The tissue localization of <i>Aeromonas salmonicida</i> in rainbow trout, <i>Salmo gairdneri</i> Richardson, following three methods of administration

Piscirickettsiosis pathogenesis was examined using some tissues as entry portals of Piscirickettsia salmonis in coho salmon. Juvenile fish, weighing approximately 8.4 g, were used in this trial. Inocula were prepared using the strain SLGO-95 of P. salmonis. The micro-organism was cultured in the CHSE-214 cell line as described by Fryer et al. (1990) and doses containing 10 4.7 and 10 3.7 TCID 50 were prepared. Each dose was used to infect the fish via skin, gills and intestine. Skin and gills were exposed by calibrated drops, and the intestine by an intubation through the anal opening. Some fish were injected intraperitoneally with the same P. salmonis doses, as positive virulence controls. Sham-inoculated fish for each of the tested routes were also included as negative controls. Piscirickettsiosis was experimentally reproduced with all the inoculation methods. Cumulative mortalities and survival analyses showed that the most effective entry portal was skin followed by intestinal intubation and finally by gill infection. KEY WORDS: Piscirickettsia salmonis · Pathogenesis · Fish disease · Coho salmonResale or republication not permitted without written consent of the publisher

Section: Discussionmentioning

confidence: 61%

Experimental infection of coho salmon Oncorhynchus kisutch by exposure of skin, gills and intestine with Piscirickettsia salmonis

Smith

Rojas²,

Guajardo³

et al. 2004

“…In salmonids, ASS has been reported to colonize gill tissue, reaching high bacterial numbers at sites of oxygen exchange (Tatner et al 1984, Effendi & Austin 1995, Ferguson et al 1998, Svendsen et al 1999. In our turbot model, all ASS strains were detected in the gill tissue at the early stages of infection but, as was shown for the epidermal mucus layer, only the virulent strain persisted in the gill tissue throughout the infection.…”

Section: Discussionmentioning

confidence: 75%

“…Consequently, although avirulent as well as virulent ASS strains can localize to the epidermal mucus layer, to persist at this site, virulent ASS strains must encode mechanisms to evade the host immunity. These data suggest the possibility that ASS may use the epidermis as a portal of entry into turbot.In salmonids, ASS has been reported to colonize gill tissue, reaching high bacterial numbers at sites of oxygen exchange (Tatner et al 1984, Effendi & Austin 1995, Ferguson et al 1998, Svendsen et al 1999. In our turbot model, all ASS strains were detected in the gill tissue at the early stages of infection but, as was shown for the epidermal mucus layer, only the virulent strain persisted in the gill tissue throughout the infection.…”

mentioning

confidence: 75%

Colonization of turbot tissues by virulent and avirulent Aeromonas salmonicida subsp. salmonicida strains during infection

Farto¹,

Milton²,

Bermúdez³

et al. 2011

Preventing disease outbreaks in cultured turbot Psetta maxima L. caused by Aeromonas salmonicida subsp. salmonicida (ASS) requires a better understanding of how this pathogen colonizes its host. Distribution of 1 virulent and 2 avirulent ASS strains in turbot tissues was investigated during early and late stages of infection following an immersion challenge. To track bacteria within the turbot, the ASS strains were tagged with green fluorescent protein (GFP). Both virulent and avirulent strains colonized the epidermal mucus, gills, and intestine within the first 12 h post challenge, suggesting that these sites may serve as points of entry into turbot. Although the avirulent strains colonized these initial sites in the turbot tissues, they were rarely found in the internal organs and were cleared from the host 4 d post challenge. In contrast, the virulent ASS strain was found in the liver and kidney as early as 12 h post challenge and was found in the muscle tissue at very late stages of infection. The virulent strain persisted in all tested host tissues until death occurred 7 d post challenge, suggesting that ASS must colonize and survive within the turbot tissues for an infection to result in death of the fish. Comparisons of the distribution profiles of both virulent and avirulent strains during early and late stages of an infection in turbot has provided important information on the route and persistence of an ASS infection in this host.KEY WORDS: Aeromonas salmonicida · Persistence · Turbot · Green fluorescent protein · GFP · Immersion challenge Resale or republication not permitted without written consent of the publisherDis Aquat Org 95: [167][168][169][170][171][172][173] 2011 for ASS in other internal organs and did not analyze the transmission of the bacteria through the internal tissues. Interestingly, Hodgkinson et al. (1987) compared infectivity of virulent and avirulent strains in salmonids but only during the first 24 h post challenge, showing inconclusive results since the virulent strain showed an avirulent behavior. Thus, additional studies are needed to investigate the fate of both virulent and avirulent ASS strains during the progression of early and late stages of disease. In particular, studies using non-salmonid fish such as turbot will give a broader understanding on how ASS colonizes its host and will provide information for the design of new therapeutic strategies to protect against this pathogen in aquaculture.The green fluorescent protein (GFP) from Aequorea victoria has been used successfully as a genetic marker for the detection of bacterial pathogens during the infection of fish (Ling et al. 2000, 2001, O'Toole et al. 2004, Welch & Wiens 2005, Chu & Lu 2008. In most cases, expression of GFP in the bacterial cell does not interfere with growth or virulence (Chalfie et al. 1994, Valdivia et al. 1996, Ling et al. 2000, Chu & Lu 2008. In addition, GFP fluorescence, which is induced by UV light, facilitates visualization of bacteria in fish tissues and the quantification o...

