Antibody Signatures Reflect Different Disease Pathologies in Patients With Schistosomiasis Due to Schistosoma japonicum.

Infection with Schistosoma japonicum causes high levels of pathology that is predominantly determined by the cellular and humoral response of the host. However, the specific antibody response that arises during the development of disease is largely undescribed in Asian schistosomiasis-endemic populations. A schistosome protein microarray was used to compare the antibody profiles of subjects with acute infection, with early or advanced disease associated with severe pathology, with chronic infection, and subjects exposed but stool negative for S. japonicum eggs to the antibody profiles of nonexposed controls. Twenty-five immunodominant antigens were identified, including vaccine candidates, tetraspanin-related proteins, transporter molecules, and unannotated proteins. Additionally, individuals with severe pathology had a limited specific antibody response, suggesting that individuals with mild disease may use a broad and strong antibody response, particularly against surface-exposed proteins, to control pathology and/or infection. Our study has identified specific antigens that can discriminate between S. japonicum-exposed groups with different pathologies and may also allow the host to control disease pathology and provide resistance to parasite infection.

Immunomodulatory mechanisms during Echinococcus granulosus infection.

The pathologic events that ensue after humans ingest the eggs of Echinococcus granulosus and continue while cystic echinococcosis develops, provide an excellent example illustrating the evasive strategies helminth parasites use to develop, progress and cause chronic disease. The hydatid cyst secretes and exposes numerous immunomodulatory molecules to the host's immune system. By characterizing these molecules we can understand the mechanisms that E. granulosus uses for increasing the efficiency and persistency of infection in the host. These molecules modulate both the innate and adaptive arms of the immune response and appear to target cellular and humoral responses. In this review, we discuss recent advances in the immunobiology of host-E. granulosus interactions that provide intriguing insights into the complex interplay between host and parasite that ultimately facilitates parasite survival.

The prevalence of intestinal parasites in dogs from Prague, rural areas, and shelters of the Czech Republic.

The prevalence of intestinal parasites was evaluated by examination of dog faecal samples in the Prague city centre, agricultural areas, and two shelters. The overall prevalence of parasites (i.e., protozoa and helminths, mentioned below) in Prague was 17.6%. Toxocara canis was the most common parasite, and was recovered from 6.2% of dogs, followed by Cystoisospora spp. (2.4%), Cryptosporidium spp. (1.4%), Trichuris sp. (1.1%), Taenia-type (1.0%), Giardia spp. (0.1%), Toxascaris sp. (0.9%), Dipylidium sp. (0.7%), Sarcocystis spp. (0.6%), Capillaria spp. (0.6%), Neospora/Hammondia spp. (0.5%), Ancylostoma sp. (0.4%), Uncinaria sp. (0.4%), and Spirocerca sp. (0.2%). The prevalence of infections with helminths and protozoans in two animal shelters in Prague was examined at the dog's admittance ir reception to the shelters and during housing. T. canis eggs (6.5%), Cystoisospora (4.4%), and Giardia (3.3%) cysts were the most prevalent. Significant increases in the prevalence of some parasites were found after a stay in the shelter. Giardia spp. showed an 11-fold increase in prevalence of dogs placed in the shelters for a longer time; Cryptosporidium spp. had a 7-fold increase, Capillaria spp. a 5-fold, Spirocerca sp., Neospora/Hammondia spp., and Cystoisospora spp. a 4-fold increase over dogs examined at the time of admittance to the shelter (p<0.01). Dog in rural areas were infected significantly more frequently (p<0.01) than those in Prague. In 540 faecal samples from rural areas, the overall prevalence of parasites (i.e., protozoa and helminths mentioned below) was 41.7%. The prevalence of T. canis was 13.7%, followed by Cystoisospora spp. (8.0%), Taenia spp. (3.5%), Sarcocystis spp. (3.0%), Giardia spp. (2.2%), Cryptosporidium spp. (2.0%), Trichuris sp. (1.7%), Toxascaris sp. (1.7%), Dipylidium sp. (1.3%), Neospora/Hammondia spp. (1.3%), Spirocerca sp. (1.1%), Uncinaria sp. (0.9%), Ancylostoma sp. (0.7%), and Capillaria spp. (0.6%). Examinations of dogs in urban and rural areas showed, with the exception of Trichuris sp. in Prague, a higher occurrence of nematode infection in autumn, notably T. canis (chi2>8.3, d.f.=3, p<0.04).

