The Origin and Evolution of Human T-Cell Lymphotropic Virus Types I and II

Studies on human T-cell lymphotropic virus types I (HTLV-I) and II (HTLV-II) are briefly reviewed from the viewpoint of molecular evolution, with special reference to the evolutionary rate and evolutionary relationships among these viruses. In particular, it appears that, in contrast to the low level of variability of HTLV-I among different isolates, individual isolates form quasispecies structures. Elucidating the mechanisms connecting these two phenomena will be one of the future problems in the study of the molecular evolution of HTLV-I and HTLV-II.     

Interaction between the immune and central nervous systems

Much of the understanding of tolerance has focused on the requirements for antigen-specific lymphocyte activation and function. However, there is increasing evidence for anatomic regulation of effector access to self antigens. Recently, a number of studies have provided evidence for tissue-specific “addressins” in chemokine/chemokine receptor pairs. The central nervous system (CNS) provides special anatomic barriers to the movement of cells from the vascular compartment to the parenchyma. Herein I raise the possibility that antigen, perhaps through specialized antigen-presenting cells, may play a role in regulating access of activated lymphocytes into the CNS parenchyma. The results suggest that a reexamination of the widely held dogma that all activated lymphocytes have access to the CNS parenchyma is nessary to understand the relationship between the immune and central nervous systems.     

The interface between tapasin and MHC class I: identification of amino acid residues in both proteins that influence their interaction

Prior to the binding of antigenic peptide, a complex of chaperone proteins associates with the Major Histocompatibility Complex (MHC) class I heavy chain/β₂m heterodimer. Although each dornain of the MHC class I heavy chain contains amino acid resid uses that influence chaperone binding, there are several pieces of evidence that point to an interaction between the MHC clas 1α2/α3 domains and tapasin. In egard to the site on tapasin involved in the tapasin/MHC interface, we have found that a particular region of tapasin (containing amino acid residues 334–342) is necessary for the binding of tapasin to the MHC class I heavy chain. Our results also indicate that amino acids in this region of tapasin also affect the proportion of MHC class I open forms expressed at the cell surface and MHC class I egress from the endoplasmic reticulurn. Based on these results and those obtained by other laboratories, a model for MHC class I/tapasin interaction is proposed.     

Glucocorticoids down-regulate dendritic cell function in vitro and in vivo

Exogenous glucocorticoid hormones are widely used as therapeutical agents, whereas endogenous glucocorticoids may act as physiological immunosuppressants involved in the control of immune and inflammatory responses. The optimal activation of T lymphocytes requires two distinct signals: the major histocompatibility complex-restricted presentation of the antigen and an additional co-stimulatory signal provided by the antigen-presenting cells. There is ample evidence that, among the cells able to present the antigen, the dendritic cells (DC) have the unique property to activate antigen-specific, naive T cells in vitro and in vivo, and are therefore required for the induction of primary immune responses. In this work, we tested whether glucocorticoids affected the capacity of DC to sensitize naive T cells. Our data show that, in vitro, the steroid hormone analog dexamethasone (Dex) affects the viability of DC, selectively downregulates the expression of co-stimulatory molecules on viable DC, and strongly reduces their immunostimulatory properties. In vivo, a single injection of Dex results in impaired antigen presenting function, a finding which correlates with reduced numbers of splenic DC. These results show that glucocorticoids regulate DC maturation and immune function in vitro and in vivo and suggest that this mechanism may play a role in preventing overstimulation of the immune system.     

猪囊尾蚴抗原的免疫化学研究

应用琼脂双扩散(DID)、免疫电泳(IEP)、聚丙烯酰胺凝胶电泳(PAGE)和十二烷基硫酸钠聚丙烯酰胺凝胶电泳(SDS-PAGE)对猪囊尾蚴的各部分抗原,即完整幼虫、囊液、头节和囊壁抗原进行分析。实验结果表明,4种抗原间存在相同的抗原成分。囊液中含有糖蛋白和脂蛋白。囊液、头节和囊壁蛋白质的主要分子量均在100KDa以下。囊液与头节有3条分子量相同的主带(60、46、38KDa),与囊壁只有1条分子量(46KDa)相同主带。从免疫学和生物化学角度初步探索了囊液、头节和囊壁蛋白质之间的相互关系及主要蛋白质组分。     

