The fish first line of defence against infections through the skin epidermis is the skin mucus. In a previous study, we have investigated the s kin mucus proteome of common carp (Cyprinus carpio ) at 1 day and 9 days post-exposure with Ichthyophthirius multifiliis. U sing nano-LC ESI MS/MS, we have earlier identified that the abundance of 44 skin mucus proteins has been differentially regulated, including proteins associated with host immune response and wound healing .
Herein, i n skin mucus samples, we identified six proteins of I. multifiliis , associated with the skin mucus in common carp. A lpha and beta tubulins were detected , in addition to elongation factor alpha , 26S proteasome regulatory subunit , 26S protease regulatory subunit 6B, and the heat shock protein 90. In skin mucus samples, in addition to 44 differentially regulated common carp proteins we identified six proteins of I. multifiliis , connected to the skin mucus in common carp.
The recognised proteins are apparently involved in motility, virulence and general stress during parasite growth and development, after parasite attachment and invasion. Alpha and beta tubulins were identified, also elongation factor alpha, 26S proteasome regulatory subunit , 26S protease regulatory subunit 6B, and the heat shock protein 90.
The identification of these six I. multifiliis proteins in infected common carp skin mucus suggests their possible role in the parasite invas ion strategy of this ciliate and effectively of carp immune defences.
Phagosome and proteasome are two KEGG pathways that were recognised between these parasite proteins, reflecting the proteolytic and phagocytic properti es needed throughout growth and development demonstrating effective host invasion strategy of I. multifiliis .
The identification of hsp90, which is apparently triggered by eEF through HSF and b-tubulins, which are key for ciliary function, suggests roles in mobility and virulence as well as in homeostasis regulation and cellular stress during host invasion and development.
The identified proteins are involved in heat shock response, which suggests they are crucial for parasite development, virulence and pathogenicity. The identification of hsp90 during infection indicates it may act as a suitable drug and vaccine target and can be tested as vaccine/vaccine adjuvant.
The results obtained from this study can support us to reveal molecular aspects of the interplay between carp and I. multifiliis . This may help us understand I. multifiliis invasion strategy at the skin mucus barrier. The data may support the development of novel drugs, vaccines, and diagnostics suitable for management and prevention of ichthyophthiriosis in fish .