Recombinant antigens used as diagnostic tools for lymphatic filariasis.

Lymphatic filariasis (LF) is a parasitic disease caused by the worms Wuchereria bancrofti, Brugia malayi, or Brugia timori. It is a tropical and subtropical illness that affects approximately 67 million people worldwide and that still requires better diagnostic tools to prevent its spread and enhance the effectiveness of control procedures. Traditional parasitological tests and diagnostic methods based on whole protein extracts from different worms are known for problems related to sample time collection, sensitivity, and specificity. More recently, new diagnostic tools based on immunological methods using recombinant antigens have been developed. The current review describes the several recombinant antigens used as tools for lymphatic filariasis diagnosis in antigen and antibody capture assays, highlighting their advantages and limitations as well as the main commercial tests developed based on them. The literature chronology is from 1991 to 2021. First, it describes the historical background related to the identification of relevant antigens and the generation of the recombinant polypeptides used for the LF diagnosis, also detailing features specific to each antigen. The subsequent section then discusses the use of those proteins to develop antigen and antibody capture tests to detect LF. So far, studies focusing on antibody capture assays are based on 13 different antigens with at least six commercially available tests, with five proteins further used for the development of antigen capture tests. Five antigens explored in this paper belong to the SXP/RAL-2 family (BmSXP, Bm14, WbSXP-1, Wb14, WbL), and the others are BmShp-1, Bm33, BmR1, BmVAH, WbVAH, BmALT-1, BmALT-2, and Wb123. It is expected that advances in research with these antigens will allow further development of tests combining both sensitivity and specificity with low costs, assisting the Global Program to Eliminate Lymphatic Filariasis (GPELF).

Self-reactive IgG4 antibodies are associated with blocking of pathology in human lymphatic filariasis.

Lymphatic filariasis, a chronic disfiguring disease exhibits complex pathology. Based on different clinical manifestations, infected individuals are categorized into asymptomatic-carriers and chronic-patients. The mechanism behind differential clinical outcomes remains unclear. Roles of filaria-specific B cell responses in filariasis have been documented, whereas the contribution of B1 cell response and poly-specific IgG and IgA in the context of clinical filariasis is not deciphered. In this study, we measured the poly-specific IgG and IgA levels in different clinical categories of filariasis. Asymptomatic-carriers exhibited increased IgG4 antibodies against both filarial-antigens as well as auto-antigens compared to other clinical categories, although IgG against these auto-antigens remained lower. IgA levels against both filarial and auto-antigens were decreased in asymptomatic-carriers. A positive correlation between anti-filarial IgG4 and IgG4 against auto-antigens were observed, suggesting the synergistic role of poly-specific natural IgG4 with anti-filarial IgG4 in blocking the pathogenesis in asymptomatic microfilarial cases.

A Novel Ligand of Toll-like Receptor 4 From the Sheath of Wuchereria bancrofti Microfilaria Induces Proinflammatory Response in Macrophages.

Background: Lymphatic filariasis, frequently caused from Wuchereria bancrofti infection, is endemic in several parts of the globe and responsible for human health problems and socioeconomic loss to a large extent. Inflammatory consequences originating from host-parasite interaction play a major role in the disease pathology and allied complications. The identity of the key mediator of this process is yet unknown in filarial research. Methods: Microfilarial protein (MfP) was isolated from the sheath of W. bancrofti microfilariae through ultrafiltration, followed by chromatographic separation. Expression of signaling molecules was studied by enzyme-linked immunosorbent assay and immunoblotting. Binding of MfP to Toll-like receptor 4 (TLR4) was determined by co-immunoprecipitation, fluorescein isothiocyanate-probing, and surface plasmon resonance analysis. Results: We found that MfP (approximately 70 kDa) binds to macrophage-TLR4 and triggers nuclear factor kappa beta activation that upregulates secretion of proinflammatory cytokines. Microfilarial protein failed to induce inflammation in either TLRKO macrophage or macrophage treated with TLR4 inhibitor, indicating that MfP acts through TLR4. We have also detected phenotypic transformation of macrophages from anti-inflammatory (M2) to proinflammatory (M1) subtype after incubation with MfP. Conclusions: Microfilarial protein appears to be a new ligand of TLR4 from W. bancrofti. Determination of its functional attributions in the host-parasite relationship, especially immunopathogenesis of filarial infection, may improve our understanding.

