Central importance of immunoglobulin A in host defense against Giardia spp

Giardia lamblia binding immunoglobulin protein triggers maturation of dendritic cells via activation of TLR4-MyD88-p38 and ERK1/2 MAPKs

Much remains unknown about the mammalian immune response to Giardia lamblia, a protozoan pathogen that causes diarrhoeal outbreaks. We fractionated protein extracts of G. lamblia trophozoites by Viva-spin centrifugation, DEAE ion exchange and gel filtration chromatography. Resultant fractions were screened for antigenic molecules by western blots analysis using anti-G. lamblia antibodies (Abs), resulting in identification of G. lamblia binding immunoglobulin protein (GlBiP). Maturation of mouse dendritic cells (DCs) in response to recombinant GlBiP (rGlBiP) was detected by increased expression of surface molecules such as CD80, CD86 and MHC class II; these mature DCs, produced pro-inflammatory cytokines (TNF-α, IL-12 and IL-6). Especially, the truncated rGlBiP containing the heat-shock protein 70 domain-induced cytokine production from mouse DCs. rGlBiP-induced DC activation was initiated by TLR4 in a MyD88-dependent way and occurred through activation of p38 and ERK1/2 MAPKs as well as increased activity of NF-κB and AP-1. Moreover, CD4(+) T cells stimulated with rGlBiP-treated DCs produced high levels of IL-2 and IFN-γ. Together, our results suggest that GlBiP contributes to maturation of DCs via activation of TLR4-MyD88-p38, ERK1/2 MAPK, NF-κB and AP-1.

Diagnostic significance of reduced IgA in children

Introduction:

The finding of reduced value of immunoglobulin A (IgA) in children is frequent in daily medical practice. It is important to correctly interpret the findings as adequate further diagnostic evaluation of the patient in order to make the determination on the significance of such findings. In children younger than 4 years always consider the transient impairment of immunoglobulins, maturation of child and his immune system can lead to an improvement in the clinical picture. In older children decreased IgA may lead to serious illnesses that need to be recognize and acknowledge through the appropriate diagnostic methods.

Material and methods:

Research was realized at the University Clinical Center Tuzla. Children with suspected deficient immune response due to reduced values of IgA observed and, goes through further diagnostic evaluation at the Polyclinic for Laboratory Medicine, Department of Immunology and Department of Microbiology, as well as the Clinic of Radiology. In the period of year 2013, there were a total of 91 patients with reduced values of IgA, age up to 13 years, of which 55 boys and 36 girls.

Results:

Our study followed 91 patients, for the year 2013, through their medical charts and made evaluation of diagnostic and screening tests. The significance of this paper is to draw attention to the importance of diagnostic approach to IgA deficient pediatric patient and relevance of knowledge of individual diagnostic methods as well as to the proper interpretation of the results thereof.

Identification of an immunogenic protein of Giardia lamblia using monoclonal antibodies generated from infected mice

The humoral immune response plays an important role in the clearance of Giardia lamblia. However, our knowledge about the specific antigens of G. lamblia that induce a protective immune response is limited. The purpose of this study was to identify and characterise the immunogenic proteins of G. lamblia in a mouse model. We generated monoclonal antibodies (moAbs) specific to G. lamblia (1B10, 2C9.D11, 3C10.E5, 3D10, 5G8.B5, 5F4, 4C7, 3C5 and 3C6) by fusing splenocytes derived from infected mice. Most of these moAbs recognised a band of ± 71 kDa (5G8 protein) and this protein was also recognised by serum from the infected mice. We found that the moAbs recognised conformational epitopes of the 5G8 protein and that this antigen is expressed on the cell surface and inside trophozoites. Additionally, antibodies specific to the 5G8 protein induced strong agglutination (> 70-90%) of trophozoites. We have thus identified a highly immunogenic antigen of G. lamblia that is recognised by the immune system of infected mice. In summary, this study describes the identification and partial characterisation of an immunogenic protein of G. lamblia. Additionally, we generated a panel of moAbs specific for this protein that will be useful for the biochemical and immunological characterisation of this immunologically interesting Giardia molecule.

Immunological aspects of Giardia infections

Immunodeficiency, particularly antibody deficiency, predisposes to increased intensity and persistence of Giardia infections. Giardia-infected immunocompetent hosts produce serum and intestinal antibodies against Giardia trophozoites. The number of Giardia muris trophozoites, in mice with G. muris infection, is reduced by intra-duodenal administration of anti-G. muris antibody. Giardia intestinalis antigens that are recognised by human anti-trophozoite antibodies include variable (variant-specific) and invariant proteins. Nitric oxide (NO) appears to contribute to host clearance of Giardia trophozoites. Arginine is a precursor of NO and is metabolised by Giardia trophozoites, possibly reducing its availability for generation of NO by the host. Work with mice suggests that T lymphocytes and interleukin-6 (IL-6) contribute to clearance of Giardia infection via mechanisms independent of antibodies.

Systemic and local mucosal immune responses induced by orally delivered Bacillus subtilis spore expressing leucine aminopeptidase 2 of Clonorchis sinensis

Human clonorchiasis caused by Clonorchis sinensis (C. sinensis) has been increasingly prevalent in recent years so that an effective measure is essential and urgent to control the infectious disease. Oral delivery of antigens from C. sinensis may be an important approach to effectively induce both systemic and local immune responses to anti-infection of the parasite. In the current study, we used Bacillus subtilis (B. subtilis) spores as a delivery vehicle to introduce leucine aminopeptidase 2 of C. sinensis (CsLAP2), an excretory/secretory antigen with high immunogenicity, expressing on their surface. SDS-PAGE, western blotting, and flow cytometry indicated that CsLAP2 was successfully expressed on the surface of B. subtilis spores (CotC-CsLAP2 spores). BALB/c mice were treated with spores intragastrically. On day 31 after the treatment, we found that mice intragastrically treated with CotC-CsLAP2 spores exhibited higher IgG, IgG1, IgG2a, and IgA level in sera as well as higher sIgA level in bile and intestinal lavage fluid compared to mice orally administrated with spores not expressing CsLAP2 (CotC spores) and naïve mice. The peak titer of IgG/IgA presented on day 31/49 after oral administration. IgG1 level was lower than IgG2a in group administrated with CotC-CsLAP2 spores. sIgA-secreting cells were obviously observed in intestinal epithelium of mice orally treated with CotC-CsLAP2 spores. After incubated with CotC-CsLAP2, the levels of IFN-γ, IL-6, IL-10, IL-17A, and TNF significantly increased in the supernatant of splenocytes isolated from mice orally treated with CotC-CsLAP2 spores, while there was no statistically significant difference of IL-4 level representing Th2 response among the groups. Our study demonstrated that oral administration of CsLAP2 delivered by B. subtilis spore elicited obvious systemic and local mucosal immunity. Secretory IgA and Th1-Th17 cellular immunity might involved in mechanisms of the immune response.

