. This G(i)-coupled RASSL, Rs1.3, exhibited no measurable signaling to the G(s) or G(q) pathway. These findings show that the signaling repertoire of Rs1 can be expanded and controlled by receptor engineering and drug selection.     

In Vivo Evidence that Lithium Inactivates Gi Modulation of Adenylate Cyclase in Brain

In vivo microdialysis of cyclic AMP from prefrontal cortex complemented by ex vivo measures was used to investigate the possibility that lithium produces functional changes in G proteins that could account for its effects on adenylate cyclase activity. Four weeks of lithium administration (serum lithium concentration of 0.85 +/- 0.05 mM; n = 11) significantly increased the basal cyclic AMP content in dialysate from prefrontal cortex of anesthetized rats. Forskolin infused through the probe increased dialysate cyclic AMP, but the magnitude of this increase was unaffected by chronic lithium administration. Inactivation of the inhibitory guanine nucleotide binding protein Gi with pertussis toxin increased dialysate cyclic AMP in control rats, as did stimulation with cholera toxin (which activates the stimulatory guanine nucleotide binding protein Gs). The effect of pertussis toxin was abolished following chronic lithium, whereas the increase in cyclic AMP after cholera toxin was enhanced. In vitro pertussis toxin-catalyzed ADP ribosylation of alpha i (and alpha o) was increased by 20% in prefrontal cortex from lithium-treated rats, but the alpha i and alpha s contents (as determined by immunoblot) as well as the cholera toxin-catalyzed ADP ribosylation of alpha s were unchanged. Taken together, these results suggest that chronic lithium administration may interfere with the dissociation of Gi into its active components and thereby remove a tonic inhibitory influence on adenylate cyclase, with resultant enhanced basal and cholera toxin-stimulated adenylate cyclase activity.     

Genetic control of autoimmune myocarditis mediated by myosin-specific antibodies

 Autoimmune disease involves both the development of autoreactivity and the expression of organ damage, and susceptibility is genetically complex. We recently reported that in autoimmune myocarditis susceptibility to antibody-mediated cardiac injury is strain specific. DBA/2 mice develop myocarditis following administration of myosin-specific antibody, while BALB/c mice do not. This susceptibility appears to be controlled by expression of myosin in the myocardial extracellular matrix. CByD2F1 mice are both resistant to induction of myocarditis and do not demonstrate extracellular myosin, indicating a recessive genetic component to these traits. A backcross analysis of susceptibility using DBA/2×CByD2F1 mice revealed a locus on chromosome 12 that is strongly linked with myocarditis. In male mice there was a second region on chromosome 1 that also contributes to disease susceptibility. However, genetic susceptibility in both female and male mice was genetically complex. This study demonstrates that the genetic basis of tissue injury can be analyzed separately from the genetic basis of autoreactivity. Future studies will determine whether the genetic factors identified in this study are also involved in susceptibility to rheumatic fever. Received: 18 May 1998 / Revised: 3 July 1998     

Regional Amyloid Deposition in Amnestic Mild Cognitive Impairment and Alzheimer's Disease Evaluated by [18F]AV-45 Positron Emission Tomography in Chinese Population

Background

To compare the neocortical amyloid loads among cognitively normal (CN), amnestic mild cognitive impairment (aMCI), and Alzheimer''s disease (AD) subjects with [¹⁸F]AV-45 positron emission tomography (PET).

Materials and Methods

[¹⁸F]AV-45 PET was performed in 11 CN, 13 aMCI, and 12 AD subjects to compare the cerebral cortex-to-whole cerebellum standard uptake value ratios (SUVRs) of global and individual volumes of interest (VOIs) cerebral cortex. The correlation between global cortical [¹⁸F]AV-45 SUVRs and Mini-Mental State Examination (MMSE) scores was analyzed.

Results

The global cortical [¹⁸F]AV-45 SUVRs were significantly different among the CN (1.08±0.08), aMCI (1.27±0.06), and AD groups (1.34±0.13) (p = 0.0003) with amyloidosis positivity rates of 9%, 62%, and 92% in the three groups respectively. Compared to CN subjects, AD subjects had higher SUVRs in the global cortical, precuneus, frontal, parietal, occipital, temporal, and posterior cingulate areas; while aMCI subjects had higher values in the global cortical, precuneus, frontal, occipital and posterior cingulate areas. There were negative correlations of MMSE scores with SUVRs in the global cortical, precuneus, frontal, parietal, occipital, temporal, posterior cingulate and anterior cingulate areas on a combined subject pool of the three groups after age and education attainment adjustment.

Conclusions

Amyloid deposition occurs relatively early in precuneus, frontal and posterior cingulate in aMCI subjects. Higher [¹⁸F]AV-45 accumulation is present in parietal, occipital and temporal gyri in AD subjects compared to the aMCI group. Significant correlation between MMSE scores and [¹⁸F]AV-45 SUVRs can be observed among CN, aMCI and AD subjects.     

Demonstration of a glycoprotein derived from the Ceacam10 gene in mouse seminal vesicle secretions

CEACAM10 was purified from mouse seminal vesicle secretions by a series of purification steps that included ion exchange chromatography on a DEAE-Sephacel column and ion exchange high-performance liquid chromatography on a sulfopropyl column. It was shown to be a 36-kDa glycoprotein with an N-linked carbohydrate moiety. The circular dichromoism spectrum of CEACAM10 in 50 mM phosphate buffer at pH 7.4 appeared as one negative band arising from the beta form at 217 nm. CEACAM10 was expressed predominantly in seminal vesicles of adult mice. Both CEACAM10 and its mRNA were demonstrated on the luminal epithelium of the mucosal folds in the seminal vesicle. The amount of Ceacam10 mRNA in the seminal vesicle was correlated with the stage of animal maturation. Castration of adult mice resulted in cessation of Ceacam10 expression, while treatment of castrated mice with testosterone propionate in corn oil restored Ceacam10 expression in the seminal vesicle. During the entire course of pregnancy, Ceacam10 might be silent in the embryo. A cytochemical study illustrated the presence of the CEACAM10 binding region on the entire surface of mouse sperm. CEACAM10-sperm binding greatly enhanced sperm motility in vitro.