Mercury-stimulated histamine uptake and binding in cultured astroglial and cerebral endothelial cells

BACKGROUND: The reference method for detecting specific Epstein-Barr virus (EBV) antibodies is indirect immunofluorescence (IF) with EBV-infected cells. The availability of protein purified from infected cells and more recently of recombinant polypeptides designed to contain immunodominant epitopes, has enabled the development of commercial enzyme-linked immunosorbent assays (ELISA) for the specific serodiagnosis of EBV infection. OBJECTIVE: Evaluation of ELISA-based EBV serodiagnosis in comparison with indirect immunofluorescence. STUDY DESIGN: We have first compared three commercial ELISA test systems with our in house indirect immunofluorescence assay for classifying correctly a set of serum samples into clinical categories (acute infection, past infection, interfering non-EBV infection, persistent infection). Additionally a prospective analysis with the best performing ELISA test (Enzygnost) was then carried out by running the ELISA test in parallel with the indirect immunofluorescence assay on 324 consecutive clinical samples sent to our laboratory for EBV serodiagnosis. RESULTS: For the serodiagnosis of past EBV infection and acute EBV infection all three commercial ELISAs performed well in comparison with indirect immunofluorescence. When testing samples positive for cytomegalovirus (CMV), Toxoplasma or herpes simplex IgM, interference in the IgM tests was observed with the three ELISAs. In some instances we could demonstrate that the positive IgM results were due to EBV reactivation. The observed discrepancies between ELISA and IF for the serodiagnosis of chronic EBV infection or EBV reactivation, point to the difficulty for the serodiagnosis of persistent EBV infection on single serum samples. According to our prospective study the EBV IgG determination was accurate. A positive IgM result was not always indicative of an acute infection. Positive IgM results due to EBV reactivation were observed. A positive EBV nuclear antigen (EBNA) IgG result in those samples precluded acute infection. CONCLUSIONS: 90-95% of samples could be classified correctly into clinical categories by a two parameter ELISA system detecting IgG and IgM against a standardized mixture of EBV antigens, allowing standardization and automation of EBV-specific serology. The absence of EBNA IgG was useful as a second line confirmatory assay for acute EBV infection.     

A new Combi test for simultaneous detection of antibodies to viral capsid, early and EBNA antigens of Epstein-Barr virus

In order to facilitate the differentiation between a recent (acute) and a past Epstein-Barr virus (EBV) infection, the Combi test was developed. This test is an anticomplement immunofluorescence test (ACIF) requiring only a single serum dilution to be tested on a single cellular spot. The cell line used expresses viral capsid antigen (VCA) and early antigen (EA) in about 5 to 10 percent of the cells as well as EBV nuclear antigens (EBNA) in more than 90 percent of cells. A satisfactory agreement between the Combi test and other tests for antibodies to EBV was obtained (IgG and IgM antibodies to VCA by IFA and EIA and antibodies to EBNA by ACIF including tests for heterophile and complement-fixing antibodies). When the standard serological tests gave negative results, the Combi test was also negative (absence of any fluorescence in the cells). Serologically confirmed recent (acute) infections lead to specific fluorescence in only 5 to 10 percent of the cells, while past infections result in fluorescence in 90 percent or more of the cells. For the diagnosis of a reactivated EBV infection or of EBV-associated malignancies, other tests should be employed. The test is based on the measurement of the activation and specific distribution of the C3 component of complement; the antibody class differentiation is therefore not necessary. The presence of rheumatoid factor (RF) and the IgG competition phenomenon do not influence the results of the Combi test. An introduction of the Combi test will enable a simplified, less expensive and more reliable serodiagnosis of EBV infections.     

