A Hospital-Based Serological Survey of Cryptosporidiosis in the Republic of Korea

The seroprevalence of cryptosporidiosis was examined using patients'' sera collected from hospitals located in 4 different areas of the Republic of Korea. ELISA was used to measure antibody titers against Cryptosporidium parvum antigens from a total of 2,394 serum samples, which were collected randomly from patients in local hospitals; 1) Chungbuk National University Hospital, 2) Konkuk University Hospital, 3) local hospitals in Chuncheon, Gangwon-do (province), 4) Jeonnam National University Hospital, from 2002 through 2003. Of the 2,394 samples assayed, 34%, 26%, and 56% were positive for C. parvum-specific IgG, IgM, and IgA antibodies, respectively. Positive IgG titers were most common in sera from Jeonnam National University Hospital, Gwangju, Jeollanam-do, and positive IgM titers were most common in sera from Chungbuk National University Hospital, Cheongju, Chuncheongbuk-do. The seropositivity was positively correlated with age for both the IgG and IgA antibodies but was negatively correlated with age for the IgM antibodies. Western blotting revealed that 92%, 83%, and 77% of sera positive for IgG, IgM, and IgA ELISA reacted with 27-kDa antigens, respectively. These results suggested that infection with Cryptosporidium in hospital patients occurs more commonly than previously reported in the Republic of Korea.     

Detection of IgG binding to Schistosoma mansoni recombinant protein RP26 is a sensitive and specific method for acute schistosomiasis diagnosis

We recently described the first recombinant Schistosoma mansoni protein RP26, which was capable of acute infection diagnosis. The aim of the present work was to further characterize the RP26 diagnostic properties in immunoblot and enzyme-linked immunosorbent (ELISA) assays. Testing sera from uninfected donors and sera from patients with acute or chronic Schistosoma infection by Western blot immunoassay revealed 100% specificity and 100% sensitivity for acute infection identification. Sera from uninfected, acute, and chronic schistosomiasis were also probed for IgG, IgG4, IgA, and IgM reactivity to RP26 plus soluble egg antigens (SEA) in ELISA. The mean IgG reactivity to RP26 by sera from acute schistosomiasis patients was significantly higher than the chronic ones. The IgG4, IgA, and IgM reactivities to RP26 were low and similar in both infected groups. The mean IgA and IgM reactivities to SEA were significantly higher in the group of acute compared to chronic group, whereas mean IgG4 reactivity was higher in chronic group. To estimate the specificity of Schistosoma infection diagnosis sera from patients infected with other different parasites were tested to detect IgG reactivity to RP26 and IgA and IgM reactivity to SEA. For IgA against SEA detection, 72% of sera were positive and 48% of sera were positive for IgM detection. Based on these results we can suggest that detection of sera IgG binding to RP26 is a sensitive and specific method for acute schistosomiasis diagnosis. Therefore, RP26 is a candidate for immunodiagnostic kit development.     

Assay of IgA to Shigella flexneri during shigellosis

Abstract An enzyme-linked immunosorbent assay (ELISA) to Shigella flexneri 2a whole bacterium was used to determine IgM, IgG and IgA serum titers in 50 acute-phase shigellosis patients and 37 controls, i.e., hospital patients without known recent infections. Compared to controls, the shigellosis patients displayed statistically raised average serum titers to S. flexneri in all 3 above immunoglobulin classes, most notably IgA, which displayed an average 42-fold increase. Specific IgM and IgG were 5- and 16-fold higher, respectively. All sera displayed statistically raised titers in at least one immunoglobulin class. A Widal agglutination detected a 7-fold increase in serum titers; this was comparable to the IgM ELISA. Statistical analysis showed that the intra-assay error of the ELISA varied from 5 to 14%, depending on the absorbance from which titers were calculated. A second ELISA was performed on the above shigellosis sera to determine titers to purified lipopolysaccharide (LPS): a statistical correlation was found between these and the above values for all 3 immunoglobulin classes. We conclude that the use of S. flexneri whole bacterium as an antigen in an IgA ELISA is a statistically valid and convenient parameter for monitoring shigellosis, comparable to the use of LPS as antigen, and more sensitive than IgM or IgG ELISAs or agglutinations.     

