Maxadilan-simile expression in Nyssomyia neivai, a sandfly vector in an endemic region of Brazil, and its immunogenicity in patients with American tegumentary leishmaniasis

BACKGROUND Maxadilan (Max) is a salivary component in the sandfly Lutzomyia longipalpis (Lutz & Neiva 1912), a vector of visceral leishmaniasis. Max has a powerful vasodilatory effect and is a candidate vaccine that has been tested in experimental leishmaniasis. Nyssomyia neivai (Pinto 1926) is a vector of the pathogen responsible for American tegumentary leishmaniasis (ATL) in Brazil. OBJECTIVE We searched for Max expression in Ny. neivai and for antibodies against Max in ATL patients. METHODS cDNA and protein were extracted from the cephalic segment, including salivary glands, of Ny. neivai and analysed by polymerase chain reaction, DNA sequencing, and blotting assays. The results were compared with data obtained from Lu. longipalpis samples. We quantified antibodies against Max in serum samples from 41 patients with ATL (31 and 10 with the cutaneous and mucocutaneous forms, respectively) and 63 controls from the endemic northeastern region of São Paulo state, using enzyme-linked immunosorbent assay. FINDINGS Recognition of a Max-simile peptide by specific antibodies confirmed expression of a Max sequence in Ny. neivai (GenBank EF601123.1). Compared to controls, patients with ATL presented higher levels of antibodies against Max (p = 0.004); 24.4% of the patients with ATL and 3.2% of the controls presented anti-Max levels above the cutoff index (p = 0.014). The anti-Max levels were not associated with the specific clinical form of ATL, leishmanin skin test response, absence or presence of amastigotes in histopathologic exam, results of indirect immunofluorescence testing for leishmaniasis, or duration of cutaneous form disease. MAIN CONCLUSION High serum anti-Max levels did not protect patients against ATL, but confirmed previous natural exposure to Ny. neivai bites in this ATL endemic region.

Urticaria papular y sus agentes causales en Colombia / Papular urticaria: A review of causal agents in Colombia

Resumen La urticaria papular es una enfermedad alérgica causada por la picadura de insectos, la cual predomina en el trópico. El objetivo de esta revisión fue profundizar en sus aspectos epidemiológicos e inmunológicos, particularmente con base en datos publicados en Latinoamérica. Se hizo una revisión no sistemática mediante la búsqueda electrónica de artículos sobre la epidemiología de la urticaria papular, las características entomológicas de los agentes causales y los mecanismos inmunológicos asociados. Según los diversos reportes de centros médicos de Latinoamérica la urticaria papular es frecuente; el único estudio de prevalencia publicado indica que afecta a una cuarta parte de los niños escolares de Bogotá. Hay información sobre la relación causal entre la exposición domiciliaria a la pulga, la pobreza y la urticaria papular en Bogotá, una ciudad representativa de las altitudes andinas. No hay estudios que indaguen directamente sobre los insectos causales en zonas cálidas, aunque se sospecha clínicamente de los mosquitos Aedes aegypti y Culex quinquefasciatus. En cuanto a su patogenia, se destaca la participación de mecanismos celulares que involucran las células colaboradoras Th2, lo cual explica que sea una condición de hipersensibilidad retardada. El papel de la inmunoglobulina E (IgE) en la urticaria papular no está tan claro. Se desconocen los antígenos derivados de los insectos que causan la enfermedad, aunque se plantea que existen moléculas comunes de reacción cruzada entre los insectos, tales como el alérgeno Cte f 2 en la pulga, y sus homólogos en los mosquitos. La urticaria papular es una condición frecuente en Latinoamérica que debe investigarse en profundidad. La caracterización inmunológica de los componentes moleculares que causan esta condición puede resolver interrogantes sobre su etiología y su patogenia.

Abstract Papular urticaria is a chronic allergic reaction induced by insect bites, which is common in the tropics. The objective of this review was to deepen on epidemiological and immunological aspects of this disease, focused on data published in Latin American countries. We conducted a non-systematic review of the literature through electronic search on the epidemiology of papular urticaria, the entomological characteristics of the causative agents and associated immunological mechanisms. Several reports from medical centers suggest that papular urticaria is common in Latin America. Only one epidemiological survey designed to estimate prevalence of papular urticaria has been published, reporting that about a quarter of children under six years of age is affected by this condition in Bogotá. There is evidence on the causal relationship among exposure to indoor fleas, poverty and papular urticaria in Bogotá, a representative city of the Andean altitudes. Information about causal insects in tropical warmer areas is scarce, although from clinical reports Aedes aegypti and Culex quienquefasciatus appear to be the most common. Th2 cellular-mediated mechanisms are involved in its pathogenesis, which explains its delayed hypersensitivity. The role of immunoglobulin E is not clear in this disease. Insect-derived antigens directly involved in papular urticaria etiology are unknown. However, it is possible that common molecules among causal insects mediate cross-reactive reactions, such as Cte f 2 allergen, found in cat fleas, and its counterparts in mosquitoes. Papular urticaria is a frequent disease in Latin America that should be further investigated. Immunological characterization of the molecular components that cause this condition may solve questions about its pathogenesis.