Ambulatory sports in asthma improves physical fitness and reduces asthma-induced hospital stay

BACKGROUND: Prevention of posttransfusion non-A,non-B hepatitis in recipients of blood components improved considerably with the introduction of the second-generation of hepatitis C virus (HCV) antibody tests. In 1993, third-generation HCV antibody assays were introduced in Europe. STUDY DESIGN AND METHODS: The performance of three generations of anti-HCV enzyme-linked immunosorbent assay (ELISA) (ELISA-1, -2, -3) was compared in routine blood donor screening (99,394 donations were tested with ELISA-1, 167,999 donations with ELISA-2, and 262,090 donations with ELISA-3) and in serial samples from nine patients with documented acute posttransfusion HCV infection. RESULTS: Eight (0.01%) repeat donors, previously negative in ELISA-1, were found positive in ELISA-2 and were confirmed as positive in second-generation recombinant immunoblot assay and/or cDNA polymerase chain reaction. In the donor population, no difference in the sensitivity of ELISA-2 and -3 was observed. The specificity of the three generations of ELISAs was comparable (99.8, 99.7, and 99.7%). In seroconversion samples, ELISA-2 and -3 detected HCV antibodies at the same time in seven patients, but in two patients, ELISA-3 found HCV antibodies, respectively, 63 and 77 days earlier than ELISA-2 did. In the seroconversion samples, ELISA-2 and -3 were significantly more sensitive than second- and third-generation recombinant immunoblot assays. CONCLUSION: ELISA-3 did not detect more HCV-infected individuals in a donor population that previously tested negative in ELISA-2, but it did detect HCV antibodies earlier in some patients with acute HCV infection. ELISA-2 and -3 were significantly more sensitive than second- and third-generation recombinant immunoblot assays.     

Detection of immunoglobulin M antibodies to glycoprotein G-2 by western blot (immunoblot) for diagnosis of initial herpes simplex virus type 2 genital infections

Western blots (immunoblots) for the detection of immunoglobulin M (IgM) antibodies specific for herpes simplex virus type 1 (HSV-1) and HSV-2 in patients' sera were developed. The locations of the type-specific glycoprotein G (gpG-2) of HSV-2 (92- and 140-kDa forms) and glycoprotein C of HSV-1 (gpC-1), which carries mostly type-specific antigenic epitopes, were checked with specific monoclonal antibodies. Western blot assays for IgM antibody to gpC-1 or gpG-2 were performed after depletion of IgG by precipitation with anti-human IgG. In patients with primary HSV-2 genital infections, seroconversion of IgM and IgG antibodies to both the 92- and 140-kDa forms of gpG-2 was observed, although both antibodies appeared in convalescent-phase serum after the first week. IgM and IgG antibodies to low-molecular-size polypeptides (40 to 65 kDa) were the first antibodies observed in patients with primary infection, but these antibodies were cross-reactive with HSV-1 and HSV-2. However, in patients with recurrent HSV-2 infections, IgG antibodies to both forms of gpG-2 and the low-molecular-size polypeptides were found no matter how early after onset the patient was bled, and IgM to gpG-2 did not appear. In patients with nonprimary initial genital HSV-2 infections, IgG antibody to HSV-1 was demonstrated in the first serum specimen, and HSV-2-specific IgM was found in 39% of the serum specimens. Hence, the Western blot assay can be used to test for IgM antibody to gpG-2, allowing for the retrospective diagnosis of inital HSV-2 infections and its use as a supplementary test to the gpG-2 IgG enzyme-linked immunosorbent assays developed elsewhere. In contrast, IgM antibody to gpG-2 is not usually detected in patients with recurrent HSV-2 infections.     

