Antibodies to HTLV-I in populations of the southwestern Pacific

Sera collected from 1,102 individuals in 14 populations of the southwestern Pacific between 1956 and 1979 were tested by ELISA for antibodies to human T-cell leukemia virus type I (HTLV-I). Selected sera were also tested by particle agglutination and immunoblotting. Six of the populations had prevalences of antibodies greater than 4%, two populations had prevalences greater than 15%. Six populations had antibody prevalences of 2% or less. Three populations from the coast and northern islands of New Guinea had high prevalences of antibodies, while three New Guinea highland groups had virtually none. One population from the Solomon Islands had a high prevalence, while two others had very low prevalences. Two populations from small remote islands in Vanuatu both had high prevalences. Pacific sera did not neutralize a standard strain of virus readily neutralized by Japanese, European, and American sera. We conclude that infections with HTLV-I, some acquired more than 20 years ago, are widespread throughout the southwestern Pacific, even in several very isolated populations, although others have been spared. Some strains of HTLV-I in populations of the Pacific may have substantially different envelope proteins from prototype strains of America, Europe, and Japan.     

Enzyme-immunoassay in diagnosis of hepatitis with emphasis on the detection of "e" antigen (HBeAg).

A brief survey of the application of enzyme-immunoassay (EIA) for the detection of hepatitis B surface antigen (HBsAg), hepatitis A, and their corresponding antibodies is given. The preliminary results of a similar EIA for detection of hepatitis B-related "e" antigen (HBeAg) and its antibody (anti-HBe) are reported. This EIA is much more sensitive than immunodiffusion: at least 128 times for HBeAg and at least 512 times for anti-HBe. HBsAg and its antibody do not interfere with the test. Only a few sera strongly positive for rheumatoid factor gave rise to false-positive results, as was demonstrated by a confirmatory test.     

Enzyme-linked immunosorbent assay (ELISA) for antibodies to Clostridium difficile toxins in patients with pseudomembranous colitis and antibiotic-associated diarrhoea

Enzyme-linked immunosorbent assay (ELISA) was established with purified toxins from Clostridium difficile as antigene to measure antibody response in patiensts with pseudomembranous colitis (PMC) and prolonged antibiotic-associated diarrhoea (AAD). Positive ELISA titres were defined in a control population. Antibodies of IgG class against toxin B were demonstrated in 6/88 (7%) control sera and in 31/61 (51%) sera from 11/19 (58%) patients. Antibodies of IgA class were found in one patient while antibodies of IgM class were not demonstrated. ELISA antibodies against toxin A were not demonstrated. For comparison a neutralization test was performed and neutralizing antibodies to toxin B but not to toxin A were demonstrated in 10/61 (16%) sera from 4/19 (21%) patients and in none of the controls. ELISA was found to be a more sensitive assay than neutralization. ELISA antibodies were detected from the third week of the disease while neutralizing antibodies appeared after 5 weeks. Lack of an antibody response in ELISA seemed to correlate to a more severe colitis.     

恙虫病东方体Sta56抗原的原核表达、纯化及其在间接ELISA中的应用

目的　构建含恙虫病东方体sta5 6基因的重组表达质粒 ,在E .coli中表达Sta5 6重组抗原 ,纯化后用于间接ELISA检测恙虫病。方法　从含有恙虫病东方体Karp株sta5 6基因的重组质粒TOPO sta5 6扩增出截短的sta5 6 ,定向插入pET30a载体 ,转化大肠杆菌BL2 1(DE3) ,IPTG诱导表达 ,用SDS PAGE及Westernblot进行分析 ;采用电洗脱方法纯化重组抗原并应用于间接ELISA检测恙虫病。结果　以截短的sta5 6基因片段构建了重组表达质粒pETOt95 7,重组的Sta5 6抗原可在E .coli中以融合蛋白的形式有效表达 ,SDS PAGE显示了一条相对分子质量 (Mr)为 4 0 .3× 10 3 的蛋白表达带 ,West ernblot证实该融合蛋白能被恙虫病患者阳性血清所识别。电洗脱纯化的重组抗原应用于间接法ELISA检测恙虫病 ,与间接免疫荧光法IFAT比较 ,其敏感性和特异性分别为 91.7%和 76 .5 %。结论　在大肠杆菌中表达的Sta5 6重组抗原具有免疫反应性 ,纯化后可用作免疫诊断试剂。     

ELISA检测TT病毒及感染状况报告

ＴＴ病毒（ＴＴＶ）是近几年来新发现的一种与输血相关的新型病毒。近年来报道甚多，但在贵州地区至今尚无有关捐血人群ＴＴＶ感染方面的报道。笔者采用酶联免疫吸附试验（ＥＬＩＳＡ），对贵阳地区近年来部分捐血人群进行ＴＴＶ实验检测，旨在了解贵阳地区捐血人群的ＴＴＶ感染情况，并提供有实用价值的资料。１ 材料和方法１．１材料 调查对象：贵阳地区捐血者１９９９年６月至２００１年４月共３３５例。实验标本全部来自血液中心街头流动采用血车及来我中心捐血者。及时分离血清置－２０℃冻存保存备检。ＥＩＪＳＡ读数仪为ＫＭ＿2型（…     

Antigenic properties of ovalbumin following heat denaturation at different temperatures: Comparison with enzymatic Denaturation

