Molecular Identification of Eimeria Species in Desi Chickens Using ITS-1 rDNA PCR Analysis

ABSTRACT: Eimeria (E.) species are protozoan parasites responsible for coccidiosis, a widespread and economically significant disease affecting all chicken breeds. Coccidiosis negatively impacts poultry health and performance, leading to substantial economic losses in the global poultry sector. The present study aimed to assess the current status of coccidiosis in desi chickens reared on farms and processed at retail poultry dressing centers in Bengaluru, Karnataka, India. A polymerase chain reaction (PCR) assay targeting the internal transcribed spacer one (ITS-1) region of ribosomal DNA (rDNA) was performed to identify Eimeria species in desi chickens (dual purpose of broilers and layers) aged one to eight weeks. Among different DNA extraction methods tested for Eimeria oocysts in desi chickens, including liquid nitrogen, hypochlorite, direct, sonication, and glass bead techniques, the glass bead method proved to be the most efficient for oocyst disruption and genomic DNA extraction. Two species, E. tenella and E. acervulina, were successfully identified based on distinct bands of 278 base pairs (bp) and 145 bp, respectively, observed on a 2% agarose gel. The minimum number of oocysts required for DNA extraction was 32 oocysts (0.10 ng) for E. tenella and 127 oocysts (0.41 ng) for E. acervulina. Amplicon sizes of 278 bp for E. tenella and 145 bp for E. acervulina were consistently obtained. Among the identified species in the present study, E. tenella was the most predominant cause of coccidiosis in desi chickens.

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