Allergenome characterization of the mosquito Aedes aegypti

Safety evaluation of the food enzyme mucorpepsin from the non-genetically modified Rhizomucor miehei strain LP-N836

The food enzyme mucorpepsin (EC 3.4.23.23) is produced with the non-genetically modified Rhizomucor miehei strain LP-N836 by Meito Sangyo Co., Ltd. The native enzyme can be chemically modified to produce a more thermolabile form. The food enzyme is free from viable cells of the production organism. It is intended to be used in the processing of dairy products for the production of cheese and fermented dairy products. Dietary exposure to the food enzyme-total organic solids (TOS) was estimated to be up to 0.108 mg TOS/kg body weight (bw) per day in European populations. Genotoxicity tests did not indicate a safety concern. The systemic toxicity was assessed by means of a repeated dose 90-day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 95 mg TOS/kg bw per day, the mid-dose tested, which when compared with the estimated dietary exposure, resulted in a margin of exposure of at least 880. A search for the similarity of the amino acid sequence of the food enzyme to known allergens was made and four matches with respiratory allergens and one with a food allergen (mustard) were found. The Panel considered that the risk of allergic reactions upon dietary exposure to this food enzyme, particularly in individuals sensitised to mustard proteins, cannot be excluded. Based on the data provided, the Panel concluded that both the native and thermolabile forms of this food enzyme do not give rise to safety concerns under the intended conditions of use.

The role of Aedes aegypti in inducing/aggravating IgE-mediated allergic airway disease: extensive computational studies for identification of allergenic proteins

Respiratory allergies have become a major public health concern and affect one-third of the world's population. Several factors like environmental changes, industrialization, and immunologic interactions are reported to contribute to allergic respiratory diseases. Immunological reactions because of mosquito bite (allergic proteins) have been reported to have a high contribution to IgE-mediated allergic airway disease but they are largely ignored. In this study, we aim to predict the potential allergens (proteins) from Aedes aegypti that might play a role in the reactions of IgE-mediated allergic airway diseases. The allergens are identified from an extensive literature search and the 3D structures were prepared using the SwissDock server. Computational studies were performed to identify the potential allergens that might be responsible for IgE-mediated allergies. Our docking and molecular dynamics (MD) simulation results suggest that ADE-3, an allergen from Aedes aegypti, has the highest docking score and is predicted to be responsible for IgE-mediated allergic reaction(s). Overall, this study highlights the importance of immunoinformatics, and the obtained information can be used for designing prophylactic peptide vaccine candidates and inhibitors for controlling IgE-mediated inflammations.Communicated by Ramaswamy H. Sarma.

Safety evaluation of the food enzyme mucorpepsin from the non-genetically modified Rhizomucor miehei strain M19-21

The food enzyme mucorpepsin (EC 3.4.23.23) is produced with the non-genetically modified Rhizomucor miehei strain M19-21 by Meito Sangyo Co., Ltd. The enzyme is chemically modified to produce a thermolabile form. The food enzyme was considered free from viable cells of the production organism. It is intended to be used in the processing of dairy products for the production of cheese and fermented dairy products. Based on the maximum use levels, dietary exposure was estimated to be up to 0.108 mg TOS/kg body weight (bw) per day in European populations. Genotoxicity tests did not indicate a safety concern. The systemic toxicity was assessed by means of a repeated dose 90-day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 226 mg TOS/kg bw per day, the highest dose tested, which, when compared with the estimated dietary exposure, results in a margin of exposure of at least 2093. A search for the similarity of the amino acid sequence of the food enzyme to known allergens was made and four matches to respiratory allergens and one match to a food allergen (mustard) were found. The Panel considered that the risk of allergic reactions upon dietary exposure to this food enzyme, particularly in individuals sensitised to mustard proteins, cannot be excluded. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns, under the intended conditions of use.

