RESUMEN
The aim was to evaluate the performance of selected individual major histocompatibility complex (MHC) class I and class II alleles and combinations of these on disease resistance against furunculosis. The material, consisting of 2,145 Atlantic salmon (Salmo salar) from seven families, contained four MHC class I (UBA) alleles and two MHC class II alpha (DAA) alleles. The included alleles were previously shown to influence resistance towards furunculosis. The fish were challenged with the bacterium Aeromonas salmonicidae, causing furunculosis. The total mortality in the material was 84.0%, and both dead and surviving fish were genotyped for UBA and DAA. For MHC class II fish with DAA*0301 were more resistant than fish with DAA*0201, which were significantly more susceptible (P < 0.05). For MHC class I, the ranking of performance of the alleles differed from previous results, and fish with allele UBA*0601 were found to be most resistant while fish with UBA*0501, UBA*0201 and UBA*0301 were more susceptible. The analysis of combined MHC class I and class II genotype detected that fish with genotypes UBA*0501/*0501;DAA*0301/*0301, UBA*0601/*0601;DAA*0301/*0301 and UBA*0601/*0601;DAA*0201/*0201 were most resistant (P < 0.05), while the genotypes associated with increased susceptibility were UBA*0501/*0501; DAA*0201/*0301 and UBA*0501/*0501;DAA*0201/*0201 (P < 0.05). In addition, Cox regression analysis show that both family and MHC alleles contributed significantly to survival. Thus, in addition to reproducing the effect on resistance and susceptibility of many MHC class I and class II alleles individually, we also detected an effect of certain MHC class I and class II combinations suggestive of cross-talk between the class I and class II pathways.
Asunto(s)
Aeromonas salmonicida/inmunología , Enfermedades de los Peces/inmunología , Forunculosis/veterinaria , Infecciones por Bacterias Gramnegativas/veterinaria , Antígenos de Histocompatibilidad Clase II/inmunología , Antígenos de Histocompatibilidad Clase I/inmunología , Salmo salar/inmunología , Alelos , Animales , Femenino , Enfermedades de los Peces/genética , Enfermedades de los Peces/microbiología , Forunculosis/genética , Forunculosis/inmunología , Forunculosis/microbiología , Predisposición Genética a la Enfermedad , Genotipo , Infecciones por Bacterias Gramnegativas/genética , Infecciones por Bacterias Gramnegativas/inmunología , Infecciones por Bacterias Gramnegativas/microbiología , Antígenos de Histocompatibilidad Clase I/genética , Antígenos de Histocompatibilidad Clase II/genética , Estimación de Kaplan-Meier , Masculino , LinajeRESUMEN
Infectious salmon anaemia virus (ISAV) is an aquatic orthomyxovirus causing a multisystemic disease in farmed Atlantic salmon (Salmo salar) where disease development, clinical signs, and histopathology vary to a large extent. Here, an experimental trial was designed to determine the effect of variation in viral genes on virus-host interactions, as measured by disease susceptibility and immune responses. The fish were infected using cohabitant transmission, representing a natural route of infection. Variation caused by host factors was minimized using MHC compatible A. salmon half-siblings as experimental fish. Virus isolates were selected according to HE genotype, as European ISAV isolates can be genotyped according to deletion patterns in their hemagglutinin-esterase (HE) surface glycoprotein, and the course of disease they typically induce, classified as acute versus protracted. The different ISAV isolates induced large variations in death prevalence, ranging from 0-47% in the test-group and 3-75% in the cohabitant fish. The use of MHC compatible experimental fish made it possible to determine the relative contribution of humoral versus cellular response in protection against ISA. Ability to induce a strong proliferative response correlated with survival and virus clearance, while induction of a humoral response was less protective.