On the mechanism determining the TH1/TH2 phenotype of an immune response, and its pertinence to strategies for the prevention, and treatment, of certain infectious diseases

It is well recognized that the physiological/pathological consequences of an immune response, against a foreign or a self-antigen, are often critically dependent on the class of immunity generated. Here we focus on how antigen interacts with the cells of the immune system to determine whether antigen predominantly generates Th1 or Th2 cells. We refer to this mechanism as the 'decision criterion' controlling the Th1/Th2 phenotype of the immune response. A plausible decision criterion should account for the variables of immunization known to affect the Th1/Th2 phenotype of the ensuing immune response. Documented variables include the nature of the antigen, in terms of its degree of foreignness, the dose of antigen and the time after immunization at which the Th1/Th2 phenotype of the immune response is assessed. These are quantitative variables made at the level of the system. In addition, the route of immunization is also critical. I describe a quantitative hypothesis as to the nature of the decision criterion, referred to as the Threshold Hypothesis. This hypothesis accounts for the quantitative variables of immunization known to affect the Th1/Th2 phenotype of the immune response generated. I suggest and illustrate how this is not true of competing, contemporary hypotheses. I outline studies testing predictions of the hypothesis and illustrate its potential utility in designing strategies to prevent or treat medical situations where a predominant Th1 response is required to contain an infection, such as those caused by HIV-1 and by Mycobacterium tuberculosis, or to contain cancers.

Antibody and cytokine responses to Giardia excretory/secretory proteins in Giardia intestinalis-infected BALB/c mice

The humoral and cellular responses against excretory/secretory proteins and soluble extracts of Giardia intestinalis were evaluated in the course of experimental G. intestinalis infection in BALB/c mice. Production of IgG1, IgG2a, IgA, and IgE antibodies against excreted/secreted proteins and soluble extract was detected after infection by G. intestinalis. Specific IgA antibody against E/S proteins and soluble extract form intestinal fluids in infected mice was detected by ELISA. The Western blotting identified proteins of 30, 58, 63, and 83 kDa for IgA and IgG, respectively. High proliferation rate in vitro of spleen cell and secretion of interleukin-4 (IL-4) at 21 days p.i. after stimulation with excreted/secreted proteins and low proliferative response in the presence of soluble extract in infected BALB/c mice was observed. High production of interferon gamma (IFN-γ) and interleukin-5 (IL-5) at the time of decreasing cyst output (14-21 days p.i.) in infected mice was recorded, suggesting the important role of these cytokines in the control of the infection. Interestingly, progressive and gradual increase of the interleukin-10 after stimulation with both preparations was recorded from 7 days until 28 days after infection, indicating the possible regulatory effect of these antigens on the immune response during Giardia infection. Therefore, the infection by Giardia duodenalis stimulates a mixed response Th1 and Th2, mainly stimulated by excretory/secretory antigens. The immunogenicity of these antigens may be a suitable for identification of the proteins related with the effective immune response in the course of infection by G. duodenalsis.

Resistance to reinfection in mice as a vaccine model for giardiasis

Infection with Giardia is the most commonly diagnosed parasitic cause of diarrhea in the developed world, yet no vaccine exists for human use and a commercially available veterinary vaccine is of limited utility. We have used the adult C57BL/6 mouse model of infection with Giardia duodenalis to better understand immunity to secondary infections with this parasite. Mice were primed by infection with either the GS or WB strains of Giardia and treated with metronidazole on day 7-12 to eliminate the primary infections. Challenge infections on day 21 or day 60 after the primary infections resulted in ~50-fold fewer parasites at day 5 than were found in unprimed mice that only received the challenge infection. Resistance to challenge infections was also observed in B cell deficient µMT mice and when primed mice were challenged with parasites of a different strain. While primed mice developed IgA, mast cell, and T cell responses against the parasite, no specific responses correlated with protection against challenge infections. Together these data suggest that development of an effective vaccine for giardiasis should be feasible since strong immunity can be developed against reinfection in the adult mouse model. Moreover we show that antibody responses are not essential for a protective vaccine and that protection is not parasite strain-specific.

Mucosal immunology of HIV infection

Recent advances in the immunology, pathogenesis, and prevention of human immunodeficiency virus (HIV) infection continue to reveal clues to the mechanisms involved in the progressive immunodeficiency attributed to infection, but more importantly have shed light on the correlates of immunity to infection and disease progression. HIV selectively infects, eliminates, and/or dysregulates several key cells of the human immune system, thwarting multiple arms of the host immune response, and inflicting severe damage to mucosal barriers, resulting in tissue infiltration of 'symbiotic' intestinal bacteria and viruses that essentially become opportunistic infections promoting systemic immune activation. This leads to activation and recruitment or more target cells for perpetuating HIV infection, resulting in persistent, high-level viral replication in lymphoid tissues, rapid evolution of resistant strains, and continued evasion of immune responses. However, vaccine studies and studies of spontaneous controllers are finally providing correlates of immunity from protection and disease progression, including virus-specific CD4(+) T-cell responses, binding anti-bodies, innate immune responses, and generation of antibodies with potent antibody-dependent cell-mediated cytotoxicity activity. Emerging correlates of immunity indicate that prevention of HIV infection may be possible through effective vaccine strategies that protect and stimulate key regulatory cells and immune responses in susceptible hosts. Furthermore, immune therapies specifically directed toward boosting specific aspects of the immune system may eventually lead to a cure for HIV-infected patients.

Transcriptomic analysis of the host response to Giardia duodenalis infection reveals redundant mechanisms for parasite control

The immune system has numerous mechanisms that it can use to combat pathogens and eliminate infections. Nevertheless, studies of immune responses often focus on single pathways required for protective responses. We applied microarray analysis of RNA in order to investigate the types of immune responses produced against infection with the intestinal pathogen Giardia duodenalis. Infection with G. duodenalis is one of the most common causes of diarrheal disease in the world. While several potential antiparasitic effector mechanisms, including complement lysis, nitric oxide (NO), and α-defensin peptides, have been shown to inhibit parasite growth or kill Giardia in vitro, studies in vivo have thus far shown clear roles only for antibody and mast cell responses in parasite control. A total of 96 transcripts were identified as being upregulated or repressed more than 2-fold in the small intestine 10 days following infection. Microarray data were validated using quantitative PCR. The most abundant category of transcripts was antibody genes, while the most highly induced transcripts were all mast cell proteases. Among the other induced transcripts was matrix metalloprotease 7 (Mmp7), the protease responsible for production of mature α-defensins in mice. While infections in Mmp7-deficient mice showed only a small increase in parasite numbers, combined genetic deletion of Mmp7 and inducible nitric oxide synthase (iNOS, Nos2) or pharmacological blockade of iNOS in Mmp7-deficient mice resulted in significant increases in parasite loads following infection. Thus, α-defensins and NO are redundant mechanisms for control of Giardia infections in vivo.

