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Alterations in certain immunological parameters in the skin mucus of the carp, Cirrhinus mrigala, infected with the bacteria, Edwardsiella tarda

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Abstract

The bacterial fish pathogen Edwardsiella tarda causes heavy stock mortality, severely hampering fish production, resulting in great economic loss to the farming industry. The first biological barriers that confer immune protection against pathogen entry are the fish mucosal surfaces. The present study was undertaken to investigate the influence of E. tarda on certain enzymatic and non-enzymatic parameters in the skin mucous secretions of the fish Cirrhinus mrigala using spectrophotometry and zymography. Fish were randomly divided into three groups: control, vehicle control, and infected. A sublethal dose of E. tarda (2.2 × 106 CFU/fish) suspended in 50 μL of PBS was injected intra-peritoneally at 0 day (d). Subsequently, mucus samples were collected at 2 d, 4 d, 6 d and 8 d post-infection. The activities of lysozyme (LYZ), protease (PROT), alkaline phosphatase (ALP), acid phosphatase (ACP), catalase (CAT), peroxidase (PER), superoxide dismutase (SOD), and glutathione S-transferase (GST) decreased significantly in the skin mucus of the challenged fish, indicating the suppressed immune system and decreased antioxidant capacity of C. mrigala to E. tarda infection. Lipid peroxidation (LPO) and total nitrate-nitrite were significantly higher at several time points post-infection, suggesting that physiological functions have been impaired following pathogen challenge. The present findings could be relevant for fish aquaculture and underline the importance of skin mucus not only for assessing fish immune status but also for identifying early warning signals of disease caused by pathogens.

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Acknowledgements

Jyoti Singh was supported by Joint CSIR UGC NET-JRF. The authors thank Dr. Neeraj Sood, Principal Scientist and Dr. Ravindra, SRF, National Bureau of Fish Genetic Resources, Lucknow, India, for providing Edwardsiella tarda isolate. The authors also thank Research grant for Faculty (IoE Scheme) under Dev. Scheme No.6031. Financial support by UGC-CAS program of Department of Zoology, BHU is also acknowledged.

Funding

Present work was financially supported by Council for Scientific and Industrial Research, New Delhi, India, and Research grant for Faculty (IoE Scheme) under Dev. Scheme No.6031 and UGC-CAS program of Department of Zoology, BHU, Varanasi, India.

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Authors and Affiliations

  1. Department of Zoology, Skin Physiology Laboratory, Centre of Advanced Study, Institute of Science, Banaras Hindu University, Varanasi, Uttar Pradesh, 221005, India

    Jyoti Singh & Swati Mittal

  2. Department of Zoology, MSM Samta College (BR Ambedkar Bihar University), Jandaha, Vaishali, Bihar, 844505, India

    Ayan Srivastava

  3. Udai Pratap Autonomous College, Bhojubir, Varanasi, Uttar Pradesh, 221002, India

    Ashwini Kumar Nigam

  4. Zoology Section, Mahila Mahavidyalaya, Banaras Hindu University, Varanasi, Uttar Pradesh, 221005, India

    Usha Kumari

  5. Department of Zoology, Banaras Hindu University, Present Address: 9, Mani Nagar, Near Asha Modern School, Kandawa road, Near Chitaipur, Varanasi, Uttar Pradesh, 221106, India

    Ajay Kumar Mittal

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  1. Jyoti Singh
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  2. Ayan Srivastava
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  3. Ashwini Kumar Nigam
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  4. Usha Kumari
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  5. Swati Mittal
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  6. Ajay Kumar Mittal
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Contributions

Jyoti Singh designed and conducted the experiments and drafted the manuscript. Ayan Srivastava and Ashwini Kumar Nigam assisted in the execution of experiments, and interpretation and statistical analysis of data. Usha Kumari, Swati Mittal and Ajay Kumar Mittal were involved in the critical analysis of data, reading and editing of the manuscript. All authors discussed the results and approved the final version of the manuscript.

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Correspondence to Swati Mittal.

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All experiments in this study were performed under the guidance of ethical regulation from the institutional animal care and use committee, Banaras Hindu University (Ref No. BHU/DOZ/IAEC/2019-20/013).

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Singh, J., Srivastava, A., Nigam, A.K. et al. Alterations in certain immunological parameters in the skin mucus of the carp, Cirrhinus mrigala, infected with the bacteria, Edwardsiella tarda. Fish Physiol Biochem 49, 1303–1320 (2023). https://doi.org/10.1007/s10695-023-01258-6

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