Serodiagnosis and Immunotherapy in Infectious Disease最新文献

This study was conducted to assess the value of ELISA findings in relation to negative findings in the Brucella-antihuman globulin (Coombs) test and in relation to the clinical condition of patients. One hundred and thirty three serum specimens, representing the same number of patients, submitted for serologic testing for brucellosis and showing negative Coombs, were tested by ELISA to determine their Brucella-IgG, -IgM and -IgA antibodies. Concordant negative results between Coombs and ELISA were found in 95 (71.4%) patients whose medical records also did not reveal suggestive clinical signs or symptoms of brucellosis. The elevated ELISA readings in the remaining 38 (28.6%) patients were distributed as follows: IgG + IgM + IgA in 1 patient, IgG + IgM in 8 patients, IgG alone in 24 patients and IgM alone in 5 patients. The clinical review of these patients indicated no current disease in 21 (15.8%), scanty evidence of brucellosis in 8 (6.0%) and suggestive or sufficient evidence in 9 (6.8%). Thus, ELISA is the test of choice to resort to in the case of clinical suspicion of brucellosis, even when the Coombs test shows negative findings.

Eight commercially-available tests were compared for the diagnosis of Epstein-Barr virus (EBV)-associated infectious mononucleosis (IM). They consisted in four slide agglutination assays (one of them using horse erythrocytes and three of them latex beads coated with purified bovine erythrocyte antigen), in a classical Paul-Bunnell-Davidsohn (PBD) tube-test using sheep erythrocytes, and in three assays intended to detect EBV-specific IgM antibodies either by indirect immunofluourescence (one test) or by ELISA (two tests). Sixty serum specimens from patients with symptoms compatible with IM were selected on the following criteria: presence of EBV-specific IgM by at least 2 of the 3 specific assays and absence or very low titres (≤5) of antibodies to EBV nuclear antigen (EBNA). Using this panel of positive samples, the sensitivity of the 8 assays ranged from 55 to 100%. The EBV-specific IgM tests exhibited the higher sensitivities, especially the one using a combination of peptides directed to different viral antigens. Whereas the PBD tuve test was shown to be time-consuming and insensitive, even in young adults, the slide agglutination tests were easy to perform and exhibited sensitivities ranging from 70 to 80%. The latter tests represent a good alternative to EBV-specific serology for the rapid diagnosis of IM; however, in case of negativity, an EBV specific testing must be done, especially in children under 5 years.

Sera from 192 children participating in studies of a pertussis toxoid vaccine were analyzed by enzyme-linked immunosorbent assay (ELISA) for pertussis toxin IgG antibodies and by the Chinese hamster ovary cell assay for pertussis toxin neutralizing antibodies. A significant linear correlation was found between titers obtained by ELISA and the neutralization assay (r = 0.84, P < 0.0001). The study shows that these two assays give similar information for groups of sera, although an antibody titer obtained by one method could generally not be used to predict a titer for the other method with accuracy in an individual serum. We propose that ELISA alone can be used in studies of IgG antibody response to pertussis toxin after vaccination with pertussis toxoid.

The effects of destruction of carbohydrate moieties of Echinococcus granulosus antigen by sodium periodate treatment, and/or blocking phosphorylcholine specific antibodies by the addition of free reagent, were investigated to improve sensitivity and specificity of enzyme-linked immunoabsorbent assay (ELISA) for diagnosis of hydatid disease. Sera were collected, in Uruguay and Sweden, from patients with confirmed hydatidosis, non-hydatid tapeworm infections, other disorders, and healthy donors. ELISA performed with sodium periodate or free phosphorylcholine increased sensitivity, but decreased specificity. Western blot analysis showed reduced recognition of the 38 kDa antigen following both treatments, and of the 15.5 kDa antigen after periodate treatment. Addition of free phosphorylcholine enhanced the recognition of two antigens, 26 and 50 kDa, which may represent new cross-reacting epitopes.

Recombinant Escherichia coli LamB proteins containing meningococcal PorA epitopes were used for the analysis of the human antibody response to specific PorA epitopes. Sera from meningococcal cases, carriers and controls were examined by an ELISA-inhibition assay. Antibody to the serosubtype P1.16 epitope was detected with similar frequency regardless of whether recombinant E. coli LamB protein containing P1.16 or SDS-PAGE purified meningococcal class 1 protein (serosubtype P1.16) was used as the antigen.

Considerable efforts are being made in the search for suitable candidates for an effective serogroup B meningococcal vaccine, but with limited success. We have identified a novel, high molecular weight antigen of approximately 200 kDa. The antigen was expressed during invasive disease as 100% of convalescent case sera contained antibody compared with approximately 50% of carriers. Many clinical isolates did not appear to express the 200 kDa antigen, but corresponding sera contained antibody, indicating in vivo expression. Antibody to this antigen cross-reacted with meningococci of diverse phenotypes. Further investigation of this antigen is required to determine its potential as a future vaccine component.

Superficial Chlamydia trachomatis infections are diagnosed by antigen detection whereas serological investigations are mainly performed to detect deep-seated infections. In this study the genus-specific IPAzyme and two species-specific microimmunofluorescence (MIF) tests were compared for detecting antibodies against C. trachomatis in women undergoing laparoscopy for diagnostic purposes or for ligation of the fallopian tubes. Microbiological findings were similar in both groups. C. trachomatis was detected in 4 of 38 women with ligation and in 6 of 61 women with diagnostic laparoscopy. Serum IgG antibody titres by IPAzyme were clearly positive in 24 out of 61 of the diagnostic group and in 12 out of 38 of the ligation group. However, 14 (39%) of the 36 IPAzyme-positive results were caused by antibodies against Chlamydia pneumoniae and/or Chlamydia psittaci, only 4 (11%) were caused by anti-C. trachomatis IgG and 8 (22%) were caused by both antibodies as tested by a conventional MIF; in 10 all MIF titres were lower than 1:32. A commercial MIF still containing too much genus-specific lipopolysaccharides was more sensitive, but also more crossreactive than the conventional MIF. IPAzyme IgA were only found in association with positive IPAzyme IgG results. We conclude that in case of presumed deep-seated C. trachomatis infection only sensitive species-specific assays for detecting C. trachomatis antibodies are helpful. IPAzyme and other genus-specific assays cannot be recommended to detect antibodies to C. trachomatis in the serum, because positive results are caused mainly by antibodies against respiratory chlamydiae.

The serological diagnosis of parvovirus B19 (PVB19) was performed by radioimmunoassay or enzyme-linked immunosorbent assay (ELISA), using plasma-derived antigen, in view of the difficulties in obtaining the virus. Since the development of recombinant proteins, a number of commercial kits for detecting both specific immunoglobulin G (IgG) and IgM have become available. We evaluated seven methods, including indirect- and μ-chain-capture ELISA, indirect immunofluorescence and Western blot, in an effort to identify PVB19 IgM. In acute samples of erythema infectiosum, the sensitivity ranged from 37% to 91%; in all samples from primary PVB19 infections, including acute and convalescent samples of erythema infectiosum, and from other primary infections in adults, the sensitivity varied from 31% to 79%. When samples from rubella, measles, infectious mononucleosis and healthy pregnant women were tested, specificity ranged from 67% to 100%. Not all the kits evaluated can be used to diagnose PVB19 infections in view of the limitations of some kits with respect to sensitivity and, more importantly, specificity.