activity at least to the CHSE 214 cell culture has been recorded Romalde and

Activity at least to the chse 214 cell culture has

This preview shows page 338 - 340 out of 594 pages.

activity, at least to the CHSE-214 cell culture, has been recorded (Romalde and Toranzo, 1993). Evidence has been presented that Y. ruckeri may have a siderophore-mediated iron uptake system (Romalde et al., 1991; Fernandez et al., 2004), in parallel to Aer. salmonicida and V. anguillarum. Romalde and colleagues revealed that >3 OMP were induced in iron-limiting conditions. Ruckerbactin, a catecholate siderophore iron acquisition system, has been described (Fernandez et al, 2004). As a result of a commendable study, Davies (1991) reported on the OMP of 135 Y. ruckeri isolates. Several 36.5-40.5 kDa peptidoglycan-associated proteins and a 36.5 or 38 kDa heat- modifiable protein were characterised. This 39.5 kDa peptidoglycan-associated protein was apparently not produced during logarithmic growth, but increased quantitatively in the stationary phase. An example of the new approach in examining pathogenicity involved an inbred fish model, i.e. platyfish (Xiphophorus maculatus) and cultured fish cells. In particular.
Image of page 338
Pathogenicity 319 infection with Y. ruckeri involved bathing in suspensions containing 10^ to 10^ cells (Kawula et ai, 1996). The result, in terms of invasion of key tissues, may be summarised as follows: Cell type % invasion Rainbow trout gonad 2.6 Rainbow trout kidney 2.3 Minnow epithelial cells 10.2 Using a strain which had been genetically tagged with green fluorescent dye and by means of immersion and i.p. infectivity experiments, it was observed that the patho- gen moved extracellularly and to a less extent intracellularly to the kidney, spleen and peripheral blood (Welch and Wiens, 2005). Y. ruckeri may be able to outcompete other micro-organisms, which may be an advantage for any potential pathogen, by the production of water-soluble anti- microbial compounds (Michel and Faivre, 1987). Flavobacteriaceae representatives Little is known about the pathogenicity of the cytophagas, flavobacteria or flexi- bacters. Kimura et al. (1978a) established that fatal infections by Fla. branchiophilum were only induced following water-borne challenge in salmonids weighing < 1.1 g each. Pathogenicity experiments with juvenile rainbow trout demonstrated that the organism occurred abundantly in the gills within 18-24h after exposure to a dilute bacterial suspension, i.e. 10-20 ml of a 48 h broth culture in 21 of freshwater. The gill lamellae became very swollen, but the reasons for subsequent fatalities remain unknown (Wakabayashi et al, 1980). Initial attachment of the pathogen to host cells may be by means of piH (Heo et al, 1990). In laboratory-based experiments, black sea bream were more susceptible to T. maritimum than red sea bream following i.m. injection of 0.02 ml of culture per fish, or infection by bathing or direct application of cultures to the tail or mouth. Mortalities, of up to 10%, occurred in 3 days (Wakabayashi et al, 1984). An infection model has also been estabhshed for turbot in which the fish were immersed for 18 h with the LD50 corresponding to containing 5 x 10^ and 5 x 10^ cells/ml for isolates from sole (serogroup 03) and turbot (serogroup 02), respectively (Avendano-Herrera et al., 2004a). In contrast, i.p. injection failed to establish an
Image of page 339
Image of page 340

You've reached the end of your free preview.

Want to read all 594 pages?

  • Spring '20
  • Bacteria, representative, gram-negative bacteria

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern

Stuck? We have tutors online 24/7 who can help you get unstuck.
A+ icon
Ask Expert Tutors You can ask You can ask You can ask (will expire )
Answers in as fast as 15 minutes
A+ icon
Ask Expert Tutors