Serodiagnosis and Immunotherapy in Infectious Disease最新文献

Objectives: To determine the sensitivity of four HIV screening tests when testing pooled samples from individuals with low antibody levels. Methods: Samples were obtained from 10 individuals with strong positive WB results, 11 seroconverting individuals and 8 individuals with late stage disease. Samples were tested individually and with pool sizes of 5, 10 and 20 using the BioChem test, the SYVA test, the CBC Recombigen test and Organon-Teknika's Vironostika test. Results: Samples from individuals with strong positive WB results tested positive according to all four tests at all pool sizes. One of the samples from the eight individuals with late stage disease tested negative with a pool size of 20 for all four tests and with pool sizes of 5 and greater with CBC Recombigen, SYVA and Organon-Teknika. More than half of the pools of size 20 containing samples from seroconverting individuals tested negative with SYVA, CBC Recombigen and Organon-Teknika. Sensitivity varied between 18% and 82% when samples were pooled in groups of 10 and between between 27% and 100% when samples were pooled in groups of 5. Conclusions: Pooling of samples from individuals with late-stage disease or who are in the process of seroconverting is not recommended when the results of each test are critical. When only the aggregate results are of interest, such as in anonymous seroprevalance studies, the loss in sensitivity due to pooling samples from these individuals will not qualitatively affect prevalence estimates.

Accurate estimation of the onset of maternal toxoplasma infection is essential to establish the risk of congenital infection. Methods based on immunoglobulin (Ig) M assays are compromised by the variable persistence of the patient's IgM response. Measurement of toxoplasma-specific IgG avidity and IgA was performed in 37 clinical cases where the IgM response was known to have persisted for 6− > 24 months. Recent onset infection could be excluded by lack of detectable IgA in 30 cases and by the presence of high avidity IgG in 36 cases. Measurement of IgA or IgG avidity [4] can be used to estimate the duration of toxoplasma infection despite the patient's unusually prolonged IgM response.

This work aimed to evaluate serology in relation to non-quantitative polymerase chain reaction (PCR) and pp65-antigenemia for the follow-up of cytomegalovirus (CMV) infection in heart transplant recipients. Besides conventional serology, antibodies were also detected by immuno Western blotting (IWB) and by recombinant enzyme immunoassay (EIA). Twenty-five CMV infected patients were evaluated. Twelve of them experienced symptomatic infection and underwent 9-(1,3-dihydroxy-2-propoxymethyl) guanine (DHPG) therapy whereas 13 asymptomatic infections were not treated. Risk factors for developing a symptomatic infection were a high antigenemia level as well as a high and delayed IgM response to ppUL44 (p52) and a low IgG response to the virus. PCR was the most sensitive procedure for detecting CMV infection (24 out of 25 infected patients and a mean time of 40 days after transplant), followed by IWB-IgM (23 patients and 40 days) and antigenemia (22 patients and 41 days). All the 12 symptomatic infections could be detected by one of the three above-mentioned methods, whereas no single test could identify all the 13 asymptomatic infections. The combination of two tests that could detect all the 25 CMV infections was PCR plus a serological procedure (IWB-IgM or recombinant EIA for p52) and pp65-antigenemia associated with IWB-IgM. As PCR results did not correlate with the onset of CMV symptomatic infection, the present data indicate that the most rational follow-up for CMV infection in heart transplant recipients can be obtained by antigenemia and IWB-IgM.

Ten commercially available assays (two passive latex agglutination assays, seven ELISAs and an immuno-blot filtration assay) for detecting Toxoplasma gondii-specific antibodies were evaluated using 168 serum samples from organ donors and transplant recipients. Results were compared with the ‘gold standard’ Sabin-Feldman dye test to give values for sensitivity and specificity for each kit. These ranged from 86.0% to 97.4% for sensitivity and from 93.6% to 100% for specificity. From these results recommendations for a kit of choice for testing organ donors and transplant recipients were formulated.

A quality control survey of various kits for measuring antibody to hepatitis B surface antigen (anti-HBs) was undertaken by the Serology Special Interest Group of the Australian Society of Microbiology due to concern about the performance of these tests in the field. A total of 20 panels of sera, derived from people with diverse histories with respect to hepatitis B infection and vaccination, were distributed to 19 participating laboratories using seven different commercial anti-HBs assays (representing five manufacturers) throughout Victoria. Participants were blinded with respect to replicates. Assay results were analysed to take account of the market dominance of the Abbott IMx method. In general, all tests performed adequately with respect to linearity over the range tested. Reproducibility within and between assays shows that some assays are performing inadequately in the field for quantitating anti-HBs. There was only one false positive result, from a laboratory using Amerlite, but a small number of results where a person's immune status would have been falsely reported as non-immune. Additionally, the two laboratories which used the same radioimmunoassay (RIA) test kit reported in different units, so that numerically values six to 12 times higher were reported by one laboratory compared to the other. These results underscore the need for statistically relevant independent evaluation in the absence of the licensing of kits prior to market release, and ongoing monitoring of test performance in the field, including participation in quality assurance exercises which should be regularly available.

We have studied the prevalence of anti-human herpesvirus 6 (HHV-6) antibodies in different population groups from Spain. Serum samples from 271 children between 0 and 15 years old, 512 intravenous drug addicts (IVDA) (262 seropositive for human immunodeficiency virus (HIV)) and 254 healthy individuals (100 pregnant women). The indirect immunofluorescence technique was used for antibody investigation from initial dilutions of 1 : 40. Seroprevalence studies showed antibody presence in 37.6%. The highest positivity was found in the group of children (49.4%, P<0.001), followed by the pregnant women (39%), the IVDAs (34%) and healthy subjects (28%). When the IVDA group was split into HIV positive and HIV negative, no significant difference was found between them (P = 0.45). Antibody titres oscillated between 1 : 40 and 1 : 2560, with the greatest frequency at 1 : 40 in both male and female patients. A statistically significant difference (P < 0.05) was only found between sexes in the control group.

We report the development of a convenient and reliable polymerase chain reaction (PCR)-based microassay for the amplification and detection of specific DNA sequences with potential applications in the diagnostics field. The major features of our system are: (a) the complete system is carried out entirely in the same microtitre well; (b) the PCR is performed in two instead of the traditional three temperatures, thus reducing the time for 35 cycles to under 2 h; (c) the probe is already immobilized onto the solid phase, allowing direct hybridization of the PCR products; (d) one of the two primers is already biotinylated at the 5' end, thus detecting one of the two actual specific products, and (e) the whole process is designed to an enzyme-linked immunosorbent assay (ELISA)-like system for easy use and takes only 3 h, rendering the system particularly suitable for a busy clinical laboratory and automation. The method was successfully applied for the detection of human immunodeficiency virus type 1 (HIV-1) from patient lymphocyte samples.