An i-type lysozyme (CfLyzI) involved in innate immunity is essential for the survival of Chlamys farreri during Vibrio stimulation

Lysozymes act as key components of the innate immunity in invertebrates and play a pivotal role in early defense against invading microbe infection. In this study, an i-type lysozyme homology was identified and characterized in Zhikong scallop Chlamys farreri (designated as CfLyzI). The full-length cDNA sequence of CfLyzI contained a 702 bp open reading frame (ORF), which encoded a polypeptide of 233 amino acids and contained a typical destabilase function domain. The mRNA transcripts of CfLyzI were detectable in all the investigated tissues, including hemocytes, muscle, mantle, gill, hepatopancreas and gonad with the peak level in hemocytes. Being stimulated by Vibrio splendidus, the mRNA transcripts of CfLyzI significantly increased in hemocytes. The CfLyzI-suppressed scallops turned to be more susceptible to Vibrio. All these results indicated that CfLyzI acted as an efficient effector in the innate immunity and was also essential for hosts’ survival during Vibrio stimulation in Zhikong scallop.