中国对虾病原菌(鳗弧菌)的研究

1987年7～10月福建省平谭县对虾养殖场发生了一起严重的流行病。病虾活动力减弱,食欲下降,个体消瘦,头胸甲心区附近呈白色或浅桔红色,血淋巴液稀薄、混浊、不能凝固。因病虾步足、游泳肢及尾扇呈鲜红色,被称为“红腿病”。死亡率可高达90％以上。从五只垂死病虾的心脏血淋巴液中分离到细菌作纯焙养,经肌肉注射和浸泡的人工感染方法,得到了与虾池中患病虾相同的症状。菌原菌是革兰氏阴性短杆鼠。以极生单鞭毛运动。发酵葡萄糖,产酸不产气。氧化酶、过氧化氢酶阳性。能还原硝酸盐成亚硝酸盐。精氨酸脱羧;鸟氨酸、赖氨酸不脱羧。V.P.阳性.在42℃中不能生长。不能在无盐和含有8％NaCl 的胨水中生长,但在含有3％和6％NaCl的胨水中生长良好。对弧菌抑制剂0/129敏感。经鉴定为鳗弧菌(Vibrio anguillarum Bergman)。     

Effect of Dietary Protein Sources in Microdiets on Feeding Behavior and Growth of Red Sea Bream,Pagrus major,During Weaning and Metamorphosis

ABSTRACT

The use of two protein sources, krill meal (protein 62% dry matter) and soybean protein (protein 85.2% dry matter), and their effect on growth performance and feeding behavior of red sea bream, Pagrus major, during weaning and metamorphosis, was studied using microbound diets. High levels of dietary soybean protein (25% of the diet) resulted in a poor feeding response and marked anorexia, resulting in high mortalities and poor growth. Moderate levels of dietary soybean protein (17-19% of diet) resulted in higher growth. Krill meal contributed to an increase in food consumption. A possible reason for the reduced growth of fish fed soybean protein-based diets was the lower palatability of these diets. Alternative sources of protein could replace fish meal, if these sources are more palatable to the fish.     

Two pathogens of Greenshell™ mussel larvae, Perna canaliculus: Vibrio splendidus and a V. coralliilyticus/neptunius-like isolate

Bacterial pathogens of Greenshell™ mussel (GSM) larvae can cause batch losses during hatchery production. Twenty-two isolates were screened using a larval bioassay. Two strains were identified as potential pathogens. Phenotypic identification of these strains revealed two non-reactive Gram-negative, oxidase positive rods. Sequencing of the 16S rRNA gene identified Vibrio splendidus and a V. coralliilyticus/neptunius -like isolate as pathogens of GSM larvae, with an ability to cause 83% and 75% larval mortality in vitro , respectively, at a concentration of 10² CFU mL⁻¹. Histopathology indicated that the route of infection was via the digestive system. Using healthy larvae as target hosts, Koch's postulates were confirmed for the two isolates. This is the first report on pathogens of GSM larvae.     

大黄鱼弧菌病综合防治对策的初步研究

在5月下旬用哈维氏弧菌(Vibrio harveyi)灭活菌苗对大黄鱼(Pseudosciaena crocea)幼鱼进行浸泡免疫，7月至8月高温季节投喂添加防病药物或者uharveyi灭活菌苗的配合饲料，进行了综合防病试验。试验结果表明，uharveyi灭活菌苗浸泡免疫接种可以有效地预防uharveyi对受免大黄鱼的感染，但是，受免鱼对副溶血弧菌(V.parahaemolyticus)的感染则没有显著的保护；高温季节投喂添加药物的配合饲料能够有效地降低大黄鱼的死亡率，而将药物添加在鱼糜中后的投喂方式则不能获得明显防病效果；对受免鱼口服灭活菌苗后在56d内仍然可以观察到加强免疫效果。     

斜带石斑鱼溶藻弧菌病的研究

从患病的斜带石斑鱼肝和肾组织分离的两株病原菌,进行纯化培养、人工感染、VITEK-AMS-32自动微生物分析鉴定及药敏试验,经形态和生理生化测定,确定为溶藻弧菌(Vibrioalginolyticus)。组织病理变化主要表现为鳃、肝和肾细胞变性、坏死,病变组织炎性细胞浸润,呈变质性炎症。     

Treating experimentally induced vibriosis (Listonella anguillarum) in cod, Gadus morhua L., with florfenicol

