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.

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.

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...

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.

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.

Early stages ofAscaris suuminduce airway inflammation andhyperreactivity in a mouse model

The inflammatory and functional changes that occur in murinelung after infection with 2500 infectiveAscaris suumeggswere studied in this work. A sequential influx of neutrophils,mononuclear cells and eosinophils occurred into airwaysconcomitantly with migration of larvae from liver to thelungs. Histological analysis of the lung showed a severe intraalveolarhaemorrhage at the peak of larval migration (day 8)and the most intense inflammatory cell infiltrate on day 14.AscarisL3 were found in alveolar spaces and inside bronchioleson day 8. The number of eosinophils was elevated inthe blood on days 8 and 14. The peak of eosinophil influx intothe lung was at day 14, as indicated by the high levels of eosinophilperoxidase activity, followed by their migration into theairways. The antibody response against egg and larval antigensconsisted mainly of IgG1 and IgM, and also of IgE andanaphylactic IgG1, that cross-reacted with adult worm antigens.Total IgE levels were substantially elevated during theinfection. Measurement of lung mechanical parametersshowed airway hyperreactivity in infected mice. In conclusion,the murine model ofA. suuminfection mimics the Th2-induced parameters observed in pigs and humans and can beused to analyse the immunoregulatory properties of thishelminth.

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.

Antibody responses in onchocerciasis as a function of age and infection intensity.

Onchocerciasis is caused by the filarial nematode Onchocerca volvulus and is a major public health problem in West and Central Africa. With only partial and long-term treatment currently available, there is a need to develop a suitable vaccine. We analysed the antibody response to infective L3 larvae because this stage is thought to be associated with host protective immunity. In addition, we have related our findings to the age, gender and current infection intensity of our participants: variables that may significantly influence antibody production. Interestingly, whilst 90% of our study group were seropositive for adult specific immunoglobulin (Ig)E, only 23% produced L3 specific IgE. This is in contrast to IgG4 where seropositivity was comparable at 96% and 92%, respectively. Furthermore, IgG levels were significantly affected by age and the intensity of infection but unaffected by host gender. This finding is independent for the IgG subclass (IgG1, IgG2, IgG3 and IgG4) and its specificity (L3 versus adult antigen). In summary, we show that L3 larvae induce little specific IgE and the antibody response shows a different isotype balance than that against adult antigens. Both host and parasite variables can influence antibody production in this disease.

Clinical features of paragonimiasis cases recently found in japan: parasite-specific immunoglobulin M and G antibody classes.

We retrospectively analyzed clinical features in 30 patients who were referred to our laboratory and given a diagnosis of Paragonimus westermani infection in 1999. Our results indicate that pleurisy with eosinophilia and dominant immunoglobulin (Ig) M antibody are characteristic features of the early stage of paragonimiasis, whereas IgG antibody is dominant in the late stage. Thus, in addition to tests for parasite-specific IgG antibody, tests for IgM-class antibody should always be considered for patients with pleurisy in whom paragonimiasis is suspected.

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.

IgG-subclass antibody responses and the natural history of hepatic cystic echinococcosis in asymptomatic patients.

Given that cystic echinococcosis (CE) is a serious clinical problem in endemic countries, there is still relatively little information available on the natural history of the human disease. The aim of the present study was to correlate serological status with pathology, in ultrasound-characterised, asymptomatic cases of human CE. Serum concentrations of IgG reacting with antigen B from cyst fluid and of similarly specific IgG1, IgG2, IgG3 and IgG4 were determined by ELISA and further investigated by immunoblotting. CE cases with simple cysts (Type I), or cysts with clear laminations and daughter cysts (Types II and III) exhibited elevated IgG4 seropositivity, whereas concentrations of specific IgG1 and IgG4 declined in CE cases characterised by cyst infiltration or calcifications (Types IV and V). The responses of each specific IgG subclass were used, in association with an ultrasound classification, to try to develop an immunoserological natural-history profile of CE in asymptomatic patients. Specific IgG4 antibody responses were particularly associated with the evolutive phase of CE (Types I, II and III), whereas the IgG1, IgG2 and IgG3 responses tended to be associated with the involutive phase (Types IV and V). These results indicated that an IgG4 antibody response was associated with (or was a marker for) cystic development, growth and disease progression, whereas the IgG1, IgG2 and IgG3 responses occurred predominantly when cysts became infiltrated or were destroyed by the host. The findings support the view that evolutive and subsequent involutive phases occur in untreated CE.