The immune system has multiple weapons which it uses to help control infections. Many infections result in activation of several of these response mechanisms, but it is not always clear which responses actually contribute to control of the pathogen and which are bystander effects. This study used the intestinal parasite Giardia duodenalis to examine the redundancy in immune responses during infections in mice. Our results showed that at least four distinct mechanisms are activated following infections. Furthermore, by blocking two pathways at the same time, we showed that both mechanisms contribute to control of the infection, whereas blocking single responses showed no or minimal effect in these cases.

Gut TFH and IgA: key players for regulation of bacterial communities and immune homeostasis

The main function of the immune system is to protect the host against pathogens. However, unlike the systemic immune system, the gut immune system does not eliminate, but instead nourishes complex bacterial communities and establishes advanced symbiotic relationships. Immunoglobulin A (IgA) is the most abundant antibody isotype in mammals, produced mainly in the gut. The primary function of IgA is to maintain homeostasis at mucosal surfaces, and studies in mice have demonstrated that IgA diversification has an essential role in the regulation of gut microbiota. Dynamic diversification and constant adaptation of IgA responses to local microbiota require expression of activation-induced cytidine deaminase by B cells and control from T follicular helper and Foxp3(+) T cells in germinal centers (GCs). We discuss the finely tuned regulatory mechanisms for IgA synthesis in GCs of Peyer's patches and emphasize the roles of CD4(+) T cells for IgA selection and the maintenance of appropriate gut microbial communities required for immune homeostasis.

Administration of kefir-fermented milk protects mice against Giardia intestinalis infection

Giardiasis, caused by the protozoan Giardia intestinalis, is one of the most common intestinal diseases worldwide and constitutes an important problem for the public health systems of various countries. Kefir is a probiotic drink obtained by fermenting milk with 'kefir grains', which consist mainly of bacteria and yeasts that coexist in a complex symbiotic association. In this work, we studied the ability of kefir to protect mice from G. intestinalis infection, and characterized the host immune response to this probiotic in the context of the intestinal infection. Six- to 8-week-old C75BL/6 mice were separated into four groups: controls, kefir mice (receiving 1 : 100 dilution of kefir in drinking water for 14 days), Giardia mice (infected orally with 4×10(7) trophozoites of G. intestinalis at day 7) and Giardia-kefir mice (kefir-treated G. intestinalis-infected mice), and killed at 2 or 7 days post-infection. Kefir administration was able to significantly reduce the intensity of Giardia infection at 7 days post-infection. An increase in the percentage of CD4(+) T cells at 2 days post-infection was observed in the Peyer's patches (PP) of mice belonging to the Giardia group compared with the control and kefir groups, while the percentage of CD4(+) T cells in PP in the Giardia-kefir group was similar to that of controls. At 2 days post-infection, a reduction in the percentage of B220-positive major histocompatibility complex class II medium cells in PP was observed in infected mice compared with the other groups. At 7 days post-infection, Giardia-infected mice showed a reduction in RcFcε-positive cells compared with the control group, suggesting a downregulation of the inflammatory response. However, the percentages of RcFcε-positive cells did not differ from controls in the kefir and Giardia-kefir groups. An increase in IgA-positive cells was observed in the lamina propria of the kefir group compared with controls at 2 days post-infection. Interestingly, the diminished number of IgA-positive cells registered in the Giardia group at 7 days post-infection was restored by kefir feeding, although the increase in IgA-positive cells was no longer observed in the kefir group at that time. No significant differences in CXCL10 expression were registered between groups, in concordance with the absence of inflammation in small-intestinal tissue. Interestingly, a slight reduction in CCL20 expression was observed in the Giardia group, suggesting that G. intestinalis might downregulate its expression as a way of evading the inflammatory immune response. On the other hand, a trend towards an increase in TNF-α expression was observed in the kefir group, while the Giardia-kefir group showed a significant increase in TNF-α expression. Moreover, kefir-receiving mice (kefir and Giardia-kefir groups) showed an increase in the expression of IFN-γ, the most relevant Th1 cytokine, at 2 days post-infection. Our results demonstrate that feeding mice with kefir reduces G. intestinalis infection and promotes the activation of different mechanisms of humoral and cellular immunity that are downregulated by parasitic infection, thus contributing to protection.

Effects of dietary zinc manipulation on growth performance, zinc status and immune response during Giardia lamblia infection: a study in CD-1 mice

Associations between Giardia lamblia infection and low serum concentrations of zinc have been reported in young children. Interestingly, relatively few studies have examined the effects of different dietary zinc levels on the parasite-infected host. The aims of this study were to compare the growth performance and zinc status in response to varying levels of dietary zinc and to measure the antibody-mediated response of mice during G. lamblia infection. Male CD-1 mice were fed using 1 of 4 experimental diets: adequate-zinc (ZnA), low-zinc (ZnL), high-zinc (ZnH) and supplemented-zinc (ZnS) diet containing 30, 10, 223 and 1383 mg Zn/kg respectively. After a 10 days feeding period, mice were inoculated orally with 5 × 10⁶G. lamblia trophozoites and were maintained on the assigned diet during the course of infection (30 days). Giardia-free mice fed ZnL diets were able to attain normal growth and antibody-mediated response. Giardia-infected mice fed ZnL and ZnA diets presented a significant growth retardation compared to non-infected controls. Zinc supplementation avoided this weight loss during G. lamblia infection and up-regulated the host’s humoral immune response by improving the production of specific antibodies. Clinical outcomes of zinc supplementation during giardiasis included significant weight gain, higher anti-G. lamblia IgG antibodies and improved serum zinc levels despite the ongoing infection. A maximum growth rate and antibody-mediated response were attained in mice fed ZnH diet. No further increases in body weight, zinc status and humoral immune capacity were noted by feeding higher zinc levels (ZnS) than the ZnH diet. These findings probably reflect biological effect of zinc that could be of public health importance in endemic areas of infection.

Giardia: both a harmless commensal and a devastating pathogen

The highly prevalent protozoan Giardia lamblia is an enteropathogen that can be asymptomatic in some individuals, while leading to persistent diarrhea and substantial morbidity in others. In this issue of the JCI, Bartelt et al. describe a mouse model of the disease and investigate the contribution of coincident malnutrition with the development of symptomatic infection. This work in part explains how Giardia infection can lead to growth retardation, and may offer insights that guide future therapeutic strategies.

