Lysozyme transgenic Atlantic salmon (Salmo salar L.)

Disease outbreaks are a major constraint to salmon aquaculture worldwide. Therefore, there is considerable interest in finding means to alleviate this problem by enhancing their innate immune system. Because lysozyme is an important component of this system, we generated a line of transgenic Atlantic salmon using a gene construct consisting of a rainbow trout lysozyme gene under the control of the ocean pout antifreeze protein gene promoter op5a (opAFP-rtLys). The results show that the transgene exhibited Mendelian inheritance at both the F-1 and the F-2 generations and demonstrated that it had integrated into a single chromosome in the genetic founder. Sequence analysis of F-2 generation salmon revealed the presence of a complete copy of an intact lysozyme transgene integrant that was identical in sequence to that of the construct. The computationally translated peptide sequence of the lysozyme coding region differed by four amino acids from those present in GenBank (accession nos CAA42084; AAG34564). Reverse transcriptase-polymerase chain reaction analysis demonstrated the expression of the transgene in most body tissues. However, Northern analysis revealed that visible levels of mRNA were only evident in the spleen, skin and kidney. The lysozyme lytic activity of kidney tissue extracts from F-2 transgenic salmon was 40% greater than it was in non-transgenic siblings.