Protective Immunization of Atlantic Salmon (Salmo salar L.) against Salmon Lice (Lepeophtheirus salmonis) Infestation

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Effekt av ulike immuniseringsregimer mot pankreassykdom (PD) hos Atlantisk laks (Salmo salar L.), og betydningen av lakselus (Lepeophtheirus salmonis Krøyer) som stressfaktor ved immunisering.

Den kommersielle vaksinestrategien som hittil har vært brukt i Norge for å bekjempe pankreassykdom (PD) har ikke hatt optimal effekt, ettersom en fremdeles opplever sykdom og dødelighet, til tross for vaksinasjon. Det er foreslått at tilstedeærelse av lakselus kan være en faktor som bidrar til å redusere effekten av vaksinering i felt. I denne studien er det testet ut to ulike immuniseringsmetoder for PD. Én fiskegruppe ble vaksinert mot PD med en inaktivert helvirusvaksine med SAV3 som én av komponentene (IHV-SAV3), og én fiskegruppe ble injisert i.p. med villtype SAV i ferskvann. Begge gruppene ble overført til sjøvann og smittet med SAV i en kohabitant smittemodell, 756 d/°C etter immunisering. Halvparten av karene ble tilsatt copepoditter av lakselus. Dette ble gjort for å undersøke i hvilken grad en slik stressfaktor ville kunne påvirke mottakelighet og beskyttelse av immuniseringen. Det oppstod en signifikant bedre beskyttelse mot PD ved immunisering med levende virus, enn det en kunne se ved vaksinering med en inaktivert helvirusvaksine. Begge immuniseringsmetodene ga likevel beskyttelse mot SAV-indusert dødelighet, lesjoner i hjertevev og høye nivåer av virus. Tilstedeværelse av lakselus førte til en redusert effekt av vaksinen IHV-SAV3. Den vaksinerte fisken som hadde blitt eksponert for lakseluscopepoditter hadde signifikant høyere nivåer av virus i hjertevev, sammenlignet med fisken som ikke var blitt utsatt for denne stressfaktoren. Forsøket bekrefter tidligere studier, der en har sett at en ervervet immunitet mot SAV gir en svært god beskyttelse mot re-infeksjon av viruset. Det er også vist at lakselus har en negativ effekt på vaksineeffekt

Vaccination with ectoparasite proteins involved in midgut function and blood digestion reduces salmon louse infestations

Infestation with the salmon louse Lepeophtheirus salmonis (Copepoda, Caligidae) affects Atlantic salmon (Salmo salar L.) production in European aquaculture. Furthermore, high levels of salmon lice in farms significantly increase challenge pressure against wild salmon populations. Currently, available control methods for salmon louse have limitations, and vaccination appears as an attractive, environmentally sound strategy. In this study, we addressed one of the main limitations for vaccine development, the identification of candidate protective antigens. Based on recent advances in tick vaccine research, herein, we targeted the salmon louse midgut function and blood digestion for the identification of candidate target proteins for the control of ectoparasite infestations. The results of this translational approach resulted in the identification and subsequent evaluation of the new candidate protective antigens, putative Toll-like receptor 6 (P30), and potassium chloride, and amino acid transporter (P33). Vaccination with these antigens provided protection in Atlantic salmon by reducing adult female (P33) or chalimus II (P30) sea lice infestations. These results support the development of vaccines for the control of sea lice infestations.This research was funded by PHARMAQ AS, grant number Agreement PHARMAQ-CSIC.Peer reviewe

Protective Immunization of Atlantic Salmon (Salmo salar L.) against Salmon Lice (Lepeophtheirus salmonis) Infestation

Vaccination against salmon lice (Lepeophtheirus salmonis) is a means of control that averts the negative effects of chemical approaches. Here, we studied the immunogenicity and protective effect of a vaccine formulation (based on a salmon lice-gut recombinant protein [P33]) against Lepeophtheirus salmonis infestation in Atlantic salmon in a laboratory-based trial. Our findings revealed that P33 vaccine can provide a measure of protection against immature and adult salmon lice infestation. This protection seemed to be vaccine dose-dependent, where higher doses resulted in lower parasitic infestation rates. We also provide immunological evidence confirming that P33-specific immune response can be triggered in Atlantic salmon after P33 vaccination, and that production of P33-specific antibodies in blood can be detected in vaccinated fish. The negative correlation between P33-specific IgM in salmon plasma and salmon lice numbers on vaccinated fish suggests that protection against lice can be mediated by the specific antibody in salmon plasma. The success of P33 vaccination in protecting salmon against lice confirms the possibility of employing the hematophagous nature of the parasite to deliver salmon-specific antibodies against lice-gut proteins

Protective Immunization of Atlantic Salmon (Salmo salarL.)against Salmon Lice (Lepeophtheirus salmonis) Infestation

Vaccination against salmon lice (Lepeophtheirus salmonis) is a means of control that averts the negative effects of chemical approaches. Here, we studied the immunogenicity and protective effect of a vaccine formulation (based on a salmon lice-gut recombinant protein [P33]) against Lepeophtheirus salmonis infestation in Atlantic salmon in a laboratory-based trial. Our findings revealed that P33 vaccine can provide a measure of protection against immature and adult salmon lice infestation. This protection seemed to be vaccine dose-dependent, where higher doses resulted in lower parasitic infestation rates. We also provide immunological evidence confirming that P33-specific immune response can be triggered in Atlantic salmon after P33 vaccination, and that production of P33-specific antibodies in blood can be detected in vaccinated fish. The negative correlation between P33-specific IgM in salmon plasma and salmon lice numbers on vaccinated fish suggests that protection against lice can be mediated by the specific antibody in salmon plasma. The success of P33 vaccination in protecting salmon against lice confirms the possibility of employing the hematophagous nature of the parasite to deliver salmon-specific antibodies against lice-gut proteins