Although McCarthy et al 1984 reported optimistically that their vaccine worked

Although mccarthy et al 1984 reported optimistically

This preview shows page 367 - 369 out of 594 pages.

Although McCarthy et al. (1984) reported optimistically that their vaccine worked in fish, close scrutiny of the data suggests success comparable with that of Paterson et al. (1981). McCarthy and co-workers used a number of vaccine formulations without adjuvants, including a formalised (0.3% v/v formaldehyde) suspension of cells grown in KDM2, a lysed cell suspension (this was lysed at pH 9.5 by the addition of ION sodium hydroxide for 1 h, after which the pH was re-adjusted to 7.2 with ION hydrochloric acid), and 50% concentrates of the vaccine. Juvenile rainbow trout were vaccinated by i.p. injection, hyperosmotic infiltration and by 2min immersion. Vaccinated fish were maintained for 6 weeks at ITC and then challenged by i.p. injection with living cells of the homologous organism. Best success occurred with the lysed preparation, administered by i.p. injection, although failure greeted attempts to vaccinate fish by immersion or hyperosmotic infiltration. When >80% of the unvac- cinated controls were infected, <10% of the vaccinated fish were affected. This seems encouraging until it is realised that the workers measured the presence of infection by the presence of macroscopic lesions and the occurrence of Gram-positive bacteria in
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Control 349 the anterior part of the kidney. The occurrence of carriers could not be assessed, because the Gram-staining method is not the most sensitive technique for ascertain- ing the presence of renibacteria. Attenuated cells of Ren. salmoninarum or Arthro- bacter davidanieli (Salonius et al, 2005) (a commercially available live vaccine named Renogen) gave limited protection, but addition of purified Ren. salmoninarum geno- mic DNA or synthetic oHgodeoxynucleotides did not improve protection of chinook salmon following i.p. challenge with a virulent culture (Rhodes et al., 2004a). More recently, a comparison was made between inactivated whole cells of two cultures including the type strain without or with prior heating at 37°C for 48 h that destroys the p57 antigen, a recombinant product based on the p57 antigen in FIA, Renogen and PBS with or without FIA. Following i.p. injection vaccination, the chinook salmon were co-habited with mortalities recorded up to 285 days with the result that protective immunity was not demonstrated in any group (Alcorn et al., 2005). Although renibacterium is normally regarded as being nutritionally fastidious, two "strains" were isolated from colonies on KDM2 that could grow on regular laboratory media, i.e. TSA and BHIA, and were non-pathogenic when injected i.p. into Atlantic salmon at a dose of 5 x 10^ (Daly et al., 2001). When evaluated as live vaccines, the culture which grew on TSA (= Rs TSAl) led to an RPS of 50 and 74% at 74 and 60 days after challenge (Daly et al., 2001). Mycobacteriaceae representatives Although there are no vaccines commercially available against fish-pathogenic mycobacteria, it is recognised that there is a cell-mediated response in fish, i.e.
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