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Isolation of etiological agent of hydropericardium syndrome in chicken embryo liver cell culture and its serological characterization.

The virus causing hydropericardium syndrome was isolated in chicken embryo liver (CEL) cell culture from livers obtained from naturally infected broilers. The cytopathic effects characterized by rounding and degeneration of cells were visible 36 hr post infection in first passage. At 4th passage level, the infectivity titre was 5.24 log10 TCID50/ml. In May-Grunwald and Giemsa stained cells, basophilic intranuclear inclusions ('bird eye' inclusion), typical of aviadenovirus infection, were observed. The specificity of inclusion was confirmed by indirect immunofluorescence. Various serological tests, such as agar gel precipitation test, counter immuno electrophoresis, micro serum neutralization test and enzyme linked immunosorbent assay were also standardized to confirm the isolation of etiological agent of hydropericardium syndrome in CEL cell culture and to diagnose the disease in poultry.

Adenoviridae Infections↗

Properties of a chicken lymphoblastoid cell line from Marek's disease tumor.

Properties of a chicken lymphoblastoid cell line (MSB-1) from a Marek's disease tumor were studied. The cell line grew well at 41 degrees C in medium RPMI-1640 supplemented with 10% bovine fetal serum and had a doubling time of 8-12 hours. Cells grown in stationary suspension culture did not attach to the vessel and had the morphology of typical lymphoblasts. At 37 degrees C, the cell line grew initially but ceased to divide after several subcultures. In the subcultures maintained for 48-72 hours, 1-2% of the cells produced Marek's disease virus (MDV)-specific intracellular and mambrane antigens and contained herpesvirus particles when examined by the electron microscope. Cocultivation of these cells with duck or chicken embryo fibroblast cultures resulted in transfer of infection and production of microplaques typical of MDV. Peripheral nerve lesions and lymphoid tumors characteristic of Marek's disease were caused by inoculation of susceptible chicks with MSB-1 cells or duck cells infected with strain BC-1 of MDV recovered from the MSB-1 cell line. No specific tumors were produced at the site of inoculation, and infection was readily transmitted to cagemates. Tumors were also produced in the skeletal muscles and seemed to be largely virus induced. MSB-1 cell line was free of C-type virus particles.

Animals↗

Pathogenic and serologic studies of Japanese quail infected with JM strain of Marek's disease herpesvirus.

Japanese quail were inoculated with Marek's disease herpesvirus at 1 day of age, and a second group of the same age was infected by contact with inoculated quail. A third group raised in our laboratory as a source of hatching eggs was accidentally infected with Marek's disease (MD). All quail were observed and examined for periods up to 360 days; the usual clinical signs of MD were not observed. However, the birds were susceptible to MD infection because of the evidence that: 1) The MD-specific agar gel-preceipitation (AGP) antigen was found in the feather tips or feather follicular epithelium of some of them; 2) the MD-specific AGP antibody was found in 6 of 57 exposed to MD; and 3) the virus was recovered from 4 MD-exposed birds by subpassage of their kidney cultures into quail embryo fibroblasts. The specificity of the AGP antigen or antibody in MD-infected quail was examined by the line of identity and cross-absorption tests. The antigen specificity was tested against similar to 700 sera from chickens and quail. Although most of these sera reacted with quail-positive antigen (QPA) prepared from MD-infected quail, some sera from infected or uninfected normal chickens reacted nonspecifically with QPA and with an antigen prepared from normal quail. By gel filtration on Sephadex G-150, the specific antigenic component could be separated from the nonspecific component(s) in QPA.

Animals↗

Investigation of a chronic feed-passage problem on a broiler farm in northwest Arkansas.

A commercial broiler farm with a history of poor feed conversion and chronic feed-passage problems was chosen for investigation. Chickens were taken from the broiler flock at specified intervals during growout and tested by virus isolation and enzyme-linked immunosorbent assay (ELISA) for avian reovirus. Abnormal tissue pathology was first seen in the broilers at 9 days of age and continued sporadically throughout the growout period. Antireovirus antibody levels began to increase at 24 days of age. Avian reovirus and avian adenovirus was recovered at different intervals starting at 17 and 31 days of age, respectively. One-day-old specific-pathogen-free chicks housed in filtered-air positive-pressure isolation units were inoculated with two inocula recovered from the field study. Avian reovirus was recovered from the tissues of both treatment groups using chick kidney cells. Significant weight differences were seen in one of the two treatment groups. This avian reovirus was given the name SS-412.

Animals↗

Influence of sampling methodology on reported incidence of Salmonella in poultry.

Salmonella is a major pathogen associated with poultry food products. Over the past 20 years, pressure to reduce human illness from poultry-related salmonellosis has resulted in intensive research activity as well as stronger regulatory standards in Europe, North America, and, because of international trade policies, throughout the world. In the United States, implementation of a Hazard Analysis Critical Control Point-based inspection program has been credited with reducing the incidence of Salmonella-positive carcasses from approximately 20 to 10%. Since 1998, however, the reported incidence of Salmonella in retail poultry from 12 countries implementing similar pathogen reduction programs, including the United States, has averaged 29% positive for Salmonella. Although these reports examined products at retail outlets and used a variety of sampling methodologies, these results appear to contradict the U.S. Department of Agriculture claims for Salmonella reduction. The purpose of this review is to examine this contradiction with a focus on the potential impact of sampling methodology on reported incidences of Salmonella.

Animals↗

Rapid diagnosis of avian influenza (AI) and assessment of pathogenicity of avian H5 and H7 subtypes by molecular methods.

