Cytomegalovirus infection in Gambian infants leads to profound CD8 T-cell differentiation

Cytomegalovirus (CMV) infection is endemic in Gambian infants, with 62% infected by 3 months and 85% by 12 months of age. We studied the CD8 T-cell responses of infants to CMV following primary infection. CMV-specific CD8 T cells, identified with tetramers, showed a fully differentiated phenotype (CD28(-) CD62L(-) CD95(+) perforin(+) granzyme A(+) Bcl-2(low)). Strikingly, the overall CD8 T-cell population developed a similar phenotype following CMV infection, which persisted for at least 12 months. In contrast, primary infection was accompanied by up-regulation of markers of activation (CD45R0 and HLA-D) on both CMV-specific cells and the overall CD8 T-cell population and division (Ki-67) of specific cells, but neither pattern persisted. At 12 months of age, the CD8 T-cell population of CMV-infected infants was more differentiated than that of uninfected infants. Although the subpopulation of CMV-specific cells remained constant, the CMV peptide-specific gamma interferon response was lower in younger infants and increased with age. As the CD8 T-cell phenotype induced by CMV is indicative of immune dysfunction in the elderly, the existence of a similar phenotype in large numbers of Gambian infants raises the question of whether CMV induces a similarly deleterious effect.     

Synthesis of polyglycerol phosphate by Bacillus stearothermophilus.

A particulate enzyme preparation from Bacillus stearothermophilus synthesized 1,3-poly(glycerol phosphage) from CDPglycerol at an optimum pH of 8.0 and the reaction was stimulated by divalent cations. Km for CDPglycerol was 0.18 mM. The synthesis was inhibited by CMP, CDP, and CTP and by concentrations of CDP-glycerol above 0.49 mM. The reaction was irreversible, The product had an average chain length of 8 glycerol units. About two thirds of the polymers were synthesized in entirety while the ramainder were attached to some acceptor by their phosphate end. The enzome was able to synthesize only a limited amount of polymer.     

Dynamic compression counteracts IL-1β induced inducible nitric oxide synthase and cyclo-oxygenase-2 expression in chondrocyte/agarose constructs

Background  

Nitric oxide and prostaglandin E₂ (PGE₂play pivotal roles in both the pathogenesis of osteoarthritis and catabolic processes in articular cartilage. These mediators are influenced by both IL-1β and mechanical loading, and involve alterations in the inducible nitric oxide synthase (iNOS) and cyclo-oxygenase (COX)-2 enzymes. To identify the specific interactions that are activated by both types of stimuli, we examined the effects of dynamic compression on levels of expression of iNOS and COX-2 and involvement of the p38 mitogen-activated protein kinase (MAPK) pathway.     

Epstein-Barr virus but not cytomegalovirus is associated with reduced vaccine antibody responses in Gambian infants

Background

Epstein-Barr virus (EBV) and cytomegalovirus (CMV) are persistent herpesviruses that have various immunomodulatory effects on their hosts. Both viruses are usually acquired in infancy in Sub-Saharan Africa, a region where childhood vaccines are less effective than in high income settings. To establish whether there is an association between these two observations, we tested the hypothesis that infection with one or both viruses modulate antibody responses to the T-cell independent meningococcal polysaccharide vaccine and the T-cell dependent measles vaccines.

Methodology/Principal Findings

Infection with EBV and CMV was diagnosed by the presence of virus-specific IgM in the peripheral blood or by the presence of IgG at higher levels than that found in umbilical cord blood. Anti-meningococcus IgG and IgM were quantified by ELISA. Anti-measles antibody responses were quantified by haemagglutinin antibody inhibition assay. Infants infected with EBV had reduced IgG and IgM antibody responses to meningococcal polysaccharides and to measles vaccine. Infection with CMV alone predicted no changes in the response to meningococcal polysaccharide. While CMV alone had no discernable effect on the antibody response to measles, the response of infants infected with both CMV and EBV was similar to that of infants infected with neither, suggesting that the effects of CMV infection countered the effects of EBV on measles antibody responses.

Conclusions

The results of this exploratory study indicate that infection with EBV is associated with reduced antibody responses to polysaccharides and to measles vaccine, but suggest that the response to T-cell dependent antigens such as measles haemagglutinin may be restored by infection with CMV.     