Probiotic Lactobacillus rhamnosus GG modulates the mucosal immune response in Giardia intestinalis-infected BALB/c mice

BACKGROUND

Gut homeostasis can be altered by the oral administration of health-promoting microorganisms, namely probiotics that are known to reinforce the host immune response.

AIM

The aim of this study was to elucidate the immunomodulatory effect of orally administered probiotic Lactobacillus rhamnosus GG (LGG) in Giardia-infected mice.

METHODS

BALB/c mice were fed orally with probiotic LGG either 7 days prior to or simultaneously with the challenge dose of Giardia trophozoites. The administration of the probiotic was continued for 25 days, and immunomodulatory potentials in terms of secretory immunoglobulin A (IgA) levels, CD8+ and CD4+ T lymphocytes, and expression of pro-inflammatory [tumor necrosis factor-alpha, interferon-gamma (INF-γ)] and anti-inflammatory cytokines [interleukin (IL)-4, IL-6, IL-10] were studied.

RESULTS

Oral feeding of LGG prior to or simultaneously with the test dose of Giardia seems to have modulated both arms (humoral and cellular) of the mucosal immune system since a significant increase in the levels of specific secretory IgA antibody, IgA+ cells, and CD4+ T lymphocytes were observed in contrast with the decreased percentage of cytotoxic CD8+ T lymphocytes. The stimulated mucosal immune response in probiotic fed Giardia-infected mice was further correlated with the enhanced levels of anti-inflammatory cytokines IL-6 and IL-10 and reduced levels of pro-inflammatory cytokine INF-γ.

CONCLUSIONS

This is the first study to show that oral administration of the effective probiotic LGG to Giardia infected mice could be used as a bacterio-therapy that restores the normal gut microflora and modulates the mucosal immune response.

Serum levels of zinc, copper, vitamin B12, folate and immunoglobulins in individuals with giardiasis

BACKGROUND

Giardia lamblia is one of the most important intestinal parasites. The aim of this study was to measure serum levels of IgA, IgE, zinc, copper, vitamin B12 and folate in individuals with giardiasis in comparison to normal subjects.

METHODS

The study was carried out among 49 Giardia positive and 39 age and sex matched healthy volunteers. Examination of stool samples was done by direct wet smear and formol-ether concentration method. Serum samples were obtained for further laboratory examination. IgA levels were measured by Single Radial Immune Diffusion (SRID). IgE levels were measured by ELISA kit. Zinc and copper levels was measured by Ziestchem Diagnostics Kit and colorimetric endpoint-method respectively. Vitamin B12 and folate levels were measured by DRG Diagnostics Kit and Enzyme Immunoassay method respectively. All data were analyzed using SPSS version 17.

RESULTS

There was a statistically significant difference in IgA, IgE, copper and zinc levels between positive and negative groups (P<0.05). There was no significant difference between vitamin B12 and folate levels between the two groups. Mean values of Giardia positive and negative groups for IgA were 309.26 and 216.89 mg/dl, IgE 167.34 and 35.49 IU/ml, copper 309.74 and 253.61 μg/dl and zinc 69.41 and 144.75 μg/dl respectively.

CONCLUSION

The results showed levels of IgA may correlate more closely with giardiasis than IgE. Regarding trace elements, giardiasis elevated serum copper levels, while it decreased serum zinc. Finally, there was no significant difference in serum levels of vitamin B12 and folic acid between the two groups.

Immunophenotyping in post-giardiasis functional gastrointestinal disease and chronic fatigue syndrome

Background

A Giardia outbreak was associated with development of post-infectious functional gastrointestinal disorders (PI-FGID) and chronic fatigue syndrome (PI-CFS). Markers of immune dysfunction have given conflicting results in CFS and FGID patient populations. The aim of this study was to evaluate a wide selection of markers of immune dysfunction in these two co-occurring post-infectious syndromes.

Methods

48 patients, reporting chronic fatigue in a questionnaire study, were clinically evaluated five years after the outbreak and grouped according to Fukuda criteria for CFS (n=19) and idiopathic chronic fatigue (n=5) and Rome II criteria for FGIDs (n=54). 22 Giardia exposed non-fatigued individuals and 10 healthy unexposed individuals were recruited as controls. Peripheral blood lymphocyte subsets were analyzed by flow cytometry.

Results

In peripheral blood we found significantly higher CD8 T-cell levels in PI-FGID, and significantly lower NK-cell levels in PI-CFS patients. Severity of abdominal and fatigue symptoms correlated negatively with NK-cell levels. A tendency towards lower T-cell CD26 expression in FGID was seen.

Conclusion

Patients with PI-CFS and/or PI-FGID 5 years after Giardia lamblia infection showed alterations in NK-cell and CD8-cell populations suggesting a possible immunological abnormality in these conditions. We found no significant changes in other markers examined in this well-defined group of PI-CFS and PI-FGID elicited by a gastrointestinal infection. Controlling for co-morbid conditions is important in evaluation of CFS-biomarkers.

High prevalence of Giardia duodenalis Assemblage B infection and association with underweight in Rwandan children

Background

Giardia duodenalis is highly endemic in East Africa but its effects on child health, particularly of submicroscopic infections, i.e., those below the threshold of microscopy, and of genetic subgroups (assemblages), are not well understood. We aimed at addressing these questions and at examining epidemiological characteristics of G. duodenalis in southern highland Rwanda.

Methodology/Principal Findings

In 583 children <5 years of age from communities and health facilities, intestinal parasites were assessed by triplicate light microscopy and by PCR assays, and G. duodenalis assemblages were genotyped. Cluster effects of villages were taken into account in statistical analysis. The prevalence of G. duodenalis as detected by microscopy was 19.8% but 60.1% including PCR results. Prevalence differed with residence, increased with age, and was reduced by breastfeeding. In 492 community children without, with submicroscopic and with microscopic infection, underweight (weight-for-age z-score <−2 standard deviations) was observed in 19.7%, 22.1%, and 33.1%, respectively, and clinically assessed severe malnutrition in 4.5%, 9.5%, and 16.7%. Multivariate analysis identified microscopically detectable G. duodenalis infection as an independent predictor of underweight and clinically assessed severe malnutrition. Submicroscopic infection showed respective trends. Overall, G. duodenalis was not associated with gastrointestinal symptoms but assemblages A parasites (proportion, 13%) were increased among children with vomiting and abdominal pain.

