[Immunisation of fancy chickens against Newcastle disease]. / Zur Immunisierung von Rassehühnern gegen die Newcastle-Krankheit.

The German Regulation on Fowl plague which is in force since 1994 laid down that any chicken of all races and all hybrids must be vaccinated against Newcastle disease (ND) in a mode that an adequate immunity is achieved. Onset, duration, and resistance to challenge of immunity induced by vaccination is well documented in the scientific literature for hybrid chicken of the layer and meat types. These data prove also innocuity and efficacy of the registered vaccines. In contrast, only a few and incomplete data exist on the development of ND directed immunity in fancy chickens. The present study describes vaccinations of chickens of 14 different hobby breeds with live LaSota vaccine (conjunctival application of 10(6) embryo-infective dose50 per bird) and with an inactivated oil-emulsion vaccine (intramuscular application of 0.5 ml per bird) and subsequent intramuscular challenge infections using the highly virulent NDV strain Herts 33/66. Chickens of all 14 breeds tolerated the application of both vaccines. All fancy chickens reacted with the production of serum antibodies which were measured in the haemagglutination inhibition (HI) and virus neutralisation (VN) tests. According to the scientific literature, maximal antibody levels are reached in hybrid chickens between day 10 and 20 post vaccination. In contrast, in fancy chickens the antibody maxima are delayed to the seventh to eighth week post vaccination. All fancy chickens vaccinated either once with live LaSota virus or with live and inactivated vaccines resisted challenge with the highly virulent Herts 33/66 strain of NDV and did not develop any signs of disease. There are indications for gradual differences in susceptibility of different breeds of fancy chickens. The levels of non-specific neutralisation as measured in the virus neutralisation test differ between breed. Also, the viral content in tissues obtained from non-vaccinated but challenged birds differ markedly. It is concluded from the results of this study that fancy chickens can also successfully protected against Newcastle disease by using live and inactivated vaccines which are licensed for hybrid chickens. However, the optimal time for the detection of maximal antibody levels in fancy chickens is reached seven to eight weeks post vaccination.

Response of domestic geese to lentogenic and velogenic strains of Newcastle disease virus.

A total of 54 domestic white meat-type geese were included in vaccination/challenge trials to evaluate susceptibility to disease and humoral immune responses using the haemagglutination inhibition (HI) and virus neutralization (VN) tests against Newcastle disease (ND). Two groups of twenty geese, five weeks of age, were conjunctivally vaccinated with either 100 x 10(6) or 2.5 x 10(6) EID50 (egg infectious dose 50 per cent) per bird of live La Sota virus, respectively, and 14 geese remained unvaccinated. At 15 weeks of age all vaccinated geese and seven unvaccinated geese were subcutaneously injected with 0.5 ml of inactivated oil emulsion ND vaccine, whereas seven geese remained as negative controls. At an age of 20 weeks, all 54 geese were challenged with 10(8.0) EID50 per bird of the viscerotropic velogenic NDV strain Herts 33/56. Live virus application as well as the oil emulsion vaccine did not induce discernible clinical signs and have no detrimental effect on body weight gains. At days 1, 3, 5, 8, 13, 16, 20, 23 and 27 after the application of lentogenic vaccine pharyngeal and cloacal swabs were taken, after challenge samples were taken at days 2, 5 and 8. Lentogenic as well as velogenic virus were never reisolated. Low and shortlived antibody responses post vaccination were equally well measured in HI and VN tests. Only two out of seven unvaccinated but challenged geese developed signs of ND whereas all vaccinated/challenged geese remained normal but developed high to moderate levels of HI and VN antibodies. Since domestic geese do not readily excrete NDV's in detectable amounts and since they do not contain detectable amounts of the challenge virus fourteen days post challenge in their tissues the assumption is promoted that geese do not play a major role in the epidemiology of Newcastle disease.

Ferrioxamine E-supplemented pre-enrichment and enrichment media improve various isolation methods for Salmonella.