Identification of antigenic proteins encoded by human herpesvirus 8 and seroprevalence in the general population and among patients with and without Kaposi's sarcoma

To establish a sensitive and specific antibody assay, potent antigenic proteins encoded by human herpesvirus 8 (HHV8) were studied. Fifteen recombinant HHV8-encoded proteins were produced as glutathione S-transferase fusion proteins. The sera from AIDS-associated Kaposi's sarcoma (KS) patients reacted with four proteins encoded by open reading frames (ORFs) K8.1, 59, 65, and 73 in a Western blot assay. An enzyme-linked immunosorbent assay (ELISA) using these four proteins as antigens (mixed-antigen ELISA) revealed that all 26 sera derived from KS patients (24 with and 2 without human immunodeficiency virus infection) became positive for anti-HHV8 antibodies. The presence of HHV8 was demonstrated in 14 (1. 4%) of 1,004 sera from the Japanese general population and 10 (1.9%) of 527 sera from patients without HHV8-associated diseases. The presence of immunoglobulin G (IgG) and IgM antibodies against HHV8 examined further by the mixed-antigen ELISA and Western blotting revealed IgG antibody in all ELISA-positive sera, while IgM antibody against ORF K8.1 was absent. These data suggest that the ORF 73 and 65 proteins are potent antigens for a sensitive serological assay.     

Serodiagnostics of chlamydial infections--significance of positivity in IgA and/or IgM antibody classes only

There was followed the development of serological findings in patients with proved positivity only in classes IgA and/or IgM of chlamydial antibodies (without IgG), which can be suspected of showing "false" positivity. 184 patients were repeatedly examined for chlamydial antibodies in their sera (interval between collections up to three months) using a genus specific rELISA. Sera were also tested for the evidence of IgM antibodies against capside antigen of Epstein-Barr virus (EBV) and against cytomegalovirus (CMV) using ELISA methods. In 75 (40.8%) of patients, IgA/IgM individual positivities were demonstrated even during the following sample test(s). In 28 (15.2%) of them, IgG evidence preceded and in 29 (15.7%) other patients positive seroconversion followed in this class. In 13 (7.1%) patients, IgG antibodies disappeared and subsequently reappeared. Only in 39 (21.2%) of these probands, antibodies IgA/IgM were not demonstrated at another examination. Active EBV, resp. CMV infection was proved in 24 (13.0%), resp. in 18 (9.8%) of patients. It is concluded that the evidence of positivities only in classes IgA and/or IgM mostly signal the onset of a primary infection (reinfection) or an active infection in patients with IgG production failures respectively. In these cases, a "false" positivity can be supposed to occur only in a minor extent.     

Schistosoma japonicum: Immunological response to circulating polysaccharide antigens in rabbits with a light infection

To study the detectability of circulating polysaccharide antigens and the immunological response to such antigens in rabbits with a light Schistosoma japonicum infection, sera of five rabbits infected with 50 cercariae were studied up to 29 weeks post infection (p.i.). While one rabbit developed no worm burden, the other rabbits developed low worm burdens (4 to 16 worms). In the sera of these rabbits, the only polysaccharide antigen demonstrable with immunoelectrophoresis (IEF), was the circulating anodic antigen (CAA). With the enzyme-linked immunosorbent assay (ELISA), CAA was detectable from 5 to 6 weeks p.i. in the sera of the two rabbits with the highest number of worm couples. The lowest CAA level which was detectable in unconcentrated sera from which serum proteins had been removed was 125 ng CAA/ml, corresponding with a worm burden of 4.5 worm/kg body wt. During the entire infection, CAA-specific immune complexes were only demonstrable in very low concentrations. Antibodies against polysaccharide antigens were assessed with immunofluorescent antibody (IFA) on Rossman's fixed sections of adult worms, with the ELISA, and with IEF. Specific IgA, IgG, and IgM antibodies were detectable from 2 to 3 weeks p.i. with IFA and ELISA. These early antibodies were shown to be directed against gut-associated antigens, while antibodies against parenchyma-associated antigens were found later in the infection. With IEF, antibodies against two trichloroacetic acid (TCA)-soluble antigens were detectable, including the major, S. japonicum-specific antigen 2.     

Class IgG,IgM and IgA antibodies againstStaphylococcus aureus antigens in human serum and saliva

Using the ELISA method antibodies against the sonicate, teichoic acid (TA) and exoproducts ofStaphylococcus aureus were determined in sera and saliva of healthy individuals. Main serum antibodies against all the antigens used were shown to be class IgG antibodies. However, antigens of the sonicate stimulated significantly even the systemic IgA response. In the saliva class IgA antibodies predominated, but IgG antibody levels against TA and exoproducts approached the level of IgA antibodies. Levels of IgM antibodies against all antigens tested were low in both the serum and saliva which corresponds with the anamnestic type of response. On the basis of these results one may assume that not only IgG, but also IgA antibodies are important in the systemic immunity against staphylococcal infection and in the immunity of mucous membranes; besides IgA, even class IgG antibodies play an important role.     