This study was performed to determine the efficacy of orally administered florfenicol in the treatment of experimentally induced vibriosis (Listonella anguillarum) in cod, Gadus morhua. The L. anguillarum strain HI-610 was used. This strain has a minimal inhibitory concentration value of 0.5 mg L(-1) against florfenicol. Fifteen groups of 40 fish each were challenged by bath with 1.7 x 10(5) CFU mL(-1) for 1 h. Three days following challenge, medication with florfenicol was introduced in 12 of the groups. The dosages used were 10 mg kg(-1) day(-1) for 10 consecutive days in marine or salmonid pellets, 10 mg kg(-1) day(-1) for five consecutive days in marine pellets or administered at days 1, 2, 4, 6 and 8 following initiation of treatment. Among challenged unmedicated fish mortality started at day 3 post-challenge reaching a final cumulative mortality of 77% at day 15. The experiment was terminated at day 26. In the medicated groups, the majority of deaths occurred from days 3-7 post-challenge reaching final cumulative mortalities of 31% and 52%, respectively, for the fish given marine and salmonid pellets for 10 consecutive days. The fish treated with medicated marine pellets for five consecutive days and at days 1, 2, 4, 6 and 8 (sequential feeding) following initiation of treatment had cumulative mortalities of 52% and 38%, respectively. Survival of medicated fish in all groups was significantly (P < 0.005) greater than survival of challenged unmedicated fish. Furthermore, a significant difference (P < 0.001) in survival was found between fish treated for 10 consecutive days using marine pellets and the groups using marine pellets for five consecutive days and salmonid pellets for 10 consecutive days. Twenty four hours following last medication, six fish had mean plasma concentrations of 3.3 +/- 1.7 and 3.5 +/- 2.8 microg mL(-1), respectively, in fish treated for 10 consecutive days using marine and salmonid pellets. Corresponding values for fish treated for five consecutive days and by sequential feeding were 2.2 +/- 2.3 and 1.7 +/- 0.7 microg mL(-1), respectively.     

A comparative epizootiologic study of the two fish‐pathogenic serovars of Vibrio vulnificus biotype 2

Vibrio vulnificus biotype 2 is subdivided into two main serovars, serovar E, able to infect fish and humans, and serovar A, only virulent for fish. Serovar E emerged in 1976 as the causative agent of a haemorrhagic septicaemia (warm‐water vibriosis) affecting eels cultured in brackish water. Serovar A emerged in 2000 in freshwater‐cultured eels vaccinated against serovar E, causing warm‐water vibriosis with fish showing a haemorrhagic intestine as the main differential sign. The aim of the present work was to compare the disease caused by both serovars in terms of transmission routes, portals of entry and host range. Results of bath, patch‐contact and oral‐anal challenges demonstrated that both serovars spread through water and infect healthy eels, serovar A entering mainly by the anus and serovar E by the gills. The course of the disease under laboratory conditions was similar for both serovars in terms of transmission and dependence of degree of virulence on water parameters (temperature and salinity). However, the decrease in degree of virulence in fresh water was significantly greater in serovar E than in serovar A. Finally, both serovars proved pathogenic for tilapia, sea bass and rainbow trout, but not for sea bream, with significant differences in degree of virulence only in rainbow trout. In conclusion, serovar A seems to represent a new antigenic form of V. vulnificus biotype 2 with an unusual portal of entry and is better adapted to fresh water than serovar E.     

Vibrio vulnificus serovar A: an emerging pathogen in European anguilliculture

The spread of the emerging pathogen Vibrio vulnificus biotype 2 serovar A in Danish anguilliculture is reported. Serovar A was originally isolated in a Spanish eel farm in 2000 and occurred in Denmark in the summer of 2004, affecting eels of 5-10 g body weight cultured in fresh water. The Danish eels showed clinical signs different from those reported for Spanish eels, such as severe haemorrhages in the head and gill region with necrosis of the soft tissues. Danish isolates were biochemically and serologically identical to Spanish serovar A strains and also highly virulent for eels by both intraperitoneal injection and immersion challenges. Vaccination with Vulnivaccine, a vaccine against V. vulnificus serovar E, cross-protected eels against serovar A. The LD(50) for experimentally infected vaccinated animals was significantly higher than for non-vaccinated animals.     

Mycoflora of the 'green water' culture system of tiger shrimp Penaeus monodon Fabricius

This study was conducted to quantify and characterize the mycoflora associated with the ‘green water’ culture system of Penaeus monodon. Samples of water, tilapia gut and mucus, and shrimp hepatopancreas from three shrimp farms were collected during 15, 30, 45 and 60 days of culture (DOC). Results showed that high fungal loads were observed in tilapia gut (total: 117–1352 colony forming unit (CFU) 5 cm hind gut^?1; yeasts: 0–136 CFU 5 cm hind gut^?1) and mucus (total: 12–311 CFU (5 cm²)^?1; yeasts: 0–88 CFU (5 cm²)^?1), while minimal fungal populations were observed in water samples (total: 0–110CFU mL^?1; yeasts: 0–5 CFU ml^?1). Shrimp hepatopancreas harboured a very low number of filamentous fungi (0–27 CFU 0.1 g^?1) and yeasts (0–7CFU 0.1 g^?1) especially at 60 DOC. The filamentous fungal isolates were dominated by Penicillium and Aspergillus species, while the yeast populations were dominated by Rhodotorula and Saccharomyces species. The dominance of these fungi on tilapia mucus and gut and their presence in the rearing water might play an important role in the overall mechanisms involved in the control of luminous Vibrio in the ‘green water’ grow‐out culture of P. monodon.