Serum antibody isotype responses of Fasciola-infected sheep and cattle to excretory and secretory products of Fasciola species.

This study investigated the immunoglobulin isotype responses of sheep and cattle chronically infected with Fasciola hepatica and Fasciola gigantica to adult F. hepatica excretory/secretory products (Fh-ES) or F. gigantica excretory/secretory products (Fg-ES), respectively. An antibody enzyme-linked immunosorbent assay (Ab-ELISA) was used to determine serum antibody (total Ig, IgG(1), IgM, IgG(2) and IgA) responses. At necropsy, the mean number of flukes recovered was lower in cattle than in sheep. All F. hepatica and F. gigantica infected sheep and cattle showed an increased total Ig levels from 3 to 4 weeks post-infection (wpi). Among isotypes IgG(1) was most dominant while IgM was the earliest (2 wpi) to be detected in both sheep and cattle infected with both F. hepatica and F. gigantica animals. IgG(2) response was early (2 wpi) in sheep infected by F. hepatica but there was no response in sheep infected with F. gigantica. There was a late and strong IgG(2) response in cattle infected with both flukes. The IgA isotype showed an early and a clear biphasic response in sheep with F. hepatica but was less pronounced in F. gigantica infected sheep. While IgA response to Fh-ES was noticed 5 wpi in F. hepatica infected cattle, it appeared much later (21 wpi) in those infected with F. gigantica. The dominance of IgG(1) isotype in infected sheep and cattle suggest an associated Th2 response. This early response to adult Fasciola spp. ES antigen suggests an early exposure to the antigen presumably through the cross-reacting ES products of juvenile flukes. There is clearly difference in IgG(2) isotype response in cattle (resistant) compared to sheep (susceptible). The late IgG(2) response in cattle may suggest late Th1 involvement in bovine cellular responses to adult Fh-ES/Fg-ES.

Differential recognition of two cloned Brugia malayi antigens by antibody class.

The humoral and cellular immune response to filarial parasites is complex. Numerous studies have shown that antibodies to a large number of protein and non-protein antigens may be produced over the course of infection and that immune recognition of any given antigen may vary by disease manifestation and by immunoglobulin class. We have used the techniques of molecular cloning to attempt to dissect this complex interaction, and describe here two clones, isolated from an expression library constructed from Brugia malayi genomic DNA, whose products are recognized by distinct immunoglobulin classes. A lambda gt11 fusion protein containing part of the B. malayi myosin tail region is recognized by antibodies of the IgG class from a high percentage of bancroftian filariasis patients. A fusion protein containing a collagen-like sequence is less frequently and weakly recognized under the same experimental conditions, but is almost universally recognized when the developing reagent is specific for IgE. We thus identify specific filarial proteins against which the infected human host responds preferentially with antibodies of a specific immunoglobulin class.

Parasite-specific antibody profile in human fascioliasis: application for immunodiagnosis of infection.

The antibody isotype response to an adult Fasciola worm antigen preparation (FWAP) was examined in sera from 60 Egyptians with parasitologically confirmed fascioliasis by an ELISA. The FWAP-specific IgG1 and IgG4 antibodies were found in 97-100% of the patients. The ratio of the mean absorbance values between infected patients and healthy controls was 9.7 and 29.7 for IgG1 and IgG4 antibodies, respectively. The IgM, IgA, IgG2, and IgG3 antibodies were less dominant. In contrast to IgG1 antibodies, which were often detected in sera from patients infected with Schistosoma, Echinococcus granulosus, Ascaris lumbricoides, Ancylostoma duodenale, or Hymenolepis nana, FWAP-specific IgG4 antibodies were detected exclusively in the sera of patients with fascioliasis. The data thus support the conclusion that an IgG4/ELISA with crude FWAP as antigen may be used for sensitive and accurate immunodiagnosis of human fascioliasis.

A longitudinal study of local and peripheral isotype/subclass antibodies in Dictyocaulus viviparus-infected calves.

