RESUMO
BACKGROUND: Knockdown resistance (kdr) is a well-characterized target-site insecticide resistance mechanism that is associated with DDT and pyrethroid resistance. Even though insecticide resistance to pyrethroids and DDT have been reported in Anopheles albimanus, Anopheles benarrochi sensu lato (s.l.), Anopheles darlingi, Anopheles nuneztovari s.l., and Anopheles pseudopunctipennis s.l. malaria vectors in Latin America, there is a knowledge gap on the role that kdr resistance mechanisms play in this resistance. The aim of this study was to establish the role that kdr mechanisms play in pyrethroid and DDT resistance in the main malaria vectors in Colombia, in addition to previously reported metabolic resistance mechanisms, such as mixed function oxidases (MFO) and nonspecific esterases (NSE) enzyme families. METHODS: Surviving (n = 62) and dead (n = 67) An. nuneztovari s.l., An. darlingi and An. albimanus mosquitoes exposed to diagnostic concentrations of DDT and pyrethroid insecticides were used to amplify and sequence a ~ 225 bp fragment of the voltage-gated sodium channels (VGSC) gene. This fragment spanning codons 1010, 1013 and 1014 at the S6 segment of domain II to identify point mutations, which have been associated with insecticide resistance in different species of Anopheles malaria vectors. RESULTS: No kdr mutations were detected in the coding sequence of this fragment in 129 samples, 62 surviving mosquitoes and 67 dead mosquitoes, of An. darlingi, An. nuneztovari s.l. and An. albimanus. CONCLUSION: Mutations in the VGSC gene, most frequently reported in other species of the genus Anopheles resistant to pyrethroid and DDT, are not associated with the low-intensity resistance detected to these insecticides in some populations of the main malaria vectors in Colombia. These results suggest that metabolic resistance mechanisms previously reported in these populations might be responsible for the resistance observed.
Assuntos
Anopheles/genética , DDT/farmacologia , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Mosquitos Vetores/genética , Piretrinas/farmacologia , Animais , Anopheles/efeitos dos fármacos , Colômbia , Malária , Especificidade da EspécieRESUMO
Background: Cellular immune mechanisms of the resistance to infection by T cruzi as well as the pathogenesis of Chagas disease are still controversial. Aim: To quantify and analyse the peripheral blood immune cells from chagasic and non chagasic patients by flow cytometry. Patients and methods: Peripheral blood samples were taken from 21 individuals seropositive for Chagas disease, under no specific treatment. Control samples from 21 healthy blood donors were also obtained. To quantify immune cells populations by flow cytometry, antibodies against CD3, CD4, CD8, CD16/56, CD45/14, CD19 and HLA-DR markers were used. Results: The percentage of CD8+ cells was low and the CD4+/CD8+ ratio was high in chagasic patients, compared to their non infected counterparts. No statistically significant differences in the number of CD4+, NK, B, CD4+HLADR+ and CD8+HLADR+ cells, were observed within the two groups. Conclusions: These results show that Chilean chronic chagasic patients have lower percentage of CD8+ cells and higher CD4+/CD8+ ratio than non infected individuals
Assuntos
Humanos , Masculino , Adulto , Feminino , Pessoa de Meia-Idade , Doença de Chagas , Imunofenotipagem/métodos , Trypanosoma cruzi , Linfócitos T CD4-Positivos , Estudos de Casos e Controles , Contagem de Linfócitos , Linfócitos T CD8-Positivos , Citometria de Fluxo/métodosRESUMO
Background: Chagas disease is endemic in Chile. Allopurinol and itraconazole have activity against Trypanosoma cruzi and are recommended for the treatment of chronic disease in adults. Aim: To evaluate the chemotherapeutic effects of allopurinol and itraconazole using conventional and non conventional serologic test. Patients and methods: Sera of 90 patients with chonic Chagas disease were studied before and after 9 to 11 months of treatment with allopurinol or itraconazole and after two month of treatment with placebo. Indirect immunofluorescence, ELISA and Western Blot analysis were the conventional serologic tests used and antibody dependent complement mediated lysis (CoML) the non conventional test. Results: There were no differences in ELISA and indirect immunofluorescence tests before and after therapy. Antigenic recognition profiles by Western Blot showed qualitative and quantitative differences in a small number of cases. CoML showed that the greater negativity was achieved in the Chagasic group treated with allopurinol or itraconazole that had a negative xenodiagnosis before drugs treatment (35.8 and 61.6 percent, respectively). Conclusions: There is a reversion of lytic activity in sera of patients with negative xenodiagnosis before treatment, suggesting the parasitemia could be an important parameter to be considered in the chemotherapy of Chagas disease