Wuchereria bancrofti infection in Haitian immigrants and the risk of re-emergence of lymphatic filariasis in the Brazilian Amazon

Abstract INTRODUCTION: Lymphatic filariasis (LF) is a public health problem in Haiti. Thus, the emigration of Haitians to Brazil is worrisome because of the risk for LF re-emergence. METHODS: Blood samples of Haitian immigrants, aged ≥18 years, who emigrated to Manaus (Brazilian Amazon), were examined using thick blood smears, membrane blood filtration, and immunochromatography. RESULTS: Of the 244 immigrants evaluated, 1 (0.4%) tested positive for W. bancrofti; 11.5% reported as having received LF treatment in Haiti. CONCLUSIONS: The re-emergence of LF in Manaus is unlikely, due to its low prevalence and low density of microfilaremia among the assessed Haitian immigrants.

Role of cysteine-58 and cysteine-95 residues in the thiol di-sulfide oxidoreductase activity of Macrophage Migration Inhibitory Factor-2 of Wuchereria bancrofti.

Macrophage Migration Inhibitory Factor (MIF) is the first human cytokine reported and was thought to have a central role in the regulation of inflammatory responses. Homologs of this molecule have been reported in bacteria, invertebrates and plants. Apart from cytokine activity, it also has two catalytic activities viz., tautomerase and di-sulfide oxidoreductase, which appear to be involved in immunological functions. The CXXC catalytic site is responsible for di-sulfide oxidoreductase activity of MIF. We have recently reported thiol-disulfide oxidoreductase activity of Macrophage Migration Inhibitory Factor-2 of Wuchereria bancrofti (Wba-MIF-2), although it lacks the CXXC motif. We hypothesized that three conserved cysteine residues might be involved in the formation of di-sulfide oxidoreductase catalytic site. Homology modeling of Wba-MIF-2 showed that among the three cysteine residues, Cys58 and Cys95 residues came in close proximity (3.23Å) in the tertiary structure with pKa value 9, indicating that these residues might play a role in the di-sulfide oxidoreductase catalytic activity. We carried out site directed mutagenesis of these residues (Cys58Ser & Cys95Ser) and expressed mutant proteins in Escherichia coli. The mutant proteins did not show any oxidoreductase activity in the insulin reduction assay, thus indicating that these two cysteine residues are vital for the catalytic activity of Wba-MIF-2.

Circulating filarial antigen detection in brugian filariasis.

Human lymphatic filariasis (LF) is a major cause of disability globally. The success of global elimination programmes for LF depends upon effectiveness of tools for diagnosis and treatment. In this study on stage-specific antigen detection in brugian filariasis, L3, adult worm (AW) and microfilarial antigenaemia were detected in around 90-95% of microfilariae carriers (MF group), 50-70% of adenolymphangitis (ADL) patients, 10-25% of chronic pathology (CP) patients and 10-15% of endemic normal (EN) controls. The sensitivity of the circulating filarial antigen (CFA) detection in serum samples from MF group was up to 95%. In sera from ADL patients, unexpectedly, less antigen reactivity was observed. In CP group all the CFA positive individuals were from CP grade I and II only and none from grade III or IV, suggesting that with chronicity the AWs lose fecundity and start to disintegrate and die. Amongst EN subject, 10-15% had CFA indicating that few of them harbour filarial AWs, thus they might not be truly immune as has been conventionally believed. The specificity for antigen detection was 100% when tested with sera from various other protozoan and non-filarial helminthic infections.

Changes in Antibody Levels during and following an Episode of Acute Adenolymphangitis (ADL) among Lymphedema Patients in Léogâne, Haiti.

