罗非鱼海豚链球菌疫苗及其免疫效果的研究

用筛选到的海豚链球菌(Streptococcus iniae)临床分离菌株CMS005,甲醛灭活制备成疫苗并对其进行了注射、浸泡和口服免疫奥尼罗非鱼的效果研究。结果显示:实验室水族箱试验的注射、浸泡和口服免疫的最佳免疫保护率分别为90.5%、61.9%和14.3%,水泥池小网箱试验的最佳免疫保护率分别为100%、86.1%和66.7%。免疫剂量对浸泡免疫效果的影响大于注射和口服免疫,加强免疫可显著提高浸泡和口服免疫效果,超声波处理可以提高浸泡免疫效果。注射和口服免疫7 d和15 d后均可控制罗非鱼海豚链球菌病的继续发生;未免疫组罗非鱼月累计死亡率为4%~16%,而免疫组罗非鱼月累计死亡率低于0.5%;疫苗产生的免疫保护力可持续2~3个月。     

Vaccination strategies with oral booster for surubim hybrid (Pseudoplatystoma corruscans × P. reticulatum) against haemorrhagic septicaemia

This study evaluated the efficiency of differently prepared vaccines against Aeromonas hydrophila in the hybrid surubim (Pseudoplatystoma corruscans × P. reticulatum). Survival and haemato‐immunological parameters were compared between the treatments: non‐vaccinated fish (C); bacterin‐vaccinated fish (B); bacterin plus oral booster vaccinated fish (B+O); bacterin and toxoid‐vaccinated fish (B+T) and bacterin, toxoid and oral booster‐vaccinated fish (B+T+O). Fourteen‐days vaccinated fish from B+O and B+T+O were fed with an oral booster for 4 days. After 1 week, the fish were intraperitoneally challenged with 2 × 10⁸ CFU mL^?1 of A. hydrophila. Fish from the treatment B+T+O showed the lowest cumulative mortality (11.36%) 96 h after challenge, compared with other treatments (22.72–44.04%), and a relative survival of 74%. Serum immunoglobulin in B+T+O fish was higher than in other treatments. All vaccinated fish showed an increased agglutination titre when compared with non‐vaccinated fish, both before and after challenge. Fish fed with oral booster showed an increase in phagocytic percentage before and after challenge. It can be inferred that the oral booster vaccination was efficient in reducing mortality in hybrid surubim by enhancing the response against haemorrhagic septicaemia due to A. hydrophila infection.     

Field validation of experimental challenge models for IPN vaccines

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 degrees 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.     

Vaccination trials of sea bass,Dicentrarchus labrax (L.), against Photobacterium damsela subsp. piscicida,using novel vaccine mixtures

Bacterial cells of the marine fish pathogen Photobacterium damsela subsp. piscicida were grown in novel culture media. A mixture of whole cells and extracellular components was inactivated and used in bath, intraperitoneal (i.p.) and oral vaccination of sea bass, Dicentrarchus labrax, employing two sizes of fish. A commercial vaccine was used for comparative purposes. Control and immunized fish were either bath or intraperitoneally challenged 6 and 12 weeks post-vaccination. Small fish had significantly higher relative percentage survival with the novel vaccine mixture both at 6 and 12 weeks post-vaccination by bath, in comparison with the commercial vaccine. No protection was afforded at 6 or 12 weeks post-immunization by either vaccine after challenge via i.p. injection. Sea bass (1.5-2 g) intraperitoneally vaccinated with various adjuvanted vaccine mixtures were not protected against pasteurellosis. In contrast, larger sea bass (20 g) benefited from vaccination with the novel vaccine mixtures. Intraperitoneal challenge with the pathogen resulted in protection in both fish groups vaccinated with novel vaccine mixtures, whereas control fish suffered high mortalities (> 80%). Orally vaccinated fish were immersion challenged with the pathogen. At 6 and 12 weeks post-vaccination the control fish had a high mortality and the fish vaccinated with the novel vaccine mixture achieved good protection.     