Safety evaluation of the food enzyme mucorpepsin from the non-genetically modified Rhizomucor miehei strain FRO

The food enzyme mucorpepsin (EC 3.4.23.23) is produced with the non-genetically modified Rhizomucor miehei strain FRO by DSM Food Specialties B.V. The enzyme can be chemically modified to produce a thermolabile form. The food enzyme is free from viable cells of the production organism. It is intended to be used in three food manufacturing processes: processing of dairy products for the production of (1) cheese, (2) edible rennet casein, (3) fermented dairy products. Dietary exposure to the food enzyme-total organic solids (TOS) was estimated to be up to about 0.072 mg TOS/kg body weight (bw) per day in European populations. Genotoxicity tests did not indicate a safety concern. The systemic toxicity was assessed by means of a repeated dose 90-day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 2000 mg TOS/kg bw per day, the highest dose tested, which, when compared with the estimated dietary exposure, results in a margin of exposure of at least 27,778. A search for the similarity of the amino acid sequence of the food enzyme to known allergens was made and five matches were found. The Panel considered that a risk of allergic reactions upon dietary exposure to this food enzyme cannot be excluded, but is considered low, except for individuals sensitised to mustard proteins, for whom the risk will not exceed that of mustard consumption. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns under the intended conditions of use.

Mosquito allergy: Immunological aspects and clinical management

Mosquito allergy has been conceived as the cutaneous reactions that appears during and after mosquito biting process; a perception that is supported by several scientific research. Additional data have led to conceive that other manifestations of allergic responses may occur as a cause of the exposure to somatic mosquito allergens. Two main phenotypes of mosquito allergy are identifiable: the cutaneous allergic reactions, induced by salivary allergens, and other manifestations of the allergic responses such as asthma and allergic rhino conjunctivitis that are caused by somatic allergens. The cutaneous reactions have kept the focus of attention of the scientific community. It appears as skin lesions that resembles the phenotype of papular urticaria with a defined natural history of the disease. Although these two phenotypes of mosquito allergy seem to be well differentiated in terms of the allergens that are involved and the routes of exposures, other factors such as geographical distribution, may participate. Mosquitoes have adapted to the host immune response against bites, producing immunomodulatory molecules that counteract such defensive response. The role that the immunomodulatory molecules have on the allergic immune response has not been studied yet and it is still not known if affects all mosquito allergy phenotypes. Only a few studies of allergen specific immunotherapy for cutaneous allergic reactions induced by mosquito bites have been done, and none for respiratory allergic responses. The clinical practice focuses on symptom management and avoiding mosquito bites as much as possible. Avoiding mosquitoes, using different well described methods, is still the best option to limit contact with these insects. The lack of knowledge of mosquito allergy have raised several questions that affects the clinical management of this allergic disease, from its diagnosis, prevention and immunotherapy.

Genomics of Shrimp Allergens and Beyond

Allergy to shellfishes, including mollusks and crustaceans, is a growing health concern worldwide. Crustacean shellfish is one of the "Big Eight" allergens designated by the U.S. Food and Drug Administration and is the major cause of food-induced anaphylaxis. Shrimp is one of the most consumed crustaceans triggering immunoglobulin E (IgE)-mediated allergic reactions. Over the past decades, the allergen repertoire of shrimp has been unveiled based on conventional immunodetection methods. With the availability of genomic data for penaeid shrimp and other technological advancements like transcriptomic approaches, new shrimp allergens have been identified and directed new insights into their expression levels, cross-reactivity, and functional impact. In this review paper, we summarize the current knowledge on shrimp allergens, as well as allergens from other crustaceans and mollusks. Specific emphasis is put on the genomic information of the shrimp allergens, their protein characteristics, and cross-reactivity among shrimp and other organisms.

Identification of an immunodominant IgE epitope of Der f 40, a novel allergen of Dermatophagoides farinae

Background

House dust mites (HDMs), including Dermatophagoides pteronyssinus (Der p) and Dermatophagoides farinae (Der f) species, represent a major source of inhalant allergens that induce IgE-mediated anaphylactic reactions. HDM allergen identification is important to the diagnosis and treatment of allergic diseases. Here, we report the identification of a novel HDM allergen, which we suggest naming Der f 40, and its immunodominant IgE epitopes.

Methods

The recombinant protein Der f 40 was expressed using a pET prokaryotic expression system and purified with Ni-NTA resins. IgE binding activity was evaluated by IgE-western blot, dot-blot, and ELISA. Mast cell activation testing was performed to assess the cellular effects of IgE binding in mouse bone marrow derived mast cells (BMMCs) expressing human FcεRI. IgE binding assays were performed with truncated and hybrid Der f 40 protein molecules to find immunodominant IgE epitopes.