Supplementation of pre-enrichment broth and enrichment broth media with ferrioxamine E (1 microgram/ml) significantly improved the recovery of Salmonella from artificially or naturally contaminated foods. Based on the selectivity of ferrioxamine E, Salmonella enteritidis and S. typhimurium could be isolated also from various mixed cultures (one Salmonella cell in 10(3)-10(4)-fold concentration of cells of competitors) by shaking for 6 h in supplemented buffered peptone water followed by cultivation on XLD- or XLT-4 agars. Isolation of Salmonella from these pre-enrichment cultures by use of Dynabeads-Anti-Salmonella was highly effective. 27 S. typhimurium strains were isolated from 762 naturally infected chicken giblets by use of unsupplemented Tetrathionate broth. However, 33 S. typhimurium isolates were obtained with ferrioxamine E-supplemented Tetrathionate broth from the same samples. Three Salmonella isolates out of 50 evenly divided meat meal samples were obtained by use of ferrioxamine E-supplemented buffered peptone water followed by direct streaking onto XLD- and Rambach agars, no Salmonella isolates could be detected by the conventional method.

[Immunizing against salmonella infections with live and inactivated vaccines]. / Immunisierung gegen Salmonella-Infektionen mit Lebend- und Inaktivat-Vakzinen.

A live attenuated auxotrophic S. typhimurium (S. tm.)-mutant was used by orally administration via drinking water several times during rearing, combined with 1- or 2-times parenteral injection of an autogenous S. enteritidis (S. e.)/S. tm.-oil emulsion vaccine. In a 8-month period, more than 500,000 birds were vaccinated. The vaccine was safe. Challenge test showed protection in the vaccinates and their offspring. The number of isolates in the farms detected by regular monitoring decreased. The protection of the live-culture mutant lasted about only 8 to 10 weeks. A. S. tm.-mutant more potent for chickens will be tested now. We consider vaccinations as one important factor in a salmonella control program, especially for commercial layers and broiler breeders.

[Vaccination against infectious anemia of poultry (CAA)--results of field studies]. / Impfungen gegen die Infektiöse Anämie des Geflügels (CAA)--Ergebnisse von Feldversuchen.

Infectious anemia of poultry is a disease of high economical significance. Connatal infection of chicks with the chicken anemia agent (CAA) via the embryonated egg causes anemia along with severe immunosuppression, thus rendering the chicken susceptible for secondary infections. In order to prevent infection of young chicks, it is necessary to induce immunity against CAA in parent flocks, with the aim to prevent connatal spread of the infection and provide maternal protection for baby chicks. In this publication, the efficacy and use of a live CAA vaccine is reported. From autumn 1986 until summer 1990, 3 experimental vaccine charges were applied in 85 broiler parent flocks with totally 3.1 million chickens. In addition, totally 293,000 broiler breeder and 171,000 layer breeder chicken were vaccinated in 1989/90. The vaccine was administered between the 13th and 19th week of life by drinking water without adverse effect to the birds. Chicken anemia symptoms were observed only at the begin of laying period in two parent flocks. These flocks had been vaccinated in the 17th and 19th week, respectively. The offsprings of all other vaccinated parent flocks remained free of chicken anemia. Day-old chicks derived from vaccinated parent flocks were protected against CAA challenge infection. It is emphasized, that vaccination should be performed within the 13th to 15th week of life, because according to our observations, this will lead to an immediate seroconversion.

[The occurrence of a reovirus variant in a German broiler flock]. / Zum Aufreten einer Reovirus-Variante in deutschen Broilerbeständen.

Broilers deriving from a parent flock, which had been effected in the 6th. month of hatching egg production, show arthritis beginning with the 12th day of life. The tarso-metatarsal joint has been affected. Birds show stunting. Body weights at slaughter and feed conversion of the affected flocks were reduced. The percentage of condemned birds before slaughter was highly increase and came up to 3-5%. Chickens of other breeder flocks, which were reared with the diseased birds, showed viral arthritis at an age of 18-20th day of life. The boilers derived from parent flocks which had been vaccinated twice during the with a 1133 reo live vaccine and before laying with an oil based vaccine of the antigen type WVU. A reovirus has been isolated (isolate K 171/87), which caused viral arthritis in 1133-immune day old chicks after parenteral and oral application. Infection of these chickens with the pathogenic reovirus of the antigen type 1133 didn't cause a disease. Also by serological examinations it was shown, that the reo-isolate K 171/87 possesses a different antigenicity. The kind of occurrence indicates, that this reovirus infection has been transmitted vertically from one parent flock and it spread laterally to chickens of other parent flocks in broiler farms.

Anaemia-dermatitis of broilers: field observations on its occurrence, transmission and prevention.