INTRODUCTION: Episodes of acute adenolymphangitis (ADL) are often the first clinical sign of lymphatic filariasis (LF). They are often accompanied by swelling of the affected limb, inflammation, fever, and general malaise and lead to the progression of lymphedema. Although ADL episodes have been studied for a century or more, questions still remain as to their etiology. We quantified antibody levels to pathogens that potentially contribute to ADL episodes during and after an episode among lymphedema patients in Léogâne, Haiti. We estimated the proportion of ADL episodes hypothesized to be attributed to specific pathogens. METHODS: We measured antibody levels to specific pathogens during and following an ADL episode among 41 lymphedema patients enrolled in a cohort study in Léogâne, Haiti. We calculated the absolute and relative changes in antibody levels between the ADL and convalescent time points. We calculated the proportion of episodes that demonstrated a two-fold increase in antibody level for several bacterial, fungal, and filarial pathogens. RESULTS: Our results showed the greatest proportion of two-fold changes in antibody levels for the carbohydrate antigen Streptococcus group A, followed by IgG2 responses to a soluble filarial antigen (BpG2), Streptococcal Pyrogenic Exotoxin B, and an antigen for the fungal pathogen Candida. When comparing the median antibody level during the ADL episode to the median antibody level at the convalescent time point, only the antigens for Pseudomonas species (P-value = 0.0351) and Streptolysin O (P-value = 0.0074) showed a significant result. CONCLUSION: Although our results are limited by the lack of a control group and few antibody responses, they provide some evidence for infection with Streptococcus A as a potential contributing factor to ADL episodes. Our results add to the current evidence and illustrate the importance of determining the causal role of bacterial and fungal pathogens and immunological antifilarial response in ADL episodes.

Helminth infection alters IgE responses to allergens structurally related to parasite proteins.

Immunological cross-reactivity between environmental allergens and helminth proteins has been demonstrated, although the clinically related implications of this cross-reactivity have not been addressed. To investigate the impact of molecular similarity among allergens and cross-reactive homologous helminth proteins in IgE-based serologic assessment of allergic disorders in a helminth-infected population, we performed ImmunoCAP tests in filarial-infected and noninfected individuals for IgE measurements to allergen extracts that contained proteins with high levels of homology with helminth proteins as well as IgE against representative recombinant allergens with and without helminth homologs. The impact of helminth infection on the levels and function of the IgE to these specific homologous and nonhomologous allergens was corroborated in an animal model. We found that having a tissue-invasive filarial infection increased the serological prevalence of ImmunoCAP-identified IgE directed against house dust mite and cockroach, but not against timothy grass, the latter with few allergens with homologs in helminth infection. IgE ELISA confirmed that filaria-infected individuals had higher IgE prevalences to those recombinant allergens that had homologs in helminths. Mice infected with the helminth Heligmosomoides polygyrus displayed increased levels of IgE and positive skin tests to allergens with homologs in the parasite. These results show that cross-reactivity among allergens and helminth proteins can have practical implications, altering serologic approaches to allergen testing and bringing a new perspective to the "hygiene hypothesis."

[Lymphatic filariasis transmission assessment survey in schools three years after stopping mass drug treatment with albendazole and ivermectin in the 7 endemic districts in Togo]. / Enquête d'évaluation de la transmission de la filariose lymphatique en milieu scolaire, 3 ans après l'arrêt du traitement de masse à l'albendazole et à l'ivermectine dans les 7 districts endémiques du Togo.

The aim of this study is to verify the level of transmission of lymphatic filariasis three years after stopping mass drug treatment in the 7 endemic districts in Togo. The survey was conducted in 2012 in Togo's 7 endemic districts grouped into four evaluation units (EU) using the WHO-recommended transmission assessment survey (TAS) protocol. Children aged 6-7 years were screened for Wuchereria bancofti antigen using the immunochromatographic card (ICT) method. A cluster sampling method was used to select eligible children in schools as the net primary-school enrolment ratio is greater than or equal to 75% in each of the four EUs. The number of children and schools to be selected in each EU, the randomization list for the selection of these children and the critical cut-off number of positive cases not to exceed were automatically generated using the Survey Sample Builder (SSB) tool, (NTD Support Center, Atlanta, Ga, USA). For confirmation, positive cases were subsequently tested for microfilaremia using nocturnal thick blood smear and for filarial antigen using Og4C3 antigen ELISA (TropBio ELISA Kit®, Townsville, Queensland, Australia). An EU is considered to have passed the test successfully (it is assumed that transmission can no longer be sustained), when the number of positive cases is below the critical cut-off number set by the SSB, which is roughly equivalent to 2% prevalence. Of the 1 706 children surveyed in Kpendjal-Tone's EU, 1 549 in Binah-Doufelgou's EU, 1 550 in Kozah's EU and the 1 575 in Amou-Haho's EU, 8 (0.46%), 1 (0.08%), 0 (0.00%) and 4 (0.25%) ICT positive cases respectively were detected. The number of positive ICT tests was well below 18, the critical cut number for each of the 4 EUs. All 13 ICT positive cases tested negative for nocturnal microfilaremia and Og4C3 ELISA. We conclude that all four EU passed the TAS with success, and the transmission of Wuchereria bancrofti is no longer likely to be sustained in the 7 endemic districts in Togo 3 years after stopping the MDA. A new TAS will be carried out in 2015, after which, if the results are still good, the country will submit a dossier to WHO for verification of the elimination of lymphatic filariasis.

