Maternal Transfer and Protective Role of the Alternative Complement Components in Zebrafish Danio rerio

Abstract

Embryos of most fish develop externally and are exposed to an aquatic environment full of potential pathogens, whereas they have little or only limited ability to mount an efficient and protective response. How fish embryos survive pathogenic attacks remains poorly defined. Here we demonstrate that the maternal immunization of female zebrafish with formalin-killed Aeromonas hydrophila causes a significant increase in C3 and Bf contents in the mother, a corresponding rise in the offspring, and induces a remarkable increase in the hemolytic activities in both the mother and offspring. In addition, the embryos derived from the immunized mother are significantly more tolerant to A. hydrophila challenge than those from the unimmunized fish, and blocking C3 and Bf activities by injection of the antibodies against C3 and Bf into the embryos render them more susceptible to A. hydrophila. These results clearly show that the protection of zebrafish embryos against A. hydrophila can be achieved by the maternally-transferred immunity of the complement system operating via the alternative pathway. This appears to be the first report providing in vivo evidences for the protective role of the alternative complement components in the early embryos of zebrafish, paving the way for insights into the in vivo function of other maternally-transferred factors in fish.

Mortality Caused by Bath Exposure of Zebrafish (Danio rerio) Larvae to Nervous Necrosis Virus Is Limited to the Fourth Day Postfertilization

“…The expression of the Mx and IL-1␤ genes was also upregulated in the naive dechorionated larvae, probably due to the stress from the operation and/or environmental antigenic stimulation. These and previously published results (30) indicate that the innate immune system is active in larvae at the 2nd dpf. On the other hand, untreated eggs were not stimulated, suggesting that the larva shell reduces the interaction with external stimulators, including NNV.…”

Comparison of fecundity and offspring immunity in zebrafish fed Lactobacillus rhamnosus CICC 6141 and Lactobacillus casei BL23

“…In zebrafish, higher levels of C3, Bf, and hemolytic activity along with lower mortality rates were documented in the offspring of parental brood fish immunized with A. hydrophila or corresponding antigens (Wang et al 2009. All these studies on the transmission of maternal immunity focused on microbial pathogens, largely ignoring other possible effects on the offspring from the administration of probiotics to the mother fish.…”

Deciphering microbial landscapes of fish eggs to mitigate emerging diseases

“…These results indicate that along with established factors influencing disease susceptibility, such as genetic inheritance (broodstock effect), developmental stage of the salmon eggs, environmental and other stress conditions (Hansen and Olafsen, 1999), the microbiota are also a determining factor in health and disease of fish eggs that have an immature adaptive immune system and depend on other defences for protection. In terms of genetic inheritance, components of the complement immune system were shown to be maternally transferred to the eggs for rainbow trout, zebrafish and amphibian eggs (Lovoll et al, 2006;Poorten and Kuhn, 2009;Wang et al, 2009;Walke et al, 2011), and a paternal genetic component contributed to resistance against Saprolegnia in frog eggs (Sagvik et al, 2008). The relative contribution of the genetic inheritance, the fish egg microbiome or their interplay to protect against Saprolegniosis is not clear yet.…”