Analysis by enzyme-linked immunosorbent assay and immunoblot of the antibody responses of patients infected with Mycobacterium marinum

The serum antibody responses of a total of 14 patients with active or recently cured Mycobacterium marinum infections were analysed via a combination of enzyme-linked immunosorbent assay (ELISA) and the immunodevelopment of Western blots of M. marinum antigen. Normal human sera and sera from patients with active pulmonary tuberculosis were also analysed as controls. The detectable IgG response of M. marinum patients, as demonstrated by ELISA, was highly variable and did not differ significantly from normal controls. IgA and IgM levels were generally low in the M. marinum patients and were not significantly different from normal controls. Immunodevelopment of Western blots of M. marinum antigen with the sera of patients with M. marinum infections revealed that a number of antigens were recognised. Of particular note was an 18-kDa species that was recognised by 11 out of 14 patients (and by none of the normal controls). The 18-kDa antigen may be a useful serodiagnostic marker in the identification of M. marinum infections.     

A quantitative enzyme-linked immunosorbent assay for Dermatophagoides pteronyssinus-specific immunoglobulin G

A monoclonal mouse anti-human IgG was used to develop an enzyme-linked immunosorbent assay (ELISA) for the measurement of Dermatophagoides pteronyssinus (DP)-specific IgG in human sera. This monoclonal antibody (HG2-25) binds to all subclasses of IgG but not to IgA, IgM, or IgE. For the assay, the DP antigen is coated firmly on polystyrene beads through physical adsorption and any leakable antigen is washed off. The assay gives satisfactory reproducibility and parallelism of the dilution curves. Using 0.1% human serum albumin as a substitute for the DP-specific IgG preabsorbed diluent gave extremely low backgrounds and high sensitivity. Horseradish peroxidase-labeled HG2-25 prepared with the optimum degree of conjugation and free of polymerized conjugates gave responses fairly proportional to the doses. This ELISA gives a satisfactory recovery and is not affected by nonspecific IgG levels in human sera.     

Diagnostic use of ELISA, IgG, IgM, IgA and ELISA IgG avidity in recent and chronic toxoplasmosis]

Toxoplasmosis, a world-wide zoonotic infection, is generally asymptomatic and benign in immunocompetent individuals, but it can be serious in immunodeficiencies particularly in patients with acquired immunodeficiency syndrome and in children infected in utero. So, it is important to dispose methods which permit discriminate between recent and chronic infections. In order to contribute to improve the diagnosis of toxoplasmosis ELISA IgG, IgM, IgA and ELISA IgG avidity were performed in 15 and 24 sera from patients suspected of having acute and chronic infection respectively, according dye test (DT) titres. ELISA IgG was positive in both groups, ELISA IgM was positive in 78.6 and 58.3% respectively, while ELISA IgA was positive in 85.7 and 33.3% of recent and chronic group respectively. In those sera with low IgG avidity (18.8%) we found specific IgM in 71.5 and 4.2% and IgA in 78.6 and 0.0% of recent and chronic groups respectively. Parallelling, 208 sera samples were classified according to the results of DT, indirect hemagglutination and complement fixation tests in the following groups: acute (97), intermediate (36), chronic (35) and negative (40). The results were: acute (96.9-64.9-55.6 and 65.9%); intermediate (97.2-63.8-44.4 and 47.2%); chronic (45.7-42.8-5.7 and 34.3%) for IgG, IgM, IgA and low IgG avidity respectively. The use of both acute markers, IgA and low IgG avidity in the diagnosis of toxoplasmosis is discussed.     