Follow-up in 103 patients with catecholamine-secreting tumours

BACKGROUND: It is necessary to have an easy and quickly test to distinguish "false positive" rubella IgM results and residual antibodies from the antibodies produced in the primary infection, in pregnant women. The avidity of IgG antibodies test seems to differentiate between primary rubella infection and past infections, reinfections or postvaccination, showing its utility in the diagnosis of primary infection in other infectious diseases. METHOD: For 30 months, 178 sera from 157 patients with clinical and/or epidemiological rubella suspicion or with a positive rubella IgM result as result of an accidental serological finding, were remitted to our laboratory for a serological follow up. We distinguished 3 patient groups: outbreak group, 112; pregnant women, 36, and newborn 11. Rubella IgM antibodies by indirect EIA previous the rheumatoid factor absorption; IgG antibodies of low avidity by indirect EIA previous treatment of serum with 6 M urea, were detected in the sera. It considered a positive result, a rubella avidity index (AI) < 50%. RESULTS: In the epidemic outbreak group, 90.2% of the patients were not vaccinated. 80% of cases occurred in young men between 14 an 20 years old. From 109 patients (97.3%) with rubella IgG antibodies, 92 (84.4%) showed AI-IgG lower than 50%. In this group, the mean rate of AI-IgG rubella was 29.0%. In the pregnant women group, except for two of them, rubella IgM antibodies were an accidental finding in a serological pregnancy screening. Thirty patients (83.8%) showed AI-IgG rubella > 50%. The two pregnant women who had evidence of clinical and epidemiological rubella showed AI-IgG rubella of 37.4% and 20.9%. Another four pregnant women showed AI-IgG rubella close to cut-off (44.7-49.0%). The mean AI-IgG rubella in this group was 71.8%. The mean AI-IgG Rubella between the epidemic outbreak group and the pregnant women group, 29.0 and 71.8% respectively, was statistical significance (p < 0.001). CONCLUSIONS: The avidity IgG test is simple and quickly, and it allow to exclude most of positive results because of residual IgM antibodies and false reactive.     

Growth arrest of Epstein-Barr virus immortalized B lymphocytes by adenovirus-delivered ribozymes

Epstein-Barr virus (EBV) infection is associated with several human diseases that involve unrestricted proliferation of B lymphocytes. EBV nuclear antigen 1 (EBNA-1) is expressed in all EBV-infected cells and plays an essential role in persistence of the EBV genome. EBNA-1 has also been reported to have oncogenic potential. As an approach for treating EBV infections, we examined the capacity of EBNA-1 ribozymes delivered by recombinant adenoviruses to suppress EBNA-1 expression and to block virus-induced B cell proliferation. In contrast to primary B cells, EBV-transformed B lymphoblastoid cell lines expressed alphav integrins, the adenovirus internalization receptors, and were also susceptible to adenovirus-mediated gene delivery. Adenovirus delivery of a specific ribozyme (RZ1) to lymphoblastoid cell lines, suppressed EBNA-1 mRNA and protein expression, significantly reduced the number of EBV genomes, and nearly abolished cell proliferation in low serum. Adenovirus delivery of RZ1 also prevented EBV infection of an established EBV-negative B cell line. These studies demonstrate the potential use of adenovirus-encoded ribozymes to treat EBV-induced lymphoproliferative disorders.     

Current developments in the laboratory diagnosis of rubella

Thirty years after the introduction of the hemagglutination inhibition assay (HAI), laboratory diagnosis of rubella virus infection has achieved a high reliability. While the HAI remains the reference standard against which newer assays are compared, routine laboratory diagnosis is based mainly on ELISA tests which permit a more rapid and less cumbersome detection of specific IgG and IgM antibody. Although quantification of immunoglobulin G against rubella virus is performed using WHO standards, the correlation between different ELISAs is relatively poor. Despite substantial improvements in virus isolation and nucleic acid amplification techniques, serology remains the mainstay of diagnosis for both acquired and postnatal diagnosis of congenital infection. Differentiation between primary and re-infection is of critical importance during pregnancy and can be achieved relatively reliably by antibody avidity determination or by immunoblot. While current anti-rubella IgM ELISAs are relatively sensitive, their specificity may be limited by cross reactivity with other viruses, i.e. parvovirus B19 and Epstein-Barr virus. Maternal reinfection with congenital rubella syndrome is very rare, however it may be misdiagnosed in the absence of significant IgG antibody titer change and/or IgM antibody.     