Section: Discussionmentioning

confidence: 99%

“…Overall antigen could be localised for up to 72 h post feeding. Antigen uptake has been observed 2 to 6 d post delivery in various experiments (Davina et al 1982, Tatner et al 1984, Rombout et al 1985.Further, there was a difference in the location of FC and BF antigens, the former being located within intraepithelial macrophages and the latter within bigger vacuoles of epithelial cells. This difference in localization appears to be due to the difference in the size of the 2 particulate antigens; BF antigens are usually in large flocs while those of FCs are small.…”

mentioning

confidence: 99%

Uptake and processing of biofilm and free-cell vaccines of Aeromonas hydrophila in Indian major carps and common carp following oral vaccination-antigen localization by a monoclonal antibody

Azad¹,

Shankar²,

Mohan³

et al. 2000

Uptake and processing of biofilm (BF) and free-cell (FC) vaccines of Aeromonas hydrophila were studied in the Indian major carps catla Catla catla, and rohu Labeo rohita and in the common carp Cyprinus carpio following a single dose oral vaccination of 10 11 CFU g -1 fish. Fish were sampled at 0.5, 1, 3, 6, 12, 24 h and at 2, 3, 5 and 10 d following vaccination and antigen localization was studied in the gut, kidney and spleen employing monoclonal antibody based immunofluorescence and immunoperoxidase. The general pattern of antigen localization was similar in catla, rohu and common carp. Initially, both the BF and FC antigens were localized in the gut lumen, followed by their uptake by intraepithelial vacuoles and macrophages. Antigen administered orally was also seen in the spleen and kidney. Both BF and FC antigens were detected in the gut lumen of carp within 30 min following oral delivery. However, BF antigen remained in the lumen of the hindgut for 48 h compared to 6 h in the case of FC antigen. In the early stages, BF antigen was localized in the gut epithelial vacuoles while FC antigen was associated with the small macrophages of the hindgut. Antigen localization in spleen and kidney was observed at 3 h and persisted even up to 10 d following oral delivery. In general, there was a distinct difference between BF and FC vaccines in the duration of retention and quantity of uptake in the gut, kidney and spleen.KEY WORDS: Biofilm vaccine · Uptake and processing · Indian major carps · Aeromonas hydrophila · Monoclonal antibody Resale or republication not permitted without written consent of the publisherDis Aquat Org 43: [103][104][105][106][107][108] 2000 We have developed a biofilm of Aeromonas hydrophila for oral vaccination of Indian major carps which has produced better humoral and protective responses compared to the free-cell (FC) vaccine of this pathogen (Azad et al. 1997). The glycocalyx of the biofilm (BF) vaccine is believed to protect the antigen against destruction in the gut, thus facilitating its transport in intact condition to the immune responsive areas (Azad et al. 1999). However, this concept needs further investigation with respect to antigen retention in the gut lumen, and the uptake and processing mechanisms of the BF vaccine.Detailed accounts of particulate antigen uptake and processing in the gut of common carp following oral vaccination have been previously provided . Antigen localization studies in other cultured fish species following oral or anal intubation of antigens are also available (Davina et al. 1982, Gergopolou & Vernier 1986, Press et al. 1996. Oral vaccination has great potential in Indian aquaculture. However, there is little information on the uptake and processing of antigens following oral vaccination of the widely cultured Indian major carps.The present work employs a monoclonal antibody to analyse the retention, mode of uptake and processing of BF and FC antigens of Aeromonas hydrophila in Indian major carps following oral vaccination. Common carp was ...