Morphological and Molecular Characterization of a New Myxozoan, Myxobolus grassi sp. nov. (Myxosporea), Infecting the Grass Carp, Ctenopharyngodon idella in the Gomti River, India.

Naireen Fariya,Mahender Singh,Rehana Abidi,Gokhlesh Kumar,Mansour El-Matbouli,Harpreet Kaur

doi:10.3390/pathogens11030303

Abstract

Myxosporeans are well-known parasites infecting food fishes in fresh and marine water around the globe. Grass carp (Ctenopharyngodon idella), a freshwater food fish commonly cultured in India with has significant economic importance. Herein, the study focuses on the description of a new myxosporean species, Myxobolus grassi sp. nov. from the gills as primary site and liver as secondary site of infection in grass carp. Both organs (gill and liver) were infected concurrently in the host and the prevalence of grass carp infection was 4.05% in gill filaments and liver, respectively. Identification of species was based on the morphological and morphometric features of the myxospore as well as 18S rDNA sequence data. A smear from gill and liver exhibited hundreds of morphologically similar myxospores. BLAST search revealed 98% sequence similarity and 0.03 genetic distance with M. catlae (KM029967) infecting gill lamellae of mrigal carp (Cirrhinus cirrhosus) from India and 98–84% sequence similarity with other myxobolids in India, China, Japan, Malaysia, Turkey and Hungary. Phylogenetically, it clustered with other myxobolids infecting gills and related organs (i.e., vital organ) of Indian cyprinid carp species. On the basis of myxospore morphology and 18S sequence, we propose M. grassi sp. nov.

Highlights

Myxozoans are economically important groups of microscopic parasites among freshwater fishes comprising more than 2000 known species [3,4]
The present study reports morphological identification and molecular characterization based on 18S rDNA of M. grassi sp. nov. infecting the gill filaments and liver of grass carp
M/G/GC/10.2.2018 as paratype has been deposited with Dr Harpreet Kaur, Department of Zoology, Punjab University, Chandigarh, India Site of infection: Gill filaments (Vascular epithelium) and liver Prevalence: 4.05% Etymology: The present species is termed as M. grassi sp. nov. after the common name of the fish host i.e., grass carp

Summary

Introduction

Fishes are considered as a healthy source of animal protein, providing essential nutrients to the human diet. Grass carp (Ctenopharyngodon idella) is a cyprinid food fish, having a major contribution in freshwater aquaculture globally. It grows quickly with minimal input cost. Fish culture has been associated with livelihood and income in India, thereby contributing to the economy. C. idella is prone to diseases, which affects the health of the fish [2]. Poor management or lack of awareness on better management practices in fish culture might manifest the risk of extensive harmful parasites. Myxozoans are economically important groups of microscopic parasites among freshwater fishes comprising more than 2000 known species [3,4]. The genus Myxobolus (Myxobolidae) encompasses largest number of species worldwide [5]. A synopsis of 744 and 112 nominal Myxobolus species was compiled by Eiras et al [6,7]

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Conclusion