Although infection with the bovine lungworm, Dictyocaulus viviparus, stimulates high levels of resistance, the mechanisms involved in immunity to this parasite remain poorly understood. In an attempt to address the possible role of antibody in protective immunity, a longitudinal study was carried out in which the levels of both local and peripheral parasite-specific IgG, IgG1, IgG2, IgM and IgA were measured by ELISA. Five calves were infected orally with ten third stage larvae per kilogram on days 0, 65 and 112. Three challenge controls remained uninfected until day 112. Peripheral responses were measured in serum collected weekly and local responses were measured in bronchoalveolar lavage fluid (BALF) collected pre-infection and on two occasions after each infection. After the secondary infection, there were increases in respiratory rates in all the calves, but four of five calves had no first stage larvae (L1) in their faeces, suggesting that the parasites reached the lungs but did not develop to patency. Respiratory rates remained within normal limits after the tertiary infection and there were no parasites in the lungs at postmortem. Locally, in BALF, levels of all the antibody isotypes/subclasses increased after the primary infection, then again after the secondary infection. The highest levels of antibody were detected after the tertiary infection, when the calves were fully immune. In contrast, serum antibody levels increased from day 21 after primary infection and rose again after secondary infection, but thereafter slowly declined, with no increases after tertiary infection. Our findings suggest that the local antibody response was important in the immune response to D. viviparus infections in calves.

Studies on the isolation and characterisation of a reaginic antibody in a cat.

A reaginic antibody has been demonstrated, by passive cutaneous anaphylaxis (PCA), in the serum of a cat infected with the microfilariae of Brugia pahangi. Recipient cats and pigs were challenged with an extract of Ascaris suum after either a four-hour or a 72-hour period of sensitisation. When the serum was heat treated at 56 degrees C it lost its PCA activity. Gel filtration of the serum revealed a pattern of positive PCA fractions similar to that observed in other species. Attempts to purify the PCA-positive material by Superose gel filtration and ion exchange chromatography by fast protein liquid chromatography (FPLC) were unsuccessful. Affinity chromatography of PCA-positive material by FPLC on protein A demonstrated two bound peaks, the second of which was PCA-positive and eluted as a single peak by ion exchange chromatography. The PCA-positive material from gel filtration did not bind to protein G. The protein A, PCA-positive peak provides a partially purified reaginic antibody for further study.

Serological investigation in children infected with Ascaris lumbricoides.

The study included 260 hospitalised children with suspected infection with human ascaris. In serological diagnostics a protein antigen obtained from Ascaris lumbricoides was used. ELISA method was applied. IgG antibodies were detected. Positive results were found in 15% of the examined children. No relation to the gender or demographic conditions was found. The most frequently observed symptoms in the patients with Ascaris lumbricoides were: abdominal pain--87%, diarrhoea 15%. In 31% of the cases eosinophilia was found. Scatoscopy was carried out for all the patients, using the PARASEPT system and Kato and Miura methods as well as decantation and flotation. The examination, which was repeated three times, did not show cysts or eggs. Serological investigation exhibits higher sensitivity than the traditional methods. Their use in recognising ascariasis in humans significantly facilitates diagnostic procedures, especially in the lung phase of the disease, the larval stage or in cases of infection with an individual parasite, when the faeces samples do not contain the eggs. Serological investigation is also useful in all cases of suspected VLM.

Bovine IgG subclasses and fertility of Echinococcus granulosus hydatid cysts.

Hydatidosis is an important zoonotic disease of worldwide distribution, causing important health problems to humans and major economical losses in infected livestock. Echinococcus granulosus, the etiological agent of hydatid disease, induces a humoral immune response in the intermediate host (human and herbivorous) against hydatid cyst antigens. Specifically, IgGs are found in the laminar and germinal layers and inside the lumen of fertile and infertile hydatid cysts. In the germinal layer of infertile cysts IgGs are found in an order of magnitude greater than in the germinal layer of fertile cysts; a fraction of those IgGs are associated with high affinity to germinal layer proteins, suggesting their binding to specific parasite antigens. We have previously shown that those immunoglobulins, bound with high affinity to the germinal layer of hydatid cysts, induce apoptosis leading to cyst infertility. In the present work the presence of IgG1 and IgG2 subclasses in the germinal layer of both fertile and infertile hydatid cysts is reported. IgG1 is the most relevant immunoglobulin subclass present in the germinal layer of infertile cysts and bound with high affinity to that parasite structure. Contrarily, though the IgG2 subclass was also found in the germinal and adventitial layers, those immunoglobulins show low affinity to parasite antigens. We propose that the binding of an IgG1 subclass to parasite antigens present in the germinal layer is involved in the mechanism of cyst infertility.

Immunoglobulin G subclass responses to recombinant Em18 in the follow-up of patients with alveolar echinococcosis in different clinical stages.

