RESUMO
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.
Assuntos
Aeromonas salmonicida/imunologia , Doenças dos Peixes/imunologia , Furunculose/veterinária , Infecções por Bactérias Gram-Negativas/veterinária , Antígenos de Histocompatibilidade Classe II/imunologia , Antígenos de Histocompatibilidade Classe I/imunologia , Salmo salar/imunologia , Alelos , Animais , Feminino , Doenças dos Peixes/genética , Doenças dos Peixes/microbiologia , Furunculose/genética , Furunculose/imunologia , Furunculose/microbiologia , Predisposição Genética para Doença , Genótipo , Infecções por Bactérias Gram-Negativas/genética , Infecções por Bactérias Gram-Negativas/imunologia , Infecções por Bactérias Gram-Negativas/microbiologia , Antígenos de Histocompatibilidade Classe I/genética , Antígenos de Histocompatibilidade Classe II/genética , Estimativa de Kaplan-Meier , Masculino , LinhagemRESUMO
The relationship between genetic variation in major histocompatibility complex (MHC) Class I and II genes and susceptibility to sea lice Lepeophtheirus salmonis (Krøyer) in Atlantic salmon Salmo salar (L.) was studied in cage-reared post smolts. Polymorphic repeat markers located in the 3' untranslated regions (3UTR) of the genes Sasa-UBA (MHC Class I) and Sasa-DAA (MHC Class II) were screened in 1004 fish sampled from 11 full-sibling families. This gave rise to a total of 7 and 5 alleles, and 17 and 13 genotypes respectively. Significant relationships between both Sasa-UBA-3UTR and Sasa-DAA-3UTR genotypes and abundance of lice were observed within the pooled material, within individual families, and within the pooled material with both markers combined. However, most of these associations were either weak, linked with variation in fish size among genotypes, or influenced by family background genome. Nevertheless, within one family, the Sasa-DAA-3UTR 248/278 genotype displayed a significantly higher (33%) abundance of lice compared with the Sasa-DAA-3UTR 208/258 genotype, and this difference was not influenced by fish size. Consequently, the results of this study indicate a link between MHC Class II and susceptibility to lice.