The Effects of Letrozole in Transfer of Maternal Immunity against Lactococcosis to Eggs and Larvae in Rainbow Trout (Oncorhynchus mykiss, Walbaum)


This study evaluated transfer of maternal lysozyme and immunoglobulin (IgM) against Lactococcus garviea, the causative agent of lactococcosis to eggs and larvae in rainbow trout. Changes in circulating lysozyme and IgM during development of eggs and larvae were measured by a method based on the ability of lysozyme to lyse the bacterium Micrococcus lysodeikticus and enzyme-linked immunosorbent assay (ELISA) respectively. For doing this, twelve broodstocks were injected weekly with 2.5 mg·kg-1 letrozole (an endocrine disrupter component) two months before spawning season and vaccinated intraperitoneally (i.p) with a bacterin (inactivated L. garviae) one month before spawning. Twelve broodstocks for vaccination and twelve female rainbow trouts as control group were also immiunised (i.p) with the bacterin and injected (i.p) with PBS respectively. Results showed that at day 8 after hatching, lysozyme and IgM levels during pre-larval stages decreased gradually, as yolks were absorbed. Lysozyme and IgM levels were significantly higher in the letrozole injected immiunised parents 30 days after immunisation as well as their larvae compared to the control group (p < 0.05). These results showed the lysozyme and IgM detected from day 0 to day 8 derived from maternal fish while the lysozyme and IgM detected from day 10 onward are neo-synthesized lysozyme and IgM. The present study indicated the role of the injection of letrozole (two months before spawning) and parent immunisation with a bacterin (inactivated L. garviae) (one month before spawning) in maternal transfer of lysozyme and IgM levels to eggs and larvae.

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Akbary, P. , Mirvaghefi, A. , Akhlaghi, M. , Amiri, B. and Fereidouni, M. (2015) The Effects of Letrozole in Transfer of Maternal Immunity against Lactococcosis to Eggs and Larvae in Rainbow Trout (Oncorhynchus mykiss, Walbaum). Food and Nutrition Sciences, 6, 254-264. doi: 10.4236/fns.2015.62026.

Conflicts of Interest

The authors declare no conflicts of interest.


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