Experimental Cryptobia salmositica (Kinetoplastida) infections in Atlantic salmon, Salmo salar L.: cell-mediated and humoral immune responses against the pathogenic and vaccine strains of the parasite

Hatchery-reared Atlantic salmon, Salmo salar L., were vaccinated intraperitoneally (i.p.) with a live attenuated Cryptobia salmositica vaccine (either 100 000 or 5000 parasites fish⁻¹) and 4 weeks later were challenged with the parasite (either 100 000 or 5000 parasites fish⁻¹). Unvaccinated, infected salmon had high parasitaemias and were anaemic. Fish given a high dose (100 000 parasites fish⁻¹) had higher parasitaemias than fish given the lower dose. Vaccinated fish had low parasitaemias and a mild anaemia, but recovered quickly after challenge. Complement-fixing antibody increased in vaccinated fish after challenge and was highest at 2 weeks post-challenge. The cell-mediated response (both T cells and B cells) was depressed in infected fish until 4 weeks after infection. In vaccinated fish, the humoral response (i.e. B-lymphocytes) was greater than the cell-mediated response (i.e. T-lymphocytes). In contrast, infected fish had a greater cell-mediated than humoral immune response.     

Tissue localization of Aeromonas salmonicida in Atlantic salmon, Salmo salar L., following experimental challenge

Three groups of Atlantic salmon, Salmo salar L., were exposed to live, colony-forming, radiolabelled Aeromonas salmonicida bacteria in a bath challenge: (1) fish with artificial wounds; (2) fish with a reduced epidermal mucus layer caused by removal of the mucus layer on two occasions by a swabbing procedure; and (3) a control group of untreated fish. Fish were killed 2, 6 and 24 h after challenge, and radioactivity (cpm g^–1) was measured in the blood, mucus, skin, wound area, gills, anterior kidney, posterior kidney, spleen, midgut and hindgut. The highest levels of radioactivity were measured in the wound areas and in the gills. There was a significant positive correlation between the levels of radioactivity in the gills and blood, and between the mucus and skin at 2 h post-challenge. Two hours after the bath challenge, live A. salmonicida bacteria were found in the blood of fish in the 'swabbed' and 'artificial wound' groups, and not in the control group. Twenty-four hours after the bath challenge, the kidney of fish from all groups contained viable bacteria, whereas the blood was negative.     

Growth of sablefish (Anoplopoma fimbria) in marine net-pens

Sablefish (Anoplopoma fimbria) were reared in 1.6 × 2.0 × 1.2 m deep net-pens for 36 months using low-cost, locally available diets (frozen salmon and herring). Post-capture mortality, wound repair, and adaptability to floating net-pens were investigated. Results showed no mortality directly related to capture and rapid healing of wounds resulting from capture. All fish adapted to captivity without apparent difficulty.For grow-out trials, 36 age 1+ fish were tagged for individual identification. Male and female fish were identified using an immunodiffusion technique. Net-pen adaptability studies tested three diets. Maximum observed mean weight gains were 0.10 kg per fish per month. After 2 years, there was no significant difference in growth (length or weight) between any of the diets. A different weight gain was recorded between male and female fish fed the salmon diet.     

Immunization of channel catfish, Ictalurus punctatus Rafinesque, against Ichthyophthirius multifiliis (Fouquet): killed versus live vaccines

Abstract. Fish surviving infection with the pathogenic ciliated protozoan, Ichthyophthirius multifiliis (Fouquet, 1876), become resistant to subsequent infection by the parasite. The acquired immunity suggests that development of a vaccine against the parasite may be possible. Because of the advantages of immunoprophylaxis for treatment of the disease, an effort has been made to determine whether fish exposed to killed parasite preparations can resist subsequent lethal challenge. Both the route of administration and the effects of stage specific antigens have been examined. Channel catfish vaccinated by intraperitoneal (i.p.) injection or bath immersion with killed I multifiliis tomites show 100% mortality following a standard challenge protocol. Similarly, 100% mortality was observed in test groups injected with tomite cilia. In both cases, a consistent difference in days to death between control and test group animals was observed. Although complete mortality was seen with fish injected with tomite preparations, fish vaccinated with killed trophonts (the feeding stage of the parasite) had a much greater degree of protection with approximately 50% of fish surviving an otherwise lethal challenge. Finally, animals injected intraperitoneally with live tomites showed nearly complete immunity and were identical in their response to fish which survive natural infection. The response of fish vaccinated with live parasites indicates that animals injected intraperitoneally can develop surface immunity and that i.p. injection is a suitable route of administration for potential I. multifiliis vaccines.     

