Zhonghua Minguo wei sheng wu ji mian yi xue za zhi = Chinese journal of microbiology and immunology最新文献

Antibody responses of sero-confirmed flavivirus-infected patients were investigated by hemagglutination-inhibition (HI) tests against acute phase sera (S1) and convalescent phase sera (S2) using JE virus (JEV) JaGAr# 01 strain antigen (J-Ag) and dengue virus (DV) type 1 Hawaiian strain antigen (D-Ag). Analysis of the test results showed that depending on the combinations of HI responses to both antigens, the sero-confirmed patients could be divided into five classes: primary JE, secondary JE, primary D (JEV-uncontracted), primary D(JEV-contracted), and secondary D(JEV-contracted) patients. The diagnostic combinations of responses to HI tests for the infections were discussed and defined in this paper.

The bacterium Serratia marcescens shows population surface migration (swarming) phenomenum on an LB swarming plate, and differentiated cells can be observed at the swarming front. How the cell population differentiates during swarming on the agar surface is not known, neither is it clear whether cells with differentiated characteristics can be observed in broth culture. To monitor the population cell differentiation in a highly sensitive way without cell destruction, experiments were designed using bacterial luciferase genes luxAB as the reporter genes to allow direct monitoring of the differentiating cells through bioluminescence. An isogenic S. marcescens strain was constructed with luxAB under the control of the promoter of flagellin gene hag (phag::luxAB). Patterns of cell differentiation were monitored either by direct X-ray film exposure and/or by Autolumat luminometer detection. Results show that population cell differentiation on the agar surface occurs first in a temporal and then spatial way during colonial growth. It was also found that cells harvested from both the spreading agar plate and broth culture showed differentiation patterns similar to those from swarming cells, suggesting that the agar surface culture may not be essential for the formation of differentiated cells.

Competitive ELISA was used for the detection of neutralizing antibody to JE. Based on the principle that human serum JE antibody competed with JE monoclonal antibody (MAb) for JE antigen, it was found that 3 JE MAbs (E3-3, NPF-5 and NNN-5) were suitable for competitive ELISA for the detection of JE neutralizing antibody. The sensitivity of cometitive ELISA for 29 JE confirmed serum specimens with titer of plaque reduction neutralization test (PRNT) was checked to be 82.1% (23/28). The specificity of E3-3 MAb to JE used in competitive ELISA was 100%. Correlation coefficient of JE confirmed cases of 57 hemagglutination inhibition (HI) titers in 1995 and 37 PRNT titers in 1994 compared with competitive ELISA were 0.744 and 0.732, respectively. Compared the competitive ELISA titers of 154 sera of healthy people with PRNT titers, the results showed that 70% of the sera could be detected by competitive ELISA which saved a lot of time and manpower.

The bacteria which could perform nitrification and denitrification simultaneously from nitrogen containing wastes in Taiwan were isolated by using the probes made from random DNA fragments of Thiosphaera pantotropha. Two isolates were identified and named Alcaligenes faecalis subsp. faecalis strain 1 and strain 2 respectively. The effects on nitrification and denitrification by different medium pH, oxygen content, addition of different electron donors or inhibitors were studied. The isolates not only could perform nitrification, but also denitrification even in the presence of oxygen. Potassium cyanide could inhibit denitrification; hydrazine and hydroxyamine could inhibit nitrification. Alcaligenes faecalis subsp. faecalis strain 2 shows better denitrification.