Gastric carcinoma in young adults

Among 47 blood donors tested positive with HCV EIA 2.0 Abbott, 27 (57.4%) also reacted with four ?third-generation' EIAs. The presence of anti-HCV antibodies was confirmed with 3 different immunoblot assays in 16 of 27 sera (34.0%) while 10 samples (21.3%) had indeterminate profile with antibodies usually directed against structural core antigen. Anti-HCV core IgM response was found in 12 of 47 sera (25.5%) and HCV viremia detected by the polymerase chain reaction (PCR) procedure was observed in 15 samples (31.9%). A comparative study of the different markers confirmed a good correlation between a strong antibody response in EIAs and immunoblot assays and the presence of HCV RNA in the serum; only 2 immunoblot indeterminate samples were PCR positive. An association was observed between IgM antibodies against "core' epitopes and HCV RNA carriage: all IgM-positive sera were found positive by PCR. However, the direct detection of viral genome remains the best method for identifying HCV carriers in the blood donor population.     

Oligonucleotide-poly-L-ornithine conjugates: binding to complementary DNA and RNA

A lysate of human herpesvirus type 6 (HHV6) infected HSB2 cells was used as antigen for an enzyme-linked immunosorbent assay (ELISA) for the detection of IgG and IgM antibody to HHV6. 78 clinical samples were tested for the presence of HHV6-specific IgM. Nine specimens, all from children under 4.5 years of age, were found to be reactive indicating probable acute infection with HHV6. Sera from 12 healthy adult blood donors and from 88 of 90 adults over the age of 35 with unspecified health conditions tested negative for HHV6 IgM, indicating a minimum specificity estimate of nearly 98% in these patients. Cross-reactivity of antibody to other herpes viruses with the HHV6 ELISA antigen was not detected. Six hundred and ninety-six serum samples from individuals of different age groups were examined for IgG antibody status. In 94% of these samples, IgG antibody was detected. Our data suggests that most Canadians possess antibody to HHV6 by 1 yr of age and that on average, antibody levels remain high through early adulthood but begin to decline with advancing age. The ELISA described is a reliable test for the measurement of IgG and IgM antibodies for both clinical diagnosis and epidemiological studies.     

Sex-associated differences in cold-induced UCP1 synthesis in rodent brown adipose tissue

OBJECTIVE: To evaluate the usefulness of new ELISA for human parvovirus B19 (B19) antibodies and PCR for the diagnosis of acute onset of B19 polyarthritis. METHODS: We evaluated the reproducibility and sensitivity on the detection of anti-B19 antibody by ELISA using recombinant VP-1 and VP-2 (empty particle), and then studied for the prevalence of IgM and IgG B19 antibody in 125 samples for anti-B19 tests. The random study on anti-B19 antibody assay as well as PCR for B19-DNA was also performed in 130 cases with acute onset of arthritis excluding those with known origins, 224 with rheumatoid arthritis and 149 with other categories. RESULTS: The results by using B19-empty particle ELISA were reproducible and showed the assay was a sensitive way for clinical use. IgM anti-B19 antibodies were positive not only in all samples from erythema infectiosum, but also often in those from hemolytic anemia, pure red cell aplasia, fetal hydrops, hepatic injury, fever of unknown origin. Among 130 with acute onset of arthritis, 21 showed positive tests for IgM anti-B19 antibody and/or B19 DNA. On the other hand, 4 among 224 patients with rheumatoid arthritis were positive for IgM anti-B19 antibody, but all of 149 in control group were negative for IgM anti-B19 antibodies and for B19 DNA. CONCLUSION AND DISCUSSION: Anti-B19 ELISA using B19-empty particle which has been introduced as a routine test system, is a useful tool for the diagnosis of acute onset of B19 arthritis. An additional examination using PCR for B19 DNA may contribute for understanding persistent B19 polyarthritis or reactivation of B19 infection.     

