The production of antibodies (Abs) in chickens and the extraction of specific Abs from egg yolk (IgY Abs) are increasingly attracting the interest of the scientific community, as demonstrated by the significant growth of the IgY literature. This review offers detailed and comprehensive information about IgY-technology, including: a) possibilities for hen keeping in accordance with the Three Rs principles; b) new insights into the IgY transfer mechanism from blood to yolk as a biological basis for the technology; c) the comparative characteristics of IgY Abs and IgG Abs; d) the high efficacy of the technique, in view of the extraordinary amount of IgY Ab produced by one hen in one year (between 20g and 40g IgY in total); e) comparisons between the efficacies of IgY Abs and IgG Abs (rabbit, sheep, mouse) in several immunological assays; f) immunisation protocols, as well as the most commonly used IgY-extraction procedures; g) new possibilities for application in human and veterinary medicine, including strategies for the treatment of Helicobacter pylori infection or fatal intestinal diseases in children, particularly in poor countries, for reducing the use of antibiotics, and, in Asia and South America, for producing Abs against snake, spider and scorpion venoms; and h) the use of IgY Abs in various fields of research, also taking into consideration recent developments in South America (particularly Argentina and Cuba) and in Asia.

Faeces samples were collected from 302 untreated calves on the day of onset of diarrhoea and from 49 healthy calves at 32 farms experiencing outbreaks of diarrhoea. At least four diarrhoeic calves were sampled on each farm, and samples were examined for rotavirus, coronavirus, cryptosporidium, enterotoxigenic Escherichia coli and Salmonella species. Although all these enteropathogens were excreted more frequently by the diarrhoeic than by the healthy calves, the difference was significant overall only for rotavirus. Rotavirus was excreted by 18 per cent of healthy calves, coronavirus by 4 per cent, cryptosporidium by 14 per cent, and no enterotoxigenic E coli or Salmonella species were detected. The most common enteropathogen in diarrhoeic calves was rotavirus, which was excreted by more than half the diarrhoeic calves on 18 farms. Coronavirus was excreted at a similar high prevalence on one farm, cryptosporidium on five farms and enterotoxigenic E coli on three farms. Concurrent infection with two or more microorganisms occurred in 15 per cent of diarrhoeic calves. There was no difference in the isolation rate of campylobacters between diarrhoeic and healthy calves.

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Seventeen complicated outbreaks of infectious coryza in layer, broiler-breeder, and broiler flocks were studied. In the layer flock outbreaks, drops in egg production of up to 35% were seen. In the broiler flocks and several of the layer flocks, losses due to persistent mortality and/or culling varied between 2 and 5%. Signs of infectious coryza in both layers and broiler-breeders were typical; in broilers, however, swollen head-like syndrome was seen. Except in one flock, no viral diseases were clinically or serologically detected. Excluding broiler-breeders, birds from most other flocks were serologically positive for Mycoplasma gallisepticum, and some were also positive for M. synoviae. Haemophilus paragallinarum was isolated from all of the outbreaks, but only as a pure culture in three outbreaks. Isolation of H. paragallinarum from sites such as liver, kidney, and particularly tarsal arthritis and ocular globes appears to be reported for the first time. Serovar A was isolated in eight outbreaks, serovar B in six, serovar C in one, and untypable serovars in two. The severity of these infectious coryza outbreaks may have been increased by concurrent salmonellosis, pasteurellosis, and mycoplasmosis, although under certain conditions H. paragallinarum is able to cause septicemia. Ten of the outbreaks occurred in birds vaccinated against infectious coryza; this may be due to the use of vaccines that do not provide protection against the types of H. paragallinarum that affect poultry in the region.