Evaluation of IgG, IgM, and IgA antibodies to mycoplasma penetrans detected by ELISA and immunoblot in HIV-1-infected and STD patients, in São Paulo, Prazil

The aim of the present study was to determine the frequency of IgG, IgA, and IgM antibodies to Mycoplasma penetrans in HIV-1-infected patients and in patients with sexually transmitted diseases. We tested serum samples from 106 HIV-1-positive patients and 110 individuals with clinical symptoms of urethritis. ELISA and the immunoblot test were performed using M. penetrans lipid associated membrane proteins as antigen. By ELISA, we found a higher frequency (P < 0.05) of IgG against M. penetrans in HIV-1-infected and STD patients (25.5 and 17.3%) than in controls (1.2%), as well as a higher frequency of IgA (P < 0.05) (15.1 and 17.3% compared to 1.2%). For IgM, no differences were observed (P >/= 0.05) (3.8, 9.1, and 5. 8%, respectively). When the frequencies of IgG, IgM, and IgA antibodies of the HIV-1-infected patients were compared taking into account the CD4/CD8 cell ratios < 0.3 and >/= 0.3, no significant differences were observed between the two groups (13.3, 10, and 20%, compared to 20, 0, and 5%, respectively) (P > 0.05), possibly due to the low number of samples on which we could perform T-cell counts (53/106). The M. penetrans peptide of 38 kDa, considered immunodominant, was recognized in immunoblot by 51.8% of positive sera by ELISA for IgG, 50.0% for IgM, and 75% for IgA in the AIDS patients group, and by 47.4, 60.0, and 75.0%, respectively, in the sexually transmitted disease group. Cross-reactions in immunoblot for IgG were observed in sera from individuals infected with Mycoplasma pneumoniae and Mycoplasma hominis, and cross-reactions in immunoblot for IgA were observed in sera from individuals infected with M. hominis; all of them were ELISA negative to M. penetrans.     

Specificity of the microimmunofluorescence assay for the serodiagnosis of Chlamydia pneumoniae infections.

Chlamydia pneumoniae infections are mostly confirmed using an indirect microimmunofluorescence test for which potential cross-reactions between antigens from different chlamydial species are not well documented. Using this assay, 928 sera (507 subjects) submitted for Chlamydia pneumoniae serology were tested for specific IgM and IgG to this bacteria using the TW-183 antigen. IgM and IgG reactivities to Chlamydia trachomatis serotypes C, D, E, and L2 and Chlamydia psittaci strain 6BC antigens were also tested. A sample was interpreted as positive only when evenly fluorescent elementary bodies were observed. Twenty-five subjects (4.9%) showed serological evidence of recent Chlamydia pneumoniae infection (IgM positive and (or) IgG seroconversion); 11 of them also showed serological evidence of recent infection with at least one other chlamydial species. Specificity was 50 and 63% for IgM and IgG detection, respectively. These results suggest that mixed or temporally related infections might occur, or, more likely, that some Chlamydia pneumoniae IgM or IgG reactivities might be due to heterotypic antibodies.     

Immunoglobulins anti-Anisakis simplex in patients with gastrointestinal diseases

The nematode Anisakis simplex causes anisakidiasis, a disease that often mimics other gastrointestinal diseases. Patients with digestive haemorrhaging, Crohn's disease, digestive cancer and appendicitis were analysed for antibodies to A. simplex. Antibody detection was carried out by enzyme-linked immunosorbent assay (ELISA) and immunoblotting using crude extract (CE) antigen and excretory-secretory (ES) products. Total immunoglobulin (Igs), IgG, IgM, IgA and IgE were studied. The highest percentage was obtained when Igs were tested against CE antigen. A higher percentage of positivity was observed with the appendicitis group. The Crohn's disease group showed the highest levels of IgG against the ES antigen. Using immunoblotting, 24% and 48% of sera from patients with symptoms of Crohn's disease and digestive haemorrhaging, respectively, showed a positive immunorecognition pattern of CE antigen. The prevalence of detectable antibodies against A. simplex is higher in patients with digestive disorders than in the healthy population. A linear correlation was observed between prothrombin activity and Igs-CE, IgA-CE and IgA-ES but not between IgE-CE and the other immunoglobulin levels. Specific IgA is associated with a higher activity index of Crohn's disease. Specific antibodies were observed against A. simplex in patients with appendicitis and gastrointestinal cancer, indicating a higher rate of positivity for IgA.     

