Maternal Transfer And Protection Role In Zebrafish Offspring Following Vaccination Of Brood Stock With A Live Attenuated Vibrio Anguillarum Vaccine

In different fish species, lack of immune competence in the early stages of life leads to severe mortality. Many studies have shown that maternal immunity can pass some immune components to the offspring and protect them, but the use of live attenuated vaccine in maternal immunity is restrained. Recent research has proved that vaccinated turbot with live Vibrio anguillarum could strength the maternal transfer of immune factors. However, the zebrafish, which as one of the most thoroughly studied teleosts, with a wealth of genetic and genomic information available, should be considered as the ideal model for live attenuated vaccine maternal immunity studies in finfishes. It also has value as a model system for infectious disease because of the ease of using particular stages to examine specific aspects of development of immunity.In the present study, at 14 days post immunization of the zebrafish brood stock with the live attenuated vaccine Vibrio anguillarum MVAV6203, we demonstrated that the egg cytosol prepared from the newly fertilized eggs from immunized zebrafish has a higher capability of killing V. anguillarum MVM425, which provided the evidence for the functional role of maternal immunity with the live attenuated vaccine. Larvae from immunized zebrafish also showed a higher capability of resisting the V. anguillarum MVM425 from proliferation after immersion infection.Then via RT-qPCR, the expression levels of some immune parameters among embryos during different development stages from immunized and mock-immunized female fish were compared. Immunization with a live attenuated vaccine resulted in undesirable effects on immune parameters transcriptions. The transcriptional levels of the innate cell gene markers like spi.1, l-plastin, mpx and gata-1 were up-regulated and advanced expressed in the embryos from the immunized female zebrafish than the naive embryos during early development stages. Investigation through 2-D electrophoresis and indirect enzyme linked immunosorbent assay (ELISA) revealed that the protein expression profiles were different between these two groups, there also exited an increase in antibody response in the egg cytosol following immunization of the female zebrafish prior to breeding, which was transferred to larvae through the egg. The rise of specific antibody against V. anguillarum MVM425, V. harveyi and V. alginolyticus were detected in 24 hpf larvae from the immunized brood stock. Meanwhile, the higher content of the total IgM and specific antibody against V. anguillarum MVAV425 in 24,48,72 hpf eggs/larvae were correlated with their higher antibacterial activity against V. anguillarum MVAV425.This report showed that via vaccination with a live attenuated vaccine, the immune cell development was enhanced and the maternally derived antibody could protect early embryos and larvae from the attack of specific pathogens. Hence, treatment with live attenuated vaccine V. anguillarum MVAM6203 of the zebrafish brood stock could be considered a promising method for stimulated larval development and improved juvenile quality, which is one of the main bottlenecks for developing a viable fish farming industry.