Enterococcus avium isolated from Apis mellifera beebread produces a thermoresistant bacteriocin with a strain-dependent inhibitory effect on Listeria and without effect on gram-negative bacteria. The bacteriocin appeared to be a polypeptide of about 6 kDa. Genetic analyses revealed no extrachromosomal material in E. avium.Our general objective is to characterize and select lactic acid bacteria (LAB) that may be of probiotic relevance (1-3). Beebread is processed pollen stored with the addition of various enzymes and honey, which is subjected to lactic acid fermentation (11) by LAB present in flowers, silage, and the environment. Enterococci have been isolated from vegetable matter, reptiles, and insects, but there are no references to these microorganisms associated with honeybees (9, 17). Since no previous studies of LAB associated with the common honeybee were found, we screened the Apis mellifera intestinal tract and beebread samples for these microorganisms.Enterococcus avium PA1 was isolated from Streptococcus selective medium (1) incubated at 37°C for 24 to 48 h and characterized by biochemical tests (8), by carbohydrate fermentation pattern (APICH50), and on the basis of its 16S rRNA sequences.Inhibition assays performed with E. avium PA1 cell-free supernatant (CFS) from brain heart infusion (BHI) broth were studied with the well diffusion assay (18). Twenty-three microliters of CFS was placed in wells cut in BHI agar plates previously seeded with the indicator strains (final concentration, ca. 1 ϫ 10 9 CFU ml Ϫ1 ). The plates were incubated at 25 to 30°C for 12 to 24 h and examined for inhibition halos. The inhibitory substance suspension titer was determined by serial twofold dilution and expressed in arbitrary units (AU) per milliliter (7). Indicator strains and their sensitivities to E. avium PA1 CFS at pH 5.5 are indicated in Table 1.The physicochemical nature of the antagonistic substance was determined by studying the anti-Listeria activity of the CFS at pH 5.5 heated to 121°C for 15 min in an autoclave and treated with proteolytic enzymes (trypsin, papain, ␣-chymotrypsin, and pepsin), catalase, and lysozyme. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis was performed with 20 l CFS mixed with 7 l of running buffer and heated at 100°C for 5 min (16). After 3 h electrophoresis at 65 V, gel was removed and assayed for molecular weight estimation and biological assay (4). Extrachromosomal material was also determined in E. avium PA1 cells (5).The mode of action of bacteriocin on nonproliferating L. monocytogenes cells was studied. An overnight culture of L. monocytogenes 01/198 in BHI broth was harvested by centrifugation, and cells were resuspended in phosphate buffer (0.05 M, pH 7.00) to a final concentration of ca. 10 9 CFU ml Ϫ1. A bacteriocin solution was mixed in equal amounts with the cell suspension and incubated for 2 h at 37°C. Counts of listeriae were determined on BHI agar (1.5%, wt/vol) incubated at 30°C for 24 h.The assays were performed in triplicate. Data were analy...

A search for bioactive compounds, inhibitors of Paenibacillus larvae, the causal agent of American foulbrood, a honeybees' disease, was carried on. Extracts of two fungal strains, Alternaria brassicicola and Alternaria raphani, isolated from pollen collected from beehives, exhibited a specific inhibitory activity against this bacterium. From these extracts and by means of chromatographic steps and bioassay-guided fractionation, three tetramic acids were isolated. The compounds were identified by spectroscopic methods and the absolute stereochemistry was chemically determined. L-Tenuazonic acid was shown to be responsible for the antibiotic activity. This compound showed a MIC of 32 lg/ml, comparable with that of oxytetracycline, an antibiotic currently used for the prevention of American foulbrood.q Dedicated to the memory of Dra Alicia M. Seldes.

Fowl typhoid is under control in poultry farms of developed countries, but it still endemically subsists in commercial laying hen farms of some countries. It has been demonstrated that Salmonella live vaccines can elicit cross-immunity against members of the same Kauffmann-White scheme serogroup. In this work, we explored the protection conferred by TAD Salmonella vac E, a live Salmonella enterica serovar Enteritidis vaccine, against fowl typhoid. Three groups of laying hens were vaccinated with different vaccination schedules starting on the first day of life, and afterwards were infected with 2 x 10(5) CFU of a virulent Salmonella Gallinarum strain, either at wk 28 or wk 52. Mortality, fecal shedding, and organ invasion of Salmonella Gallinarum were assessed. In this work we demonstrated that this Salmonella Enteritidis vaccine is able to cross-immunize against Salmonella Gallinarum. At wk 28, hens vaccinated with three oral doses or with two oral doses combined with one subcutaneous dose were protected by the vaccine. At wk 52, when hens were infected 36 wk after the final immunization, the vaccine was not able to confer protection. Thus, revaccination every 3 mo would be highly recommended. In countries where Salmonella Gallinarum subsists together with Salmonella Enteritidis, control programs should include vaccination of laying hens using safe attenuated Salmonella strains.

Malignant oedema is a fatal disease of several animal species, produced by one or more members of the Clostridium genus. We report here a case of malignant oedema in a 1-year-old Friesian sheep after a blood sample was collected from the jugular vein. Clostridium septicum and Clostridium sordellii were isolated from the lesions and also demonstrated by a fluorescent antibody test. This report stresses the need for maintaining a clean environment for animals and for strict hygienic measures during procedures that generate wounds, together with immunity acquired by proper vaccination, for prevention of malignant oedema.