比色法与核磁共振法测定A、C、Y、W135群脑膜炎球菌荚膜多糖氧乙酰基含量的比较

目的比较Hestrin比色法(简称比色法)和核磁共振(nuclear magnetic resonance,NMR)法在检测A、C、Y、W135群脑膜炎球菌荚膜多糖氧乙酰基(O-Acetyl,OAc)含量的相关性和精密度。方法用比色法和NMR法测定A、C、Y、W135群脑膜炎球菌荚膜多糖及其多糖衍生物,Y、W135群荚膜多糖水解物的OAc含量,比较分析两种方法的相关性及精密度。结果两种方法检测A、C、Y、W135群脑膜炎球菌荚膜多糖OAc含量的决定系数分别为R~2≥0.954、R~2≥0.960、R~2≥0.969、R~2≥0.972;比色法检测3批C群脑膜炎球菌荚膜多糖(PSC)OAc含量的精密度,SD值分别为0.21、0.21、0.18,对应CV值分别为9.03%、9.01%、8.70%(95%置信区间);NMR法检测3批A群脑膜炎球菌荚膜多糖(PSA)OAc含量的精密度,SD值分别为0.66、0.78、0.83,对应CV值分别为0.72%、0.85%、0.93%(95%置信区间);结论比色法和NMR法在检测A、C、Y、W135群脑膜炎球菌荚膜多糖OAc含量方面相关性良好,精密度良好,核磁法较比色法精密度更高。     

Four monoclonal antibodies against capsular polysaccharides of Neisseria meningitidis serogroups A,C, Y and W135: Its application in identity tests

Murine hybridoma monoclonal antibodies (MAbs) were produced against the capsular polysaccharide (CPs) of serogroups A, C, W₁₃₅ and Y meningococci (MenA, MenC, MenW, MenY) in order to develop immunological reagents for the identification of meningococcal polysaccharides. Each serogroup-specific MAb reacted with the CPs from its homologous serogroup only and did not react with CPs from the other three serogroups. The affinity constant (Ka) of the four MAbs measured by non-competitive ELISA was 6.62 × 10⁹, 2.76 × 10⁹, 1.48 × 10⁹ and 3.8 × 10⁹ M^?1 for MenA, MenC, MenW and MenY MAbs respectively. The application of these MAbs for identity tests was demonstrated by their abilities to correctly identify the CPs from serogroups A, C, W₁₃₅ and Y in meningococcal CPs-based vaccines through ELISA. The MAbs obtained in this work are a very valuable set of tools for study meningococcal polysaccharides vaccines.     

Nucleotide sequence analysis of purH and purD genes from Salmonella typhimurium

The purH and purD genes coding for the 5'-phosphoribosyl 5-amino-imidazole-4-carboxamide (AICAR) transformylase and 5'-phosphoribosyl-glycinamide (GAR) synthetase, respectively, were identified on a 4.8 kb Eco RI fragment of chromosomal DNA from Salmonella typhimurium. Nucleotide sequence analysis of the cloned fragment revealed the presence of two large open reading frames (O.R.F.), which were separated by 11 base pairs (bp). Substantial DNA and amino acid sequence homology was noted between the purH and purD genes of S. typhimurium and Escherichia coli. Expression of the Salmonella purD gene in a T7 polymerase/promoter system revealed the presence of a 49 kDa protein band by SDS-PAGE and subsequent autoradiography. The purH gene of Salmonella was not expressed since the 5' end of this gene was not cloned.     

Nucleotide sequence analysis of the Leptospira biflexa serovar patoc rpsL and rpsG genes.

The Leptospira biflexa rpsL and rpsG genes were sequenced. Although similar in many respects, proteins encoded by these L. biflexa genes had several unusual features when compared with homologous proteins of other organisms. Unlike the rpsL genes of other eubacteria, the L. biflexa rpsL gene is adjacent to a rpoC-like gene.     

