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The Effect of Stress on the Skin Welfare of Lumpfish (Cyclopterus lumpus Linnaeus, 1758) Broodstock

The aim of this study was to build on the work already conducted in optimising lumpfish broodstock temperature, photoperiod and nutrition by providing vital information on the stress relationship between mucosal barrier functions and the sexual development of lumpfish broodstock. From a population of approx. 300 fish of 1587 g (SEM ± 704 g), a sub-population of 20 fish was injected with 30 mg/kg fish cortisol implants on 5 January 2018. The control group was not treated with implants. The stress-induced cortisol implant group showed elevated plasma cortisol over a period of approximately one month. Analyses of mucus cell area and density suggested that induced stress could produce a positive functional response (stimulus) in lumpfish early in the experiment through a gentle increase in the barrier strength of the skin, reduced mucus cell size and increased density of mucous cells, resulting in a strengthening of the respiratory capacity of the gills. Mucous cell density and calculated barrier strength in the skin were significantly negatively correlated with plasma cortisol, while in the gill filaments of females, there was a significant negative correlation between mucous cell density and oestrogen levels. The reduced density of “empty” cells (Q cells) after stress induction indicates that these cells are important for the maintenance of homeostasis (physiological equilibrium). The fish in this experiment were considered more robust compared to previous analyses on smaller lumpfish.

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Characterization of anti-AAV2 neutralizing antibody levels in sheep prior to and following intravitreal AAV2.7m8 injection

AbstractGene augmentation therapy is a promising treatment for incurable, blinding inherited retinal diseases, and intravitreal delivery is being studied as a safe alternative to subretinal injections. Adeno-Associated Viruses (AAV) are commonly-used vectors for ocular gene augmentation therapy. Naturally occurring pre-operative exposure and infection with AAV could result in presence of neutralizing antibodies (NAB’s) in patients’ serum, and may affect the safety and efficacy of treatment. Our aim was to characterize the humoral response against AAV pre- and post-intravitreal delivery of AAV2.7m8 vectors in a naturally-occurring sheep model of CNGA3 achromatopsia. Serial serum neutralization assays were performed to screen sheep for pre-exiting anti-AAV2 NAB’s, and to assess the effect of intravitreal AAV2.7m8 injection on post-operative NAB titers and intraocular inflammation in sheep. The effect of viral dose and transgene type were also assessed. Serological screening revealed pre-operative seropositivity in 21.4% of animals, with age being a risk factor for the presence of anti-AAV2 NAB’s. NAB titers increased following intravitreal AAV administration in the majority of sheep. There was no significant difference in the degree of post-operative serum neutralization between pre-operatively seronegative sheep and those with pre-existing antibodies. However, only sheep with pre-existing antibodies presented with signs of post-operative inflammation. We conclude that pre-existing anti-AAV2 NAB’s do not affect the level of post-operative NAB titers; however, they increase the risk of post-operative ocular inflammation. Our results could have implications for the management of AAV-mediated ocular gene therapies, a technology being increasingly studied and used in patients.

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