Rederivation of a mutant line (prop 1) of zebrafish Danio rerio infected with Pseudoloma neurophilia using in vitro fertilization with eggs from pathogen-free wild-type (AB) females and sperm from prop 1 males.

Along with the growing number of laboratories that work with zebrafish (Danio rerio), it is necessary to have animals with good sanitary quality. Specific pathogens can interfere with the experimental results and in the life quality of the animals. Pseudoloma neurophilia is a parasite with high potential for interference in behavioural, morphology, toxicological and genetic research, and is very common in zebrafish facilities. With that, we implemented a protocol for the pathogen elimination in a genetically modified lineage (prop 1) using eggs from specific pathogen-free (SPF) wild-type fish (AB line) for in vitro fertilization, along with water recirculation equipment disinfection, appropriate PCR screening and back crossing protocols. This resulted in SPF prop 1 heterozygotes, which allowed us to move forward with subsequent crossings to develop homozygote prop 1 mutants for our research. Hence, this demonstrates a useful strategy for an individual research laboratory to rederive a specific mutant free line that is not available from other SPF laboratories.

Toxicity of spike fragments SARS-CoV-2 S protein for zebrafish: A tool to study its hazardous for human health?

Despite the significant increase in the generation of SARS-CoV-2 contaminated domestic and hospital wastewater, little is known about the ecotoxicological effects of the virus or its structural components in freshwater vertebrates. In this context, this study evaluated the deleterious effects caused by SARS-CoV-2 Spike protein on the health of Danio rerio, zebrafish. We demonstrated, for the first time, that zebrafish injected with fragment 16 to 165 (rSpike), which corresponds to the N-terminal portion of the protein, presented mortalities and adverse effects on liver, kidney, ovary and brain tissues. The conserved genetic homology between zebrafish and humans might be one of the reasons for the intense toxic effects followed inflammatory reaction from the immune system of zebrafish to rSpike which provoked damage to organs in a similar pattern as happen in severe cases of COVID-19 in humans, and, resulted in 78,6% of survival rate in female adults during the first seven days. The application of spike protein in zebrafish was highly toxic that is suitable for future studies to gather valuable information about ecotoxicological impacts, as well as vaccine responses and therapeutic approaches in human medicine. Therefore, besides representing an important tool to assess the harmful effects of SARS-CoV-2 in the aquatic environment, we present the zebrafish as an animal model for translational COVID-19 research.