Leishmania-specific surface antigens show sub-genus sequence variation and immune recognition.

A family of hydrophilic acylated surface (HASP) proteins, containing extensive and variant amino acid repeats, is expressed at the plasma membrane in infective extracellular (metacyclic) and intracellular (amastigote) stages of Old World Leishmania species. While HASPs are antigenic in the host and can induce protective immune responses, the biological functions of these Leishmania-specific proteins remain unresolved. Previous genome analysis has suggested that parasites of the sub-genus Leishmania (Viannia) have lost HASP genes from their genomes

Leishmania-Specific Surface Antigens Show Sub-Genus Sequence Variation and Immune Recognition

Single-celled Leishmania parasites, transmitted by sand flies, infect humans and other mammals in many tropical and sub-tropical regions, giving rise to a spectrum of diseases called the leishmaniases. Species of parasite within the Leishmania genus can be divided into two groups (referred to as sub-genera) that are separated by up to 100 million years of evolution yet are highly related at the genome level. Our research is focused on identifying gene differences between these sub-genera that may identify proteins that impact on the transmission and pathogenicity of different Leishmania species. Here we report the presence of a highly-variant genomic locus (OHL) that was previously described as absent in parasites of the L. (Viannia) subgenus (on the basis of lack of key genes) but is present and well-characterised (as the LmcDNA16 locus) in all members of the alternative subgenus, L. (Leishmania). We demonstrate that the proteins encoded within the LmcDNA16 and OHL loci are similar in their structure and surface localisation in mammalian-infective amastigotes, despite significant differences in their DNA sequences. Most importantly, we demonstrate that the OHL locus proteins, like the HASP proteins from the LmcDNA16 locus, contain highly variable amino acid repeats that are antigenic in man and may therefore contribute to future vaccine development

The role of natural killer cells in the early period of infection in murine cutaneous leishmaniasis

In order to study the role of natural killer (NK) cells during the early period of Leishmania infection, BALB/c mice were selectively and permanently depleted of NK cells by injection with 90Sr and subsequently infected with Leishmania (Leishmania) amazonensis (HSJD-1 strain). 90Sr is known to selectively deplete NK cells, leaving an intact T- and B-cell compartment and preserving the ability to produce both interferon alpha and IL-2. This method of depletion has advantages when compared with depletion using anti-NK cell monoclonal antibodies because the effect is permanent and neither activates complement nor provokes massive cell death. In the present study, after one month of treatment with 90Sr, the depletion of NK cells was shown by a more than ten-fold reduction in the cytotoxic activity of these cells: 2 x 106 spleen cells from NK-depleted animals were required to reach the same specific lysis of target cells effected by 0.15 x 106 spleen cells from normal control animals. The histopathology of the skin lesion at 7 days after Leishmania infection showed more parasites in the NK cell-depleted group. This observation further strengthens a direct role of NK cells during the early period of Leishmania infection

Correlation of meta 1 expression with culture stage, cell morphology and infectivity in Leishmania (Leishmania) amazonensis promastigotes

The parasitic protozoan Leishmania (Leishmania) amazonensis alternates between mammalian and insect hosts. In the insect host, the parasites proliferate as procyclic promastigotes andthen differentiate into metacyclic infective forms. The meta 1 gene is preferentially expressed during metacyclogenesis. Meta 1 expression profile determination along parasite growth curves revealed that the meta 1 mRNA level peaked at the early stationary phase then decreased to an intermediate level. No correlation was observed between meta 1 expression and infectivity. Conversely, infectivity correlated with the increase of apoptotic cells in the late stationary phase

Halitose: proposta de um protocolo de avaliação Halitosis: an assessment protocol proposal

A Halitose é um sintoma constrangedor com significativo impacto social. Ela afeta milhões de pessoas ao redor do mundo e muitos recursos são investidos em produtos para a melhora do hálito, sem sucesso. O estudo da halitose com uma abordagem científica se justifica, uma vez que a halitose é causa de restrição social, diminui a qualidade de vida e pode ser indicativo da presença de doenças mais graves. OBJETIVO: Elaborar um protocolo de avaliação da halitose com o objetivo de minimizar custos, evitar exames desnecessários e orientar o diagnóstico causal. MÉTODO: O protocolo foi elaborado baseado na literatura e na experiência pessoal dos autores, adotando uma anamnese baseada em evidências. RESULTADO: Existem muitas causas da halitose e a maioria delas está relacionada com a cavidade oral, outras estão relacionadas com doenças otorrinolaringológicas e respiratórias. Doenças gastrointestinais, alterações das funções renais e hepáticas e outras síndromes metabólicas são causas menos freqüentes, porém importantes de halitose. CONCLUSÃO: Existem custos importantes envolvidos no diagnóstico e tratamento da halitose, incluindo consultas ambulatoriais, avaliação de especialistas e exames complementares. Estes custos poderiam ser minimizados adotando uma anamnese baseada em evidências e um organograma para uma investigação clínica racional.<br>Halitosis is an embarrassing symptom with a significant social impact. Halitosis affects millions of people worldwide and many resources are spent annually in products to improve halitus, unsuccessfully. The study of halitosis in a scientific basis is justified once halitosis causes social restriction, decreases life quality and may be an indication of serious diseases. AIM: To elaborate a protocol for halitosis assessment in order to minimize costs, avoid unnecessary tests and provide a guideline for diagnosis. METHODS: The protocol was created based on the literature and on the authors’ personal experiences, adopting an evidence-based anamnesis. RESULTS: There are many causes of halitosis and most of them are related to the oral cavity; others are related to otolaryngologic and respiratory diseases. Gastrointestinal diseases, liver/renal impairment and other metabolic syndromes are less frequent, but also important causes of halitosis. CONCLUSION: There are important costs involved in halitosis assessment and treatment, including medical appointments, specialist assessment, and complementary tests. Such costs would be minimized by adopting a protocol of evidence-based anamnesis and a flowchart for a rational clinical investigation