Prevalence and Factors Associated with Leishmania infantum Infection of Dogs from an Urban Area of Brazil as Identified by Molecular Methods

Visceral leishmaniasis (VL) is a disease caused by the parasite Leishmania infantum, and dogs are the most important domestic reservoirs of the agent. During recent decades, VL has expanded to large Brazilian urban centers. In the present work, we have demonstrated by using molecular techniques that the rate of canine infection as detected by serology has been considerably underestimated. Two groups of seronegative dogs (infected and non-infected according to molecular methods) were further evaluated from data obtained through interviews with owners of the animals. The factors associated with Leishmania infection in dogs were a family income of less than two minimum salaries, the knowledge of the owner regarding the vector, the dog spending most of its time in the backyard and the dog never having had a previous serological examination. Awareness regarding the factors associated with canine infection will improve health services and the understanding of the disease's expansion in urban areas

Shotgun proteomics to unravel the complexity of the leishmania infantum exoproteome and the relative abundance of its constituents.

The exoproteome of some Leishmania species has revealed important insights into host–parasite inter-action, paving the way for the proposal of novel disease-oriented interventions. The focus of the presentinvestigation constituted the molecular profile of the L. infantum exoproteome revealed by a shotgunproteomic approach. Promastigotes under logarithmic phase of growth were obtained and harvestedby centrifugation at different time points. Cell integrity was evaluated through the counting of viableparasites using propidium iodide labeling, followed by flow cytometry analysis. The 6 h culture super-natant, operationally defined here as exoproteome, was then conditioned to in solution digestion andthe resulting peptides submitted to mass spectrometry. A total of 102 proteins were identified and cat-egorized according to their cellular function. Their relative abundance index (emPAI) allowed inferencethat the L. infantum exoproteome is a complex mixture dominated by molecules particularly involved innucleotide metabolism and antioxidant activity. Bioinformatic analyses support that approximately 60%of the identified proteins are secreted, of which, 85% possibly reach the extracellular milieu by means ofnon-classic pathways. At last, sera from naturally infected animals, carriers of differing clinical forms ofCanine Visceral Leishmaniasis (CVL), were used to test the immunogenicity associated to the L. infantumexoproteome. Western blotting experiments revealed that this sub-proteome was useful at discrimi-nating symptomatic animals from those exhibiting other clinical forms of the disease. Collectively, themolecular characterization of the L. infantum exoproteome and the preliminary immunoproteomic assaysopened up new research avenues related to treatment, prognosis and diagnosis of CVL

Profile of anti-Leishmania antibodies related to clinical picture in canine visceral leishmaniasis.

This research investigated the profile of anti-Leishmania antibodies in different clinical forms of canine visceral leishmaniasis (CVL). Naturally infected dogs were divided into two groups: subclinical dogs (SD, n = 10) and clinical dogs (CD, n = 68). Non-infected dogs (ND, n = 7) comprised the negative control group. The humoral response was evaluated by the profile of total IgG, IgG1, IgG2, IgM, IgA and IgE, determined by ELISA. Infected animals showed increased levels of total IgG, IgA and IgE in addition to IgG1 and IgG2 in groups SD and CD, when compared with group ND. Furthermore, it was observed that IgG2 and IgM were correlated with symptomatology, while total IgG, IgG1 and IgA were negatively correlated and IgE showed no correlation. It follows that serum levels of IgG2 anti-Leishmania are correlated with typical clinical signs of disease. Furthermore the determination of specific anti-Leishmania antibodies could be an important tool in monitoring CVL clinical picture

Performance of LBSap vaccine after intradermal challenge with L. infantum and saliva of Lu. longipalpis : immunogenicity and parasitological evaluation.

In the last decade, the search for new vaccines against canine visceral leishmaniasis has intensified. However, the pattern related to immune protection during long periods after experimental infection in vaccine trials is still not fully understood. Herein, we investigated the immunogenicity and parasitological levels after intradermal challenge with Leishmania infantum plus salivary gland extract in dogs immunized with a vaccine composed of L. braziliensis antigens plus saponin as an adjuvant (LBSap vaccine). The LBSap vaccine elicited higher levels of total anti-Leishmania IgG as well as both IgG1 and IgG2. Furthermore, dogs vaccinated had increased levels of lymphocytes, particularly circulating B cells (CD21+) and both CD4+ and CD8+ T lymphocytes. LBSap also elicited an intense in vitro cell proliferation associated with higher levels of CD4+ T lymphocytes specific for vaccine soluble antigen and soluble lysate of L. infantum antigen even 885 days after experimental challenge. Furthermore, LBSap vaccinated dogs presented high IFN-c and low IL-10 and TGF-b1 expression in spleen with significant reduction of parasite load in this tissue. Overall, our results validate the potential of LBSap vaccine to protect against L. infantum experimental infection and strongly support further evaluation of efficiency of LBSap against CVL in natural infection conditions

Distribution of seronegative dogs (<i>n</i> = 1213) according to the characteristics of the animals, Brazil 2008.

<p>Distribution of seronegative dogs (<i>n</i> = 1213) according to the characteristics of the animals, Brazil 2008.</p

Hierarchical framework of risk factors for <i>Leishmania infantum</i> infection in dogs.

<p>Hierarchical framework of risk factors for <i>Leishmania infantum</i> infection in dogs.</p

Municipality of Belo Horizonte, state of Minas Gerais, Brazil, subdivided into sanitary areas.

<p>Municipality of Belo Horizonte, state of Minas Gerais, Brazil, subdivided into sanitary areas.</p