Silvia S. Longoni

An Iron-Superoxide Dismutase Antigen-Based Serological Screening of Dogs Indicates Their Potential Role in the Transmission of Cutaneous Leishmaniasis and Trypanosomiasis in Yucatan, Mexico

An increasing number of studies have reported high infection rates for American cutaneous leishmaniasis in dogs, which have thus been proposed as the reservoir host. Canine leishmaniasis is widespread in different states in Mexico, where a number of Leishmania species have been isolated from dogs. In the present study, the detection of different Leishmania species is described in stray dogs from two localities, namely Tulum and Celestún on the Yucatan Peninsula (Mexico). The use of iron-superoxide dismutase excreted by the parasites as the antigen fraction and enzyme-linked immunosorbent assay and western blot tests allowed us to confirm the presence of at least three species of Leishmania (Le. mexicana, Le. braziliensis, and Le. panamensis), some of which are reported for the first time in this species. In addition to a high prevalence of Le. mexicana and Le. braziliensis, and to a lesser degree, Le. panamensis, there is a significant prevalence of Trypanosoma cruzi, suggesting that the dog may be a source of transmission of trypanosomiasis. However, a more thorough epidemiological study on the dog population, both wild as well as urban, of the Yucatan Peninsula will be required to design a control strategy for these diseases, paying particular attention to the population affected and even broadening the study to other Mexican states as well as neighboring countries. These results again confirm that iron-superoxide dismutase excreted by the different trypanosomatid species constitutes a good source of antigen for serodiagnosis in epidemiological studies.

Diterpenoid alkaloid derivatives as potential chemotherapeutic agents in American trypanosomiasis.

The use of natural products for the treatment of protozoal infections (Leishmania and Trypanosoma spp.) is well known and has been documented since ancient times. We have already established an in vitro culture system using mammalian host cells (Vero) infected with Trypanosoma cruzi in which the time course of parasite growth is determined quantitatively. This system was used to screen anti-T. cruzi agents using two experimental models: simultaneous cell infection and compound addition or preincubation of the parasite with the test compound prior to cell infection. Among 64 diterpenoid alkaloids tested, including C19 and C20 skeletons, five C20 compounds were active on T. cruzi epimastigotes: azitine, isoazitine and 15,22-O-diacetyl-19-oxodihydroatisine had moderate effects on the parasite, while atisinium chloride and 13-oxocardiopetamine were potent T. cruzi epimastigote growth inhibitors with activity levels similar to that of benznidazole, used as the reference drug. Additionally, these compounds decreased the ability of metacyclic forms to invade mammalian cells, their intracellular replications and their transformation into trypomastigotes, with no toxicity to the host cell. These results suggest that these alkaloids are structural leads of clinically active compounds against T. cruzi and probably other members of the Trypanosomatidae.

Detection of different Leishmania spp. and Trypanosoma cruzi antibodies in cats from the Yucatan Peninsula (Mexico) using an iron superoxide dismutase excreted as antigen.

Although human leishmaniasis has been reported in 20 states in Mexico, no case of leishmaniasis has been reported in cats to date. In the Yucatan Peninsula, it has been found that dogs may act as reservoirs for at least three Leishmania species (Leishmania mexicana, Leishmania braziliensis, and Leishmania panamensis). In this study we identified specific antibodies against these three Leishmania spp. and Trypanosoma cruzi in the sera from 95 cats from two States on the Yucatan Peninsula, namely Quintana Roo and Yucatan, by ELISA and Western blot techniques using whole extract and an iron superoxide dismutase excreted by the parasites as antigens. As well as demonstrating the presence of trypanosomatid antibodies in the feline population on the Yucatan Peninsula, we were also able to confirm the high sensitivity and specificity of the iron superoxide dismutase antigen secreted by them, which may prove to be very useful in epidemiological studies.

Prevalence of antibodies against three species of Leishmania (L. mexicana, L. braziliensis, L. infantum) and possible associated factors in dogs from Mérida, Yucatán, Mexico.

