FERREIRA, L. C.; http://lattes.cnpq.br/2873464959081374; FERREIRA, Larissa Claudino.
Resumo:
The cattle tick, Rhipicephalus microplus, is the hematophagous ectoparasite with the
greatest economic and health impact on Brazilian cattle. The most used method of
controlling this parasite is the application of synthetic chemical acaricides, with emphasis
on drugs of the macrocyclic lactone class, such as ivermectin. There are different
mechanisms involved in antiparasitic resistance, including the increased activity of cellular
efflux pumps such as ABC membrane transporters (ATP binding cassettes), which aid in
cellular detoxification of parasites, causing drug resistance. This resistance mechanism has
already been described in ivermectinresistant
populations of R. microplus. As macrocyclic
lactones are similar compounds, we investigated the hypothesis of crossresistance
between
different drugs of this group (ivermectin, eprinomectin and moxidectin) and the
participation of ABC transporters as the resistance mechanism involved. Four populations
of resistant R. microplus were analyzed, from the semiarid
region of Northeast Brazil, from
the states of Paraíba and Ceará, with two properties in each state. For this, Larval Immersion
Tests were performed with and without the use of Cyclosporine A (CsA), comparing with
the susceptible and reference strain Porta Alegre, observing the synergism between CsA
and ivermectin, eprinomectin and moxidectin in these populations. Among the populations
analyzed, crossresistance
between moxidectin and ivermectin was observed and CsA acted
as a synergist, reducing its lethal doses, while for and eprinomectin the results were
different from those found for the other macrocyclic lactones used. It is suggested that other
resistance mechanisms may be involved for eprinomectin in resistant populations in the
semiarid region of Northeastern Brazil.