Antigenic and cross-protection studies on two turbot scuticociliate isolates

Turbot resistance to Philasterides dicentrarchi is more dependent on humoral than on cellular immune responses

“…As mentioned earlier, the I 1 isolate is more virulent than the C 1 isolate and the isolates induced homologous but not heterologous protection when included in a vaccine [11]. The differences in virulence may be related to differences in the mechanisms of pathogenicity as well as to differences in the resistance to host immune defences.…”

“…Isolation and culture of P. dicentrarchi P. dicentrarchi specimens, isolates I 1 and C 1 , were obtained aseptically from ascitic fluid of turbot suffering an outbreak of scuticociliatosis that occurred on two local fish farms (Galicia, Spain) [1,11,12]. The isolates were cultured at 18 C in L-15 Leibovitz medium, supplemented with 10% inactivated foetal bovine serum (FBS), lipids (lecithin and Tween 80), nucleosides, glucose and an antibiotic antimycotic solution (100 units/ml of penicillin G, 0.1 mg of streptomycin sulphate and 0.25 mg/ml of amphotericin B) (complete L-15), as previously described [20].…”

“…A vaccine against this ciliate, which generated a large increase in the levels of specific antibodies in serum and conferred high protection in turbot, has recently been developed [8,9]. It has been suggested, on the basis of morphological and virulence studies, that there may exist different strains of scuticociliates that are pathogenic for turbot [10] and it has been found that vaccination with different P. dicentrarchi isolates does not always confer cross-protection [11]. Characterisation of seven P. dicentrarchi isolates obtained from outbreaks of turbot scuticociliatosis in different parts of the Iberian Peninsula showed intraspecific variation at morphological and genetic levels [12].…”

In vivo innate immune responses of groper (Polyprion oxygeneios) against Miamiensis avidus infection and lack of protection following dietary vitamin C administration

“…In the case of scuticociliates, some vaccine candidates have been proposed [6]. However, M. avidus displays intraspecies morphological, genetic [7] and antigenic variability [8] and different serotypes have been reported [9]. The latter data render vaccine therapies against this parasite highly unlikely.…”

Differences in the in vitro susceptibility to resveratrol and other chemical compounds among several Philasterides dicentrarchi isolates from turbot

“…However, a high degree of intraspecific genetic variation was found among several isolates of P. dicentrarchi obtained from turbot fish farms in Spain and Portugal, after morphological and genetic characterization of the isolates (Alvarez-Pellitero et al 2004;Budiño et al 2011). This is important because vaccination experiments with different serotypes of this scuticociliate did not find any cross protection between the serotypes (Piazzon et al 2008;Song et al 2009). Another possible way of combating this parasite is to use chemical compounds to control the free-living forms of the ciliate, thus reducing the infective pressure on the fish.…”