Novel gene isolated from Caligus rogercresseyi: A promising target for vaccine development against sea lice (original) (raw)
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PLoS ONE, 2020
Infection 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. To address this, vaccination is a cost-effective and environmentally friendly control approach. In this study, efficacy of a vaccine candidate, containing a peptide derived from ribosomal protein P0, was validated post infestation with L. salmonis, at the lab-scale. The sampling results showed good potential of the vaccine candidate when administered intraperitoneally in the host, in reducing the ectoparasite load, through reduction of adult female lice counts and fecundity and with greater presumptive effect in F1 lice...
Experimental Parasitology, 2014
The salmon louse (Lepeophtheirus salmonis), an ectoparasitic copepod of salmonid fish, is a major threat to aquaculture in Norway, Ireland, Scotland and Canada. Due to rise in resistance against existing pesticides, development of novel drugs or vaccines is necessary. Posttranscriptional gene silencing by RNA interference (RNAi), when established in a high throughput system is a potential method for evaluation of molecular targets for new medical compounds or vaccine antigens. Successful use of RNAi has been reported in several stages of salmon lice. However, when we employed a previously described protocol for planktonic stages, no reproducible down-regulation of target genes was gained. In the present study, we describe a robust method for RNAi, where nauplius larvae are soaked in seawater added double stranded RNA (dsRNA). In order to test for when dsRNA may be introduced, and for the efficacy and duration of RNAi, we performed a series of experiments on accurately age determined larvae, ranging from the hatching egg to the copepodid with a salmon louse coatomer and a putative prostaglandin E synthase gene. Presumptive knock-down was monitored by real time PCR. Significant gene silencing was obtained only when nauplius I larvae were exposed to dsRNA during the period in which they molted to nauplius II. A knock down effect could be detected 2days after soaking, and it remained stable until the last measurement, on day 12. Soaking nauplius I larvae, knock-down was verified for six additional genes with a putative role in molting. For one chitinase, a loss-of-function phenotype with abnormal swimming was obtained. Hence, RNAi, induced in the nauplius, may facilitate studies of the molecular biology of the louse, such as the function of specific genes in developmental processes and physiology, host recognition, host-parasite interaction, and, in extension, the engineering of novel medicines.
Akirins in sea lice: First steps towards a deeper understanding
We cloned the uncharacterized 22 L. salmonis akirin-2 (my32-Ls) based 23 on EST sequence. 24 These genes/proteins have the main 25 characteristics of akirins from 26 invertebrates. 27 3D models predicted a a-helical 28 structure in the 'non-disordered' 29 C-terminal region. 30 Immunization with purified my32-Ls 31 elicited a specific antibody response 32 in mice and fish. 3 3 g r a p h i c a l a b s t r a c t 35 35 3 7 a b s t r a c t 51 Sea lice (Copepoda, Caligidae) are the most widely distributed marine pathogens in the salmon industry. 52 Vaccination could be an environmentally friendly alternative for sea lice control; however, research on 53 the development of such vaccines is still at an early stage of development. Recent results have suggested 54 that subolesin/akirin/my32 are good candidate antigens for the control of arthropod infestations, includ-55 ing sea lice, but background knowledge about these genes in crustaceans is limited. Herein, we charac-56 terize the my32 gene/protein from two important sea lice species, Caligus rogercresseyi and 57 Lepeophtheirus salmonis, based on cDNA sequence isolation, phylogenetic relationships, three dimen-58 sional structure prediction and expression analysis. The results show that these genes/proteins have 59 the main characteristics of akirins from invertebrates. In addition, immunization with purified recombi-60 nant my32 from L. salmonis elicited a specific antibody response in mice and fish. These results provide an 61 improvement to our current knowledge about my32 proteins and their potential use as vaccine candi-62 dates against sea lice in fish.
Vaccines, 2021
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 c...
Fish & Shellfish Immunology, 2015
One of the most significant threats to the Chilean salmon aquaculture industry is the ectoparasitic sea louse Caligus rogercresseyi. To cope with sea lice infestations, functional diets have become an important component in strengthening the host immune response. The aim of this study was to evaluate molecular mechanisms activated through immunostimulation by in-feed plant-derived additives in Atlantic salmon infected with sea lice. Herein, a transcriptome-wide sequencing analysis was performed from skin and head kidney tissues, evidencing that the immune response genes were the most variable after the challenge, especially in the head kidney, while other genes involved in metabolism were highly expressed individuals fed with the immunostimulants. Interestingly, defensive enzymes such as Cytochrome p450 and serpins were down-regulated in infested individuals, especially in skin tissue. Additionally, MHC-I and MHC-II genes were differentially expressed after the incorporation of the in-feed additives, giving some cues about the protection mechanisms of plant-derived compound as immunostimulants for infested salmons. This is the first published study that evaluates the transcriptomic response of sea lice-infested Atlantic salmon fed with in-feed additives.
