Maternal transfer of humoral specific and non-specific immune parameters to sea bream (Sparus aurata) larvae

Immunisation of sea bream (Sparus aurata L.) broodstock with a novel vaccine mixture of Photobacterium damsela subsp. piscicida SK7 (Phdp) was performed during the period of egg development and the changes in specific and non-specific humoral immune parameters were measured. Total immunoglobulin level, specific antibody titre, anti-protease activity and lysozyme activity were significantly higher in immunised parents compared to the control. After spawning significantly higher anti-protease activity, lysozyme activity and total immunoglobulin level were detected in the eggs from immunised parents. Specific antibody titres against Phdp were only detected in the eggs from the immunised parents. The larvae from immunised parents also expressed significantly higher levels of specific and non-specific humoral immune parameters compared to the controls. A small amount of total immunoglobulin was detected in larvae decreasing gradually until day 8 post-hatching and then an increase was measured in larvae from immunised parents, whereas no immunoglobulin was detected at days 4, 6 and 8 in larvae from non-immunised parents. The specific antibody titre against Phdp was detected only in larvae from immunised broodstock until day 14 post-hatching. The higher humoral immune parameters in eggs and larvae from immunised parents in comparison to eggs and larvae from non-immunised parents, suggest transfer of maternal specific and non-specific immune factors.