Structural characterization of recombinant human erythropoietins by fluorophore-assisted carbohydrate electrophoresis

Two enzyme immunoassay (EIA) systems were compared for their ability to detect Borrelia burgdorferi sensu lato specific IgG and IgM antibodies and to differentiate between symptomatic (83 patients with neuroborreliosis) and asymptomatic seropositive subjects (80 healthy controls). Antibody concentrations were determined by EIA; the antigens used were either a sonicate of B. burgdorferi or three recombinant borrelial proteins: the 14-kDa flagellin fragment, the outer surface protein C (22 kDa) and the high molecular mass protein p83 (83 kDa). In the sonicate, EIA, IgG or IgM antibodies to B. burgdorferi, or both, were detected in all patients with neuroborreliosis and in all controls. Pre-absorption of sera with Treponema phagedenis sonicate diminished the sensitivity of detection of borrelial specific IgG (IgG or IgM or both) antibodies in patients with neuroborreliosis from 80 to 57% (100 to 82%) and in the controls from 100 to 32% (100 to 37%). While being specific for B. burgdorferi, the recombinant EIAs proved to be significantly more sensitive than the sonicate EIA: IgG or IgM, or both antibodies against any of the recombinant antigens were detected in 92% of patients with neuroborreliosis and in 24% of controls. The increase in sensitivity in patients with neuroborreliosis was mostly due to the higher detection rate of IgM antibodies in the recombinant EIA (77% versus 48% in the sonicate EIA), while IgG antibodies were demonstrated with similar frequencies in both EIA systems (57% versus 60%). It was concluded that the recombinant EIAs are superior to the sonicate EIA with pre-absorption of cross-reactive antibodies in the confirmation of an acute borrelial infection and in the differentiation between symptomatic and asymptomatic infections.     

Detection of Chlamydia trachomatis antibodies by 2 novel tests: rELISA and peptide EIA

The performance of 2 newly developed enzyme immunoassays (EIAs) intended for the routine serological diagnosis of chlamydial infections was evaluated. rELISA is based on a recombinant lipopolysaccharide antigen which detects chlamydia genus-specific antibodies, and Chlamydia trachomatis EIA is based on a peptide derived from major outer membrane protein and is therefore species-specific. Both tests distinguished patients with tubal factor infertility (TFI) or pelvic inflammatory disease (PID) from the controls. The prevalence of IgA antibodies was higher for the PID patients than for the TFI patients; the finding indicates a more active state of infections for the PID patients. Furthermore, C. trachomatis EIA detected more IgG antibodies in the TFI patients than in patients with non-tubal factor infertility. In conclusion, rELISA detected chlamydial antibodies in general, and C. trachomatis EIA detected species-specific antibodies. These EIA tests may be useful in the serodiagnosis of chlamydial infection.     

Detection of IgA antibodies as important markers of acute primary infection with Toxoplasma gondii

The diagnosis of Toxoplasma gondii infection is currently based on immunological tests, but tests for IgM and IgG antibodies alone are often insufficient to estimate the risk of active disease, especially during pregnancy and in immunodeficient patients. Classically the study of anti-toxoplasma immunity involves titration of IgG antibodies, which reflect immunity to the parasite, and IgM antibodies which of present, reveal acute infection. However, technical advances have shown the limitations of these tests as tests for IgM can be positive because of residual specific IgM or even in subjects free of acute infection due to the existence of natural interfering IgM. In addition, IgM can be absent in children with congenital toxoplasmosis or subjects with secondary reactivation. The purpose of our study was to evaluated of IgA antibodies to T. gondii in serum samples which were positive in screening test. Our results confirm the diagnostic value of testing for anti-toxoplasma IgA antibodies. These antibodies are absent in uninfected subjects and are detected rapidly after primary infection. The determination of IgA complements IgM determination for the diagnosis of toxoplasmosis.     

Comparison of cardiac findings at necropsy in octogenarians, nonagenarians, and centenarians