Effects of aspirin on nasal responses in atopic subjects

Preliminary experiments indicated that solutions of aspirin (ASA) in buffered saline, pH 7.35, did not significantly change nasal airways resistance (NAR) when 0.1 ml of solution containing 22.5 mg (or less) per deciliter was sprayed into each nostril. Subsequently it was shown that this quantity of ASA administered intranasally did not significantly change NAR responses 15 min later to intranasal administration of increasing concentrations of histamine, methacholine, or an irritant (NH₃ gas). However, the same atopic subjects demonstrated significantly decreased responses to intranasal challenge with short ragweed extract (SRW) after intranasal ASA. In addition, prior oral administration of ASA, Na salicylate, and indomethacin significantly inhibited nasal challenge responses to SRW in sensitive subjects under controlled conditions.     

耐热可溶性戊型肝炎病毒基因工程抗原的表达

目的 利用硫氧还蛋白融合表达系统表达戊型肝炎病毒（Hepatitis E virus,HEV)结构基因片段，获得耐热，可溶、具有生物活性的HEV基因工程抗原。方法 将HEVORF26964-7126nt基因片段插入硫氧还蛋白融合表达载体pThioHisA，转化大肠埃希菌BL21，经IPTG诱导，表达融合蛋白。裂解细菌后，离心，取上清置于80℃处理10min，再次离心，取上清用ELISA方法测定表达产物的生物活性。结果 SDS-PAGE分析表明，HEV结构基因获得高效表达，相对分子质量约为20000，耐热，水溶性好，ELISA证实具有HEV特异抗原性。结论 应用硫氧还蛋白融合表达系统成功表达了耐热，可溶，具有生物活性的HEV基因工程抗原。     

Sequence variation within the human immunodeficiency virus V3 loop at seroconversion

Analysis of the HIV-1 V3 quasispecies present in an individual at the time of seroconversion was carried out. The polymerase chain reaction (PCR) was used to amplify proviral HIV-1 DNA extracted from peripheral blood mononuclear cells from a patient who was viraemic (p24 = 15 pg/ml) and had an equivocal HIV-1 antibody status. The PCR products were cloned and the DNA sequence determined for 15 clones. These data showed that the V3 region contained only limited sequence heterogeneity with a major variant accounting for 66% of the protein quasispecies present. The protein sequence of the principal neutralising domain on all species contained the relatively rare GPGKTL motif rather than GPGRAF. The relevance of these data for early stages of HIV infection are discussed.     

Protein sorting within the mhc class II antigen-processing pathway

Major histocompatibility complex (MHC) class II molecules are required for the presentation of antigenic peptides that are derived predominantly from internalized proteins. The assembly of MHC class II/peptide complexes occurs within endosomal compartments of antigen-presenting cells (APCs). Therefore, for assembly to occur, MHC class II molecules, foreign proteins, and accessory molecules must be sorted to appropriate intracellular sites. My laboratory is trying to understand how proteins are sorted to various antigen-processing compartments as well as to conventional endosomal organelles. Using chimeric marker proteins and a variety of biochemical and genetic approaches, we are addressing the specificity of protein sorting and the mechanisms by which sorting signals are deciphered. By using a similar chimeric protein approach to target endogenous proteins to distinct compartments, we hope to address the role of processing events in each compartment in the generation of MHC class II ligands.     

Epstein-Barr病毒壳抗原gp125的纯化和应用

目的研制ｅｐｓｔｅｉｎ－Ｂａｒ（ＥＢ）病毒诊断试剂。方法将重组痘苗病毒表达的Ｅｐｓｔｅｉｎ－Ｂａｒ病毒（ＥＢＶ）壳抗原（ＶＣＡ）主要多肽ｇｐ１２５纯化，作为诊断抗原建立了酶联免疫吸附试验（ＥＬＩＳＡ），检测了４８份鼻咽癌（ＮＰＣ）病人血清及１０份正常人血清中的ＶＣＡ／ＩｇＡ抗体。结果该方法与免疫荧光（ＩＦ）检测结果一致，但ＥＬＩＳＡ的平均几何滴度（ＧＭＴ）是ＩＦ的１２倍。结论以纯化的ＥＢ病毒壳抗原主要多肽ｇｐ１２５作为诊断抗原建立的检测方法，更适合于ＥＢＶ相关疾病的血清学诊断和血清流行病学调查。