In this study, we compared the sequential responses of immunoglobulin G (IgG) subclasses to the diagnostic antigen Em18 in sera from patients with alveolar echinococcosis. A total of 225 sera from 36 patients at different clinical stages according to the WHO-PNM staging system were tested. The antibody responses were measured for cohorts with resected and unresected parasitic lesions by enzyme-linked immunosorbent assays (ELISA). Total IgG and, to a lesser extent, IgG4 antibody levels against Em18 correlated with all PNM stages before treatment, whereas levels of IgG2 were low and IgG3 was undetectable. Antibody kinetics, however, depended on the treatment rather than on the PNM stage. For some patients, after curative surgery, IgG1 antibodies dropped below the cutoff earlier than other antibodies, followed by total IgG and IgG4 within 18 months. For some patients with recurrences after surgery, IgG1 and IgG4 reappeared, whereas patients with unresectable lesions but stable disease showed steady declines in the levels of all antibodies, and IgG1 became undetectable in some patients. Additional testing of IgE responses to Em18 showed constantly low levels at all stages and in all cohorts.

Utilidad del método Kato-Katz para diagnostico de uncinarias: experiencia en una zona rural de Honduras, 2011 / Usefulness of Kato-Katz method for the diagnosis of hookworm infections: experience in a rural region of Honduras, 2011

Antecedentes. El método Kato-Katz se utiliza para determinar infecciones por helmintos transmitidos por el suelo. A pesar de ser un método de concentración sencillo, robusto y relativamente sensible, la calidad de los resultados del Kato-Katz está sujeta a su apropiada estandarización en cada laboratorio. Objetivo. Describir el efecto negativo del aclaramiento excesivo de las muestras en la detección de uncinariasis utilizando el método de Kato-Katz en una encuesta coproparasitológica realizada en comunidades rurales Hondureñas en el año 2011. Materiales y Métodos. Se realizó un estudio epidemiológico sobre infecciones por uncinarias utilizando el método Kato-Katz en 351 niños de varias comunidades de Olancho, entre febrero y abril de 2011, encontrándose prevalencia de uncinariasis de 6.0%. La revisión del procedimiento determinó que en 228 muestras el tiempo de aclaramiento excedió dos horas. Se procedió a un segundo muestreo y se recolectaron 195 muestras de la misma población. Resultados. Las nuevas muestras se examinaron entre 60-90 minutos después de su preparación obteniéndose una prevalencia de uncinariasis de 15.9%. Conclusiones. El exceso de aclaramiento de las heces con el método Kato-Katz produjo la subestimación inicial de uncinariasis. Debido a que Kato-Katz es un método importante para la evaluación de los programas de desparasitación, su implementación en el laboratorio debe hacerse bajo supervisión...

[Detection of different class (subclass) antibodies in sera of patients with schistosomiasis japonica for diagnosis and efficiency evaluation].

The subclass antibodies against IgG1, IgG3 and IgG4 in sera of the patients with chronic Schistosomiasis japonica were detected before treatment, and after treatment--6 and 12 months respectively, using Biotin-Avidin-ELISA (BA-ELISA) established by purified 31/32 KD antigen from the adult worms. At the same time IgG1 and IgM were examined by the standard ELISA. False positive reaction with normal control and cross reaction with other parasitic diseases have not been observed. The IgG1 and IgG3 subclasses showed high sensitivity and specificity and reduced quickly 6 months after treatment. These results indicate that the level of specific IgG1 and IgG4 to the 31/32 KD adult worm protein has high value for diagnosis of Schistosomiasis japonica and evaluation of the curative efficiency of the disease.

Early antibody responses in human schistosomiasis.

Early diagnosis is important when handling patients with acute schistosomiasis. This state is usually more severe in travellers and tourists than in the immune, resident patients. With increased travelling to areas endemic for schistosomiasis, a tool is needed to solve the problem of differential diagnosis due to the non-specific symptoms of the early stages of the disease. Early appearance of antibodies against excretory/secretory antigens of the intestinal tract in the adult worm was seen in six individuals recently infected with Schistosoma mansoni, using an indirect immunofluorescence technique. The antibodies were of IgM, IgG and IgA classes, and of the IgG1, IgG3 and IgA1 subclasses as detected by ELISA using an antigen preparation of adult worm. On immunoblots, using a freeze-dried adult worm antigen, IgG1 and IgG3 antibodies recognized antigens of 32-35 kD. Antibodies against these antigens could thus be a marker of early infection in previously non exposed visitors to endemic areas.

