Persistence of Piscirickettsia salmonis and detection of serum antibodies to the bacterium in white seabass Atractoscion nobilis following experimental exposure

Abstract

White seabass Atractoscion nobilis surviving experimental exposure to Piscirickettsia salmonis harbored the bacterium for periods up to at least 123 d post injection (dpi). Intraperitoneal injections of juvenile white seabass with 1.26 × 10 2 TCID 50 P. salmonis fish -1 resulted in a 29% cumulative mortality over a 27 d period. Both molecular and histologic methods provided evidence for persistence of the bacterium in fish sampled sequentially from the surviving population. Throughout the period of acute mortality, the bacterium was detected in all impression smears of liver tissue stained with Giemsa and was reisolated in cell cultures from all dead fish sampled. Polymerase chain reaction (PCR) assays detected P. salmonis-specific DNA in 13.3 to 50% of the fish sampled at time points between 28 and 123 dpi, while cell culture reisolation was largely ineffective in detecting the bacterium. An enzyme-linked immunosorbent assay (ELISA) detected serum anti-P. salmonis antibodies in 48 of 59 white seabass exposed to P. salmonis but not in fish which were not exposed to the bacterium. At the end of the 4 mo experiment, microscopic lesions consisting of single to multiple and coalescing granulomas were found in liver and kidney tissues of 9 of 10 fish examined from the exposure group, while no lesions were detected in the fish from the control group. Immunohistochemical staining with anti-P. salmonis polyclonal antibodies detected bacterial antigens in some but not all granulomas examined from the exposure group at 4 mo. This study demonstrates that P. salmonis may persist among white seabass following infection and thus provide a potential reservoir of infection contributing to transmission both within and between fish species in the marine environment. KEY WORDS: Piscirickettsia salmonis · White seabass · Persistent infection · Carrier state Resale or republication not permitted without written consent of the publisherDis Aquat Org 73: [131][132][133][134][135][136][137][138][139] 2006 with lesser amounts in visceral organs (Comps et al. 1996, Grant et al. 1996, Skarmeta et al. 2000, McCarthy et al. 2005. P. salmonis and P. salmonis-like bacteria have been detected from a variety of marine and freshwater fish (Mauel & Miller 2002). Two of these bacteria from marine fish recently have been confirmed to be P. salmonis by phylogenetic comparisons of the small and large subunit ribosomal (16S and 23S) DNA and the internal transcribed spacer (ITS) (Arkush et al. 2005, McCarthy et al. 2005. Arkush et al. (2005) demonstrated that P. salmonis causes a disease similar to piscirickettsiosis in white seabass Atractoscion nobilis. Experimental infections with the bacterium caused mortality similar to that of P. salmonis infections in salmon, with granulomatous lesions principally in the liver and to a lesser extent in the spleen, kidney, intestine and gills. McCarthy et al. (2005) also confirmed P. salmonis as a pathogen in European sea bass Dicentrarchus labrax. Interestingly, in their report, as in an earlier rep...

Detección y asociación de Piscirickettsia salmonis en órganos y heces de salmón coho (Oncorhynchus kisutch) cultivado en el mar

“…El agente se elimina por heces, orina y bilis de individuos afectados, pudiendo penetrar piel y branquias intactas (Smith et al, 1999). Se desconoce si existen vectores marinos en la transmisión, pero la bacteria ha sido reportada en parásitos (Correal, 1995), moluscos, crustáceos, además de una diversidad de peces (Arkush et al (2006).…”

Apoptosis inhibition of Atlantic salmon (Salmo salar) peritoneal macrophages by Piscirickettsia salmonis

“…One of the major fish pathogens is Piscirickettsia salmonis, a Gram‐negative bacterium which is the aetiological agent of piscirickettsiosis (Fryer, Lannan, Garcés, Larenas, & Smith, ; Garcés et al., ). This is a septicaemic disease affecting a variety of teleost species (Arkush, Edes, McBride, Adkison, & Hedrick, ; Chen et al., ; McCarthy et al., ; Zrnčić et al., ), but is particularly severe in salmonid fish reared in Chilean nearshore sea waters, causing losses for at least US$ 100 million a year in this country (Bravo & Midtlyng, ; Smith, Rojas, & Manneschi, ). Piscirickettsia salmonis is a gamma proteobacterium (Fryer, Lannan, Giovannoni, & Wood, ) of a facultative intracellular nature (Mauel, Ware, & Smith, ; Mikalsen, Skjærvik, Wiik‐Nielsen, Wasmuth, & Colquhoun, ) that in its host cells multiplies within cytoplasmic membrane‐bound vacuoles (Fryer et al., ) and is one of the few, so far described, obligate fish pathogen (Smith, Contreras, et al., ).…”

Fast detection of Piscirickettsia salmonis in Salmo salar serum through MALDI‐TOF‐MS profiling

“…It has been reported that techniques of immunohistochemistry and its combination with other methods were also useful in the detection of P . salmonis …”

“…[24] It has been reported that techniques of immunohistochemistry and its combination with other methods were also useful in the detection of P. salmonis. [11,[25][26][27] So far, the techniques used in the diagnostic of P. salmonis are in most of the cases, expensive and time consuming. A good alternative to develop new methodologies in this area is the employment of mass spectrometry techniques.…”