Brugia malayi microfilariae induce a regulatory monocyte/macrophage phenotype that suppresses innate and adaptive immune responses.

BACKGROUND: Monocytes and macrophages contribute to the dysfunction of immune responses in human filariasis. During patent infection monocytes encounter microfilariae in the blood, an event that occurs in asymptomatically infected filariasis patients that are immunologically hyporeactive. AIM: To determine whether blood microfilariae directly act on blood monocytes and in vitro generated macrophages to induce a regulatory phenotype that interferes with innate and adaptive responses. METHODOLOGY AND PRINCIPAL FINDINGS: Monocytes and in vitro generated macrophages from filaria non-endemic normal donors were stimulated in vitro with Brugia malayi microfilarial (Mf) lysate. We could show that monocytes stimulated with Mf lysate develop a defined regulatory phenotype, characterised by expression of the immunoregulatory markers IL-10 and PD-L1. Significantly, this regulatory phenotype was recapitulated in monocytes from Wuchereria bancrofti asymptomatically infected patients but not patients with pathology or endemic normals. Monocytes from non-endemic donors stimulated with Mf lysate directly inhibited CD4+ T cell proliferation and cytokine production (IFN-γ, IL-13 and IL-10). IFN-γ responses were restored by neutralising IL-10 or PD-1. Furthermore, macrophages stimulated with Mf lysate expressed high levels of IL-10 and had suppressed phagocytic abilities. Finally Mf lysate applied during the differentiation of macrophages in vitro interfered with macrophage abilities to respond to subsequent LPS stimulation in a selective manner. CONCLUSIONS AND SIGNIFICANCE: Conclusively, our study demonstrates that Mf lysate stimulation of monocytes from healthy donors in vitro induces a regulatory phenotype, characterized by expression of PD-L1 and IL-10. This phenotype is directly reflected in monocytes from filarial patients with asymptomatic infection but not patients with pathology or endemic normals. We suggest that suppression of T cell functions typically seen in lymphatic filariasis is caused by microfilaria-modulated monocytes in an IL-10-dependent manner. Together with suppression of macrophage innate responses, this may contribute to the overall down-regulation of immune responses observed in asymptomatically infected patients.

Evaluation of diagnostic tests for Wuchereria bancrofti infection in Brazilian schoolchildren

Introduction Since the launch of the Global Programme to Eliminate Lymphatic Filariasis, more than 70% of the endemic countries have implemented mass drug administration (MDA) to interrupt disease transmission. The monitoring of filarial infection in sentinel populations, particularly schoolchildren, is recommended to assess the impact of MDA. A key issue is choosing the appropriate tools for these initial assessments (to define the best intervention) and for monitoring transmission. Methods This study compared the pre-MDA performance of five diagnostic methods, namely, thick film test, Knott's technique, filtration, Og4C3-ELISA, and the AD12-ICT card test, in schoolchildren from Brazil. Venous and capillary blood samples were collected between 11 pm and 1 am. The microfilarial loads were analyzed with a negative binomial regression, and the prevalence and associated 95% confidence intervals were estimated for all methods. The accuracies of the AD12-ICT card and Og4C3-ELISA tests were assessed against the combination of parasitological test results. Results A total of 805 schoolchildren were examined. The overall and stratified prevalence by age group and gender detected by Og4C3-ELISA and AD12-ICT were markedly higher than the prevalence estimated by the parasitological methods. The sensitivity of the AD12-ICT card and Og4C3-ELISA tests was approximately 100%, and the positive likelihood ratios were above 6. The specificity of the Og4C3-ELISA was higher than that of the AD12-ICT at different prevalence levels. Conclusions The ICT card test should be the recommended tool for monitoring school-age populations living in areas with ongoing or completed MDA. .

