Effect of low‐dose Piscirickettsia salmonis infection on haematological‐biochemical blood parameters in Atlantic salmon (Salmo salar)

Abstract

Piscirickettsia salmonis is the etiological agent of Piscirickettsiosis, a severe disease that affects Atlantic salmon (Salmo salar) farmed in Chile and many other areas (Norway, Scotland, Ireland, Canada and the USA). This study investigated the effects of low‐dose P. salmonis infection (1 × 102 CFU/ml) on Atlantic salmon. In this study, we challenged fish with an isolated representative of the EM‐90 genogroup via intraperitoneal injection for 42 days. Infected fish displayed decreased haematocrit and haemoglobin levels at day 13 post‐infection, indicating erythropenia, haemolysis and haemodilution. Conversely, their white blood cell counts increased on days 13 and 21 post‐infection. Additionally, their iron levels decreased from day 2 post‐infection, indicating iron deficiency and an inability to retrieve stored iron before infection. Their magnesium levels also decreased at day 28 post‐infection, possibly due to osmoregulatory problems. Also, we observed an increase in lactate dehydrogenase activity on days 5, 21, and 28 post‐infection, suggesting early symptoms of hepatotoxicity. Later analyses determined a decrease in plasma glucose levels from day 2 post‐infection. This may be attributed to the hypoxic conditions caused by P. salmonis, leading to an excess utilization of stored carbohydrates. Our results suggest that the blood parameters we studied are useful for monitoring the physiological status of Atlantic salmon infected with P. salmonis.

Live and inactivated Piscirickettsia salmonis activated nutritional immunity in Atlantic salmon (Salmo salar)

“…The latter was to be expected since only a living pathogen provides its functional cellular machinery for the synthesis of hemolysins to be induced in P. salmonis, and consequently, the lysis of erythrocytes in Atlantic salmon (Salmo salar) (5), which could corroborate the anemia generated by Piscirickettsiosis (2). These results are not in agreement with what was previously published by Isla et al (41), who reported a decrease in hematocrit from day 7 to 28 post-inoculation with live P. salmonis. However, this may be correlated to the bacterial dose they administered (low dose) and the size of the used smolt specimens (60-70 g), compared with the post-smolt specimens (700 g) used in this study, according to the ranges determined by .…”

“…salmonis (3 dpi); however, this decrease was not statistically significant at 7 and 14 dpi. findings agree with previous reports on smolt specimens of Atlantic salmon (Salmo salar) inoculated with a low dose of live P. salmonis (41) and in Patagonian blennie (E. maclovinus) challenged with Francisella noatunensis subsp. Noatunensis (39), which is a facultative intracellular bacterial pathogen that have similarities in terms of pathogenesis with P. salmonis (45).…”

“…This may correlate with the bacterial dose administered (medium dose) into the tissue and the experimental time evaluated (3-14 dpi) since in fish the innate (early and non-specific) and adaptive (late and specific) immune responses have activation time ranges and both are necessary to combat pathogens and/or PAMPs at the cellular and systemic levels (40). In fact, Isla et al (41) reported that IgM The hematocrit percentage in the blood of S. salar. The samples were taken at 3, 7, and 14 days after injection (dpi).…”

Investigation of the Alternations in the Muscle Quality of Swimming Crab (Ovalipes punctatus) during Cold-Chain Transportation Using Physicochemical and TMT-Based Quantitative Proteomic Analysis

“…This phenomenon could indicate hepatocyte collapse during transportation, disrupting energy storage and metabolic functions in the crab hepatopancreatic system. 40 NADH dehydrogenase [ubiquinone] iron−sulfur protein 4 was downregulated in the FC/LC comparison and upregulated in the DC/FC comparison. In contrast, phytanoyl-CoA dioxygenase peroxisomal-like was upregulated in the FC/LC comparison and downregulated in the DC/LC and DC/FC comparisons.…”

Haemato-Immunological Response of Immunized Atlantic Salmon (Salmo salar) to Moritella viscosa Challenge and Antigens

“…Several studies have investigated aspects of the fish immune system [ 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ], and examined hematological responses in vaccinated and infected fish species [ 30 , 31 ]. However, there are no studies assessing cell analysis and effective immunity in Atlantic salmon following M. viscosa infection.…”