Competition between Serum IgG,IgM, and IgA Anti-Glycan Antibodies

Anti-glycan antibodies are an abundant subpopulation of serum antibodies with critical functions in many immune processes. Changes in the levels of these antibodies can occur with the onset of disease, exposure to pathogens, or vaccination. As a result, there has been significant interest in exploiting anti-glycan antibodies as biomarkers for many diseases. Serum contains a mixture of anti-glycan antibodies that can recognize the same antigen, and competition for binding can potentially influence the detection of antibody subpopulations that are more relevant to disease processes. The most abundant antibody isotypes in serum are IgG, IgM, and IgA, but little is known regarding how these different isotypes compete for the same glycan antigen. In this study, we developed a multiplexed glycan microarray assay and applied it to evaluate how different isotypes of anti-glycan antibodies (IgA, IgG, and IgM) compete for printed glycan antigens. While IgG and IgA antibodies typically outcompete IgM for peptide or protein antigens, we found that IgM outcompete IgG and IgA for many glycan antigens. To illustrate the importance of this effect, we provide evidence that IgM competition can account for the unexpected observation that IgG of certain antigen specificities appear to be preferentially transported from mothers to fetuses. We demonstrate that IgM in maternal sera compete with IgG resulting in lower than expected IgG signals. Since cord blood contains very low levels of IgM, competition only affects maternal IgG signals, making it appear as though certain IgG antibodies are higher in cord blood than matched maternal blood. Taken together, the results highlight the importance of competition for studies involving anti-glycan antibodies.     

Impact of ELISA and immunoblot as diagnostic tools one year after eradication of Helicobacter pylori in a multicentre treatment study

The performance of serological tests for Helicobacter pylori infections is hampered by the persistence of antibodies after eradication therapy or spontaneous healing. Detection of different antigens or immunoglobulin classes might have an impact on the validity of serodiagnosis. The aim of this study was to assess the decrease in IgA and IgG antibody levels after eradication of H. pylori. Serum samples of 242 patients with active duodenal ulcer were tested with the ELISA and the immunoblot (IB) techniques for H. pylori-specific IgA and IgG antibodies before therapy and 1 year after successful eradication. From a total of 81 patients paired sera were available. At the end of the follow-up period ELISA antibody titres from the IgA class had decreased from a mean value of 6.69 to 4.26 units (P = 0.0001), and IgG class antibody titres from a mean value of 21.9 to 12.1 units (P = 0.0001). Regarding seroreversion, from 34 initially IgA positive sera 16 (47%), and from 74 IgG positive sera 18 (24%), had definitively reverted to 'negative'. One year after eradication, when tested with the immunoblot, the antibody responses against specific antigens of 37% IgA-positive sera (23/62) and 8% IgG-positive sera (6/78) reverted to 'negative', compared to a seroreversion rate of 27% of the anti-CagA IgA-positive sera (18/67) and of 9% of the anti-CagA IgG-positive sera (7/79). In conclusion, despite an overall significant decrease of H. pylori antibodies, both tests cannot be recommended for monitoring treatment success.     

Natural and immune human antibodies reactive with antigens of virulent Neisseria gonorrhoeae: immunoglobulins G, M, And A

Natural and immune human antibodies reactive with heat-labile and heat-stable antigens of virulent Neisseria gonorrhoeae were studied by use of an indirect fluorescent-antibody (IFA) procedure. The immunoglobulin class of the reactive antibodies was identified by using fluorescein-conjugated antisera specific for human IgG, IgA, or IgM in the IFA procedure. The effects of heat and mercaptoethanol on IFA reactivities were also studied. It appeared that antibodies of the IgG, IgM, and IgA classes present in the sera of both infected persons (immune antibodies) and normal persons with no history of gonococcal infection (natural antibodies) react with heat-stable somatic antigens. Immune IgG antibodies, however, were distinguishable from natural IgG antibodies by their ability to recognize heat-labile surface antigens. The distinction between natural and immune IgM antibodies was less obvious. IgM antibodies from both infected and normal persons appeared to react with heat-labile antigens. Some, but not all, infected persons had immune IgA antibodies to heat-labile as well as to heat-stable antigens. Treatment of sera with mercaptoethanol had no effect on IgG antibodies. The IFA activity of IgM antibodies was decreased, but not abolished. The effects of mercaptoethanol on IgA antibodies were variable. Some sera showed a decrease in IgA titer, and others showed an increase in IgA activity to certain antigens. Immune IgG antibodies were more resistant to heating than were natural IgG antibodies. Natural and immune IgM antibodies appeared equally sensitive to heating. IgA activity, on the other hand, was increased by heating sera at 60 C, but was decreased at higher temperatures. Thus, it appears that natural and immune human IgG antibodies to N. gonorrhoeae may be distinguished by their interactions with heat-labile antigens and by their resistance to heating.     