Results

A 106-amino acid (aa) recombinant Der f Group 40 protein (rDer f 40) was obtained (GenBank accession No. XP_046915420.1) as thiredoxin-like protein. Der f 40 was shown to bind IgE from HDM allergic serum in vitro (9.68%; 12/124 in IgE-ELISA), and shown to promote the release of β-hexosaminidase from BMMCs dose-dependently when administered with HDM allergic sera. The Der f Group 40 protein was named Der f 40 and listed in the World Health Organization and International Union of Immunological Societies (WHO/IUIS) Allergen Nomenclature Sub-committee. IgE binding assays with Der f 40-based truncated and hybrid proteins indicated that IgE binding epitopes are likely located in the C-terminal region and dependent on conformational structure. The 76-106-aa region of C-terminus was identified as an immunodominant IgE epitope of Der f 40.

Conclusion

A novel HDM allergen with robust IgE binding activity was identified and named Der f 40. An immunodominant IgE epitope of Der f 40 with conformational dependency was identified in the C-terminus (aa 76-106). These findings provide new information that may be useful in the development of diagnostic and therapeutic agents for HDM allergy.

Characterizing antibody responses to mosquito salivary antigens of the Southeast Asian vectors of malaria and dengue with a human challenge model of controlled exposure: a protocol

Background: Measurement of antibody titers directed against mosquito salivary antigens in blood samples has been proposed as an outcome measure to assess human exposure to vector bites. However, only a handful of antigens have been identified and the specificity and longitudinal dynamics of antibody responses are not well known. We report the protocol of a clinical trial of controlled exposure to mosquito bites that aims to identify and validate biomarkers of exposure to bites of mosquito vector species that transmit malaria and dengue in Southeast Asia and some other parts of the world. Methods: This study is an exploratory factorial randomized control trial of controlled exposure to mosquito bites with 10 arms corresponding to different species ( Aedes aegypti, Ae. albopictus, Anopheles dirus, An. maculatus and An. minimus) and numbers of bites (35 or 305 bites in total over 6 weeks). Blood samples will be collected from study participants before, during and after mosquito biting challenges. Candidate peptides will be identified from published literature with antigen prediction algorithms using mosquito DNA sequence data and with immunoblotting assays carried out using protein extracts of dissected mosquito salivary glands and participants samples. Antibody titers against candidate peptides will be determined in participants samples with high-throughput cutting-edge immuno-assays. Quantification of the antibody response profile over time (including an estimate of the decay rate) and the effect of the number of bites on the antibody response will be determined using linear and logistic mixed-effects models for the continuous and the binary response, respectively. Conclusion: This research is expected to generate important knowledge for vector sero-surveillance and evaluation of vector-control interventions against malaria and dengue in the Greater Mekong Subregion. Registration: This study is registered with clinicaltrials.gov (NCT04478370) on July 20 ^th, 2020.

Characterizing antibody responses to mosquito salivary antigens of the Southeast Asian vectors of malaria and dengue with a human challenge model of controlled exposure: a protocol

Background: Measurement of antibody titers directed against mosquito salivary antigens in blood samples has been proposed as an outcome measure to assess human exposure to vector bites. However, only a handful of antigens have been identified and the specificity and longitudinal dynamics of antibody responses are not well known. We report the protocol of a clinical trial of controlled exposure to mosquito bites that aims to identify and validate biomarkers of exposure to bites of mosquito vector species that transmit malaria and dengue in Southeast Asia and some other parts of the world. Methods: This study is an exploratory factorial randomized control trial of controlled exposure to mosquito bites with 10 arms corresponding to different species (Aedes aegypt, Ae. albopictus, Anopheles dirus, An. maculatus and An. minimus) and numbers of bites (35 or 305 bites in total over 6 weeks). Blood samples will be collected from study participants before, during and after mosquito biting challenges. Candidate peptides will be identified from published literature with antigen prediction algorithms using mosquito DNA sequence data and with immunoblotting assays carried out using protein extracts of dissected mosquito salivary glands and participants samples. Antibody titers against candidate peptides will be determined in participants samples with high-throughput cutting-edge immuno-assays. Quantification of the antibody response profile over time (including an estimate of the decay rate) and the effect of the number of bites on the antibody response will be determined using linear and logistic mixed-effects models for the continuous and the binary response, respectively. Conclusion: This research is expected to generate important knowledge for vector sero-surveillance and evaluation of vector-control interventions against malaria and dengue in the Greater Mekong Subregion. Registration: This study is registered with clinicaltrials.gov (NCT04478370) on July 20th, 2020.