Antibody responses to the fucosylated LacdiNAc glycan antigen in Schistosoma mansoni-infected mice and expression of the glycan among schistosomes.

Infections of animals with parasitic worms, such as Schistosoma mansoni, induce humoral immune responses to carbohydrate antigens, raising the possibility that such antigens might be useful targets for the development of vaccines and new diagnostic approaches. Here we describe the identification of fucosylated LacdiNAc (LDNF) [GalNAc beta 1-4(Fuc alpha 1-3)GlcNAc-R] as a new carbohydrate antigen in S. mansoni that induces humoral immune responses in infected mice. The presence of antibodies was determined by ELISA using a neoglycoconjugate synthesized to express LDNF sequences. Sera from S. mansoni-infected, but not uninfected, mice contain IgM, IgG, IgA, and IgE antibodies to LDNF. The IgG antibodies are primarily of the IgG1 and IgG3 subclasses, with no detectable levels of the complement-fixing IgG2a and IgG2b isotypes. An IgM monoclonal antibody, designated SMLDNF1, was generated from the spleens of S. mansoni-infected mice, and the antibody exhibits specific recognition of LDNF sequences, but not other fucosylated glycans tested. Immunocytochemical analysis demonstrates that LDNF antigens are localized on the tegumental surface of adult S. mansoni. Western blot analysis indicates that LDNF sequences are expressed on numerous high-molecular-weight glycoproteins from the three major human schistosome species, as well as the bird schistosome Trichobilharzia ocellata. The identification of LDNF antigen on the tegumental glycoproteins of schistosomes and the ability to synthesize LDNF conjugates should aid in the development of glycan-based vaccines and immunodiagnostic tests for schistosomiasis and in determining the role(s) of the glycans in worm development and pathogenesis.

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.

Polarization of the immune response to the single immunodominant epitope of p38, a major Schistosoma mansoni egg antigen, generates Th1- or Th2-type cytokines and granulomas.

In schistosomiasis mansoni, helminth eggs secrete soluble egg antigens (SEA) that induce T-cell-mediated granulomatous tissue responses. The cloned 38-kDa peptide (p38) of SEA was shown to induce and elicit Th1-type responsiveness in H-2(k) mice. Subsequently, the immunodominant T-cell epitope (P4) of p38 was shown to elicit pulmonary granuloma formation and Th1-type cytokine production in sensitized or infected mice. Here, we report that the immune response to p38 or P4 can be polarized to a Th1 or Th2 profile when the peptides are presented intraperitoneally in soluble recombinant interleukin-12 (IL-12) or alum adjuvant, respectively. The Th1 or Th2 profile was verified by cytokine secretion, enzyme-linked spot assay, and antibody isotype characterization. Importantly, the polarized immune response generated two types of pulmonary granulomas around injected P4-coated beads. The type 1 granulomas were smaller and contained mononuclear cells and occasional thin strands of deposited collagen. In contrast, the type 2 lesions were larger and contained mononuclear cells, large numbers of eosinophils, and several thick bands of deposited collagen. By reverse transcription-PCR cytokine, message in the type 1 granuloma-bearing lungs was found for gamma interferon, tumor necrosis factor alpha, and inducible nitric oxide synthase but not for IL-4 or IL-5. Conversely, lungs with type 2 granulomas had message only for IL-4 and IL-5. These results show that in the proper cytokine environment, the response to a strong Th1 inducer peptide can be deviated to a Th2 profile.

[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.

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.

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.

Antibodies to Schistosoma japonicum (Asian bloodfluke) paramyosin induced by nucleic acid vaccination.

Nucleic acid vaccination by intramuscular or intradermal delivery of DNA plasmids encoding antigenic proteins has been shown to confer protection in experimental animals against viruses and unicellular protozoan parasites. However, this revolutionary approach has not been tested for induction of immunity to multicellular parasites, such as trematode worms. We report here, for the first time, that murine antibodies can be induced by intramuscular injection with plasmid DNA encoding fragments of Schistosoma japonicum paramyosin (Sj97), a 97 kDa molecule and a promising vaccine candidate in schistosomiasis. An additional construct containing the gene encoding full-length glutathione S-transferase (Sj26), another recognised anti-schistosome vaccine target, failed to raise detectable levels of specific antibody.