Interspecies variations in lipophosphoglycan (LPG) have been the focus of intense study over the years due its role in specificity during sand fly-Leishmania interaction. This cell surface glycoconjugate is highly polymorphic among species with variations in sugars that branch off the conserved Gal(β1,4)Man(α1)-PO(4) backbone of repeat units. However, the degree of intraspecies polymorphism in LPG of Leishmania infantum (syn. Leishmania chagasi) is not known. In this study, intraspecific variation in the repeat units of LPG was evaluated in 16 strains of L. infantum from Brazil, France, Algeria and Tunisia. The structural polymorphism in the L. infantum LPG repeat units was relatively slight and consisted of three types: type I does not have side chains; type II has one β-glucose residue that branches off the disaccharide-phosphate repeat units and type III has up to three glucose residues (oligo-glucosylated). The significance of these modifications was investigated during in vivo interaction of L. infantum with Lutzomyia longipalpis, and in vitro interaction of the parasites and respective LPGs with murine macrophages. There were no consequential differences in the parasite densities in sand fly midguts infected with Leishmania strains exhibiting type I, II and III LPGs. However, higher nitric oxide production was observed in macrophages exposed to glucosylated type II LPG.

BackgroundSandflies are vectors of Leishmania, the causative agent of leishmaniasis in mammalian hosts, including humans. The protozoan parasite is transmitted by the sandfly bite during salivation that occurs at the moment of blood feeding. The components of vector saliva include anticlotting and vasodilatory factors that facilitate blood flow and immunomodulatory factors that inhibit wound healing and quell the immune response. Not surprisingly, these factors also play important roles in the establishment of Leishmania infection. To date, the majority of knowledge that has been generated regarding the process of Leishmania infection, including L. infantum chagasi transmission has been gathered by using intradermal or subcutaneous inoculation of purified parasites.FindingsThis study presents the establishment of a transmission model of Leishmania infantum chagasi by the bite of Lutzomyia longipalpis, the vector of American visceral leishmaniasis. The parasites were successfully transmitted by infected sandfly bites to mice and hamsters, indicating that both animals are good experimental models. The L. infantum chagasi dose that was transmitted in each single bite ranged from 10 to 10, 000 parasites, but 75% of the sandflies transmitted less than 300 parasites.ConclusionsThe strategy for initiating infection by sandfly bite of experimental animals facilitates future investigations into the complex and dynamic mechanisms of visceral leishmaniasis. It is important to elucidate the transmission mechanism of vector bites. This model represents a useful tool to study L. infantum chagasi infection transmitted by the vector.

Abstract. We analyzed the development of Leishmania (Leishmania) infantum chagasi in its natural sandfly vector Lutzomyia longipalpis. In addition, we compared sandfly infections initiated with axenic amastigotes or promastigotes. Our data showed no important difference between Lu. longipalpis infection rates resulting from either type of infections. Furthermore, development of infection was equivalent in both cases. All promastigote forms were found inside the sandfly and, after blood digestion, most of the population consisted of procyclics and nectomonads. A low percentage of metacyclic forms was coincident with a high number of nectomonads during late stages of infection, but which form gives rise to metacyclic forms in L. infantum chagasi is unknown. These results also show that the promastigote infection model, at least for this situation, is suitable for obtaining of infected sandflies because it is easier and less laborious.

Objectives: To determine the prevalence of allergic rhinitis in a random group of schoolchildren aged 13 to 14 years in Brasilia, Brazil, to evaluate tendencies over 6 years and to compare prevalence rates among different socioeconomic groups.Methods: Two cross-sectional studies were undertaken 6 years apart, using the ISAAC (phases I and II) written questionnaire. Thirtynine schools were chosen at random from eight administrative regions in Brasilia, and were classified into three groups according to the socioeconomic conditions of the population.Results: A total of 3,009 questionnaires were collected. Of these 53.5% related to female children and 80% to students from public schools. Prevalence rates for diagnosed rhinitis, recent rhinitis and allergic rhinitis were 20, 29.3 and 12.2%, respectively. Rhinitis was more prevalent in private schools than public ones (17.8 versus 14.1%) and sufferers were predominantly female. Prevalence rates were also higher among populations with higher socioeconomic status (23.5 versus 12.2%). Comparison with the 1996 dataset revealed significant increases in the prevalence of diagnosed rhinitis (12.7 versus 20%, p = 0.001). These increases were observed at all socioeconomic levels.Conclusion: A large number of 13 and 14-year-old children resident in the Distrito Federal exhibit symptoms indicative of rhinitis and the majority of them have allergic rhinitis.Over a six-year period the prevalence of allergic rhinitis increased significantly, predominantly affecting females and with greater prevalence among students at private school and from families with higher socioeconomic status. ResumoObjetivos: Determinar a prevalência de rinite alérgica em um grupo aleatório de escolares de Brasília (DF), com idade entre 13-14 anos; avaliar suas tendências ao longo de 6 anos e comparar as taxas de prevalência entre diferentes grupos socioeconômicos.Métodos: Dois estudos de corte transversal foram realizados com intervalo de 6 anos, usando o questionário escrito do protocolo ISAAC (fases I e III). Nesta pesquisa, 39 escolas foram escolhidas aleatoriamente, em oito regiões administrativas de Brasília, e divididas em três grupos, segundo as condições socioeconômicas da população.Resultados: Foram obtidos 3.009 questionários, sendo 53,5% do sexo feminino e 80% de alunos de escolas públicas. As prevalências de rinite diagnosticada, rinite recente e rinite alérgica foram 20, 29,3 e 12,2%, respectivamente. A prevalência de rinite foi maior nas escolas privadas do que nas escolas públicas (17,8 versus 14,1%) e predominou no sexo feminino. Também foi maior nas populações de melhor nível socioeconômico (23,5 versus 12,2%). Comparando com dados de 1996, houve aumento significativo da prevalência de rinite diagnosticada (12,7 versus 20%, p = 0,001), aumento que ocorreu em todos os níveis socioeconômicos.Conclusão: Um grande número de crianças de 13 e 14 anos de idade do Distrito Federal está apresentando os sintomas relacionados à rinite, a maioria dos quais representa rinite alérgica.Em um pe...

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