Anaemia-dermatitis was first observed in German broiler flocks in 1977. Its frequency has increased in the past six years. Atrophy of thymus, bursa and bone marrow occur and are affected by a severe anaemia and immunosuppression. Secondary bacterial infections of the skin cause gangrenous dermatitis. Systematic investigations of outbreaks in two broiler integrations showed the syndrome to occur only in the offspring of young broiler breeders during the first 3 to 9 weeks of production. Anaemia could be reproduced experimentally in CAA-antibody negative SPF birds by injecting a bacteria-free filtrate of organ homogenates of diseased birds; birds kept in contact with the inoculated chicks remained healthy. It is concluded that anaemia-dermatitis is primarily caused by the chicken anaemia agent (CAA). Vertical transmission via hatching egg predominates with no evidence of horizontal transmission. In order to prevent egg transmission of CAA immunisation during rearing is indicated for breeder stocks.

Differential expression of endogenous virus glycoprotein in fibroblasts and sera of some adult chickens.

A rapid and convenient assay for the expression of endogenous retrovirus glycoprotein in adult chickens has been developed based on the enzyme-linked immunosorbent assay (ELISA) principle. This method has been standardized using the conventional chick helper factor test. In the course of establishing this method with a large number of specific pathogen-free (VALO) chickens, an interesting diversity became apparent; about 20% of the birds which, according to chick helper factor tests performed with feather follicle fibroblast cultures were negative for endogenous virus glycoprotein expression, exhibited relatively high titres of reactive glycoprotein in serum. However, in no case was a chick helper factor-positive animal negative in serological tests. The possibility of endogenous virus antigen expression which either cannot be detected in fibroblasts, or is incapable of functioning in the chick helper factor complementation, is discussed.

Evaluation of a vaccine against infectious bursal disease in field trials.

It has been established in field trials that the mutant strain Cu-1M of the infectious bursal disease virus can be used for vaccination against the disease. Vaccination does not cause clinical signs or significant pathological alterations in the Bursa of Fabricius, and consequently it is not accompanied by immunosuppressive effects. In the proposed vaccination scheme maternally derived antibodies do not interfere with the establishment of immune protection in young chickens.

[Potency tests with HVT-, MHV- and JMV vaccines against Marek's disease]. / Wirksamkeitsprufungen mit PHV-, MHV- und JMV-Vakzinen gegen die Marek'sche Krankheit.

Turkey herpesvirus (HVT)(FC 126) vaccine made in W. Germany, Marek's herpesvirus (MHV) (CVI 988) vaccine used in the Netherlands and experimental JMV vaccine were tested in laboratory and field trials for protection against Marek's disease. The tests were carried out with 780 SPF chicks and 3200 commercial white Leghorn chicks (with maternally derived antibodies to HVT and MHV). There were no differences in potency of HVT- and MHV vaccines. Both vaccines showed increased protection with an increased interval between vaccination and challenge. A significant protection (> 80%) resulted with both vaccine viruses after the 8th day following vaccination. JMV vaccine (embryo-adapted strain JMV-A-164) provided a 40 to 60% protection against Marek's disease depending on the time of challenge. However, there was a complete protection against the highly pathogenic JMV tumour cell inoculum. Hyperimmunisation of adult birds with JMV vaccine did not reduce the mortality in their progeny from Marek's disease.

Comparative tests on safety and potency of IBA vaccines.

During a comparative test on the pathogenicity and immunogenicity of a non-adapted and an embryo-adapted IDA virus, following observations were made: 1) the non-adapted virus remained pathogenic as determined by weight loss and bursal lesions. Clinical signs and mortality did not occur. A change in the virulence did not occur during back passages; 2) the immunosuppressive effect of the non-adapted virus was diminished by maternal antibodies; 3) the embryo-adapted virus produced little pathogenicity as demonstrated by minor weight depressions. The vaccinated birds had no recognizable pathological lesions in the bursae. Immunosuppression with this virus was not observed; 4) the embryo-adapted strain was able to induce neutralizing antibodies in birds with or without maternal antibodies. However, precipitins were not detected; 5) immunization with the embryo-adapted strain after 8 days of age was protective whereas prior to that age it was not confirming the age susceptibility factor reported by Hitchner (1971); 6) no change in virulence occurred during back passages with both test materials.