Assessment of mastitis in camel using high-throughput sequencing

PLOS ONE RESEARCH ARTICLE Assessment of mastitis in camel using highthroughput sequencing Rita Rahmeh ID1*, Abrar Akbar1, Husam Alomirah1, Mohamed Kishk ID1, Abdulaziz AlAteeqi1, Anisha Shajan1, Thnayan Alonaizi1, Alfonso Esposito2 1 Environment & Life Sciences Research Center, Kuwait Institute for Scientific Research, Kuwait City, Kuwait, 2 International Centre for Genetic Engineering and Biotechnology, Trieste, Italy * a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 Abstract Peer Review History: PLOS recognizes the benefits of transparency in the peer review process; therefore, we enable the publication of all of the content of peer review and author responses alongside final, published articles. The editorial history of this article is available here: https://doi.org/10.1371/journal.pone.0278456 Camel milk is recognized as a functional food with significant economic value. Mastitis is one of the most common and costly diseases in the dairy industry. Mastitis, which is caused by pathogens such as bacteria, viruses, fungi, and algae, has an impact on the quality and quantity of milk produced as well as animal health and welfare. There is a paucity of data on the etiological factors that cause camel mastitis. This study reports the bacterial and fungal community involved in clinical camel mastitis using Illumina amplicon sequencing. A total of 25 milk samples were analyzed, including 9 samples with mastitis and 16 healthy samples. The bacterial community in healthy samples was significantly more diverse and abundant than in mastitis samples. The fungal population in mastitis samples, on the other hand, was more diverse and abundant. As compared to healthy samples, the genera Staphylococcus, Streptococcus, Schlegelella, unclassified Enterobacteriaceae, Lactococcus, Jeotgalicoccus. and Klebsiella were found to be abundant in mastitic milk. However, the genera Corynebacterium, Enteractinococcus, unclassified Sphingomonadaceae, Atopostipes, Paenibacillus, Pseudomonas, Lactobacillus, Sphingomonas, Pediococcus and Moraxella were reduced. In the fungal community, mastitis caused a significant increase in the relative abundance of the majority of taxa, including Candida, Phanerochaete, Aspergillus, Cladosporium and unclassified Pyronemataceae, while Penicillium and Alternaria showed a decline in relative abundance. In the bacterial and fungal communities, the discriminant analysis showed 19 and 5 differently abundant genera in healthy milk and mastitic milk, respectively. In conclusion, this study showed a microbiome dysbiosis linked to clinical camel mastitis, with opportunistic pathogens outgrowing commensal bacteria that were reduced. These findings are essential in designing an appropriate control program in the camel dairy herd, as well as in preventing and treating camel mastitis. Copyright: © 2022 Rahmeh et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Introduction Data Availability Statement: The high-throughput sequencing data have been deposited in the NCBI database under the Bioproject PRJNA814002. Dromedary camels are multipurpose animals having the ability to survive the harsh climate desert conditions. They represent about 95% of the camelid population [1]. Camels constitute an important source of milk in the world especially in Asian and African regions. The OPEN ACCESS Citation: Rahmeh R, Akbar A, Alomirah H, Kishk M, Al-Ateeqi A, Shajan A, et al. (2022) Assessment of mastitis in camel using high-throughput sequencing. PLoS ONE 17(12): e0278456. https:// doi.org/10.1371/journal.pone.0278456 Editor: Pierre Germon, INRAE Centre Val de Loire: Institut National de Recherche pour l’Agriculture l’Alimentation et l’Environnement Centre Val de Loire, FRANCE Received: September 5, 2022 Accepted: November 17, 2022 Published: December 7, 2022 PLOS ONE | https://doi.org/10.1371/journal.pone.0278456 December 7, 2022 1 / 22 PLOS ONE Funding: This project was funded by Kuwait Foundation for the Advancement of Sciences (KFAS) under the project code PR18-12SL-16. This project was also funded by Kuwait Institute for Scientific Research (KISR) under the project code FB137C. RR received the funding for this work. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing interests: The authors declare that they have no competing interests. Mastitis in dromedary camel production of camel milk for human consumption was estimated to be 3.5 million tons. Camel milk is highly nutritional and deemed better than bovine milk. It is considered as functional food optimal for infant formula and for elderly. Beside its nutritional value, camel milk has therapeutic value against diabetes, asthma and jaundice [2, 3]. These traits increase the value of this milk and the local and international demand for it. As a result, camel dairy farms have been established worldwide with a steady integration into national and global economies [4, 5]. Mastitis is defined as the inflammation of the mammary gland and is considered the most critical disease in the dairy industry worldwide [6]. Mastitis can cause economic loss due to reducing milk production, deteriorated milk quality, lower probability of conception, higher treatment cost, and transmission of the disease to other species of animals [7]. Mastitis is usually epidemiologically categorized on the basis of source of infection into environmental mastitis caused by bacteria residing in the surrounding environment and contagious mastitis where the udders of the infected animal serve as a major reservoir of the pathogens which can spread from one animal to another during the milking process [8, 9]. Camels, like other dairy animals, can be affected by mastitis. This disease causes suffering for camels and poses a public health risk. According to the symptoms, mastitis in camels can also be classified as clinical or subclinical mastitis. Clinical mastitis is characterized by redness, heat and swelling of the mammary gland. However, subclinical mastitis is characterized by a lack of visible typical mastitis symptoms signs in the milk or in the udder [10, 11]. The major problems overwhelming the status of udder health in camels are tick infestation of the udder and thorny bushes, unhygienic practices, and cauterizations of the udder skin [12]. The occurrence of mastitis among lactating camels is being reported in some countries, including Somalia [13], Sudan [14], Kenya [15], and different parts of Ethiopia [16–18]. According to various studies, 45.66% of the world’s camel population suffers from mastitis, with an average prevalence of 43% in Saudi Arabia and 24% in the United Arab Emirates [19]. However, the prevalence of camel mastitis in Kuwait is not reporte (...truncated)