Maintenance of large subpopulations of differentiated CD8 T-cells two years after cytomegalovirus infection in Gambian infants

BACKGROUND: In a previously published study, we found that large differentiated subpopulations of CD8 T-cells emerged rapidly after CMV infection in young infants and persisted throughout the following year. Here we describe a follow-up study conducted on the same infants to establish whether the differentiated subpopulations continued through the second year post-infection. METHODOLOGY / PRINCIPAL FINDINGS: CMV-specific cells identified using tetramers remained more activated and differentiated than the overall CD8 population. The large subpopulation of differentiated cytotoxic (CD28(-)CD62L(-)Bcl-2(low)CD95(+)perforin(+)) cells that emerged rapidly after infection remained stable after two years. No similar subpopulation was found in CMV-uninfected infants indicating that two years after infection, CMV remained a major factor in driving CD8 T-cell differentiation. Although markers of activation (CD45R0 and HLA-D) declined throughout the first year, HLA-D expression continued to decline during the second year and CD45R0 expression increased slightly. The age-related increase in IFNgamma response observed during the first year continued but was non-significant during the second year, indicating that the rate of functional improvement had slowed substantially. CONCLUSIONS / SIGNIFICANCE: The large differentiated subpopulations of CD8 T-cells that had emerged immediately after CMV infection persisted through the second year post-infection, while levels of activation and functional capacity remained fairly constant.     

文山松毛虫质型多角体病毒形态结构及理化性质的研究

对文山松毛虫质型多角体病毒的形态结构及理化特性进行了研究,多角体大部分为六边形,少数为四边形及近园形,其大小在0.47～2.45μ之间,平均为1.1μ。病毒粒子呈球形,无囊膜,致密的核芯区由一层外壳包裹,直径为60nm。病毒粒子表面有12个刺突,放大图象可见其亚单位排列。多角体蛋白的主要成分为一种,分子量为26200道尔顿,多角体蛋白氨基酸组成中不含半胱氨酸;其碱性氨基酸与酸性氨基酸之比为1:2.16。病毒粒子结构蛋白含五条多肽组分。用SDS-热酚法提取所得核酸,其热变性紫外吸收OD_(260)值增加51.6％。抗核酸酶S_1。Tm值为86℃。在1％琼脂糖凝胶电泳中可分为9个片段,而在5％PAGE中,则可分为10个片段。各片段大小在0.66×10~6～2.85×10~6道尔顿之间,总分子量为15.35×10~6。电镜分析研究显示了CPV RNA在0.4μ、0.8μ和1.2μ处有三个分布峰。     

An Investigation into the Rate and Control of Assimilate Movement from Leaves in Pisum sativum

Export studies were made on leaves of Pisum by monitoring the¹⁴CO₂-treated source leaf at its surface at frequent intervals.Radiocarbon levels of fresh leaf samples showed a good correlationwith results from the more conventional methods of radiocarbonestimation which involve destructive analysis. The rate of export was highest in plants which had been defoliated,except for the source leaf 20 h or more before the start ofthe export study. Removal of the shoot apex reduced export andprogressive reduction in sink capacity was associated with decreasedexport rates, particularly over short time periods. Export rateswere similar in defoliated and non-defoliated plants where theshoot apex and the roots had been excised. This suggested thata decrease in the source resulted in higher export rates fromthe remaining source only when active sinks were present; thisin turn suggests that, at least under these conditions, activeremoval of photosynthate is more important in controlling exportthan the photosynthate build-up in the leaf itself. The non-destructive technique enabled comparisons to be madebetween export curves for individual plants. It was found thatin experiments replicated in time, the same relationship betweentreatments was present on different days and the shape of theexport curves was similar but the absolute values for exportedradiocarbon sometimes varied considerably.     

Chilling-induced Lipid Hydrolysis in the Oil Palm (Elaeis guineensis) Mesocarp

Oil palm fruits exposed to temperatures of 15 °C and belowshowed a significant increase in free fatty acid (FFA) contentin the mesocarp. This effect was most pronounced in fruits exposedto 5 °C when FFA levels exceeding 70% of the total oil wereobserved. The increase in FFA was accompanied by an increasein lipid-soluble phosphorus levels and a decrease in carotenecontent. Chilling did not have an effect on palm kernel oil.The results suggest the activation of a lipase in the mesocarpby low temperature stress. Key words: Lipase, oil palm, free fatty acid