Conclusions/Significance

The prevalence of G. duodenalis in high-endemicity areas may be greatly underestimated by light microscopy, particularly when only single stool samples are analysed. Children with submicroscopic infections show limited overt manifestation, but constitute unrecognized reservoirs of transmission. The predominance of assemblage B in Rwanda may be involved in the seemingly unimposing manifestation of G. duodenalis infection. However, the association with impaired child growth points to its actual relevance. Longitudinal studies considering abundant submicroscopic infections are needed to clarify the actual contribution of G. duodenalis to morbidity in areas of high endemicity.

Giardia duodenalis is a protozoan parasite causing gastroenteritis. Although the parasite occurs worldwide, its regional prevalence varies considerably. Using PCR as a highly sensitive molecular diagnostic tool, we detected G. duodenalis in 60% of 583 children younger than five years in southern Rwanda. It was by far the most frequent intestinal parasite detected in this population. Importantly, two out of three infections would have been undetected if only the commonly used light microscopy had been applied. Genotyping revealed the presence of two distinct types of parasites, and only the infrequent subtype showed a weak association with gastrointestinal symptoms. However, G. duodenalis infection was associated with underweight and clinically assessed severe malnutrition. The data call for the establishment of more sensitive than light microscopy, yet simple diagnostic tools to identify infected children as well as for the consideration of abundant submicroscopic infections in evaluating the significance of G. duodenalis in high endemicity areas.

High prevalence of Giardia duodenalis Assemblage B infection and association with underweight in Rwandan children

BACKGROUND

Giardia duodenalis is highly endemic in East Africa but its effects on child health, particularly of submicroscopic infections, i.e., those below the threshold of microscopy, and of genetic subgroups (assemblages), are not well understood. We aimed at addressing these questions and at examining epidemiological characteristics of G. duodenalis in southern highland Rwanda.

METHODOLOGY/PRINCIPAL FINDINGS

In 583 children <5 years of age from communities and health facilities, intestinal parasites were assessed by triplicate light microscopy and by PCR assays, and G. duodenalis assemblages were genotyped. Cluster effects of villages were taken into account in statistical analysis. The prevalence of G. duodenalis as detected by microscopy was 19.8% but 60.1% including PCR results. Prevalence differed with residence, increased with age, and was reduced by breastfeeding. In 492 community children without, with submicroscopic and with microscopic infection, underweight (weight-for-age z-score <-2 standard deviations) was observed in 19.7%, 22.1%, and 33.1%, respectively, and clinically assessed severe malnutrition in 4.5%, 9.5%, and 16.7%. Multivariate analysis identified microscopically detectable G. duodenalis infection as an independent predictor of underweight and clinically assessed severe malnutrition. Submicroscopic infection showed respective trends. Overall, G. duodenalis was not associated with gastrointestinal symptoms but assemblages A parasites (proportion, 13%) were increased among children with vomiting and abdominal pain.

CONCLUSIONS/SIGNIFICANCE

The prevalence of G. duodenalis in high-endemicity areas may be greatly underestimated by light microscopy, particularly when only single stool samples are analysed. Children with submicroscopic infections show limited overt manifestation, but constitute unrecognized reservoirs of transmission. The predominance of assemblage B in Rwanda may be involved in the seemingly unimposing manifestation of G. duodenalis infection. However, the association with impaired child growth points to its actual relevance. Longitudinal studies considering abundant submicroscopic infections are needed to clarify the actual contribution of G. duodenalis to morbidity in areas of high endemicity.

Giardiasis: a review on assemblage distribution and epidemiology in India

Giardiasis is a significant cause of diarrheal disease and associated morbidity in children and adults worldwide. In addition to diarrhea, it can also lead to malnutrition and cognitive deficits in children from developing countries. Giardia duodenalis is considered to be a species complex of several assemblages, of which assemblage A and B are predominantly associated with human infections. Assemblage type has been associated with risk of occurrence of symptoms and duration of illness. Hence genotyping of giardial isolates may help understand better the epidemiology and transmission ecology of the disease in a particular setting or area. In India, prevalence rates of Giardia infection in patients with diarrhea range from 0.4% to 70%, and asymptomatic cyst passage has been found to be as high as 50% in rural southern India. In this review, the global distribution of giardial assemblage, zoonotic transmission and the association of assemblage with disease have been discussed, followed by epidemiology of giardiasis in India.

Mucosal immunoglobulins and B cells of teleost fish

As physical barriers that separate teleost fish from the external environment, mucosae are also active immunological sites that protect them against exposure to microbes and stressors. In mammals, the sites where antigens are sampled from mucosal surfaces and where stimulation of naïve T and B lymphocytes occurs are known as inductive sites and are constituted by mucosa-associated lymphoid tissue (MALT). According to anatomical location, the MALT in teleost fish is subdivided into gut-associated lymphoid tissue (GALT), skin-associated lymphoid tissue (SALT), and gill-associated lymphoid tissue (GIALT). All MALT contain a variety of leukocytes, including, but not limited to, T cells, B cells, plasma cells, macrophages and granulocytes. Secretory immunoglobulins are produced mainly by plasmablasts and plasma cells, and play key roles in the maintenance of mucosal homeostasis. Until recently, teleost fish B cells were thought to express only two classes of immunoglobulins, IgM and IgD, in which IgM was thought to be the only one responding to pathogens both in systemic and mucosal compartments. However, a third teleost immunoglobulin class, IgT/IgZ, was discovered in 2005, and it has recently been shown to behave as the prevalent immunoglobulin in gut mucosal immune responses. The purpose of this review is to summarise the current knowledge of mucosal immunoglobulins and B cells of fish MALT. Moreover, we attempt to integrate the existing knowledge on both basic and applied research findings on fish mucosal immune responses, with the goal to provide new directions that may facilitate the development of novel vaccination strategies that stimulate not only systemic, but also mucosal immunity.

Mucosal immunoglobulins and B cells of teleost fish

As physical barriers that separate teleost fish from the external environment, mucosae are also active immunological sites that protect them against exposure to microbes and stressors. In mammals, the sites where antigens are sampled from mucosal surfaces and where stimulation of naïve T and B lymphocytes occurs are known as inductive sites and are constituted by mucosa-associated lymphoid tissue (MALT). According to anatomical location, the MALT in teleost fish is subdivided into gut-associated lymphoid tissue (GALT), skin-associated lymphoid tissue (SALT), and gill-associated lymphoid tissue (GIALT). All MALT contain a variety of leukocytes, including, but not limited to, T cells, B cells, plasma cells, macrophages and granulocytes. Secretory immunoglobulins are produced mainly by plasmablasts and plasma cells, and play key roles in the maintenance of mucosal homeostasis. Until recently, teleost fish B cells were thought to express only two classes of immunoglobulins, IgM and IgD, in which IgM was thought to be the only one responding to pathogens both in systemic and mucosal compartments. However, a third teleost immunoglobulin class, IgT/IgZ, was discovered in 2005, and it has recently been shown to behave as the prevalent immunoglobulin in gut mucosal immune responses. The purpose of this review is to summarise the current knowledge of mucosal immunoglobulins and B cells of fish MALT. Moreover, we attempt to integrate the existing knowledge on both basic and applied research findings on fish mucosal immune responses, with the goal to provide new directions that may facilitate the development of novel vaccination strategies that stimulate not only systemic, but also mucosal immunity.