Crystal Structure Analysis of Sarcoplasmic-Calcium-Binding Protein: An Allergen in Scylla paramamosain

The structure of allergenic proteins provides important information about the binding of allergens to antibodies. In this study, the crystal structure of Scy p 4 with a resolution of 1.60 Å was obtained by X-ray diffraction. Epitope mapping of Scy p 4 revealed that linear epitopes are located on the surface of Scy p 4. Also, conformational epitopes are mostly located in the structural conservative region. Further structural comparison, surface electrostatic potential, and hydrogen bond force analysis showed that mutation of Asp₇₀ and Asp_18/20/70 would lead to calcium-binding capacity being lost and destruction of allergenicity. Furthermore, a comparative analysis of structure showed that sarcoplasmic-calcium-binding protein (SCP) had high sequence, secondary, and spatial structural identity in crustaceans, which may be an important factor leading to cross-reactivity among crustaceans. The structure of Scy p 4 provides a template for epitope evaluation and localization of SCPs, which will help to reveal cross-reactivity among species.

Safety evaluation of a food enzyme containing aspergillopepsin I and II from the Aspergillus niger var. macrosporus strain PTG8398

The food enzyme with aspergillopepsin I (EC 3.4.23.18) and aspergillopepsin II (EC 3.4.23.19) activities is produced with a non-genetically modified Aspergillus niger var. macrosporus strain PTG8398 by Meiji Seika Pharma Co., Ltd. The food enzyme was considered free from viable cells of the production organism. It is intended to be used in wine production. Based on the maximum use levels, dietary exposure to the food enzyme-total organic solids (TOS) was estimated to be up to 0.14 mg TOS/kg body weight (bw) per day in European populations. Genotoxicity tests did not indicate a safety concern. The systemic toxicity was assessed by means of a repeated dose 90-day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 919 mg TOS/kg bw per day, the highest dose tested which, when compared with the estimated dietary exposure, results in a margin of exposure above 6,700. A search for similarity of the amino acid sequence of the food enzyme to known allergens was made and four matches with respiratory allergens were found. The Panel considered that, under the intended conditions of use, the risk of allergic sensitisation and elicitation reactions by dietary exposure cannot be excluded, but the likelihood for this to occur is considered low. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns, under the intended conditions of use.

Safety evaluation of the native and thermolabile forms of the food enzyme mucorpepsin from Rhizomucor miehei strain MMR 164

The food enzyme mucorpepsin (aspartic endopeptidase, EC 3.4.23.23) is produced with the non‐genetically modified microorganism Rhizomucor miehei strain MMR 164 by Takabio. The enzyme is chemically modified to produce a thermolabile form. The food enzyme is free from viable cells of the production organism. It is intended to be used in milk processing for cheese production. The dietary exposure to the food enzyme–total organic solids (TOS) was estimated to be up to 0.98 mg TOS/kg body weight (bw) per day in European populations. Genotoxicity tests did not raise a safety concern. The systemic toxicity was assessed by means of a repeated dose 90‐day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 1,320 mg TOS/kg bw per day, the highest dose tested, which when compared with the estimated dietary exposure, resulted in a margin of exposure of at least 1,300. Similarity of the amino acid sequence of the food enzyme to those of known allergens was searched and five matches were found. The Panel considered that, under the intended conditions of use, the risk of allergic sensitisation and elicitation reactions upon dietary exposure to this food enzyme cannot be excluded, but is considered low except for individuals sensitised to mustard proteins, but this risk will not exceed that of mustard consumption. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns under the intended conditions of use.