Detection of immunogenic proteins from Anopheles sundaicussalivary glands in the human serum

The saliva of mosquitoes has an important role in the transmission of several diseases, including malaria, and contains substances with vasomodulating and immunomodulating effects to counteract the host physiological mechanisms and enhance pathogen transmission. As immunomodulatory components, salivary gland proteins can induce the generation of specific IgG antibodies in the host, which can be used as specific biomarkers of exposure to Anopheles sundaicus . The objective of this study was to identify immunogenic proteins from the salivary glands of Anopheles sundaicus by reaction with sera from individuals living in malaria-endemic areas who are thus exposed to Anopheles mosquitoes.

Caracterização da resposta imunológica de Aedes aegypti e Culex quinquefasciatus à infecção pelo sorotipo 1 do Dengue vírus / Characterization of immune response of Aedes aegypti and Culex quinquefasciatus to infection by Dengue virus serotype 1

Os insetos podem atuar como pragas agrícolas e vetores de patógenos causadores de doenças ao homem e outros animais. Investigações a respeito do sistema imunológico de Ae. aegypti e Cx. quinquefasciatus poderão contribuir para o desenvolvimento de métodos de controle das doenças veiculadas por estes insetos, principalmente a dengue, enfermidade causadora de sério problema de saúde pública no mundo. Apesar de Ae. aegypti ser a única espécie vetora confirmada na transmissão do vírus Dengue no Brasil, considera-se também importante um melhor entendimento dos mecanismos imunológicos de Cx. quinquefasciatus tido como refratário ao vírus. Neste estudo foram utilizadas linhagens de Ae. aegypti e Cx. quinquefasciatus mantidas no Insetário do Departamento de Entomologia do CPqAM/FIOCRUZ. Três grupos experimentais de fêmeas com 10 dias de idade foram formados para cada espécie. Grupo I, composto por fêmeas alimentadas com solução sacarose (10 por cento); grupo II, fêmeas alimentadas com sangue limpo e grupo III, fêmeas alimentadas com sangue infectado com o sorotipo DENV-1. De cada grupo foram obtidos hemolinfa, glândula salivar, intestino médio e corpo gorduroso para avaliação da expressão dos antimicrobianos defensina e transferrina. Essa avaliação foi realizada através de PCR em Tempo Real utilizando o kit QuantiFast SYBR Green - One-Step qRT-PCR. A avaliação da hemodinâmica foi realizada utilizando 10 microlitros de hemolinfa de cada grupo, através da contagem das células em câmara de Neubauer...

Resistance to Toxoplasma gondii Infection in Mice Treated with Silk Protein by Enhanced Immune Responses

This study investigated whether elevated host immune capacity can inhibit T. gondii infection. For this purpose, we used silk protein extracted from Bombyx mori cocoons as a natural supplement to augment immune capacity. After silk protein administration to BALB/c mice for 6 weeks, ratios of T lymphocytes (CD4+ and CD8+ T-cells) and splenocyte proliferative capacities in response to Con A or T. gondii lysate antigen (TLA) were increased. Of various cytokines, which regulate immune systems, Th1 cytokines, such as IFN-gamma, IL-2, and IL-12, were obviously increased in splenocyte primary cell cultures. Furthermore, the survival of T. gondii (RH strain)-infected mice increased from 2 days to 5 or more days. In a state of immunosuppression induced by methylprednisolone acetate, silk protein-administered mice were resistant to reduction in T-lymphocyte (CD4+ and CD8+ T-cells) numbers and the splenocyte proliferative capacity induced by Con A or TLA with a statistical significance. Taken together, our results suggest that silk protein augments immune capacity in mice and the increased cellular immunity by silk protein administration increases host protection against acute T. gondii infection.

Native troponin-T of the American cockroach (CR), Periplaneta americana, binds to IgE in sera of CR allergic Thais.