Α1-giardin based live heterologous vaccine protects against Giardia lamblia infection in a murine model

Giardia lamblia is a leading protozoan cause of diarrheal disease worldwide, yet preventive medical strategies are not available. A crude veterinary vaccine has been licensed for cats and dogs, but no defined human vaccine is available. We tested the vaccine potential of three conserved antigens previously identified in human and murine giardiasis, α1-giardin, α-enolase, and ornithine carbamoyl transferase, in a murine model of G. lamblia infection. Live recombinant attenuated Salmonella enterica Serovar Typhimurium vaccine strains were constructed that stably expressed each antigen, maintained colonization capacity, and sustained total attenuation in the host. Oral administration of the vaccine strains induced antigen-specific serum IgG, particularly IgG(2A), and mucosal IgA for α1-giardin and α-enolase, but not for ornithine carbamoyl transferase. Immunization with the α1-giardin vaccine induced significant protection against subsequent G. lamblia challenge, which was further enhanced by boosting with cholera toxin or sublingual α1-giardin administration. The α-enolase vaccine afforded no protection. Analysis of α1-giardin from divergent assemblage A and B isolates of G. lamblia revealed >97% amino acid sequence conservation and immunological cross-reactivity, further supporting the potential utility of this antigen in vaccine development. Together. These results indicate that α1-giardin is a suitable candidate antigen for a vaccine against giardiasis.

Human cellular immune response against Giardia lamblia 5 years after acute giardiasis

BACKGROUND

Clinical and epidemiological studies have suggested the development of acquired immunity in individuals previously infected with Giardia lamblia. However, there are no data on the long-term cellular immunity and genotype cross-reactivity. An outbreak of assemblage B giardiasis in a nonendemic area made it possible to evaluate the long-term cellular mediated immunity and its specificity toward the 2 Giardia assemblages known to infect humans.

METHODS

Peripheral blood mononuclear cells from 19 individuals infected with Giardia assemblage B 5 years previously and from 10 uninfected controls were cultured with antigens from assemblage A and B Giardia trophozoites for 6 days. Cell-mediated immunity was measured by a (3)H-thymidine proliferation assay and flow cytometric analysis of activation markers HLA-DR, CD45RO, CD25, and CD26 in T-cell subsets.

RESULTS

Proliferation responses were significantly elevated in the group previously exposed to Giardia for nearly all Giardia antigens tested. Individual responses toward Giardia trophozoite whole cell, cytosolic, and excretory-secretory antigens from both assemblages correlated well. Activation marker responses were mainly seen in CD4 T cells.

CONCLUSIONS

G. lamblia infection induces long-term, albeit variable, cellular immune responses that are not assemblage specific and that are largely driven by CD4 T-cell activation.

Co-infection with Ascaris lumbricoides modulates protective immune responses against Giardia duodenalis in school Venezuelan rural children

We evaluated the effect of Ascaris lumbricoides on Giardia duodenalis infection and TH1/TH2 type immune mechanisms toward this parasite in 251 rural parasitized and 70 urban non-parasitized school children. The children were classified according to light (0-5000 eggs/g faeces) or moderate (>5001-50,000 eggs/g faeces) A. lumbricoides infection. Anti G. duodenalis skin hyper-reactivity, IgE, IgG, IL-13, IFN γ, IL6 and IL-10 levels were compared among G. duodenalis infected and non-infected children according to light or moderate A. lumbricoides infection. It was found that 62% of the A. lumbricoides moderately infected children were co-infected by G. duodenalis compared to 45% of the lightly infected group. After treatment, 42% of the A. lumbricoides moderately group were infected with G. duodenalis compared to 11% of their lightly counterparts, being A. lumbricoides IL-10 levels higher (p<0.0001) in the moderately infected group. In the A. lumbricoides lightly parasitized children, G. duodenalis infection was associated to a significant increase (p<0.005) of the levels of G. duodenalis IL-13, IFN-γ, IL-6, IgE, IgG and skin test hyper reactivity. In contrast, there was no effect of G. duodenalis infection in the elevation of these parameters among the A. lumbricoides moderately parasitized group, being those levels similarly lower as those observed in the control group. Inverse correlations were found between the levels of anti G duodenalis antibodies, skin test hyper-reactivity and cytokines with the intensity of A. lumbricoides infection (p>0.0001) and A. lumbricoides IL-10 levels (p>0.0001), suggesting that co-infection with A. lumbricoides may affect both TH1 and TH2 type immunity against G. duodenalis that may play an important role in the susceptibility to the infection after chemotherapy in children from endemic areas.

Vitamin A supplementation modifies the association between mucosal innate and adaptive immune responses and resolution of enteric pathogen infections

BACKGROUND

The efficacy of vitamin A supplementation on diarrheal disease morbidity may reflect the divergent effects that supplementation has on pathogen-specific immune responses and pathogen-specific outcomes.

OBJECTIVE

We examined how vitamin A supplementation modified associations between gut-cytokine immune responses and the resolution of different diarrheal pathogen infections.

DESIGN

Stools collected from 127 Mexican children who were 5-15 mo old and enrolled in a randomized, placebo-controlled vitamin A supplementation trial were screened for enteropathogenic Escherichia coli (EPEC), enterotoxigenic E. coli (ETEC), and Giardia lamblia. Fecal concentrations of interleukin (IL)-6, IL-8, IL-4, IL-5, IL-10, monocyte chemoattractant protein 1 (MCP-1), tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ) were measured by using an enzyme-linked immunosorbent assay. Hazard models that incorporated categorized cytokine variables (ie, nondetectable, less than the median of detectable concentrations, and at least the median of detectable concentrations) were fit to the length of pathogen infections stratified by treatment group.

RESULTS

Vitamin A-supplemented children with fecal MCP-1 or IL-8 concentrations less than the median of detectable concentrations and IL-10 concentrations of at least median concentrations had longer durations of EPEC infection than did children in the placebo group. In supplemented children, detectable fecal TNF-α or IL-6 concentrations were associated with shorter ETEC infection durations, whereas MCP-1 concentrations of at least the median were associated with longer infection durations. Children in this group who had IL-4, IL-5, or IFN-γ concentrations of at least median detectable concentrations had shorter durations of G. lamblia infection.