Safety evaluation of the thermolabile form of the food enzyme mucorpepsin from Rhizomucor miehei strain MMR 164

The food enzyme mucorpepsin (aspartic endopeptidase, EC 3.4.23.23) is produced with the non‐genetically modified microorganism Rhizomucor miehei strain MMR 164. The enzyme is chemically modified by DuPont Nutrition Biosciences (now IFF) to produce a thermolabile form. The food enzyme is free from viable cells of the production organism. It is intended to be used in milk processing for cheese production. The dietary exposure to the food enzyme–total organic solids (TOS) was estimated to be up to 0.98 mg TOS/kg body weight (bw) per day in European populations. Genotoxicity tests did not raise a safety concern. The systemic toxicity was assessed by means of a repeated dose 90‐day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 1,320 mg TOS/kg bw per day, the highest dose tested, which when compared with the estimated dietary exposure, resulted in a margin of exposure of at least 1,300. Similarity of the amino acid sequence of the food enzyme to those of known allergens was searched and five matches were found. The Panel considered that, under the intended conditions of use, the risk of allergic sensitisation and elicitation reactions upon dietary exposure to this food enzyme cannot be excluded, but is considered low except for individuals sensitised to mustard proteins, but this risk will not exceed that of mustard consumption. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns under the intended conditions of use.

Tropomyosin: A panallergen that causes a worldwide allergic problem

Background: Panallergens are proteins that take part in key processes of organisms and, therefore, are ubiquitously distributed with highly conserved sequences and structures. One class of these panallergens is composed of the tropomyosins. The highly heat-stable tropomyosins comprise the major allergens in crustaceans and mollusks, which make them important food allergens in exposed populations. Tropomyosins are responsible for a widespread immunoglobulin E cross-reactivity among allergens from different sources. Allergic tropomyosins are expressed in many species, including parasites and insects. Methods: This panallergen class is divided, according to it capacity of induced allergic symptoms, into allergenic or nonallergenic tropomyosin. Although vertebrate tropomyosins share ∼55% of sequence homology with invertebrate tropomyosins, it has been thought that the invertebrate tropomyosins would not have allergic properties. Nevertheless, in recent years, this opinion has been changed. In particular, tropomyosin has been recognized as a major allergen in many insects. Results: A high grade of homology has been shown among tropomyosins from different species, such as crustaceans and insects, which supports the hypothesis of cross-reactivity among tropomyosins from divergent species. Moreover, the emerging habit of consuming edible insects has drawn the attention of allergists to invertebrate tropomyosin protein due to its potential allergenic risk. Nevertheless, evidence about tropomyosin involvement in clinical allergic response is still scarce and deserves more investigation. Conclusion: This review intended to report allergic reactions associated with different tropomyosins when considering house dust mites, parasites, seafood, and insects, and to summarize our current knowledge about its cross-reactivity because this could help physicians to accurately diagnose patients with food allergy.

Mosquitoes: Important Sources of Allergens in the Tropics

There are more than 3,000 mosquito species. Aedes aegypti, Ae. communis, and C. quinquefasciatus are, among others, three of the most important mosquito allergen sources in the tropics, western, and industrialized countries. Several individuals are sensitized to mosquito allergens, but the epidemiological data indicates that the frequency of sensitization markedly differs depending on the geographical region. Additionally, the geographical localization of mosquito species has been affected by global warming and some mosquito species have invaded areas where they were not previously found, at the same time as other species have been displaced. This phenomenon has repercussions in the pathogenesis and the accuracy of the diagnosis of mosquito allergy. Allergic individuals are sensitized to mosquito allergens from two origins: saliva and body allergens. Exposure to saliva allergens occurs during mosquito bite and induces cutaneous allergic reactions. Experimental and clinical data suggest that body allergens mediate different manifestations of allergic reactions such as asthma and rhinitis. The most studied mosquito species is Ae. aegypti, from which four and five allergens of the saliva and body, respectively, have been reported. Many characterized allergens are homologs to arthropod-derived allergens, which cause strong cross-reactivity at the humoral and cellular level. The generalized use of whole body Ae. communis or C. quinquefasciatus extracts complicates the diagnosis of mosquito allergy because they have low concentration of saliva allergens and may result in poor diagnosis of the affected population when other species are the primary sensitizer. This review article discusses the current knowledge about mosquito allergy, allergens, cross-reactivity, and proposals of component resolved approaches based on mixtures of purified recombinant allergens to replace saliva-based or whole-body extracts, in order to perform an accurate diagnosis of allergy induced by mosquito allergen exposure.