Leishmania spp. has been recorded in humans and in dogs, and numerous studies have demonstrated that dogs act as reservoirs for visceral leishmaniasis. The objective of this study was to determine the prevalence of three species of the Leishmania genus and possible associated factors in sera of 218 dogs from two different populations in Mérida, Yucatán (Mexico). The sera were analyzed to detect antibodies against L. mexicana, L. braziliensis, and L. infantum using the superoxide dismutase- enzyme-linked immunosorbent assay (SOD-ELISA) and Western blot as confirmation. The Fe-SOD excreted was used as the antigenic fraction for the three Leishmania species. The prevalence values found were 30.2% (L. mexicana), 8.2% (L. braziliensis), and 11.9% (L. infantum), with L. mexicana seroprevalence being greater than L. braziliensis and L. infantum (p<0.05). Five percent (11/218) of the dogs showed antibodies against L. mexicana/L. braziliensis, 5.5% (12/218) with L. mexicana/L. infantum and 1.8% (4/218) with L. mexicana/L. braziliensis/L. infantum. No relationship (p>0.05) was found between antibodies against L. mexicana and breed, age, physical condition, or cutaneous lesions in dogs. This study provides evidence of antibodies against L. mexicana, L. braziliensis and L. infantum in dog populations from Mérida, Mexico.

Seroprevalence of Antibodies Against the Excreted Antigen Superoxide Dismutase by Trypanosoma Cruzi in Dogs From the Yucatan Peninsula (Mexico)

Numerous studies have shown the role of dogs as a reservoir for the American trypanosomiasis, as the bridge connecting sylvatic and peridomestic cycles. The objective of this study was to determine the prevalence of American trypanosomiasis in the dog population (630 sera) from seven localities in the Yucatan Peninsula (city of Mérida and the towns of Molas, Playa del Carmen, Akumal, Xcalacoop, Xcalac and Xahuachol). These data are key for developing control measures for the disease. The sera were analysed to detect antibodies against Trypanosoma cruzi, using Fe‐SOD excreted as the antigenic fraction by ELISA and Western blot as confirmation. The total prevalence found in the Yucatan Peninsula was some 14.76%, with 10.74% in the state of Yucatan (city of Mérida, towns of Molas and Xcalacoop) and 21.34% in the state of Quintana Roo (towns of Playa del Carmen, Akumal, Xcalac and Xahuachol). However, a more thorough epidemiological study of the dog population, both wild and urban, in the Yucatan Peninsula will be required to design a control strategy for these diseases, paying particular attention to the population affected and even broadening the study to other Mexican states as well as neighbouring countries. These results again confirm that iron‐superoxide dismutase excreted by T. cruzi constitutes a good source of antigen for serodiagnosis in epidemiological studies.

Excreted Leishmania peruviana and Leishmania amazonensis iron–superoxide dismutase purification: Specific antibody detection in Colombian patients with cutaneous leishmaniasis

Leishmania sp. survival in the vertebrate host depends on the host macrophage immune response as well as on the parasites defense against free radicals. Iron-superoxide dismutase (Fe-SOD) is a key antioxidant enzyme that contributes to radical superoxide dismutation, preventing the disease from surging and propagating itself. Leishmania sp. has various Fe-SOD isoforms, one of which (Fe-SODe) is excreted into the medium and, being highly immunogenic, can be considered a very good molecular marker. In this work, we purified the Fe-SOD enzymes excreted by L. peruviana and L. amazonensis and studied them as antigens in serodiagnosis. We used ELISA and Western blot techniques to test 51 human cutaneous leishmaniasis sera from Colombia. All 51 patients presented with dermal injuries caused by unknown Leishmania species. The results observed with the purified proteins were compared with those obtained when total soluble lysate and unpurified Fe-SODe were used as the antigen fraction. Thus, we conclude that the purified enzymes are more sensitive and specific than their unpurified counterparts and that there is no cross-reactivity between them.

Leishmania spp. Epidemiology of Canine Leishmaniasis in the Yucatan Peninsula

Canine Leishmaniasis is widespread in various Mexican states, where different species of Leishmania have been isolated from dogs. In the present study, we describe the detection of L. braziliensis, L. infantum, and L. mexicana in serum of dogs from the states of Yucatan and Quintana Roo in the Yucatan Peninsula (Mexico). A total of 412 sera were analyzed by ELISA using the total extract of the parasite and the iron superoxide dismutase excreted by different trypanosomatids as antigens. We found the prevalence of L. braziliensis to be 7.52%, L. infantum to be 6.07%, and L. mexicana to be 20.63%, in the dog population studied. The results obtained with ELISA using iron superoxide dismutase as the antigen were confirmed by western blot analysis with its greater sensitivity, and the agreement between the two techniques was very high.