Evaluation of morphometric features and molecular characterization of its 2 and 28s genes of 𝘈𝘯𝘰𝘱𝘭𝘰𝘤𝘦𝘱𝘩𝘢𝘭𝘢 sp. from a Sri Lankan elephant

Abstract

Cestodes of Anoplocephalidae family infect a range of vertebrates that include ruminants, horses, primates, and elephants. Only a few previous studies report the presence of 𝘈𝘯𝘰𝘱𝘭𝘰𝘤𝘦𝘱𝘩𝘢𝘭𝘢 sp. in elephants. As there is no data available on the biology and molecular taxonomy of this species in Sri Lanka, the present work is the first detailed morphological and molecular description of 𝘈𝘯𝘰𝘱𝘭𝘰𝘤𝘦𝘱𝘩𝘢𝘭𝘢 sp. in elephants. Adult worms were recovered at the necropsy of a wild elephant in Udawalawe, Sri Lanka that had severe cestode infection in the small intestine. The tapeworms were tightly attached to the intestinal mucosa. The intestinal mucosa showed hyperaemia, mild ulceration, mucosal thickening and irregular well-demarcated multifocal nodules of variable sizes. Macroscopic and microscopic morphometrics of the worms were obtained and the values are expressed as means (± SEM) and ranges. The length of the strobila was 5.94 ± 0.24 cm and the width ranged from 0.7- 1.8 cm. The mean circumference and the diameter of the scolex were 1.75 ± 0.07 and 0.69 ± 0.01 cm, respectively. The scolex comprised four anteriorly directed oral suckers with a diameter of 0.1 cm. We described the oval-shaped ovary, longitudinal sacculated uterus, numerous transversely arranged testes, osmoregulatory canal, unilateral genital pore, genital atrium, genital papillae, cirrus pouch, internal and external seminal vesicles and ventral longitudinal canal. No lappets were observed beneath the suckers as found in 𝘈𝘯𝘰𝘱𝘭𝘰𝘤𝘦𝘱𝘩𝘢𝘭𝘢 𝘱𝘦𝘳𝘧𝘰𝘳𝘭𝘪𝘢𝘵𝘢. We amplified nuclear ribosomal genes (the ITS-2 region and a portion of the 28S gene) and the PCR products obtained were approximately 750 and 1200 bp, respectively. We obtained 598 and 404 bp DNA sequences for the ITS and 28S regions respectively. We compared these DNA sequences with 𝘈𝘯𝘰𝘱𝘭𝘰𝘤𝘦𝘱𝘩𝘢𝘭𝘢 𝘱𝘦𝘳𝘧𝘰𝘳𝘭𝘪𝘢𝘵𝘢, a parasite of horses, as there were no elephant-derived 𝘈𝘯𝘰𝘱𝘭𝘰𝘤𝘦𝘱𝘩𝘢𝘭𝘢 nucleotide sequences available in GenBank. The nucleotide BLAST search revealed that the identity of the ITS2 region characterised (598 bp) is 99% (for a portion, 132/134 bp) between 𝘈𝘯𝘰𝘱𝘭𝘰𝘤𝘦𝘱𝘩𝘢𝘭𝘢 sp. found in this elephant and A. perfoliata. The same sequence showed 98% (for a portion, 129/131 bp) similarity with 𝘈. 𝘱𝘦𝘳𝘧𝘰𝘳𝘭𝘪𝘢𝘵𝘢 (horse). Analysis of the large ribosomal sub unit 28S gene indicated 95% similarity between 𝘈𝘯𝘰𝘱𝘭𝘰𝘤𝘦𝘱𝘩𝘢𝘭𝘢 sp. in this elephant and 𝘈𝘯𝘰𝘱𝘭𝘰𝘤𝘦𝘱𝘩𝘢𝘭𝘰𝘪𝘥𝘦𝘴 𝘥𝘦𝘯𝘵𝘢𝘵𝘢, 𝘗𝘢𝘳𝘢𝘯𝘰𝘱𝘭𝘰𝘤𝘦𝘱𝘩𝘢𝘭𝘢 𝘬𝘢𝘭𝘦𝘭𝘢𝘪 and 𝘗𝘢𝘳𝘢𝘯𝘰𝘱𝘭𝘰𝘤𝘦𝘱𝘩𝘢𝘭𝘢 𝘣𝘭𝘢𝘯𝘤𝘩𝘢𝘳𝘥𝘪. We suggest that further studies are needed to determine the species of elephant tapeworms that occur in Sri Lankan elephants.