CONCLUSION

The effect of supplementation on associations between fecal cytokine concentrations and pathogen infection resolution depends on the role of inflammatory immune responses in resolving specific pathogen infections.

Inducible nitric oxide synthase in duodenum of children with Giardia lamblia infection

The investigation were performed on children with Giardia lamblia infection, diagnosed on the basis of positive stool tests for Giardia antigen (Elisa) or by microscopical detection of trophozoites in duodenal fluid. In duodenal biopsies morphological studies and immunohistochemical reaction for inducible nitric oxide synthase (iNOS) were performed. The control group was made up of duodenal tissue of children with excluded giardiasis and inflammation of the upper part of gastrointestinal tract. The duodenal biopsies from children without Giardia lamblia infection were found to have a high immunoreactivity for iNOS in enterocytes, the cells of intestinal crypts, endothelial cells of vessels and connective tissue cells of lamina propria. In children with giardiasis: in some biopsies the expression of iNOS was as high as in control group, in others was weaker detectable and the shortening of intestinal villi was seen. There were also duodenal biopsies with the lack of immunoreactivity for iNOS, with shorter villi and a large amount of mucus in the intestinal epithelium. Beside of goblet cells, also enterocytes were loaded with mucus. The pathological changes may cause malabsorption and also may have a negative influence on the defense of the intestinal wall against Giardia lamblia infection. The different morphological and immunohistochemical results in the duodenum of children with giardiasis can elucidate a variety of clinical symptoms from asymptomatic to severe infection.

The role of secretory antibodies in infection immunity

The mucosal secretory immune system provides an important primary defence against disease, as studies of humans with mucosal humoral immunodeficiencies suggest that the absence of secretory immunoglobulin A leads to an increase in mucosal infections. However, the infection risks posed do not seem to provide the evolutionary drive to retain constitutive secretion of often 'hard won' protein, suggesting that secretory antibodies may have some other important function (or functions). This Review examines the evidence that secretory antibodies provide an important defence against infection in specific animal models and explores complementary explanations for the evolution of the secretory immune system.

Giardia lamblia: interleukin 6 and tumor necrosis factor-alpha release from mast cells induced through an Ig-independent pathway

Giardia lamblia is a common cause of both acute and chronic diarrheal disease in humans worldwide. It has been shown that mast cells, IL-6 and TNF-alpha are substantially involved in the early control of G. lamblia infection in mice. However, no studies have yet been reported concerning the interaction between mast cell and Giardia, as well as the mast cells mediators generated in response to Giardia infection. In this study we demonstrated the direct activation of mast cells by G. lamblia live trophozoites or trophozoite-derived antigens followed by an increase in tryptase expression and a significant release of the preformed mediator histamine. In addition, parasite derived antigens increased TNF-alpha and de novo synthesized cytokine IL-6, at the mRNA and protein level. These results strongly suggest that mast cells might be an important source not only of IL-6 but also of TNF-alpha during Giardia infection, playing an important role in the outcome of the infection.

Giardiasis--why do the symptoms sometimes never stop?

Although giardiasis is considered by most medical practitioners to be an easily treated infection, prolonged symptoms due to, or following, Giardia duodenalis infection can have a significant impact on quality of life. Symptom recurrence, including abdominal symptoms and fatigue, can result from re-infection, treatment failure, disturbances in the gut mucosa or post-infection syndromes. In developed countries, these sequelae can have an enormous impact on quality of life; in developing countries, particularly in children, they add yet another burden to populations that are already disadvantaged. Here, we outline current knowledge, based on individual case sequelae from sporadic infections, observations of population effects following outbreaks and studies of phenotypic and genotypic diversity between morphologically identical isolates of parasites. We also raise further questions, looking for clues as to why giardiasis sometimes becomes an intrusive, long-term problem.

Associations between mucosal innate and adaptive immune responses and resolution of diarrheal pathogen infections

The identification of immune response mechanisms that contribute to the control of diarrheal disease in developing countries remains an important priority. We addressed the role of fecal chemokines and cytokines in the resolution of diarrheal Escherichia coli and Giardia lamblia infections. Stools collected from 127 Mexican children 5 to 15 months of age enrolled in a randomized, double-blind, placebo-controlled, vitamin A supplementation trial were screened for enteropathogenic Escherichia coli (EPEC), enterotoxigenic E. coli (ETEC), and Giardia lamblia. Fecal concentrations of tumor necrosis factor alpha (TNF-alpha), monocyte chemoattractant protein-1 (MCP-1), interleukin-4 (IL-4), IL-5, IL-6, IL-8, IL-10, and interferon-gamma (IFN-gamma) were determined. Hazard models incorporating cytokine variables were fit to durations of asymptomatic and symptomatic pathogen infections, controlling for treatment group. Increased levels of TNF-alpha and IL-6 were associated with decreased durations of EPEC infection and increased ETEC durations. Increased IL-4 and IFN-gamma levels were associated with decreased and increased durations, respectively, of both EPEC and ETEC infections. Increased IL-10 levels were associated with increased and decreased durations of asymptomatic and symptomatic EPEC infections, respectively, and increased durations of both asymptomatic and symptomatic ETEC infections. Increased levels of MCP-1, IFN-gamma, IL-4, and IL-5 were associated with increased G. lamblia infection duration, while increased IL-8 levels were associated with decreased durations. Differences in proinflammatory and Treg cytokine levels are associated with differences in the resolution of inflammatory and noninflammatory pathogen infections.

Gene polymorphism in transforming growth factor-beta codon 10 is associated with susceptibility to Giardiasis

Secretory immunoglobulin A (S-IgA) antibodies have a central role in anti-Giardial defence. It has been demonstrated that transforming growth factor-beta1 (TGF-beta1) stimulates B lymphocytes to produce and secrete S-IgA. We sought to determine the association between TGF-beta1 polymorphism (T+869C) with susceptibility to Giardiasis. The TGF-beta1 genotypes and levels of salivary (S-IgA) were analysed in individuals with Giardiasis (97 symptomatic and 57 asymptomatic) and controls (n = 92). Individuals with symptomatic Giardiasis had the lowest levels of S-IgA compared to individuals in asymptomatic Giardiasis and control groups (97%, 73% and 43%, <1 g L(-1), respectively, P = 0.002). The frequency of allele C and CC genotypes of TGF-beta1 polymorphism was significantly higher among symptomatic patients than asymptomatic and control groups. Logistic regression analysis demonstrated that the individuals homozygous for allele C of TGF-beta1 had a significantly higher risk for symptomatic Giardiasis with odds ratio of 2.76 (95% CI: 3.88, 1.71, P = 0.007). Among the participants with TT genotype per cent of individuals with S-IgA level of more than 1 g L(-1) was almost twice the percentage in CC genotype individuals (14% versus 7% respectively P = 0.01). Our data suggest that CC genotype of TGF-beta1 polymorphism at codon 10 is associated with occurrence of Giardiasis.

