TDK conference 2023

In livestock production, infections caused by different parasites lead to major economic loss worldwide. The regular use of modern anthelmintic drugs significantly reduced the production loss and the lethality of infected animals. However, the permanent use of these drugs that are available nowadays led to clinically significant evolvement and spread of resistance. Besides the overuse, the inappropriate dosing (e.g. underdosing) and choice of medications (e.g. improper diagnosis) also play important role in the development of resistance. Nowadays the increased resistance against the anthelmintics alongside the antimicrobial resistance cause a considerable challenge for the livestock farmers and veterinarian practitioner as well.

In our study, we aimed to investigate the direct impact of sublethal dose of ivermectin on the treated nematodes, because ivermectin is one of the most frequently used antinematodal drug in the veterinary practice. During the experiment we used a soil worm/free living nematode called Caenorhabditis elegans (Ordo: Rhabditida). Because of its easy culturing and maintenance this species is an accepted and frequently used model in the international scientific research including studies in connection with parasitic nematodes.

During the experiment we used the wild type C. elegans strain, Bristol N2. They were maintained on NGM (nematode growth medium) substrate feeding on a bacteria strain that we cultured, called E. coli OP50. For the treatment we used NGM agar plates containing 2.5 nM ivermectin. Before the treatment we created a synchronized culture, which means that we maintained L4 larvae on each plate. These nematodes were washed onto plates containing ivermectin, and the other, control worms onto NGM plates without ivermectin. After the 5 hours long incubation we extracted mRNA from both groups – the control and the treated. After that the expression of 3 of the CYP (cytochrome P450) and 4 of the pgp (P-glycoprotein) genes were chosen to be examined by qPCR method.

Results showed that the expression of cyp13A12 and cyp13B1 genes decreased, while the expression of the pgp5 and pgp12 transport protein genes increased. The decrease of the quantity and the activity of the drug metabolizing enzymes together with the increase of the quantity and the activity of the transport molecules may lead to reduced efficacy of the drugs.

Our research promotes to obtain clearer information of the development and spreading of the resistance to anthelmintic drugs. With the help of these knowledge a more appropriate use of the anthelmintic drugs can be achieved. In addition, development of new anthelmintics targeting mechanisms exclusively present in nematodes might be also possible.