Morphological and molecular characterization ofHaemonchus contortusisolated from the small ruminants of south Gujarat, India

Abstract

SummaryThe successful design of strategic control measures against the blood-sucking gastrointestinal nematode,Haemonchus contortusin small ruminants can be facilitated by revealing its general features from morphology to the molecular level. In the south Gujarat region of India, a total of 2408H. contortuswere collected from 84 slaughtered sheep's abomasum, consisting of 347 males and 2061 females (1:6 ratio) (p<0.05). Furthermore, 726H. contortuswere collected from 61 goats, comprising 145 males and 581 females (1:4 ratio) (p<0.05). The male worms were approximately 12±0.06 mm long, while female worms were about 20±0.09 mm long. The vulvar morphotypes of the female worms were found to be 17.7% linguiform, 76.6 % knobbed/button (p<0.05), and 5.7 % smooth type, demonstrating common features ofH. contortus. The nucleotide sequences of the Internal Transcribed Spacer 1 (ITS-1) of 165 bp or ITS-2 plus of 256 bp were aligned, and it was found that the genotypes of male and female specimens of either sheep or goat origin were identical, with a 100 % match. The present isolates shared >95 % and >94 % homology with published sequences of ITS-1 and ITS-2 plus ofH. contortus, respectively, with more nucleotide transitions than transversions in the aligned sequences. The reconstructed phylogram of either ITS-1 or ITS-2 plus revealed two major clades, one forH. contortusand another for other nematodes, withHaemonchus placeishowing its proximity with the clade ofH. contortus. The study established the role of morphological and molecular features in identifying and differentiatingH. contortusparasite at the local level.