Anti-schistosome monoclonal antibodies of different isotypes--correlation with cytotoxicity.

Five monoclonal antibodies specific towards Schistosoma mansoni antigens were prepared by fusion of spleen cells of infected and immunized mouse with the murine myeloma NS-1 cells. Three of the five antibodies belonged to the IgG1 class, one was an IgM and the fifth one was an IgE. The IgE monoclonal antibody designated 54.10, induced antigen-specific degranulation of rat basophilic cell line, a property which served as the basis for the screening assay. Its biological function was demonstrated by a specific macrophage activation that led to killing of schistosomula; no such killing was obtained with anti-schistosome antibodies of other classes or with IgE of different antigenic specificity. The second monoclonal antibody of biological significance was an IgG1, designated 27.21 which is reactive in the immunofluorescence staining of surface antigens on intact schistosomula. All three monoclonal antibodies that belonged to the IgG1 class were effective in mediating killing of schistosomula by complement, with the highest effect exerted by 27.21. It is thus apparent that the 27.21 monoclonal antibody is directed against a densely distributed surface antigen on the schistosomula membrane which is possibly involved in the protective immunity. Preliminary data showed that immunoprecipitation with the 27.21 antibodies results in the isolation of three major protein bands, of 60 kd, 50 kd, 19 kd, respectively.

Kinetics of Taenia solium antibodies and antigens in experimental taeniosis.

Two groups of hamsters were infected with Taenia solium cysticerci, one of which was suppressed with methyl-prednisolone acetate on the day of infection and every 14 days thereafter. The other did not receive steroid treatment. Faecal and serum samples were taken prior to infection and then at weekly intervals. Parasite circulating- and coproantigens were detected by a capture ELISA with rabbit polyclonal antibodies against T. solium tapeworms. IgG antibodies in serum and in faecal supernatants were detected by ELISA with excretory-secretory products of T. solium adults recovered from hamsters. Infections remained up to 17 weeks in suppressed hamsters, but after week 11 no tapeworms were found in non-suppressed hosts. T. solium coproantigens in both groups of hamsters were positive from the 1st week post-infection (wpi) until the tapeworms were rejected. Circulating antigens were detected only in non-suppressed hamsters from the 3rd wpi until 1 week before T. solium was eliminated. All infected hamsters developed serum IgG antibodies against tapeworms which were detected from the 2nd wpi and decreased slowly after T. solium expulsion. Specific IgG in faecal supernatants was detected from the 3rd wpi only in non-suppressed hamsters. When suppression was stopped, coproantibodies could also be detected. The presence of IgG antibodies indicates that tapeworms induced an immune response in the experimental host and that when hamsters were suppressed with corticosteroids the immune response was impaired and did not allow the detection of IgG coproantibodies. This indicates, in addition, that the passage of T. solium antigens from the small intestine to the circulation was blocked.

Specific immunoglobulin measurements related to exposure and resistance to Schistosoma mansoni infection in Sudanese canal cleaners.

The present work comprises a longitudinal study of Schistosoma mansoni infection in occupationally hyper-exposed canal cleaners in the Sudan and the influence of chemotherapy on humoral immune parameters. The study groups included chronically infected canal cleaners (n = 19), newly recruited canal cleaners (n = 17), normally exposed adults (n = 31), school children (n = 46) and Sudanese negative controls (n = 48). Previous studies of the same canal cleaners have demonstrated that chronically infected canal cleaners were more resistant to reinfection than newly recruited canal cleaners. ELISA was used to detect specific IgE and IgG subclasses in response to whole worm antigen (WWH) and soluble egg antigen (SEA) before and 3 months after praziquantel treatment in the groups of canal cleaners and before and 1 year after treatment in normally exposed adults. When intensity of infection was correlated with IgE antibody response, the resistant group of canal cleaners (those who stopped passing ova after treatment) showed a significant positive correlation between intensity of infection and specific IgE to WWH (Spearman's correlation coefficient = 0.49, P < 0.05) compared with a highly significant negative correlation in the susceptible group (acquired new infection after treatment, Spearman's correlation coefficient = -0.94, P < 0.01). Normally exposed adults and school children had significantly less specific IgE to WWH than canal cleaners, while chronically infected canal cleaners had significantly higher levels of specific IgG1 to WWH than newly recruited canal cleaners and school children, and significantly higher levels of specific IgG4 to WWH than school children. There was a significant increase in specific IgG1 and IgG4 to WWH, 3 months after treatment, in newly recruited canal cleaners and a significant decrease, 1 year after treatment, in normally exposed adults. None of the groups studied after treatment showed a significant change in their specific IgE to WWH. Normally exposed adults had significantly lower levels of specific IgE to SEA than newly recruited canal cleaners, and significantly lower levels of specific IgG1 to SEA than other infected groups. Both newly recruited canal cleaners and school children had significantly higher levels of specific IgG2 to SEA than persons in other groups. Only small differences between groups were observed with regard to specific IgG3 and IgM to SEA. Specific IgG4 to WWH and SEA showed different patterns after treatment between the resistant and susceptible groups of canal cleaners. The resistant group maintained the same level of IgG4 to WWH after treatment compared with a significant increase in the susceptible group. On the other hand, levels of specific IgG4 to SEA showed a highly significant decrease after treatment in the resistant group. In contrast, the same antibody subclass increased after treatment in the susceptible group. Generally, results show an association between IgE and IgG1 responses to WWH and resistance to reinfection. In contrast, an association was observed between IgG2 and IgM responses to SEA and susceptibility to reinfection.

