Molecular and morphological characterization of Parabronema skrjabini of sheep and goats at three different geographical zones in Iran

Parabronema skrjabini is a spirurid nematode of the family Habronematidae that lives in the abomasum of ruminants such as sheep and goats. The purpose of this study was to investigate the molecular and morphological aspects of Parabronema skrjabini in sheep and goats in Iran. The worms were collected from these animal species from three different regions. An internal transcribed spacer 2 ribosomal DNA (ITS2-rDNA) fragment of Parabronema skrjabini was amplified by polymerase chain reaction (PCR) using a pair of specific primers (Para-Ir-R and Para-Ir-F). Morphological studies based on the body length, the frontal shield, spicules of male and egg dimensions were performed. ITS2-rDNA sequences were between 167 and 299bp in different isolates. ITS2 homology in different isolates was between 68 % and 77% compared with the sequence data in GenBank. Morphological results showed that the average length of male and female worms in sheep were 16.5mm and 36mm and in goats 16mm and 35.5mm, respectively. The average length of the small and large spicules in sheep were 657.5μm and 304.07μm and in goats 653.08μm and 302.66μm, respectively. To our knowledge, this is the first study in the world exploring the genetic diversity of Parabronema in sheep and goats. Add this sentence in discussion: the low ITS2-rDNA identity in different isolates from Iran as compared to the reference sequence in GenBank (68–77%) raise questions regarding the species identity of the parasites isolated in Iran.