The Toxoplasma gondii rhoptry protein Rop2 was expressed in Escherichia coli as a fusion protein containing 44 kDa of the 55-kDa mature Rop2, supplied with six histidyl residues at the N-terminal end (Rop2196-561). Humoral response during Toxoplasma infection of humans was analyzed by immunoglobulin G (IgG), IgA, and IgM enzyme-linked immunosorbent assay with Rop2196-561 as the antigen substrate. The analyzed sera were divided according to T. gondii-specific serological tests (IgG, IgA, or IgM indirect immunofluorescence and IgA or IgM immunosorbent agglutination assay) as group A (IgG+ IgA- IgM-; n = 35), group B (IgG+ IgA+ IgM+; n = 21), group C (IgG+ IgA+ IgM-; n = 5), and group D (IgG+ IgA- IgM+; n = 16). Twenty-six T. gondii-seronegative sera from individuals with other infections were also included (group E). Anti-Rop2 IgG antibodies were detected in 82.8% of group A sera and in 97.6% of the sera with acute-phase marker immunoglobulins (groups B, C, and D). The percentage of IgA antibody reactivity against Rop2196-561 was 17.1% in group A, 50% in group D, and 80.8% in groups B and C. The percentage of IgM antibody reactivity was 0% in groups A and C and 62% in groups B and D. Sera from group E failed to show IgA, IgM, or IgG antibody reactivity. Since T. gondii Rop2 elicits a strong humoral response from an early stage of infection, it is suggested that recombinant Rop2196-561 would be suitable for use in diagnostic systems, in combination with other T. gondii antigens, to detect specific IgG, IgA, and IgM antibodies.     

Infrequent detection of cytomegalovirus and Epstein-Barr virus DNA in synovial membrane of patients with rheumatoid arthritis

OBJECTIVE: To study the role of the cytomegalovirus (CMV), Epstein-Barr virus (EBV), herpes simplex virus types 1 and 2 (HSV-1 and 2), varicella zoster virus (VZV), and human herpes virus 6 (HHV-6) in the etiology of rheumatoid arthritis (RA). METHODS: Polymerase chain reaction (PCR) was used to detect DNA of the different herpes viruses in synovial membranes from 31 patients with chronic RA and 14 control patients. Specific antibodies were determined by indirect immunofluorescence and ELISA. RESULTS: Out of 31 patients with RA, CMV DNA was detected in synovial membranes from 2 patients and EBV DNA was detected in synovial membranes from 2 other patients. All samples from the patients with RA were negative for DNA from HSV-1 and 2, VZV, and HHV-6. All samples from the 14 control patients were negative in all PCR assays. No statistically significant differences in IgG antibodies were found for CMV, HSV-1, VZV, and HHV-6 in patients with RA compared to controls. Higher titers of IgG antibodies against EBV viral capsid antigen were found in patients with RA, with a significance of p < 0.05. CONCLUSION: Both CMV and EBV DNA were detected in synovial membranes from 6% of the patients with RA. We cannot exclude the possibility that these viruses were associated with disease development in a minority of patients with RA.     

Immunological properties of Weil-Felix test negative sera from patients with Japanese spotted fever

Sera from 4 out of 19 patients with the Japanese spotted fever were negative to OX2 antigen of Weil-Felix (WF) test. These WF test negative sera were analyzed by ELISA and immunoblot used whole cells and lipopolysaccharides (LPS) of rickettsiae and Proteus strains as antigens. These acute-phase sera have already possessed the IgG antibodies against LPS of Proteus OX2 strain, whereas IgM antibodies in these acute- and convalescent-phase sera did not react with this LPS. On the other hand, the reactivity of IgM antibodies of the convalescent-phase sera in the 2 patients with LPS of Proteus OX19 strain increased as compared with that of the acute-phase sera by ELISA, and these IgM antibodies also showed the reactivity with bands of OX19-LPS in the immunoblot. On the basis of these results, it is interpreted that the WF test negative sera from patients with Japanese spotted fever are due to the presence of IgG antibodies against OX2-LPS in the sera.     

Trypanosoma cruzi infection in mice induces a polyisotypic hypergammaglobulinaemia and parasite-specific response involving high IgG2a concentrations and highly avid IgG1 antibodies

