Effectiveness of fusion peptide-based vaccine TT-P0 on the dynamics of salmon lice (Lepeophtheirus salmonis) infection in Atlantic salmon (Salmo salar L.) [article]

Jaya Kumari Swain, Yamila Carpio, Lill-Heidi Johansen, Janet Velazquez, Liz Hernandez, Yeny Leal, Ajey Kumar, Mario Pablo Estrada
2020 bioRxiv   pre-print
AbstractInfection with parasitic copepod salmon louse Lepeophtheirus salmonis, represents one of the most important limitations to sustainable Atlantic salmon (Salmo salar L.) farming today in the North Atlantic region. The parasite exerts negative impact on health, growth and welfare of farmed fish as well as impact on wild salmonid populations. It is therefore central to ensure continuous low level of salmon lice with the least possible handling of the salmon and drug use. This necessitates
more » ... This necessitates development of an alternative preventive strategy that can document both effect on lice and that fish welfare is maintained in a satisfactory manner with high economic impact. To address this, vaccination is a cost-effective and environmentally free control approach avoiding the disadvantages of chemical and mechanical treatments. In this study, efficacy of a vaccine candidate (TT-P0), encompassing a peptide derived from ribosomal protein P0 and promiscuous T cell epitopes from tetanus toxin and measles virus, was validated post infestation with L. salmonis, at the lab-scale. The sampling results showed good potential of the TT-P0 vaccine in limiting the ectoparasite load, when administered intraperitoneal in the host, by affecting the total adult lice female counts and fecundity, with greater presumptive effect in F1 lice generation. This consequently speculate vaccine's potential to reduce the amount and frequency of chemical drug, mechanical treatment and handling stress, currently used in salmon farming practices, thus improving the fish welfare, environment and economy. On the other hand, the vaccine showed minimal secondary effects and differential modulation of pro-inflammatory, Th1, Th2 and T regulatory mediators at the transcript level with respect to different lice stages in the vaccinated groups as compared to control. Overall, the results indicated potential effectiveness of TT-P0 antigen as a good and safe vaccine candidate against salmon lice. This is a very important preliminary documentation of the TT-P0 vaccine, as a preventive measure, for sustainable and profitable growth of the salmon industry. However, further validation is necessary under field conditions.Author summaryReducing the impact of salmon lice is a major concern for salmon producers around the globe. These parasitic copepods feed on host mucus, skin and blood, causing a negative impact due to reduction in host immune competence and making them more susceptible to other infections or by transmitting pathogens to the host. Farmed salmon populations are the main reservoirs and increasing numbers of salmon lice in the farms, negatively impacts' wild salmon populations. The available control methods rely mainly on pesticides and other physical and biological treatment methods with their own limitations. In this context, development of an efficient vaccine would represent a significant advancement in sea lice control strategy, providing a practical, eco-friendly and sustainable solution with good fish welfare. However, identification of proper vaccine candidates and demonstration of their efficacy have been the main constraints for vaccine development. In the present research, we evaluated the effectiveness of a novel vaccine candidate in a laboratory trial and demonstrated that immunization with this formulation by intraperitoneal injection route, reduced total adult female counts and fecundity with minor secondary effects on the salmon. The results suggest the potential of this novel vaccine candidate against salmon lice by reducing the parasite load and minimizing the current treatment frequencies and handling stress and thus supports further investigations under field conditions as an important next step to demonstrate the effectiveness of the vaccine candidate to control lice infestations in salmon aquaculture.
doi:10.1101/2020.03.26.009829 fatcat:3l45x7p3mbfvjpkzfwpfhluipm