In vivomorphological and antigenic characteristics ofPhotobacterium damselaesubsp.piscicida

Abstract

The present study was conducted to examine the morphology and antigenicity of Photobacterium damselae subsp. piscicida by culturing the bacterium in vivo in the peritoneal cavity of sea bass (Dicentrarchus labrax) within dialysis bags with either a low molecular weight (LMW) cut-off of 25 kDa or a high molecular weight (HMW) cut-off of 300 kDa. Differences were observed in the growth rate between the bacteria cultured in vivo or in vitro. Bacteria cultured in vivo were smaller and produced a capsular layer, which was more prominent in bacteria cultured in the HMW bag. Antigenicity was examined by Western blot analysis using sera from sea bass injected with live Ph. d. subsp. piscicida. The sera recognised bands at 45 and 20 kDa in bacteria cultured in vivo in the LMW bag. Bacteria cultured in vivo in the HMW bag did not express the 45 kDa band when whole cell extracts were examined, although the antigen was present in their extracellular products. In addition, these bacteria had a band at 18 kDa rather than 20 kDa. Differences in glycoprotein were also evident between bacteria cultured in vitro and in vivo. Bacteria cultured in vitro in LMW and HMW bags displayed a single 26 kDa band. Bacteria cultured in the LMW bag in vivo displayed bands at 26 and 27 kDa, while bacteria cultured in vivo in the HMW bag possessed only the 27 kDa band. These bands may represent sialic acid. The significance of the changes observed in the bacterium's structure and antigenicity when cultured in vivo is discussed.

Molecular and Immunohistochemical Diagnosis of Photobacterium damselae Subspecies piscicida During Naturally Occurring Disease in Egypt

“…Photobacteriosis, formerly known as Pasteurellosis, is one of the most threatening bacterial diseases affecting both wild and cultured marine fish species in Europe, Japan, and the Mediterranean region (Andreoni and Magnani ) and is caused by Photobacterium damselae subspecies piscicida , Phdp. A variety of temperate marine fish species are affected by this disease, including yellowtail, Seriola quinqueradiata ; flounder, Paralichthys olivaceous ; red spotted grouper, Epinephelus akaara ; striped bass, Morone saxatilis ; black sea bream, Mylio macrocephalus ; gilt‐head sea bream, Sparus aurata ; cobia, Rachycentron canadum; and European sea bass, Dicentrarchus labrax (Magariños et al ; Romalde ; Jung et al ).…”

Secreted Extracellular Products of Flavobacterium covae as Potential Immunogenic Factors for Protection against Columnaris Disease in Channel Catfish (Ictalurus punctatus)

“…The secreted extracellular proteins (SEPs) of the F. covae 94-081 strain were extracted with dialysis bags using a modification of a previously described procedure [ 24 , 25 ]. Briefly, the 94-081 strain was inoculated into FCGM broth and incubated for 3 h at 28 °C until the optical density at 600 nm (OD600) reached ~0.5.…”