Trypanosoma cruzi infection in BALB/c mice induced a reversible polyisotypic hypergammaglobulinaemia, with particularly high levels of IgG2a, IgM and IgE. Hypergammaglobulinaemia started during the acute phase of infection and persisted during chronic disease until 11-13 weeks post-infection (w.p.i.), when immunoglobulin levels, with the exception of IgE, returned near normal values. Parasite-specific antibodies counted for 14 to 23% of gammaglobulinaemia, in acute and chronic infection respectively. The titres of IgM antibodies rose from two w.p.i. IgA, IgE and IgG subclass antibodies built up gradually over the time of parasite clearance (i.e., between three and six w.p.i.). All antibody isotypes, including IgM reached significant and stable titres throughout chronic infection. IgG2a, IgG1 and IgM antibodies had constantly higher titres than the other antibody isotypes. The dominance of IgG2a antibodies was due to their high plasma concentrations, around 70% of all antibodies available in the chronic infection. IgG1 had the highest functional avidity, whereas its concentration corresponded to only 10% of the whole antibody fraction. These results indicate that T. cruzi infection in mice induces a polyisotypic humoral immune response, dominated by some antibody isotypes, with major differences in concentrations and functional avidities. This could be of crucial importance in determining the outcome of infection.     

Influence of ultraviolet-B irradiation on engraftment, graft-versus-host disease and graft-versus-leukemia effect in a rat model for allogeneic bone marrow transplantation

Serum anti-Bartonella henselae IgG and IgM antibody titers for the diagnosis of cat scratch disease (CSD) were determined by indirect fluorescence antibody (IFA) tests. B. henselae as antigen were harvested either by cocultivating with Vero cells (cocultivated B. henselae) or by cultivating without them (non-cocultivated B. henselae). Based on the results on 110 healthy adults, cut off values were set at 1:32 for IgG, and < 1:20 for IgM antibodies. According to these criteria, IgG antibody was positive in 2.7% of the 110 adults, while nobody was positive for IgM antibody. The titers did not change depending on the types of antigen used. On the other hand, IgG antibody titers against cocultivated B. henselae tended to be higher than those against non-cocultivated B. henselae in 33 CSD suspected patients; 75.8% of the patients were anti-B. henselae IgG positive when tested with cocultivated B. henselae as antigen, while only 48.5% of the same patients gave positive results with non-cocultivated B. henselae. Anti-B. henselae IgM antibody was positive in 24.2% of the 33 CSD suspected patients against both types antigen. Vero cells themselves seemed to nonspecifically bind some IgM (but not IgG). We recommended cocultivated B. henselae as antigen for IgG IFA, and non-cocultivated B. henselae for IgM IFA in the serological tests of CSD.     

Immunoglobulin G avidity in the serodiagnosis of congenital rubella syndrome

The avidity of specific IgG was investigated in three infants with serologically verified congenital rubella infection. Two sera were taken from each infant: the first soon after birth and the second at the age of 23 to 31 months. Avidity of specific IgG was measured by a protein-denaturing enzyme immunoassay using urea as the elution factor, and avidity then determined by the end-point ratio (derived from antibody titration) and the avidity index methods. Rubella-specific IgM was present in the first sera of all patients, but not in the second sera. However, low avidity of specific IgG persisted in two children until age 23 to 31 months, as determined by the end-point ratio method. These data are in agreement with the findings of previous studies of avidity in congenital rubella, and show the usefulness of the protein-denaturing IgG-avidity assays employing the end-point ratio method for serological diagnosis of congenital rubella even after disappearance of specific IgM.     

Laboratory diagnosis of Lyme borreliosis

Three stages can be observed in Lyme borreliosis: the acute stage (with dermal and systemic disease), an intermediate stage (with neurological and cardiovascular complaints and myositis), and a chronic stage (with arthritis, low back pain, dermatological and neurological complaints). If no acute stage with erythema chronicum migrans is seen, laboratory tests must provide the diagnosis. In the so-called two-test protocol at least two different tests must be positive for a definite diagnosis. Because culture is difficult, serology (demonstration of specific IgM and IgG antibodies against spirochaetal antigens) is the preferred technique. Cross reactions, antigenic variations and differences in antigenic expression in American and European strains may cause false-negative and false-positive results with the current tests. Moreover, previous use of antibiotics can interfere with the production of specific antibodies, and the effect of therapy is not correlated with height and behaviour of antibody titres. Additional investigation with immunoblot techniques, demonstrating specific antibody patterns may be valuable. An interesting alternative, not yet fully developed, is detection of specific antigens in tissues.