Helicobacter pylori is now recognized as possibly playing an etiologic role on the development of chronic gastritis, peptic ulcers and adenocarcinoma of the distal stomach. CLO test and polymerase chain reaction (PCR) assay are rapid, biopsy-dependent diagnostic tests for H. pylori identification. In this study, we assessed four diagnostic methods (CLO test, PCR assay, culture and histological examination) for H. pylori detection in biopsy specimens from 78 patients with gastroduodenal diseases and investigating the efficiency of CLO test and PCR assay for the diagnosis of H. pylori infection. H. pylori was identified in 75.6%, 75.6%, 64.1%, 69.2% of patients by CLO test, PCR assay, culture and histological examination, respectively. Compared with the detection of H. pylori by culture and/or histological examination, the sensitivity and specificity of the CLO test were 98.2% and 81.8%, respectively, whereas the sensitivity and specificity of PCR assay were 96.4% and 77.3%, respectively. According to the H. pylori infection state as determined from the results of three concordant tests, the sensitivities of culture, CLO test, histological examination, and PCR assay were 90.9%, 96.4%, 98.2% and 100%, respectively. Whereas, the specificity was 100%, 95%, 95% and 90% for culture, CLO test, histological examination, and PCR assay, respectively. We found that both CLO test and PCR assay were highly sensitive and specific for H. pylori identification; however, PCR assay was more sensitive than other methods for detecting the specimens after patients received treatment. The results of this study suggest that CLO test is a rapid and sensitive method of screening for H. pylori infection and that PCR assay could provide an accurate indication of the state of infection both during treatment for eradication of H. pylori and at follow-up.

The importance of coagulase-negative staphylococci, especially Staphylococcus epidermidis in clinical and nosocomial infection are recognized increasingly in recent years. A rapid and accurate identification of S. epidermidis is therefore important and necessary. A new test, susceptibility to desferrioxamine, coupled with trehalose fermentation has been recommended for the identification of this organism. However, the medium and method used are different from what has been recommended by the NCCLS. To investigate the feasibility of using the desferrioxamine susceptibility test in conjunction with the routinely used disc agar diffusion test, we employed 111 staphylococcal strains (including 51 S. epidermidis isolates, 15 S. hominis and 45 other coagulase-negative staphylococci) as test organisms, and followed the procedures recommended by the NCCLS in which Mueller-Hinton agar and standard inoculum were used. Results indicated that all strains of S. epidermidis and S. hominis were susceptible to 1 mg desferrioxamine (the diameter of the inhibition zone were 28-37 mm). The minimum inhibitory concentrations of desferrioxamine to S. epidermidis and S. hominis isolates were determined to be 125 micrograms/ml. Further differentiation of S. hominis and S. epidermidis can be made by their ability to ferment trehalose, the former could while the latter could not. We conclude that the desferrioxamine susceptibility test of coagulase-negative staphylococci can be used in conjunction with the routine disc agar diffusion method. S. epidermidis can be identified rapidly and accurately by its susceptibility to 1 mg desferrioxamine and inability to ferment trehalose.

House dust mite allergens from Dermatophagoides pteronyssinus is an important cause of severe allergic asthma and rhinitis in many countries. Although several low to medium molecular weight allergens had been well characterized, limited studies on the high molecular weight IgE-binding components were reported. In this study, a 94 kD high molecular weight allergen from crude mite body extract of D. pteronyssinus was purified and characterized. Monoclonal antibody (mAb) affinity chromatography and high performance liquid chromatography were used to purify 94 kD allergen. Its antigenicity and allergenicity were confirmed by in vitro and in vivo studies. Two mAbs 2205-3.45 and 2220-7.25 specific to 94 kD high molecular weight component of D. pteronyssinus were generated. The epitopes recognized by these mAbs were species-specific. Enzyme-linked immunosorbent assay (ELISA) of IgE reactivity in the sera from 40 asthmatic children allergic to D. pteronyssinus showed that 37.5% of them had significantly higher optical density values (range 0.011 to 0.452) than normal (range 0.013 to 0.035). In in vivo skin test showed that 9 out of 20 (45%) asthmatic children were positive to 94 kD allergen. The results demonstrate that 94 kD high molecular weight component is an important allergen existing in house dust mite in Taiwan.

