Intraspecific polymorphisms of Eimeria species due to resistance against anticoccidial drugs

Abstract

 Resistance analyses were done on 15 Eimeria acervulina strains and 5 E. brunetti strains. In all, 55% of these strains proved to have complex profiles of resistance to anticoccidial drugs as judged by resistance-index (RI) evaluation. Genomic fingerprints generated by random amplified DNA (RAPD) with 16 primers via the polymerase chain reaction (PCR) revealed a high degree of similarity (SI) between nonresistant strains (SI up to 95%). Polymorphisms including band shifts, differences in banding intensity, and missing bands led to significantly low SI values (57%, 69%, 82%) in drug-resistant Eimeria strains. After experimental induction of diclazuril resistance (1, 2, and 4 ppm) in a laboratory isolate VT-1 primer 5′-CCC TGA GAT GGG AAC CTC-3′ amplified a polymorphic band of around 600 bp. Polymorphisms detected by RAPD-PCR will facilitate the selection of molecular markers and might lead to the design of diagnostic tests for drug-resistant genotypes.