Cloning and sequence analysis of genes encoding Staphylococcus hyicus exfoliative toxin types A, B, C, and D

Exfoliative toxins produced by certain strains of Staphylococcus hyicus mediate exudative epidermitis in pigs. In this study the genes coding for four different exfoliative toxin from S. hyicus (ExhA, ExhB, ExhC, and ExhD) were cloned and sequenced. The coding sequence of the four toxin genes ranged from 816 to 834 bp. The amino acid sequences of these four toxins were homologous to the earlier described exfoliative toxins SHETB from S. hyicus and ETA, ETB, and ETD from Staphylococcus aureus. The homology between the S. hyicus toxins was at the same level as the homology to the exfoliative toxins from S. aureus. The toxins showed similarity to serine proteases, including preservation of the catalytic tract in ExhA, ExhB, and ExhC. However, in ExhD, Asp in the putative catalytic tract was replaced with Glu. The recombinant toxins could be expressed in Escherichia coli, and three of the four toxins were recognized by monoclonal antibodies raised against native exfoliative toxins.     

离子色谱法测定ACYW135群脑膜炎球菌结合物中Y群及W135群多糖含量

目的利用离子色谱法即高效阴离子交换柱层析—脉冲安培检测法(HPAEC-PAD),测定ACYW135脑膜炎球菌多糖蛋白结合物中Y群和W135群多糖含量的方法,并加以验证。方法将ACYW135脑膜炎球菌多糖蛋白结合物中Y群和W135群多糖用三氟乙酸(TFA)水解为特异性单糖(葡萄糖、半乳糖),并去除水解液中残留的TFA,用HPAEC-PAD分析检测,用PA10糖分析柱分离单糖,电化学检测器测定葡萄糖及半乳糖含量,用Chromeleon色谱工作站记录并分析数据。对上述方法进行专属性、准确性、重复性验证,确定该方法的检出限和定量限。结果 Y群和W135群多糖在TFA2.5 mol/L(终浓度)、90℃、4 h可完全水解为葡萄糖、半乳糖。对照品葡萄糖及半乳糖在0.10~60.00μg/m L范围内,质量浓度和色谱峰面积呈较好的线性关系,r均大于0.99,回收率为87.94%~109.80%,相对标准偏差(RSD)为1.00%~2.00%,检出限为0.05μg/m L(信噪比3∶1),定量限为0.10μg/m L(信噪比10∶1)。结论离子色谱法可同时检测脑膜炎球菌多糖蛋白结合物中Y群和W135群糖含量,该方法操作简便、灵敏、快速,干扰小,重现性好,适用于对相关疫苗生产过程中的质量控制。     

The adhesive properties of meningococci from serogroups A, B and C

The adhesive properties of 261 meningococcal strains have been studied by the methods of the hemagglutination test, the test of adhesion on buccal epithelial cells and electron microscopy. The study has revealed that adhesive properties can be observed in the strains of all groups under study (A, B and C) isolated from patients and carriers, including those isolated from the nasopharynx, blood and liquor, adhesive properties occurring in newly isolated strains with greater frequency than in museum ones. The simultaneous use of all three above-mentioned methods increases the possibility of the detection of meningococcal strains with adhesive activity.     

Nucleotide sequence of Rhizobium meliloti nodulation genes

A Rhizobium meliloti DNA region, determining nodulation functions common in different Rhizobium species, has been delimited by directed Tn5 mutagenesis and its nucleotide sequence has been determined. The sequence data indicates three large open reading frames with the same polarity coding for three proteins of 196, 217 and 402 (or 426) amino acid residues, respectively. We suggest the existence of three nod genes on this region, which were designated as nodA, B and C, respectively. Comparison of the R. meliloti nodA, B, C nucleotide and amino acid sequences with those from R. leguminosarum, as reported in the accompanying paper, shows 69-72% homology, clearly demonstrating the high degree of conservation of common nod genes in these Rhizobium species.     

Nucleotide sequence of the Bacillus subtilis trpE and trpD genes

Several overlapping portions of the tryptophan (trp) operon of Bacillus subtilis have been cloned into plasmid pBR322. The nucleotide sequence of the region comprising the trpE and trpD genes and a portion of the trpC gene has been determined. When the deduced amino acid sequences of these genes are compared with their counterparts in Escherichia coli, several regions of striking homology are seen. The probable initiation codons for the trpE, D and C genes are each preceded by a recognizable Shine-Dalgarno sequence. The coding sequences for the trpE and trpD genes and for the trpD and trpC genes overlap slightly, leaving no intercistronic regions between the genes.     