A DNA amplification system using the polymerase chain reaction (PCR) combined with a nonradioactive digoxigenin-labeled probe hybridization was employed to detect Mycobacterium tuberculosis in clinical specimens. One hundred and thirty specimens were tested by several methods including routine culture method, acid-fast staining, BACTEC 460 detection system, PCR, and PCR-hybridization techniques. Sixteen out of 130 specimens were culture positive on Middlebrook 7H11 agar, 10 were positive with acid-fast staining, 18 were positive with BACTEC 460 detection system, 23 were positive with PCR technique, and 62 were positive with PCR-nonradioactive hybridization technique. When compared with culture results, PCR-nonradioactive hybridization had an overall sensitivity of 100% (16/16) and a specificity of 59.7% (68/114). However, 28 out of 46 (60.9%) PCR-nonradioactive hybridization positive specimens which were culture negative had clinical data supporting the diagnosis of tuberculosis. In addition, 4 specimens which were negative by routine culture but positive by BACTEC 460 detection system and two specimens which were negative by routine culture but positive by acid-fast staining were all positive by PCR-hybridization technique. These data suggest that routine culture method may not be sensitive enough to detect M. tuberculosis in all kinds of clinical specimens. Taking this deviation into account, the specificity of PCR-nonradioactive hybridization technique may be rectified range from 63% (68/108) to 79.1% (68/86). PCR itself is not satisfactory enough to detect M. tuberculosis in specimens (the sensitivity and specificity were 56.3% and 87.7%, respectively) in this study. However, when it combines with DNA hybridization technique, they can be a very powerful and rapid diagnostic tool to detect M. tuberculosis in clinical specimens.

In order to evaluate the Japanese encephalitis virus (JEV) vaccination program in rural Taiwan, we conducted a seroepidemiological survey of JEV among rural children 3 to 6 years of age in Taiwan. The children were selected through a systemic sampling following stratification by age of children in 4 selected aboriginal villages and 4 adjacent nonaboriginal villages. The overall vaccine coverage rate for the primary (2 doses) dose was 81.2% (1853/2281) with higher rates (87.7%-87.9%) found among the more recent birth cohort of 3 to 4 years of age. The neutralizing antibody (NT) against JEV was measured with plaque reduction neutralization test (PRNT) using Nakayama strain as the virus. With a positive NT antibody defined as > or = 1:10 dilution of serum yielding more than 50% plaque reduction, the overall JEV NT antibody positive rate among children receiving 3 doses of vaccine was 67%. However, the age-specific positive rates varied significantly with varying ages; the lowest of 47% being among children 4 years of age which was lower than the rates of 68%, 76% and 87% among children of 3, 5 and 6 years of age, respectively. This trend of rising seropositive rates of JEV antibody with increasing age among 4 and 6 years of age was also noted among children who had received no vaccine, suggesting the importance of natural infection among rural Taiwanese children. Despite the high frequency of natural infection, the seropositive rates of JEV antibody still correlated well with the dose of vaccine received, i.e., 67% (1122/1664), 66% (65/97), 33% (4/12) and 40% (19/47) for children receiving 3, 2, 1, and 0 dose of JE vaccines, respectively (P < 0.0001 Chi-square for trend test). When stratified analysis by dose and by type of vaccines was conducted, a significantly higher seropositive rate of JEV NT antibody was noted among children receiving JE vaccine of Beijing type (87%) than children receiving Nakayama type (39%) (p < 0.0001, Chi-square test). Our data indicated that the JEV vaccination, in conjunction with JEV natural infection, has maintained high JEV NT antibody level among rural children of Taiwan.

Pertussis toxin (PT), a typical A-B oligomer exotoxin of Bordetella pertussis, has been demonstrated to be an essential protective antigen for acellular pertussis vaccine against whooping cough. In order to investigate the associated functionality ascribed to its components, we have purified A and B oligomers for the activity study. The A oligomer (S1 subunit) of PT was expressed in E. coli B834 (DE3) harboring expression vector (pET-20b) with the insert of S1 coding region and purified by metal-chelating column. The B oligomer was isolated by a single-step purification procedure. Individually, recombinant S1 and B oligomer exhibited quite distinct biological activities in vivo. S1 subunit induced leukocytosis-promoting (LP) activity, but did not affect mouse body weight-gain. On the contrary, B oligomer reduced mouse body weight-gain but did not reveal LP activity. In vitro, the combination of S1 subunit and B oligomer could enhance the toxic activities as exhibited by native PT and showed an additive toxicity in CHO cell clustering test and hemagglutination assay.