Immunohistochemical evaluation of experimental Vagococcus salmoninarum infection in rainbow trout (Oncorhynchus mykiss, Walbaum 1792)

Abstract

The aim of this study was to investigate the pathogenesis and histopathological and immunohistochemical findings in rainbow trout (Oncorhynchus mykiss) following experimental vagococcosis. For this purpose, 60 rainbow trout were used. The experimental study used the pathogen Vagococcus salmoninarum. The fish were intraperitoneally (IP) administered with an inoculate containing 0.1 mL of the bacteria, resulting in a dose of 1.2 × 10(9) cfu mL(-1) per fish. For histopathological observations, tissue samples were taken from fish that died during the experiment and fish that survived until the end of the trial (60th day). All the tissue samples were immunohistochemically stained by the avidin-biotin-peroxidase complex and immunofluorescence methods using polyclonal antibody to detect V. salmoninarum antigens. In immunoperoxidase staining, positive reactions to bacterial antigens were most commonly seen in the kidney, heart and liver. In the immunofluorescence analysis, the distribution of antigens in the tissue and organs was similar to that observed with the immunoperoxidase staining. The results reveal an important correlation between histochemical and immunohistochemical staining in demonstrating the distribution of V. salmoninarum antigens in the affected tissues.

Identification and typing of Vagococcus salmoninarum using genomic and proteomic techniques

“…These infections are regarded as a complex of similar diseases caused by different genera and species capable of inducing damage to the central nervous system characterized by exophthalmia and meningoencephalitis. Water temperature is considered a predisposing factor for the onset of the disease (Austin & Austin, ; Buller, ; Ghittino et al, ; Yardimci et al, ). Thus, outbreaks occurring at water temperatures below 12°C are termed cool‐water streptococcosis and usually are produced by Vagococcus salmoninarum , Lactococcus piscium and Carnobacterium maltaromaticum (previous C. piscicola ), while outbreaks occurring at water temperatures above 15°C are termed warm‐water streptococcosis and are produced by Lactococcus garvieae , Streptococcus parauberis , Streptococcus iniae and Streptococcus agalactiae (synonym of S. difficilis ) (Didinen et al, ; Ghittino et al, ; Mata, Blanco, Domínguez, Fernández‐Garayzábal, & Gibello, ; Ruiz‐Zarzuela, de Bias, Gironés, Ghittino, & Múazquiz, ; Yardimci et al, ).…”

“…Water temperature is considered a predisposing factor for the onset of the disease (Austin & Austin, ; Buller, ; Ghittino et al, ; Yardimci et al, ). Thus, outbreaks occurring at water temperatures below 12°C are termed cool‐water streptococcosis and usually are produced by Vagococcus salmoninarum , Lactococcus piscium and Carnobacterium maltaromaticum (previous C. piscicola ), while outbreaks occurring at water temperatures above 15°C are termed warm‐water streptococcosis and are produced by Lactococcus garvieae , Streptococcus parauberis , Streptococcus iniae and Streptococcus agalactiae (synonym of S. difficilis ) (Didinen et al, ; Ghittino et al, ; Mata, Blanco, Domínguez, Fernández‐Garayzábal, & Gibello, ; Ruiz‐Zarzuela, de Bias, Gironés, Ghittino, & Múazquiz, ; Yardimci et al, ). In the last years, most studies have focused on the study of causative agents of warm‐water streptococcosis because they can be potentially zoonotic agents capable of causing disease in humans (Agnew & Barnes, ; Delannoy et al, ; Wang et al, ; Zaman et al, ).…”

“…In the last years, most studies have focused on the study of causative agents of warm‐water streptococcosis because they can be potentially zoonotic agents capable of causing disease in humans (Agnew & Barnes, ; Delannoy et al, ; Wang et al, ; Zaman et al, ). Nevertheless, little is known about cold‐water “streptococcosis” caused by V. salmoninarum (also known as vagococcosis) even though it is considered an emerging disease of rainbow trout ( Oncorhynchus mykiss , Walbaum 1792) in the European Union (Michel, Nougayrède, Eldar, Sochon, & Kinkelin, ; Ozcan, Ispır, & Yılmaz, ; Ruiz‐Zarzuela et al, ; Salogni, Perantoni, Pitozzi, & Alborali, ; Schmidtke & Carson, ; Yardimci et al, ). V. salmoninarum has been isolated from diseased subadults or adults of rainbow trout in Spain (Ruiz‐Zarzuela et al, ), juvenile and adult rainbow trout in France (Michel et al, ), and rainbow trout broodstock and those over 50 g in Italy (Ghittino et al, ; Salogni et al, ) and Turkey (Didinen et al, ; Tanrikul, Avsever, Onuk, & Didinen, ).…”