Vet World Vol.14 August-2021 Article-7
Research Article
Veterinary World, 14(8): 2031-2040
https://doi.org/10.14202/vetworld.2021.2031-2040
Biological and molecular characterization of a sheep pathogen isolate of Mannheimia haemolytica and leukotoxin production kinetics
2. Department of Microbiology, Immunology and Contagious Diseases, Institute of Agronomy and Veterinary Medicine Hassan II, Rabat, Morocco.
Background and Aim: Mannheimia haemolytica (Mha) is a common agent of pneumonia in ruminants globally, causing economic losses by morbidity, mortality, and treatment costs. Infection by Mha is often associated with or promoted by respiratory viral pathogens and environmental conditions. Infections due to Mha have rarely been described in small ruminants. This study reports the biological and molecular characteristics of a new Moroccan Mha isolate from small ruminants presenting typical respiratory symptoms. We also studied the cultural parameters, growth kinetics, and Lkt excretion of the isolate and its pathogenicity on laboratory animals and small ruminants.
Materials and Methods: Suspected pasteurellosis cases in sheep and goat flocks in Morocco were investigated. A local strain of Mha was isolated and identified using biochemical and molecular methods. Polymerase chain reaction-targeting specific genes were used for serotyping and phylogenetic analyses; further, leukotoxin production, cytotoxicity, and pathogenicity of the isolate in mice, goats, and sheep were investigated.
Results: Phylogeny analysis revealed 98.76% sequence identity with the USA isolate of 2013; the strain growth with a cycle of 9-10 h with leukotoxin secretion was detected by NETosis and quantified by cytotoxicity and mortality of mice. Goat and sheep infections cause hyperthermia, with characteristic postmortem lesions in the trachea and lung.
Conclusion: A local isolate of Mha from sheep that died of pneumonia was characterized for the 1st time in North Africa using biological and molecular methods. Although growth on appropriate culture media is accompanied by intense leukotoxin secretion, experimental infections of sheep and goats cause hyperthermia and typical lesions of pneumonia. Keywords: histopathology, isolation, leukotoxin, Mannheimia haemolytica, phylogeny, polymerase chain reaction.
Keywords: histopathology, isolation, leukotoxin, Mannheimia haemolytica, phylogeny, polymerase chain reaction.
How to cite this article: Bkiri D, Semmate N, Boumart Z, Safini N, Fakri FZ, Bamouh Z, Omari Tadlaoui K, Fellahi S, Tligui N, Fassi Fihri O, El Harrak M (2021) Biological and molecular characterization of a sheep pathogen isolate of Mannheimia haemolytica and leukotoxin production kinetics, Veterinary World, 14(8): 2031-2040.
Received: 28-03-2021 Accepted: 25-06-2021 Published online: 07-08-2021
Corresponding author: Dounia Bkiri E-mail: D.bkiri@mci-santeanimale.com
DOI: 10.14202/vetworld.2021.2031-2040
Copyright: Bkiri, et al. This article is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http:// creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.