Eighteen monoclonal antibodies (MAbs) raised from mice which were immunized with either native ovalbumin (NOA) or ovalbumin which had been heat denatured at 100°C, (HDOA) were used to study antigenic modifications induced by either heat or subtilisin treatment. Using enzyme immunoassays (EIA) we have defined three major groups of antigenic sites: Group I thermolabile native epitopes; Group II relatively thermostable native epitopes; Group III epitopes specific to heat‐denatured ovalbumin. Heatdenatured ovalbumin can be separated into monomers and polymers which constitute 1% and 99% of the molecules respectively. Whereas MAbs belonging to Groups I and II bound to the monomeric form (mHDOA), MAbs belonging to Group III only bound to the polymeric form (pHDOA). Plakalbumin (PK) behaved similarly to pHDOA since it was recognized by many MAbs from Group III and a few from Group II. Nevertheless, PK remained as a monomeric molecule, whereas heat‐denatured ovalbumin existed mainly as polymeric aggregates. The epitopes present on ovalbumin after different heating procedures (time/temperature) were found to be stable after cooling, thus allowing specific recognition by different MAbs. The critical modification of the protein structure was found to take place at 75°C. Two main conclusions can be drawn from these results: (i) heat and enzymatic denaturation of ovalbumin led to similar antigenic modifications—these may be explained by the exposure of hydrophobic residues in both HDOA and PK as evidenced from 8‐anilino‐1‐sulphonic acid fluorescence spectra; (ii) the panel of ovalbumin‐specific MAbs was able to differentiate between the various heat treatments which had been applied to ovalbumin within the range 65–85°C, even after subsequent cooling. The aggregation of ovalbumin molecules during the heating process constitutes the main type of antigenic modification.     

Methodologic problems in establishing normal values for IgG subclass concentrations in a pediatric population; comparison of radial immunodiffusion and ELISA methods

The aim of this study was to establish an enzyme-linked immunosorbent assay (ELISA) to measure IgG subclasses by means of monoclonal antibodies. The distribution of IgG subclass protein concentrations in sera from 227 healthy Danish children and 90 adults was measured. Furthermore, this newly established ELISA was compared with different assay systems for determination of IgG subclasses: two radial immunodiffusion methods (RID), one using polyclonal and one using monoclonal antibodies, as well as a commercially available ELISA kit. There was good agreement of results obtained by the different methods of measuring IgG3 and IgG4 concentrations. There was good correlation between results obtained by both RID methods. Despite good correlation between the assays, the ELISA kit showed higher levels of IgG1 in all investigated sera, and the ELISA kit showed no correlation with the other methods, when IgG2 was measured. Analysis of the normal ranges measured by ELISA developed in our laboratory and by RID with polyclonal antibodies showed that the levels obtained by RID were higher than those obtained by our ELISA in sera with low levels of both IgG1 and IgG2, and lower in sera with high concentrations of these two immunoglobulins. Our results emphasize the importance of establishing age-related normal limits for any novel assay measuring IgG subclass concentrations.     

Serological evidence of dengue fever among refugees, Hargeysa, Somalia

Epidemics of a malaria-like illness affected several thousand residents of the Dam Camp, a refugee camp near Hargeysa in Somalia, during 1985, 1986, and 1987. The disease was characterized by fever, chills, sweats, headache, back and joint pains for as long as 10 days in some patients. Blood smears from acutely ill patients were negative for malaria. Of 28 acute and 10 convalescent sera tested by the indirect fluorescent antibody (IFA) and by the hemagglutination inhibition (HI) tests, all were negative for antibody to Rift Valley fever, Crimean-Congo hemorrhagic fever, Sindbis, Chikungunya, yellow fever, and Zika viruses. However, antibody reactive to dengue 2 virus was detected by the IFA test in 39% (15/38), and 11 of 29 (38%) of the same sera were antibody positive by the HI test. Also, IgG antibody reactive to dengue 2 was demonstrated in 60% (17/28) of the same sera by the enzyme immunoassay (EIA), and 14% (4/28) were positive for IgM antibody. Of ten patients for which acute and convalescent sera were available, two developed four fold or greater rises in antibody titer evidencing infection. These data suggested that dengue virus may have been the cause of the epidemic among the Dam Camp refugees.     

A sensitive enzyme-linked immunosorbent assay for determination of bovine β-lactoglobulin in infant feeding formulas and in human milk

We developed a sensitive sandwich-type ELISA for measuring low levels of cow's milk (CM) β-lactoglobulin. Purified anti-β-lactoglobulin was used as coating antibody and also as second antibody conjugated with alkaline phosphatase. Polyethylene glycol 6000 was added to the incubation buffers to improve sensitivity. The detection limit of the assay was 0.002 μg/l, which is much better than sensitivities reported for other β-lactoglobulin assays. The sensitivity was not impaired by the presence of other CM proteins. The recovery from breast milk was 93% and from the diluting buffer 127%. The coefficient of variation within day was 5–15% and between days 10%. One hour after oral intake of milk, P-lactoglobulin could be detected in the breast milk of three mothers at concentrations of about 1–2 μg/l. Widely different concentrations of β-lactoglobulin were measured in two protein hydrolysates based on CM whey and casein proteins; the observed concentrations were 200 and 0.0056 μg P-lactoglobulinμ/g dry weight, respectively.     

7832例孕妇HCMV-IgM的检测分析

目的为了解孕妇人巨细胞病毒（HCMV）近期感染状况。方法采用酶联免疫吸附试验（ELISA）对7832例孕妇的静脉血标本进行了HCMV-IgM检测。结果在7832例孕妇中检测出HCMV-IgM阳性标本67例,阳性率为0.86%。结论在孕妇中巨细胞病毒有一定的近期感染率。