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Challenge Trial (challenge + trial)
Selected AbstractsField validation of experimental challenge models for IPN vaccinesJOURNAL OF FISH DISEASES, Issue 12 2007A Ramstad Abstract Atlantic salmon S1/2 pre-smolts from the VESO Vikan hatchery were assigned to study groups, i.p. immunized with commercially available, multivalent oil-adjuvanted vaccines with (Norvax Compact 6 , NC-6) or without (Norvax Compact 4 , NC-4) recombinant infectious pancreatic necrosis virus (IPNV) antigen. A control group received saline solution. When ready for sea, the fish were transported to the VESO Vikan experimental laboratory, where two identical tanks were stocked with 75 fish per group before being transferred to 10 °C sea water and exposed by bath to first passage IPNV grown in CHSE-214 cells. The third tank containing 40 fish from each group was challenged by the introduction of 116 fish that had received an i.p injection of IPNV-challenge material. The remaining vaccinated fish were transported to the VESO Vikan marine field trial site and placed in two identical pens, each containing approximately 53 000 fish from the NC-6 group and 9000 fish from the NC-4 group. In the experimental bath challenge trial, the cumulative mortality was 75% and 78% in the control groups, and the relative percentage survival (RPS) of the NC-6-immunized fish vs. the reference vaccine groups was 60% and 82%, respectively. In the cohabitation challenge, the control mortality reached 74% and the IPNV-specific vaccine RPS was 72%. In both models, the reference vaccine lacking IPNV antigen gave a moderate but statistically significant non-specific protection. In the field, a natural outbreak of infectious pancreatic necrosis (IPN) occurred after 7 weeks lasting for approximately 3.5 months before problems due to winter ulcers became dominating. During this outbreak, mortality in the NC-4 groups were 33.5% and 31.6%, respectively, whereas mortality in the NC-6 groups were 6.9% and 5.3%, respectively, amounting to 81% IPNV-specific protection. In conclusion, the IPN protection estimates obtained by experimental challenges were consistent between tanks, and were confirmed by the field results. [source] Efficacy and safety of single- and multiple-dose ketotifen fumarate 0.025% ophthalmic solution in a pediatric populationPEDIATRIC ALLERGY AND IMMUNOLOGY, Issue 6 2004Mark B. Abelson Allergic conjunctivitis can seriously disrupt children's daily activities. This study assessed the efficacy (onset and duration of action) and safety of ketotifen fumarate 0.025% ophthalmic solution compared with vehicle placebo in pediatric subjects after single and multiple dosing. This was a double-masked, multicenter, fellow-eye, placebo-controlled, conjunctival allergen challenge trial. Eligible subjects (8,16-yr-olds) who produced a qualifying reaction to allergen were randomized to a single dose (one drop) of ketotifen fumarate in one eye and vehicle placebo in the fellow eye, followed by an allergen challenge at 15 min and 8 h post-dose. Subjects who had a qualifying reaction to allergen in the placebo-treated eye and a qualifying response to ketotifen in the active-treated eye following the single dose were re-randomized to a multiple-dose treatment period. They were instructed to instill one drop of ketotifen fumarate in one eye and placebo in the other eye twice daily for 4 wk. An allergen challenge was conducted 8 h after the last dose. The primary efficacy assessment was ocular itching, judged by the subject at 3, 7, and 10 min post-allergen challenge after single- and multiple-dose treatments. Other ocular signs and symptoms were assessed at 7, 10, and 15 min post-dose. A total of 133 subjects were randomized to single-dose treatment; 105 were evaluable for efficacy. Of these, 60 were re-randomized to multiple-dose treatment, and 55 were evaluable for efficacy. After single and multiple doses, ketotifen fumarate significantly inhibited ocular itching compared with placebo at all post-challenge timepoints (p < 0.001) and also significantly reduced hyperemia, chemosis, and lid swelling (p = 0.031). No drug-related systemic adverse events were reported, and ocular adverse events were comparable to placebo. No subject discontinued prematurely due to an adverse event. These results indicate that ketotifen fumarate 0.025% ophthalmic solution is an effective and safe treatment option for children with allergic conjunctivitis. [source] Segregation of infectious pancreatic necrosis resistance QTL in the early life cycle of Atlantic Salmon (Salmo salar)ANIMAL GENETICS, Issue 5 2010A. A. Gheyas Summary In a previous study, three significant quantitative trait loci (QTL) associated with resistance to Infectious Pancreatic Necrosis (IPN) disease were identified by analysing challenge data from one sub-population of Landcatch Atlantic salmon (Salmo salar) smolt. While these QTL were shown to affect the resistance in seawater, their effect in freshwater was unknown. This study investigates the effect of these QTL on IPN resistance in salmon fry in freshwater. Twenty families with intermediate levels of IPN mortality were analysed from a freshwater challenge trial undertaken on a different sup-population of LNS salmon to that studied previously. Only the QTL from linkage group 21 (LG21) appeared to have a significant and large effect on resistance in freshwater; the same QTL was found to have the largest effect in seawater in the previous study. Variance component analysis showed a high heritability for the QTL: 0.45 ± 0.07 on the liability scale and 0.25 ± 0.05 on the observed scale. In a family where both parents were segregating for the QTL, there was a 0% vs. 100% mortality in homozygous offspring for resistant and susceptible QTL alleles. The finding that the same QTL has major effect in both freshwater and seawater has important practical implications, as this will allow the improvement of resistance in both phases through marker assisted selection by targeting this QTL. Moreover, the segregation of the LG21 QTL in a different sub-population gives further evidence of its association with IPN-resistance. [source] Effects of dietary pyridoxine on disease resistance, immune responses and intestinal microflora in juvenile Jian carp (Cyprinus carpio var. Jian)AQUACULTURE NUTRITION, Issue 3 2010L. FENG Abstract This experiment was conducted to evaluate the effects of dietary pyridoxine on disease resistance, immune responses and intestinal microflora of fish. A total of 1050 Jian carp (11.71 ± 0.05 g) were randomly distributed into seven groups, feeding diets containing graded levels of pyridoxine (0.2, 1.7, 3.2, 5.0, 6.3, 8.6 and 12.4 mg kg,1 diet). After 80 days of feeding, a challenge trial was conducted by injection of Aeromonas hydrophila for 17 days. Results indicated that with increasing dietary pyridoxine concentration up to 5.0 mg kg,1 diet, survival rate after challenge with A.hydrophila and phagocytic activity of leukocyte were improved (P < 0.05), and plateaued thereafter (P > 0.05). Red blood cell and white blood cell counts were lowest when fed the diet containing 1.7 mg pyridoxine kg,1 diet. Haemagglutination titre, lysozyme activity, acid phosphatase activity, total iron-binding capacity, antibody titre and immunoglobulin M content followed the similar pattern to that observed with survival rate. Aeromonas hydrophila, Escherichia coli and Lactobacillus counts in intestine were not affected by dietary pyridoxine concentration (P > 0.05). These results suggested that pyridoxine could enhance immune response of fish. [source] | ||||||||||