Piscirickettsiosis (SRS) is the most prevalent bacterial disease in Chilean salmon aquaculture an... more Piscirickettsiosis (SRS) is the most prevalent bacterial disease in Chilean salmon aquaculture and is responsible for high economic losses. The aim of this study was to comparatively characterize the pathogenesis of SRS in post-smolt Atlantic salmon during the early and late stages of infection with Piscirickettsia salmonis LF-89-like (PS-LF-89) and EM-90-like (PS-EM-90) using a cohabitation challenge. The pathogenesis of cohabitant fish infected with the two isolates was relatively different due to cohabitant fish infected with PS-EM-90 showing higher cumulative mortality and shorter time until death compared with PS-LF-89 fish. PS-LF-89 caused an SRS infection characterized by kidney and liver lesions, whereas PS-EM-90 caused systemic and haemorrhagic disease characterized by kidney, liver, heart, brain, skeletal muscle and intestine lesions. Decreased serum concentration of total proteins and albumin as well as increased serum ALT, AST and creatinine levels in fish infected with both isolates confirmed that changes in liver and kidney function occurred during infection. Tissue damage, expressed as an SRS histoscore, showed a strong positive correlation with the bacterial load expressed as abundance of P. salmonis 16S rRNA transcripts in the livers and kidneys of fish affected with either isolate, but the correlation was significantly higher in fish infected with PS-EM-90. The results contribute to improving the understanding of the bacteria-host interaction.
Bulletin- European Association of Fish Pathologists
The recent description of Amoebic Gill Disease (AGD) and Neoparamoeba perurans in Atlantic salmon... more The recent description of Amoebic Gill Disease (AGD) and Neoparamoeba perurans in Atlantic salmon (Salmo salar) farmed in Chile has necessitated the development of more reliable and sensitive diag- nostic tests. Final diagnosis of infection is normally confirmed by histology. However, the correla- tion between gross gill lesions and histological lesions is generally unclear. In the current study, moderate concordance level (k=0.5319) between gross pathology and histology was observed. The sensitivity and specificity of gross pathology was 77.91% and 71.05%, respectively. Neoparamoeba spp. are considered morphologically indistinguishable therefore by using histopathology limits the capacity to characterise the causative agent and it can be time consuming. We developed a PCR assay to amplify the N. perurans 18S rRNA gene from gill clinical samples of AGD-affected fish. High concordance level (k=0.95) between PCR and histological examination was observed. The sensitivity and specificit...
... 3 , MV, Dr.Med.Vet., E. PAREDES 2 , MV, Dr.med.vet.; R. IDEFONSO 2 , MV; A ALBERDI 2 , TM; P ... more ... 3 , MV, Dr.Med.Vet., E. PAREDES 2 , MV, Dr.med.vet.; R. IDEFONSO 2 , MV; A ALBERDI 2 , TM; P MACÍAS 3 , TM ... agar CFA (Colonization Factor Antigen) con el propósito de favorecer y estimular la producción de fimbrias siguiendo el procedimiento descrito por Evans y col. ...
Piscirickettsiosis (SRS) is the most prevalent bacterial disease in Chilean salmon aquaculture an... more Piscirickettsiosis (SRS) is the most prevalent bacterial disease in Chilean salmon aquaculture and is responsible for high economic losses. The aim of this study was to comparatively characterize the pathogenesis of SRS in post-smolt Atlantic salmon during the early and late stages of infection with Piscirickettsia salmonis LF-89-like (PS-LF-89) and EM-90-like (PS-EM-90) using a cohabitation challenge. The pathogenesis of cohabitant fish infected with the two isolates was relatively different due to cohabitant fish infected with PS-EM-90 showing higher cumulative mortality and shorter time until death compared with PS-LF-89 fish. PS-LF-89 caused an SRS infection characterized by kidney and liver lesions, whereas PS-EM-90 caused systemic and haemorrhagic disease characterized by kidney, liver, heart, brain, skeletal muscle and intestine lesions. Decreased serum concentration of total proteins and albumin as well as increased serum ALT, AST and creatinine levels in fish infected with both isolates confirmed that changes in liver and kidney function occurred during infection. Tissue damage, expressed as an SRS histoscore, showed a strong positive correlation with the bacterial load expressed as abundance of P. salmonis 16S rRNA transcripts in the livers and kidneys of fish affected with either isolate, but the correlation was significantly higher in fish infected with PS-EM-90. The results contribute to improving the understanding of the bacteria-host interaction.
Bulletin- European Association of Fish Pathologists
The recent description of Amoebic Gill Disease (AGD) and Neoparamoeba perurans in Atlantic salmon... more The recent description of Amoebic Gill Disease (AGD) and Neoparamoeba perurans in Atlantic salmon (Salmo salar) farmed in Chile has necessitated the development of more reliable and sensitive diag- nostic tests. Final diagnosis of infection is normally confirmed by histology. However, the correla- tion between gross gill lesions and histological lesions is generally unclear. In the current study, moderate concordance level (k=0.5319) between gross pathology and histology was observed. The sensitivity and specificity of gross pathology was 77.91% and 71.05%, respectively. Neoparamoeba spp. are considered morphologically indistinguishable therefore by using histopathology limits the capacity to characterise the causative agent and it can be time consuming. We developed a PCR assay to amplify the N. perurans 18S rRNA gene from gill clinical samples of AGD-affected fish. High concordance level (k=0.95) between PCR and histological examination was observed. The sensitivity and specificit...
... 3 , MV, Dr.Med.Vet., E. PAREDES 2 , MV, Dr.med.vet.; R. IDEFONSO 2 , MV; A ALBERDI 2 , TM; P ... more ... 3 , MV, Dr.Med.Vet., E. PAREDES 2 , MV, Dr.med.vet.; R. IDEFONSO 2 , MV; A ALBERDI 2 , TM; P MACÍAS 3 , TM ... agar CFA (Colonization Factor Antigen) con el propósito de favorecer y estimular la producción de fimbrias siguiendo el procedimiento descrito por Evans y col. ...
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