The Role of Heat Shock Protein 70 kDa in Asthma

Asthma is a complex chronic disorder of the airways, affecting immune and structural cells and inducing both protein and tissue remodeling. Heat shock proteins 70 kDa (HSP70s) are highly conserved members of the stress-induced family, possessing precisely described chaperone activity. There is growing evidence of a tight relationship between inflammatory diseases of different origins and the elevation of local HSP70 expression and secretion. Although extracellular HSP70 does not serve as a common marker of asthma, elevated HSP70 levels have been detected in the peripheral blood serum and sputum of patients with asthma, as well as in the bronchoalveolar lavage fluid of mice with induced allergic airway inflammation. Possessing diverse immunomodulating properties, extracellular HSP70 can manifest different activities in airway inflammatory processes and asthma, acting either as a pro-inflammatory trigger, or an anti-inflammatory agent. This review will discuss the effects and possible mechanisms concerning HSP70 implication in airway inflammation regulation in asthma. We examine ATPase and chaperone activities of HSP70 as potential modulators of immune responses in asthma. Given the crucial role of a chronic inflammatory response in asthma, understanding the effects of HSP70 on immune and structural cells may reveal new perspectives for the therapeutic control of inflammation.

Novel salivary gland allergens from tropical mosquito species and IgE reactivity in allergic patients

Background

Mosquito allergy is common in tropical countries but remains under-diagnosed. This may be due to the lack of knowledge and diagnostic tools for tropical mosquito allergens.

Objective

We aimed to characterize allergens from tropical mosquito species and investigate IgE reactivity in mosquito-allergic patients to the salivary gland proteins from these mosquitoes.

Methods

Salivary gland extract (SGE) from 4 mosquito species, highly distributed in the tropics, including Aedes aegypti, Aedes albopictus, Culex quinquefasciatus, and Anopheles dirus b, were studied. SGE-specific IgE and IgG ELISA were developed, and serum from 64 mosquito-allergic and 22 non-allergic healthy control subjects was assayed. Further investigations using IgE-immunoblots followed by mass spectrometry analysis were performed to identify and characterize allergens from each species.

Results

Mosquito-allergic subjects have detectable serum IgE to SGE derived from local mosquito species, while the IgE levels to Aedes communis using commercially available ELISA were mostly minimal. IgE-immunoblot analysis and mass spectrometry identified 5 novel mosquito allergens from A. albopictus (Aed al 2, Aed al 3), C. quinquefasciatus (Cul q 2.01, Cul q 3), and A. dirus b (Ano d 2). Interestingly, 4 of the 5 new allergens belong to the D7 protein family.

Conclusions & clinical relevance

Five novel allergens from 3 tropical mosquito species were characterized. The majority of mosquito-allergic subjects who live in the tropics have IgE reactivity to these allergens. Our study paves the way for the development of diagnostic tests, component-resolved diagnostics, and future immunotherapy for mosquito allergy in tropical countries.

Cellular and Humoral Responses to Cte f 2, a Cat Flea Allergen, in Children with Papular Urticaria

BACKGROUND

Papular urticaria (PU) is a common insect bite skin hypersensitivity in tropical countries. In order to gain insight into its causal allergens, we aimed to evaluate cellular and humoral immune responses to the recombinant salivary antigen Cte f 2 from the cat flea Ctenocephalides felis.

METHOD

Sixty patients with PU and 27 healthy controls were included in this study. Specific IgE, IgG, IgG1, and IgG4 against Cte f 2 and C. felis extract were determined by ELISA. The T-cell response was analyzed using a carboxyfluorescein succinimidyl ester (CFSE)-based dilution assay and Th1/Th2/Th17 cytokine measurements. In addition, a proteomic analysis of IgG and IgE reactive spots of C. felis extract was performed.

RESULTS

The frequency of IgE sensitization to Cte f 2 was similar between patients (36.7%) and controls (40.7%). The specific IgE, IgG1, and IgG4 responses to Cte f 2 and C. felis extract were not significantly different between patients and controls. Among the 3 conditions (i.e., Cte f 2, C. felis extract, and only medium) Cte f 2 was the strongest inducer of CD3+CD4+ proliferation in the patients; however, the mean response was not significantly different from those in controls (Cte f 2: 4.5 vs. 2.5%; p = 0.46). No salivary proteins were identified in C. felis, and most of the spots were identified as muscle-skeletal components (tropomyosin, actin, myosin, and ankirin).

CONCLUSIONS

Cte f 2 induces IgE and IgG production as well as T-cell proliferation in children living in a geographical area where PU induced by a flea bite is common. The use of C. felis extract is not recommended for the study of bite-induced hypersensitivity disease since salivary antigens are not well represented.