Extracts of Oliviera decumbens and Satureja khuzestanica as immunostimulants affect some innate immunity indices of Cyprinus carpio against Aeromonas hydrophila infection

In this study, the effect of extracts of two herbs (Oliviera decumbens and Satureja khuzestanica) on immune response of carp was investigated. At the beginning of experiment, fish were divided to two groups including vaccinated (using vaccine developed against A. hydrophila) and non‐vaccinated. Fish in both groups were fed diets containing O. decumbens and S. khuzestanica and combination of two herbal extracts for 5 weeks. Control fish (negative control) and fish vaccinated only (positive control) were fed basal diets without supplements of herbal extracts. Lysozyme activity, antibody titre, complement activity and bactericidal activity in serum were measured. After 5 weeks feeding, fish were infected with A. hydrophila and mortalities were recorded. In both experimental groups, no significant differences were found in terms of alternative haemolytic complement (ACH50) activity and antibody titres of Serum. In non‐vaccinated fish group, lysozyme and bactericidal activity of fish fed S. khuzestanica or combination of O. decumbens and S. khuzestanica was higher compared with control and other experimental treatments. In vaccinated fish group, the lysozyme and bactericidal activity was not significant in all treatments compared with control group. The results of this study showed that feeding non‐vaccinated and vaccinated carp with only S. khuzestanica or in combination with O. decumbens enhance only some immunity indices including lysozyme and bactericidal activity in non‐vaccinated fish and these extracts have no immunological stimulatory role on vaccinated individuals.     

Strong genetic influence on IPN vaccination-and-challenge trials in Atlantic salmon, Salmo salar L

Two series of experimental challenge trials were performed for evaluation of multivalent oil‐adjuvanted vaccines with and without an infectious pancreatic necrosis virus (IPNV) antigen component. In both the trial series, Atlantic salmon were hatched, reared, vaccinated and subjected to temperature and light manipulation to induce smoltification. When ready for sea the fish were transported to the VESO Vikan experimental laboratory for bath or cohabitant challenge with IPNV. In the first series, four vaccination and bath challenge trials involving 2‐year classes of experimental fish were conducted. In the second series, three groups of eyed eggs of Atlantic salmon allegedly differing in their innate resistance to IPNV were used (Storset, Strand, Wetten, Kjøglum & Ramstad 2007). Hatching, rearing and smoltification were synchronized for each group, and fish from each genetic group were randomly allocated IPN vaccine, reference vaccine or saline before being placed into parallel tanks for bath or cohabitant challenge. In the first series of trials, IPN‐specific mortality commenced on day 10–12 after bath challenge. Replicates showed similar results. In trials 1 and 2 belonging to the same experimental fish year class, the average cumulative control mortality reached 60.6% and 79.5%, respectively, whereas in trials 3 and 4 belonging to the following year class the control mortality was consistently below 50%. In the second series of trials, the experimental fish originating from allegedly IPN susceptible parents consistently showed the highest cumulative mortality among the unvaccinated controls (>75%) whereas smolts derived from allegedly IPNV resistant parents showed only 26–35% control mortality. The IPN‐vaccinated fish experienced significantly improved survival vs. the fish immunized with reference vaccine, with RPS values above 75% in the IPN susceptible strain. In the IPN resistant strain, the protection outcomes were variable and in part non‐significant. The outcome of both the trial series suggests that control mortalities above 50% are necessary to reliably demonstrate specific protection with IPN vaccines.