ELISA for the detection of specific IgM and IgG in human leptospirosis

ELISA was used to detect specific IgM and IgG in sera from humans with current or past leptospirosis. A serological pattern of a high IgM titre (greater than or equal to 1280), or moderately increased IgM (160-640) in conjunction with a low IgG titre (less than or equal to 20), with serovar copenhageni antigen was characteristic for approximately two-thirds of the sera from serovar icterohaemorrhagiae patients obtained in the first two months of the disease. The antigen was the supernatant of a heated and centrifuged culture of leptospires. Antigens were prepared from serovars copenhageni, grippotyphosa, hardjo and patoc. Sera from patients with icterohaemorrhagiae, grippotyphosa and hardjo infections showed cross-reactivity when different antigens were used. In past infections the IgG titres were clearly higher with the homologous antigen. ELISA for IgM and IgG allows the rapid diagnosis of acute leptospirosis.     

A quantitative enzyme-linked immunosorbent assay for bovine herpesvirus type 1 (BHV-1) antibody

A quantitative enzyme-linked immunosorbent assay (ELISA) was developed to detect and measure antibody to bovine herpesvirus type 1 (BHV-1) in cattle sera. The optical density produced from a single dilution of test serum was compared with a standard curve and the results were read and printed out from a computer interfaced to a multichannel ELISA reader. The printed results were expressed in ELISA units. The ELISA results obtained on 370 cattle sera were compared with those of the serum neutralisation test (SNT). An agreement of 90.5% was obtained when reciprocal SNT titres equal to or greater than 4 and IgG ELISA units equal to or greater than 50 were taken as indicative of a specific reaction. Of the 370 sera, 35 gave discrepant results of which 21 were SNT positive/IgG ELISA negative and 14 were SNT negative/IgG ELISA positive. When the SNT positive sera negative in the IgG ELISA were tested in an IgM ELISA, 19 were found to be positive. Thus, when the IgG and IgM ELISA results were combined the overall agreement between the ELISA and SNT increased to 95.7%. The IgG ELISA had a sensitivity of 82.4% and specificity of 94.4% relative to the SNT, whereas the combined IgG and IgM ELISA results gave a sensitivity and specificity of 98.3% and 94.4% respectively. There was a good positive correlation between the two tests (r = 0.86).     

Early diagnosis of Schistosoma mansoni in mice using assays directed against cercarial antigens isolated by hydrophobic chromatography

Two diagnostic assays are described for the early diagnosis of acute schistosomiasis, using a defined cercarial antigen preparation obtained by hydrophobic chromatography. Circulating IgM antibodies against this antigen fraction could be detected by ELISA as early as 1 wk after exposure in experimentally infected mice; IgM levels against other antigens and IgG levels against all the preparations examined were not significantly elevated until approximately 4-5 wk postinfection. Circulating antigen was detected as early as 3 days after exposure by a competitive inhibition ELISA using rabbit serum prepared against the cercarial antigen; antigen levels in the serum of mice with a 100-worm infection were found to exceed 100 ng/ml. Studies using sera from infected humans indicate that the assay can also recognize chronic S. mansoni, S. haematobium or S. japonicum infections. In a very limited field study, the specificity of the circulating antigen assay with regard to other helminthic infections was found to be 85%; sensitivity 100%. Preliminary characterization of the relevant antigen indicates that it is a relatively hydrophobic polypeptide with a molecular weight of approximately 41,000 daltons. The implications of these findings with regard to the treatment of travelers or the conduct of seroepidemiological studies in endemic areas are discussed.     

Humoral reaction to Bordetella pertussis antigens: pertussis toxin, filamentous hemagglutinin and lipopolysaccharide in children with clinical symptoms of whooping cough. II. Occurence and level of B. pertussis antigens in children with suspected whooping cough

The aim of this study was to determine and evaluate IgG, IgM and IgA levels to pertussis toxin (PT), filamentous hemagglutinin (FHA) and endotoxin (LPS) of B. pertussis in children with clinical symptoms of whooping cough. The serum samples obtained from 265 children (age range: 2 months-16 years) suspected of pertussis were examined by indirect haemagglutination (IH) and ELISA tests. Higher antibody level was most frequently observed in IgA class to PT, FHA and LPS in 45.3%, 35.1% and 66% of pertussis patients sera respectively. The least positive results were obtained in IgM class to PT and FHA (in 9.8% and 2.6% of children sera respectively) but in the case of LPS applied as the antigen in ELISA, higher IgM level was determined in 46.8% of pertussis patients sera. The four times increase of antibody level to LPS determined by IH was observed in 86.7% of children suspected of pertussis. Humoral response to B. pertussis infection is mainly connected with higher IgA level to PT, FHA, LPS and IgM to LPS in children with clinical symptoms of whooping cough.