Nucleotide sequence of the thymidylate synthase B and dihydrofolate reductase genes contained in one Bacillus subtilis operon

The nucleotide sequence of the thymidylate synthase B (thyB) and dihydrofolate reductase (dfrA) gene regions from wild-type and trimethoprim-resistant (TpR) mutant strains of Bacillus subtilis 168 was determined. The sequenced region contains two open reading frames, ORF1 and ORF2, which correspond to thyB and dfrA, respectively, and overlap by one nucleotide. The thyB-dfrA genes encode 267 and 168 amino acid polypeptides, respectively, and are present in the order of thyB - dfrA in 5'----3' orientation. This gene order differs from those which have been found in other organisms so far. S1 mapping analysis indicated that both genes were transcribed from a single promoter located upstream from the thyB gene. Thus, the genes belong to an operon. A nucleotide substitution from 'A' in the wild type to 'C' in the TpR mutant was located in the dfrA gene region, with predicted conversion of isoleucine-95 (wild type) to leucine-95 (mutant) in dihydrofolate reductase (DHFR). It is suggested that the affinity between DHFR and Tp is reduced by this alteration.     

Nucleotide sequence analysis of a mouse Y chromosomal DNA fragment containing Bkm and LINE elements

The strong suppression of crossing-over between the X and Y chromosomes permits rapid accumulation of repetitive sequences in the Y chromosome. To gain insight into the mechanism responsible for the sequence amplification, it is essential to characterize Y chromosomal repetitive sequences at the molecular level. Here, we report the entire nucleotide sequence (3,902bp) of AC11, a mouse sequence that is repeated 300 times in the Y chromosome. AC11 is AT rich (32.8% GC), and contains many short poly(A) sequences. In addition, it has Bkm and LINE sequences as well as a Y chromosome-specific sequence. The Bkm sequence consists of typical (GATA) and (GACA) repeating units, whereas the LINE sequence deviates considerably from other mouse LINE sequences (71–76% identity) and may be considered atypical. The Y chromosome-specific region seems to be unique and does not identify similar sequences in the GenBank library. The information obtained from the nucleotide sequence should form the foundation to study the evolutionary processes through which AC11-related sequences have accumulated in the mouse Y chromosome.     

Primary and secondary immune response of mice to polysaccharide antigens of meningococcal serogroups A and C

The peculiarities of the primary immune response, the formation of immunological memory and the secondary immune response to serogroup A and C meningococcal polysaccharides were studied in 7 strains of inbred mice, hybrids F1 and in noninbred animals. The passive local hemolysis test and the passive hemagglutination test indicated that the intensity of immune response to A and C polysacchardies depended on the genotype of the animals: both antigens induced the most intense response in CBA and BALB/c mice. The primary immune response to the both antigens was characterized by a short latent period, a rapid (by days 4-5) increase in the amount of antibody-producing cells in the spleen and in antibody titer in the blood serum to the maximum level, and a pronounced decrease inantibody formation by days 6-7 followed by a gradual extinction of the response. A single injection of A and C polysaccharides in a dose of 0.5 microgram induced the formation of immunological memory in mice, persisting for at least 4 weeks and manifesting after reimmunization as the increased or more prolonged synthesis of IgM and IgG.     

Nucleotide sequence of Klebsiella pneumoniae lac genes.

The nucleotide sequences of the Klebsiella pneumoniae lacI and lacZ genes and part of the lacY gene were determined, and these genes were located and oriented relative to one another. The K. pneumoniae lac operon is divergent in that the lacI and lacZ genes are oriented head to head, and complementary strands are transcribed. Besides base substitutions, the lacZ genes of K. pneumoniae and Escherichia coli have suffered short distance shifts of reading frame caused by additions or deletions or both during evolutionary divergence from a common ancestral gene. Relative to corresponding E. coli sequences, the nucleotide sequences of the lacZ and lacY genes are 61 and 67% conserved, and the lacI genes are 49% conserved. A comparison of both nucleotide and amino acid sequences revealed that the K. pneumoniae and E. coli lacI genes and lac repressor proteins each are related to the galR gene and gal repressor of E. coli to about the same extent. In terms of evolutionary relationships, the divergence of the forerunner of the galR gene from an ancestral lac repressor gene preceded separation and differentiation of the K. pneumoniae and E. coli lac repressor genes.