Functional analysis of a highly conserved abundant larval transcript-2 (alt-2) intron 2 repeat region of lymphatic filarial parasites.

The filarial-specific protein abundant larval transcript-2 (ALT-2) is expressed exclusively in the infective larval stage (L3) and is a crucial protein for establishing immunopathogenesis in human hosts. The alt-2 gene has a conserved minisatellite repeat (29 or 27bp) in intron 2 (IR2) whose significance within lymphatic filarial species is unknown. Here, we report the role of IR2 in the regulation of alt-2 gene expression using an in vitro model. Using electrophoretic mobility shift assays, we identified the presence of a putative nuclear protein binding region within IR2. Subsequent transient expression experiments in eukaryotic cell lines demonstrated that the IR2 downregulated the expression of a downstream luciferase reporter gene, which was further validated with RT-PCR. We therefore identify IR2 as a suppressor element that regulates L3 stage-specific expression of alt-2.

Bancroftian filariasis: circulating B-1 cells decreased in microfilaria carriers and correlate with immunoglobulin M levels.

B-1 cells play an important role in the outcome of infection in schistosomiasis, pneumonia and experimental filariasis. However, no information exists regarding status of B-1 cells in clinical manifestations of human filariasis. We investigated the levels of B-1 cells from the total B cells by flow cytometry. Significantly low levels of B-1 cells and IgM antibodies were detected against a wide variety of autoantigens in microfilariae carriers as compared to endemic controls and patients with chronic pathology. A positive correlation was found between IgM antibodies to actin and ss-DNA. Absorption of plasma with soluble actin, myosin and lipopolysaccharides (LPS) resulted in significant removal of antifilarial antibodies. Affinity-purified anti-ss-DNA antibodies were found to be reactive to filarial antigens and various autoantigens. Further, a positive correlation was found between polyreactive antibodies and B-1 cells in filarial-infected human subjects. After antifilarial treatment, levels of IgM antibodies to ss-DNA, actin, LPS and filarial antigen increased significantly indicating a role of polyreactive naturally occurring antibodies in filarial infection. Our findings add to the existing evidence that the B-cell defect in BALB.Xid mice account for susceptibility to murine filarial infection and indicate an important role for these antibodies in providing host protection against filarial infection.

Efeito do tratamento em massa com dietilcarbamazina na microfilaremia, antigenemia e anticorpos antifilariais em uma área endêmica do município de Olinda - PE / The effect of mass drug administration with single doses of diethylcarbamazine in microfilaremia, antigenemia e antifilarial antibodys in a endemic area in Olinda - PE

Este trabalho analisou o efeito do tratamento em massa com doses únicas anuais de Dietilcarbamazina (DEC), no período de 2007 a 2012, em indivíduos infectados por Wuchereria bancrofti, residentes em Olinda - PE. Para essa análise foram utilizadas as técnicas de filtração em membrana, na detecção da microfilaremia, o teste do cartão ICT e o Og4C3-ELISA, na detecção do antígeno circulante filarial, e o teste BM14 na avaliação dos níveis de anticorpos antifilariais. Os resultados obtidos indicam redução nas características avaliadas: após a quarta dose de DEC, a microfilaremia reduziu 100 por cento e a antigenemia pelo cartão ICT atingiu 78,1 por cento de redução após a quinta dose. A mediana do Og4C3 caiu significativamente de 7117 ua, para 1715 ua após a terceira dose, último ano que o teste foi realizado. Observou-se curva de redução também nos níveis de Bm14, com mediana da densidade ótica caindo de 2,1 para 0,1 após a quinta dose. A diminuição nas taxas das características estudadas indica que o tempo preconizado pela Organização Mundial de Saúde para a eliminação da transmissão da FL na área é suficiente para a negativação das microfilárias. Os resultados desse estudo mostram a elevada eficácia do esquema terapêutico utilizado no clareamento da microfilaremia e tratamento dos infectados, e sugerem que a utilização desse esquema na população possivelmente tenha levado a interrupção da transmissão na área. Sugere-se que haja um acompanhamento maior que cinco anos da população submetida ao tratamento para uma melhor avaliação dos níveis de anticorpos e de antigenemia filarial circulante...

