Culicoides spp. found near Lusitano stud farms in mainland Portugal which may contribute for IBH studies

Insect Bite Hypersensitivity (IBH) is a common cutaneous disease, affecting a large number of horses worldwide. Several studies have identified Culicoides spp. saliva as a clinically relevant allergen source. The prevalence of IBH in Portugal, particularly in Lusitano horses, is still not known. However, the environmental characteristics of the national territory are favorable to the activity of Culicoides, and several species of this genus can be found, namely C. imicola and C. obsoletus/C. scoticus. In this study we characterized the Culicoides population present in Lusitano stud farms with a history of IBH. Thirteen stud farms with Lusitano horses were selected in several regions of mainland Portugal for having a previous history of IBH-affected horses, with a minimum of 5 affected horses. Culicoides were collected in May and June 2016 using OVI traps, placed in these stud farms, and we were able to identify several Culicoides species. We could also verify that C. obsoletus/C. scoticus, and C. imicola were the ones most frequently found, but other species like C. pulicaris were also found.

Leishmania infantum exerts immunomodulation in canine Kupffer cells reverted by meglumine antimoniate

Kupffer cells (KC) are the liver macrophage population that resides in the hepatic sinusoids and efficiently phagocyte pathogens by establishing an intimate contact with circulating blood. KC constitute the liver host cells in Leishmania infection, nevertheless little is described about their role, apart from their notable contribution in granulomatous inflammation. The present study aims to investigate how canine KC sense and react to the presence of Leishmania infantum promastigotes and amastigotes by evaluating the gene expression of specific innate immune cell receptors and cytokines, as well as the induction of nitric oxide and urea production. Complementarily, the impact of a leishmanicidal drug - meglumine antimoniate (MgA) - in infected KC was also explored. KC revealed to be susceptible to both parasite forms and no major differences were found in the immune response generated. L. infantum parasites seem to interact with KC innate immune receptors and induce an anergic state, promoting immune tolerance and parasite survival. The addition of MgA to infected KC breaks the parasite imposed silence and increased gene expression of Toll-like receptors (TLR) 2 and TLR4, possibly activating downstream pathways. Understanding how KC sense and react to parasite presence could bring new insights into the control or even elimination of canine leishmaniasis.

Leishmania infantum antigens modulate memory cell subsets of liver resident T lymphocyte

In the recent years, the liver has been recognized as an important immune organ with major regulatory functions and immune memory, adding to the well-described vital metabolic functions. There are evidences from experimental infections performed with visceral Leishmania species that immune responses to parasite infection can be organ-specific. The liver is the compartment of acute resolving infection, with minimal tissue damage and resistance to reinfection, whereas the spleen is the compartment of parasite persistence. Control of hepatic infection in mice requires a coordinated immune response that involves the development of inflammatory granulomas. It is also described that the liver harbors populations of resident lymphocytes, which may exhibit memory characteristics. Therefore, the present study aims to address the role of the liver as an immune memory organ in the context of Leishmania infantum infection, by characterizing phenotypically resident liver T lymphocytes. The dynamics of memory T cells in L. infantum infected BALB/c mice and the effect of anti-leishmanial treatment in the differentiation of memory cell subsets were analyzed. The potential of recognition, differentiation and selection of memory lymphocytes by three L. infantum recombinant proteins were also explored. L. infantum infection generates effector and central memory T cells, but the cells did not expand when recalled, demonstrating a possible parasite silencing effect. The treatment with a leishmanicidal drug (antimoniate meglumine) increases the levels of memory and effector T cells, eliciting a more robust hepatic immune response. L. infantum parasites with a decreased sensitivity to the leishmanicidal drug favor the expansion of memory CD8⁺ T cell subset, but inhibit the proliferation of CD8⁺ T effector cells, possibly assuring their own survival. The recombinant proteins LirCyp1 and LirSOD are strongly recognized by memory cells of treated mice, indicating that these proteins might be used in a prophylactic or therapeutic vaccine formulation. Thus, L. infantum released antigens induce the development of immune memory subsets in the liver resident T cell population that specifically recognized parasite antigens, including recombinant proteins.

Isolation of Besnoitia besnoiti from infected cattle in Portugal

Besnoitia besnoiti, an obligate intracellular protozoan parasite belonging to the phylum apicomplexa, is the causative agent of bovine besnoitiosis. Besnoitiosis is responsible for significant losses in the cattle industry of Africa and Mediterranean countries due to the high morbidity rate, abortion and infertility in males. The acute stage of disease is associated with the proliferative forms (tachyzoites) and is characterized by fever, whimpery, general weakness and swelling of the superficial lymph nodes. During the following chronic stage, a huge number of cysts are formed mainly in the subcutaneous tissues. This process is non-reversible, and chronic besnoitiosis is characterized by hyper-sclerodermia, hyperkeratosis, alopecia and, in bulls, atrophy, sclerosis and focal necrosis that cause irreversible lesions in the testis. In this paper we report on the identification of large cysts in the skin of a cow and a bull in Portugal, which presented loss of hair and enlargement and pachydermis all over the body. The observation of a two-layered cyst wall within the host cell, the encapsulation of the host cell by a large outer cyst wall, and the subcutaneous localization of the cysts within the host, were characteristic for B. besnoiti. The parasites were isolated from the infected animals and successfully propagated in Vero cells without prior passages in laboratory animals. Morphological characterization of B. besnoiti tachyzoites and the amplification of the 149 bp segment from the internal transcribed spacer 1 (ITS1), aided with specific primers, confirmed the identification of B. besnoiti.