The American cockroach, Periplaneta americana, is the predominant cockroach (CR) species in Thailand and a major source of indoor allergens second only to the house dust mite. The incidence of CR allergy among allergic Thai patients is increasing but basic information on the allergenic components is scarce. In this study a recombinant troponin-T was produced by using cDNA prepared from RNA of the P. americana as a template and PCR primers designed from the P. americana troponin-T sequence deposited in the GenBank database. The recombinant protein (Mr approximately 50) did not bind to IgE in the sera of 18 skin prick test positive CR allergic patients. Rabbit polyclonal antiserum (PAb) against the recombinant troponin-T was produced and used in preparing an affinity column for the purification of native troponin-T from the crude P. americana extract (Mr approximately 47). IgE-immunoblotting revealed that the native protein bound to IgE in 3 of the 18 (16.7%) patients. Our results imply that native P. americana troponin-T, but not its recombinant counterpart, is a minor allergen among the CR allergic Thais.

Validity of MAST-CLA for diagnosis of arthropod allergy using receiver operating characteristic (ROC) analysis

Many allergists are currently focusing on the development of new diagnostic tools, and are attempting to improve both the sensitivity and specificity. A multiple allergen simultaneous test-chemiluminescent assay (MAST-CLA) is one of the most popular diagnostic tools used in the Republic of Korea. However, there remains controversy among allergists with regard to the cut-off point for a positive result. The present study was conducted in order to determine the validity of MAST-CLA as compared with that of the skin prick test, with particular emphasis on arthropod allergens, on the basis of percentage agreement rates and k-values, and also to suggest the optimal positive cutoff points using receiver operating characteristic (ROC) curves. The study was conducted with 97 subjects (54 men, 43 women). Optimal individual cut-off points were calculated as follows; class II for Dermatophagoides farinae, class I for Dermatophagoides pteronyssinus, and trace for a cockroach mix. These findings suggest that attempting to apply optimal individual cut-off points will be a good way of improving diagnostic tests, particularly MAST-CLA.

Aeroallergen sensitivity among Thai children with allergic respiratory diseases: a hospital-based study.

One hundred and twenty patients, aged 3-15 years, attending the Allergy Clinic, Thammasat University Hospital, with allergic rhinitis, asthma or both conditions were studied. Standardized skin prick tests were performed with 15 common aeroallergens. The subjects were 85 boys and 35 girls with the mean age of 8.1 years (SD = 3.4 years). There were 63 cases (53%), 22 cases (18%) and 35 cases (29%) diagnosed with allergic rhinitis only, asthma only and both conditions, respectively. The prevalence of asthma among the allergic rhinitis patients was 36 percent whereas the prevalence of allergic rhinitis among the asthmatic patients was 61 percent. The sensitization patterns for major aeroallergens among the three groups were similar with the most common sensitized allergens as D. pteronyssinus, followed by D. farinae, American cockroach, Kopok and German cockroach, respectively. Among the atopic patients, a greater number of allergen reactivity was significantly associated with the increased risk of having their coexistence of allergic rhinitis and asthma (p = 0.0046; score test for trend of odds ratio).

Immunization effect of recombinant P27/30 protein expressed in Escherichia coli against the hard tick Haemaphysalis longicornis (Acari: Ixodidae) in rabbits

We investigated the induction of resistance to Haemaphysalis longicornis infestation in rabbits that had been immunized with recombinant H. longicornis P27/30 protein. The success of immunological control methods is dependent upon the use of potential key antigens as tick vaccine candidates. Previously, we cloned a gene encoding 27 kDa and 30 kDa proteins (P27/30) of H. longicornis, and identified P27/30 as a troponin I-like protein. In this study, rabbits that were immunized with recombinant P27/30 expressed in Escherichia coli showed the statistically significant longer feeding duration for larval and adult ticks (P< 0.05), low engorgement rates in larval ticks (64.4%), and an apparent reduction in egg weights, which suggest that H. longicornis P27/30 protein is a potential candidate antigen for a tick vaccine. These results demonstrated that the recombinant P27/30 protein might be a useful vaccine candidate antigen for biological control of H. longicornis.

Identification and purification of IgE-reactive proteins in German cockroach extract

Cockroaches have been implicated as a cause of respiratory allergy in urban areas worldwide. IgE-reactive German cockroach proteins were identified with molecular weights (MWs) of 90, 66, 50, 43 and 36 KD by immunoblot analysis in both immune BALB/c mice and sensitized humans. Prominent IgE-reactive proteins were purified using FPLC by ion-exchange chromatography, gel filtration and hydrophobic chromatography. The N-terminal amino acid sequence of a purified protein with a MW of 66 KD on SDS-PAGE was Val-Thr-Leu-Lys-Lys(Val)-Met-Ile-Lys-Thr-Phe-Tyr. No homologous protein was found through a search of GenBank that indicated a novel IgE-reactive protein in German cockroach extract. Another purified protein with a MW of 36 KD reacted strongly with a monoclonal antibody against Bla g 2.