Potential use of IgG2-ELISA in the diagnosis of chronic elephantiasis and IgG4-ELISA in the follow-up of microfilaraemic patients infected with Brugia malayi.

Sera from fifty subjects with different presentations of Brugian filariasis and from common soil-transmitted helminth infections were tested for specific anti-filarial IgG and its subclasses. Anti-filarial IgG, IgG1 and IgG3 showed cross-reactivities with soil-transmitted helminthic infections and no significant differences in optical densities among the various groups of filarial patients. In comparison with other groups of subjects, IgG4-ELISA of sera from microfilaraemic patients and some previously microfilaraemic patients showed a significant increase in optical density readings, while IgG2-ELISA showed elevated optical density readings in sera of patients with chronic elephantiasis. Therefore IgG2-ELISA is potentially useful in the diagnosis of brugian chronic elephantiasis while IgG4-ELISA may be beneficial for follow-up diagnosis of treated microfilaraemic patients.

Subclass distribution and IgE responses after treatment in human schistosomiasis.

The IgG and IgA subclass distribution of specific antibodies as well as the distribution of total and specific IgE in 15 patients with schistosomiasis was determined in consecutive samples before and after initiation of treatment. An adult worm antigen preparation and a soluble egg antigen preparation were used as antigens in the ELISA assays. After initiation of treatment a rise was noted in certain subclasses and a correlation was found for specific IgG1 and IgG4 serum levels in the egg-excreting patients against adult worm antigen and for specific IgG4 and IgE levels in sera from the eight patients with a chronic disease. They also had a rise of the specific IgA1 titre and six of them also of specific IgA2. Members of eosinophilic granulocytes reached a peak after 2 weeks in seven of the eight patients. The increase of eosinophils was an early event as opposed to the incidence of peak of the determined specific isotypes. The associated rise in IgG1, IgG4 and IgE antibody concentrations and eosinophils may suggest a causal relation possibly induced by common interleukins.

The profile of IgG and IgG subclasses of onchocerciasis patients.

In this study Onchocerca gutturosa was compared with O. volvulus in an ELISA test to detect Onchocerca-specific IgG and IgG subclasses. The test was developed and standardized to detect Onchocerca-specific IgG and IgG subclasses in sera of onchocerciasis patients and endemic controls. Onchocerca volvulus and O. gutturosa crude water-soluble antigens showed no significant difference in detecting onchocerca-specific IgG antibody (T = 1.88, P greater than 0.05). The levels of IgG subclasses varied greatly. IgG4 showed the highest detected mean level (0.84 +/- 0.59) and the other three subclasses showed considerably lower mean levels (IgG1 = 0.27 +/- 0.16, IgG2 = 0.24 +/- 0.17, IgG3 = 0.28 +/- 0.12). The status and score of skin lesions were found to have significant effect on the IgG and IgG subclasses levels (all P less than 0.001). IgG4 showed a positive correlation with the microfilarial (Mf) load (r = 0.21, P less than 0.03). IgG3 levels have a significant negative correlation with the Mf load (r = -0.23, P less than 0.02). The biological significance of these IgG and IgG subclasses in onchocerciasis is discussed.