9 research outputs found
Characterization of intracytoplasmic prokaryote infections in Dreissena sp. (Bivalvia: Dreissenidae)
Microbial communities associated with healthy and White Syndrome-affected Echinopora lamellosa in aquaria and experimental treatment with the antibiotic Ampicillin
Prokaryotic and ciliate communities of healthy and aquarium White Syndrome (WS)-affected coral fragments were screened using denaturing gradient gel electrophoresis (DGGE). A significant difference (R =0.907, p < 0.001) in16S rRNA prokaryotic diversity was found between healthy (H), sloughed tissue (ST),WS-affected (WSU) and antibiotic treated(WST) samples. Although 3 Vibrio spp were found in WS-affected samples, two of these species were eliminated following ampicillin treatment, yet lesions continued to advance, suggesting they play a minor or secondary role in the pathogenesis.The third Vibrio spin-creased slightly in relative abundance in diseased samples and was abundant in non-dis-eased samples. Interestingly, a Tenacibaculum sp showed the greatest increase in relative abundance between healthy and WS-affected samples, demonstrating consistently high abundance across all WS-affected and treated samples, suggesting Tenacibaculum sp could be a more likely candidate for pathogenesis in this instance. In contrast to previous studies bacterial abundance did not vary significantly (ANOVA,F2, 6=1.000,p= 0.422) be-tween H, ST,WSU or WST. Antimicrobial activity(assessed on Vibrio harveyi cultures) was limited in both H and WSU samples (8.1% ± 8.2 and8.0% ± 2.5, respectively) and did not differ significantly (Kruskal-Wallis, χ 2 (2) =3.842, p= 0.146). A Philaster sp, a Cohnilembus sp and a Pseudokeronopsis sp. were present in all WS-affected samples, but not in healthy samples. The exact role of ciliates in WS is yet to be determined, but it is proposed that they are at least responsible for the neat lesion boundary observed in the disease
Fish Immune Responses to Myxozoa
Myxozoans evoke important economic losses in aquaculture production,
but there is almost a total lack of disease control methods as no vaccines or
commercial treatments are currently available. Knowledge of the immune
responses that lead to myxozoan elimination and subsequent disease
resistance is vital for shaping the future development of disease control
measures. Different fish immune factors triggered by myxozoan parasites
are reviewed in this chapter. Detailed information on the phenotypic and
underlying molecular aspects of innate and adaptive responses, at both
cellular and humoral levels, is provided for some well-studied fishmyxozoan
systems. The importance of the local immune response, mainly
at mucosal sites, is also highlighted. Myxozoan tactics to disable or avoid
immune responses, such as modulation of immune gene transcription and
immune evasion, are also reviewed. The existence of innate and acquired
resistance to some myxozoan species suggest promising possibilities for
controlling myxozooses through immune-based strategies, such as genetic
selection for host resistance, vaccination, immune therapies and administration
of immunostimulants