Predictive value of the eosinophil counts in the biological diagnosis of lymphatic filariasis in French Polynesia.

SETTINGS: Lymphatic filariasis is common in many tropical and subtropical areas and is a major public health issue in south Pacific islands. In endemic areas, most infected individuals are asymptomatic but may harbor microfilariae or filarial antigens in their peripheral blood. Microscopy remains the reference diagnostic tool for the identification of microfilariae but is weakly sensitive. The diagnosis of Wuchereria bancrofti infection was dramatically altered by the development of filarial antigen tests, which are easy to perform but expensive for routine use. Lymphatic filariasis is responsible for acquired eosinophilia and blood eosinophil count is commonly used as a screening tool in endemic areas. METHOD: We retrospectively analyzed all the results of eosinophil counts, antigen and microfilariae detection performed in our laboratory over a 24-month period. We calculated the prevalence of antigenemia for various eosinophilic cut offs. RESULTS: The prevalence of antigenemia was estimated at 25.78% with eosinophilia defined as a count eosinophilic PMN above 500 per mm(3). DISCUSSION: Our prevention strategy against lymphatic filariasis is based on annual mass drug administration, vector control, and systematic treatment of antigenemic and microfilaremic patients. Antigenemic and microfilaremic detection cannot be routinely performed because of their cost. Current treatments used for lymphatic filariasis are safe and cheaper than antigenic detection. A possible additional strategy to decrease the prevalence of antigenemia would be the systematic treatment of patients with hypereosinophilia.

Recombinant trehalose-6-phosphate phosphatase of Brugia malayi cross-reacts with human Wuchereria bancrofti immune sera and engenders a robust protective outcome in mice.

Trehalose-6-phosphate phosphatase of Brugia malayi (Bm-TPP) represents an attractive vaccine candidate because it is present in all the major life stages of parasite, but is absent in mammals. We have previously cloned, purified and biochemically characterized Bm-TPP. In the present study, we investigated the cross-reactivity of recombinant Bm-TPP (r-Bm-TPP) with the sera of human bancroftian patients belonging to different disease categories. In silico study using bioinformatics tool demonstrated that Bm-TPP is highly immunogenic in nature. BALB/c mice administered with r-Bm-TPP alone or in combination with Freund's complete adjuvant (FCA) generated a strong IgG response. Further investigations on the antibody isotypes showed generation of a mixed T helper cell response which was marginally biased towards Th1 phenotype. r-Bm-TPP with or without adjuvant lead to significantly increased accumulation of CD4+ and CD8+ T cells in the spleen of infected mice and increased the activation of peritoneal macrophages. Additionally, r-Bm-TPP enhanced the production of both proinflammatory (IL-2, IFN-γ) and anti-inflammatory (IL-4, IL-10) cytokines and mice immunized with r-Bm-TPP alone or in combination with FCA showed 54.5% and 67% protection respectively against B. malayi infective larvae challenge. Taken together, our findings suggest that Bm-TPP is protective in nature and might be a potential candidate for development of vaccine against lymphatic filarial infections.

Molecular mimicry between cockroach and helminth glutathione S-transferases promotes cross-reactivity and cross-sensitization.

BACKGROUND: The extensive similarities between helminth proteins and allergens are thought to contribute to helminth-driven allergic sensitization. OBJECTIVE: The objective of this study was to investigate the cross-reactivity between a major glutathione-S transferase allergen of cockroach (Bla g 5) and the glutathione-S transferase of Wuchereria bancrofti (WbGST), a major lymphatic filarial pathogen of humans. METHODS: We compared the molecular and structural similarities between Bla g 5 and WbGST by in silico analysis and by linear epitope mapping. The levels of IgE, IgG, and IgG(4) antibodies were measured in filarial-infected and filarial-uninfected patients. Mice were infected with Heligmosomoides bakeri, and their skin was tested for cross-reactive allergic responses. RESULTS: These 2 proteins are 30% identical at the amino acid level with remarkable similarity in the N-terminal region and overall structural conservation based on predicted 3-dimensional models. Filarial infection was associated with IgE, IgG, and IgG(4) anti-Bla g 5 antibody production, with a significant correlation between antibodies (irrespective of isotype) to Bla g 5 and WbGST (P< .0003). Preincubation of sera from cockroach-allergic subjects with WbGST partially depleted (by 50%-70%) anti-Bla g 5 IgE, IgG, and IgG(4) antibodies. IgE epitope mapping of Bla g 5 revealed that 2 linear N-terminal epitopes are highly conserved in WbGST corresponding to Bla g 5 peptides partially involved in the inhibition of WbGST binding. Finally, mice infected with H bakeri developed anti-HbGST IgE and showed immediate-type skin test reactivity to Bla g 5. CONCLUSION: These data demonstrate that helminth glutathione-S transferase and the aeroallergen Bla g 5 share epitopes that can induce allergic cross-sensitization.