2020
Infection 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 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 labscale. 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. .
Frontiers in Genetics
Sea lice are parasitic copepods that cause large economic losses to salmon aquaculture worldwide. Frequent chemotherapeutic treatments are typically required to control this parasite, and alternative measures such as breeding for improved host resistance are desirable. Insight into the host-parasite interaction and mechanisms of host resistance can lead to improvements in selective breeding, and potentially novel treatment targets. In this study, RNA sequencing was used to study the skin transcriptome of Atlantic salmon (Salmo salar) parasitized with sea lice (Caligus rogercresseyi). The overall aims were to compare the transcriptomic profile of skin at louse attachment sites and "healthy" skin, and to assess differences in gene expression response between animals with varying levels of resistance to the parasite. Atlantic salmon pre-smolts were challenged with C. rogercresseyi, growth and lice count measurements were taken for each fish. 21 animals were selected and RNA-Seq was performed on skin from a louse attachment site, and skin distal to attachment sites for each animal. These animals were classified into family-balanced groups according to the traits of resistance (high vs. low lice count), and growth during infestation. Overall comparison of skin from louse attachment sites vs. healthy skin showed that 4,355 genes were differentially expressed, indicating local up-regulation of several immune pathways and activation of tissue repair mechanisms. Comparison between resistant and susceptible animals highlighted expression differences in several immune response and pattern recognition genes, and also myogenic and iron availability factors. Components of the pathways involved in differential response to sea lice may be targets for studies aimed at improved or novel treatment strategies, or to prioritize candidate functional polymorphisms to enhance genomic selection for host resistance in commercial salmon breeding programs.
Caligus elongatus and other sea lice of the genus Caligus as parasites of farmed salmonids: A review
Aquaculture, 2020
This review was prompted by reports of unusually large numbers of sea lice tentatively identified as Caligus elongatus infesting farmed salmon in northern Norway. Following a brief introduction to the sea lice problem in salmonid aquaculture, the review is divided into a further eight sections. The first is a review of existing information on the life cycle and behaviour of Caligus spp. The second is a description of the morphology of different stages in the life cycle of C. elongatus. The third describes the effects of caligid infestations on salmonid hosts. The fourth reviews information on the geographical distributions and host preferences of the six species of Caligus reported from farmed salmonids in different parts of the world: C. elongatus, C. curtus, C. clemensi, C. rogercresseyi, C. teres and C. orientalis. The fifth section describes interactions between farmed and wild fish and the sixth presents information on the genetics of C. elongatus. A section reviewing the different methods used to control sea lice infestations follows. The eighth section discusses the predicted effects of climate change and invasive host species on the distribution and occurrence of caligid copepods, and the ninth gives conclusions and recommendations on how to further investigate the infestation that prompted this review. These include the confirmation of the identity of the caligid causing the problem, confirmation of the genotype involved and a study of the vertical distribution in the water column of the infective stages.
FACETS, 2017
Salmon lice ( Lepeophtheirus salmonis) are important ectoparasites of wild and farmed salmonids and cause major losses to the salmon farming industry throughout the Northern Hemisphere. With the emergence of resistance to several commonly used parasiticides, novel control strategies and integration of multiple treatment options are needed, including host immunostimulation. Here, we investigate the effects of a functional feed containing a peptidoglycan and nucleotide formulation on L. salmonis infection of Atlantic salmon ( Salmo salar) by characterizing lice infection levels, the expression of several host immune genes, and the parasite transcriptomic response to the immunostimulated host. Although initial infection intensities were low, the low dose (LD) immunostimulant diet reduced the total lice burden by 50% relative to controls. Immunostimulant fed hosts up-regulated interleukin-1β in the skin and spleen. This gene has been implicated in successful responses of several salmoni...
Development of Fish Parasite Vaccines in the OMICs Era: Progress and Opportunities
Vaccines
Globally, parasites are increasingly being recognized as catastrophic agents in both aquaculture sector and in the wild aquatic habitats leading to an estimated annual loss between 1.05 billion and 9.58 billion USD. The currently available therapeutic and control measures are accompanied by many limitations. Hence, vaccines are recommended as the “only green and effective solution” to address these concerns and protect fish from pathogens. However, vaccine development warrants a better understanding of host–parasite interaction and parasite biology. Currently, only one commercial parasite vaccine is available against the ectoparasite sea lice. Additionally, only a few trials have reported potential vaccine candidates against endoparasites. Transcriptome, genome, and proteomic data at present are available only for a limited number of aquatic parasites. Omics-based interventions can be significant in the identification of suitable vaccine candidates, finally leading to the developmen...