Interaction of zinc or vitamin A supplementation and specific parasite infections on Mexican infants' growth: a randomized clinical trial

BACKGROUND

The efficacy of micronutrient supplementation on growth may be modified by specific gastrointestinal parasite infections.

METHODS

We carried out a double-blind placebo-controlled trial to evaluate the effect of vitamin A and zinc supplementation on gastro-intestinal pathogen infections and growth among 584 infants in Mexico City. Children aged 5-15 months were assigned to receive either a vitamin A supplement every 2 months (20,000 IU of retinol for infants < or =; 1 year or 45,000 IU for infants >1 year), a daily supplement of 20 mg of zinc, a combined vitamin A-zinc supplement or a placebo, and were followed up for 1 year. Weight and length were measured once a month and morbidity histories were recorded twice a week for 12 months. Monthly stool samples were screened for Giardia duodenalis, Ascaris lumbricoides and Entamoeba spp. Growth velocity slopes, generated from the linear regression of individual child length, and height-for-age z-scores on time were analyzed as end points in regression models, adjusting for the presence of parasite infections.

RESULTS

The main effect of vitamin A supplementation was in height improvement (P<0.05), and was only found in the model evaluating infants with any parasite. There was an interaction effect of slower growth (P<0.05) found in infants infected with any parasite and supplemented with vitamin A in slower growth (P<0.05). In addition, the interaction of zinc supplementation and Giardia duodenalis or A. lumbricoides was associated with reduced growth (P<0.05).

CONCLUSION

Gastro-intestinal parasite infections may modify the effect that zinc or vitamin A supplementation has on childhood growth.

The old and new therapeutic approaches to the treatment of giardiasis: where are we?

Giardia lamblia is the causative agent of giardiasis, one of the most common parasitic infections of the human intestinal tract. This disease most frequently affects children causing abdominal pain, nausea, vomiting, acute or chronic diarrhea, and malabsorption syndrome. In undernourished children, giardiasis is a determining factor in retarded physical and mental development. Antigiardial chemotherapy focuses on the trophozoite stage. Metronidazole and other nitroimidazoles have been used for decades as the therapy of choice against giardiasis. In recent years many other drugs have been proposed for the treatment of giardiasis. Therefore, several synthetic and natural substances have been tested in search of new giardicidal compounds. This study is a review of drugs used in in vitro and in vivo tests, and also drugs tested in clinical trials (nonrandomized and randomized).

IFN-gamma, IL-5, IL-6 and IgE in patients infected with Giardia intestinalis

The immune system, its cellular and humoral response, is engaged by the host organism to fight against parasitic infections. The study group consisted of 90 patients (58 women and 32 men), aged 18-72 years, infected with G. intestinalis. The diagnosis was established based on laboratory investigations (stool examination, choloscopy, GSA-65). Blood for analysis was collected before (G1), and 2 weeks (G2) and 2 months (G3) after antiparasitic treatment. Control group consisted of 40 healthy subjects (22 women and 18 men), aged 20-45 years. The concentrations of IgE were assayed using a set of VIDAS (bioMerieux) and the concentrations of IL-5, IL-6, IFN-gamma were determined using a set of Quantikine human (R&D Systems). It was revealed that in giardiosis the concentrations of IgE and IL-5 in blood serum were twice as high, the concentration of IL-6 was two and a half times higher and the concentration of IFN-gamma was almost four times higher as compared to healthy controls.

The immunological effects of electrolyzed reduced water on the Echinostoma hortense infection in C57BL/6 mice

Electrolyzed reduced water (ERW) is widely used for drinking by people in Asia. The purpose of this study was to examine the immunological effect of ERW on the immunity of animals by supplying ERW to C57BL/6 mice infected with Echinostoma hortense metacercariae. In the non-infected groups, interleukin (IL)-4 (p < 0.001), IL-5, IL-10, IL-1beta, tumor necrosis factor (TNF)-alpha and immunoglobulin (Ig) A expression of the group fed ERW (ERW group) increased in small intestine compared with the normal control group. In the case of infected groups, the group fed ERW (ERW+E. hortense group) showed the result that IL-4, IL-5, IL-10 and Ig A expression increased, but IL-1beta and TNF-alpha (p < 0.001) decreased, and the number of goblet cells (p < 0.001) and helix pomatia agglutinin (HPA) positive cells increased compared with the group without feeding ERW. However, adult worm recovery rate was markedly increased (p < 0.05). On the other hand, the expression of all the cytokines except IL-10 in spleen was mildly increased but not significant statistically, and there was no significant difference in the numerical changes of white blood cell (WBC). These results indicate that feeding ERW may have influence on the local immune response (Th-1 type cytokines such as IL-1beta, TNF-alpha) in the small intestine but not on the systemic immune response.

Identification of T-cell stimulating antigens from Giardia lamblia by using Giardia-specific T-cell hybridomas

T-cell immune response plays an important role in controlling Giardia lamblia infections. Little is known about the G. lamblia-specific antigens that stimulate a cell-mediated immune response. The aim of the present study was to identify T-cell stimulating G. lamblia antigens. For this purpose, we generated a group of Giardia-specific T-cell hybridomas (2F9, 4D5, 6D10, 8B9, 9B10, 10F7 and 10G5). Hybridomas were screened for reactivity with G. lamblia protein extract by the CTLL bioassay. These T-cell hybridomas did not exhibit any significant activation either in the absence of G. lamblia protein extract or in the presence of irrelevant antigen (hen white egg lysozyme). To further characterize the T-cell hybridomas generated, we selected three hybridomas (10G5, 4D5 and 9B10). Giardia lamblia proteins of 90-110, 65-77 and 40-64 kDa showed T-cell stimulating activity for the hybridomas 10G5, 4D5 and 9B10, respectively, in a concentration-dependent manner. Protein extract obtained from different G. lamblia strains (GS/M-83-H7, WB C6 and a clinical isolate (YJJ)) stimulated all T-cell hybridomas, indicating that T-cell-stimulating antigens are expressed among different G. lamblia strains. In conclusion, we identified T-cell stimulating G. lamblia antigens by using Giardia-specific T-cell hybridomas. To our knowledge, these hybridomas are the first-described T-cell hybridomas specific for G. lamblia.