An ultra-simplified protocol for PCR template preparation from both unsporulated and sporulated Eimeria oocysts

Molecular biological techniques have enabled the accurate identification of the avian Eimeria parasite, however, the preparation of PCR template remains a bottleneck due to contaminants from feces and the robust oocyst's wall resistant to chemical and mechanical force. Generally, the preparation of PCR template involves three main steps: (1) pretreatment of oocysts; (2) disruption of oocysts; and (3) purification of genomic DNA. We prepared PCR templates from both unsporulated and sporulated E. tenella oocysts using various protocols, followed by species-specific PCR to define the limit of detection. Our data revealed that whereas neither pretreatment of oocysts with sodium hypochlorite nor purification of genomic DNA with commercial kits improved the limit of detection of PCR, disruption of oocysts was a critical step in the preparation of PCR templates. The most sensitive PCR assay was achieved with the template prepared by disrupting oocysts suspended in distilled water, followed by bead-beating and heating at 99°C for 5 min, which detected 0.16 oocysts per PCR. This ultra-simplified protocol for preparation of PCR template, which does not require expensive reagents or equipment, will significantly enhance the sensitive and efficient molecular identification of Eimeria. It will improve our understanding of the prevalence of this parasite at the species level and contribute to the development of techniques for the control in the field.