A rare case of reversible acquired AA-type renal amyloidosis in a chronic filariasis patient receiving antifilarial therapy.

Lymphatic filariasis is a major health problem in India with a large number of patients tending to be asymptomatic. In the Southeast and South Asian regions, Wuchereria bancrofti is the most prevalent parasite, causing filariasis in 99.4% of cases. While kidney involvement is a rare event in chronic filariasis, this case is unique because AA-type renal amyloidosis occurs in chronic W. bancrofti infection. We present here a unique case of lymphatic filariasis. The patient, a 25-year-old male who was previously diagnosed with right lower limb filarial lymphedema and had undergone lymphovenous anastomosis, was admitted for evaluation of persistent nephrotic-range proteinuria. Autoimmune markers in the form of anti-nuclear antibodies, anti-double-stranded DNA and anti-neutrophil cytoplasmic antibody were negative; C3 was normal. Urine analysis revealed inactive sediment with moderate proteinuria. Both serum and urine electrophoresis were negative for paraproteins and bone marrow aspirate and biopsy were normal. Evidence of active filarial infection was established on the basis of microfilariae in the peripheral smear and a positive W. bancrofti antigen test. Kidney biopsy revealed renal amyloidosis when stained with Congo red and anti-AA immunostain. The patient's proteinuria improved on conservative management with angiotensin-converting enzyme inhibitors and a course of antifilarial drugs. His proteinuria returned to <1 g/24 h with normalization of renal function and no significant proteinuria on periodic follow-up at 6-month and 1-year intervals. Repeat kidney biopsy after 1.5 years showed regression of amyloidosis. Repeat demonstration of filarial antigen and microfilariae in the peripheral smear were negative on multiple occasions during the follow-up period. Although various chronic infections can lead to secondary renal amyloidosis, this is the first case reported in world literature where secondary amyloidosis developed as a complication of chronic filarial infection due to W. bancrofti. This is probably also the first case reported in world literature where renal amyloidosis has an etiological association with W. bancrofti infection and where patient symptoms improved with antifilarial and antiproteinuric management.

Evaluation of synthetic peptides of WbSXP-1 for the diagnosis of human lymphatic filariasis.

Parasitic nematodes infect nearly half of the world's human population, resulting in significant morbidity and mortality. Though filariasis is not fatal, it is the second leading cause of permanent and long-term disability worldwide. Filariasis has a spectrum of disease manifestation and infectivity found among the infected individuals and also goes unnoticed for years. Furthermore, there are ample reports emerging on the genetic variation among the parasites population. Hence, it is necessary to develop diagnostics for early detection of the disease. Synthetic peptides that mimic the immunogenic regions and a conserved region similar to that of recombinant antigen will be more useful in developing diagnostics, vaccines, or therapeutics. WbSXP-1 was earlier proven as a good diagnostic antigen; B-cell epitopic analysis showed 4 potent immunodominant regions spanning the whole antigen. These synthetic peptides (N, N1, N2, and N3) were produced and used as a diagnostic candidate to detect anti-SXP antibody and conversely to detect the infected individuals. The monomeric peptides showed good reactivity against microfilareamic (MF) sera. Among them, the peptides N, N1, and N2 were found to be more reactive. Furthermore, multiple chimeric peptides in linear combinations of 2 peptides were tested for its efficacy to detect anti-SXP antibody in infected MF sera. The peptides N:N1 and N1:N2 were synthesized and tested against human clinical sera. This chimeric peptides constructed based on WbSXP-1 were found to be reactive, specifically with MF sera by ELISA. These peptide-based diagnostic method can serve as a standard better tool without cross-reactivity in lymphatic filariasis elimination program.