Avian influenza (AI) is a highly contagious viral disease of poultry that is found worldwide. There are two forms of AI: a mild form called low pathogenicity avian influenza (LPAI), and a severe form called highly pathogenic avian influenza (HPAI). HPAI is associated with the H5 and H7 subtypes of AI virus (AIV) and is subject to Federal control and International reporting. A real-time reverse transcription-polymerase chain reaction (rRT-PCR) assay has been developed and validated that can help in the early detection of AI outbreaks. The rRT-PCR assay can also be used to identify infections caused by H5 and H7 subtypes of AIV New isolates of AIV must be characterized as LPAI or HPAI for reporting and control purposes. The criteria for classification of an AI virus as HPAI are defined by the World Organization for Animal Health (OIE); the definition includes a virulence and a molecular criterion. The virulence requirement for HPAI is defined as an AIV killing 75% or more of eight inoculated chickens within 10 days. The molecular criterion is the presence of multiple dibasic amino acids at the proteolytic cleavage site of the haemagglutinin (H) protein. All HPAI viruses isolated before 2002 fulfilled both the virulence and molecular criteria. Consequently, nucleotide sequencing of the H gene and deduction of the amino acid motif at the H cleavage site has been successfully used to assess the virulence of H5 and H7 AIVs rapidly. Since 2002, however, there have been three outbreaks of HPAI where the viruses responsible for the outbreaks have either fulfilled the virulence criterion or the molecular criterion, but not both.

Amino Acid Sequence↗

[Mark's disease: V. Experimental behavior of 3 isolates taken place in the country].

Three experiments were designed to determine the parameters of virus infection, antibodies and mortality with three different MD isolates inoculated in one day old birds from commercial origin. The animals were divided in three inoculated lots (1-2-3) and three control groups (4-1, 4-2, 4-3) and were followed weekly from hatching through 17 weeks. The former were inoculated respectivelly with FOV-6, FCV-8 and FCV-9. Each day old bird received between 50-75 FPU/bird by I.P. route. Samples were taken from circulating blood of five birds by cardiac puncture with an heparinized syringe (20 U/ml), were centrifuged and the white cells inoculated to 5-15 four day old embryos by yolk salk route for virus detection; plasma was assayed by immunodiffusion against MD antigen in order to detect precipitating antibodies, and mortality was recorded after microscopical examination. Infection appeared to persist indefinitelly in the host chicken flock and coexist with (100%) precipiting antibodies, (Fig. 1-2-3). First virus isolation was accomplished after 4 weeks post-inoculation and the 100% porcentage of antibodies, was found only 1-3 weeks after the first peak of viraemia. With the most pathogenic isolate FCV-6 (ig. 1) the antibody response was significantly delayed. Maternal antibodies decreased more rapidly in inoculated than in control birds. Accumulative mortality showed isolate FCV-6 and FCV-8 as pathogenic strains and FCV-9 strain as less pathogenic. Mortality begun 1-3 weeks after the first peak of virus detection in the flock, independently of the pathogenic pattern of the isolate, but frecuencies of death were markedly different.

Animals↗

Pathogenicity for chicks of line cells from lymphoma of Marek's disease.

Pathogenicity for chicks of the MSB-1 line, a cell line derived from the tumorous tissue of a chick with Marek's disease (MD) and established by Akiyama & Kato, was studied. Five groups, including a control one, of 20 chicks each were inoculated with 1 X 10(3), 1 X 10(4), 1 X 10(5), 1 X 10(6) and no cells of a 180-day culture of the cell line at one day of age. They were housed all together in an isolation unit. An attempt was first made successfully to isolate MD virus (MDV) directly in culture of kidney cells 3 weeks after inoculation. Horizontal infection was first detected 4 weeks after inoculation. From 3 weeks after inoculation on, the disease with almost the same clinical and pathological pictures as the infection with a virulent strain of MDV showed a high incidence. Morbidity was closely related to the number of MSB-1 line cells inoculated. Parenchymal destruction was conspicuous in the central lymphoid organs of four chicks given the largest number of MSB-1 line cells and sacrificed in extremis about 4 weeks after inoculation. Establishment of MD in chicks inoculated with MSB-1 line cells carrying MDV genome seemed to be initiated under the circumstances where the line cells which had come into contact with susceptible cells in the peritoneal cavity released virulent MDV per se. Then host chicks might be infected with MDV and suffer from MD at a high rate. There was no great difference in oncogenic potential between MSB-1 line cells cultivated in vitro for 180 days and virulent MDV serially passaged through one-day-old chicks.

Animals↗

Use of electrocardiographic analysis for investigation of ascites syndrome in broiler chickens.

This study was conducted (at high altitude [1969 meters]) to determine whether chicks predisposed to cardiac failure and ascites could be identified and followed during growout with non-invasive electrocardiographic (ECG) techniques. ECG recordings were made on 40 chicks at 1 week of age. All recordings were analyzed by quantifying the amplitude in millivolts of the R-, S-, and T-waves in each of the recordings. During the study, ascites-related mortality was 40%, with the majority of the deaths occurring between 5 and 8 weeks of age. Chicks exhibiting moderate-to-severe right ventricular hypertrophy, as identified by ECG analysis at 1 week of age, were predisposed to development of ascites. Thus, the variability in ascites-related mortality observed in field cases may be directly related to the number of predisposed chicks at the time of placement in the broiler house.

Animals↗

Induction of oral lesions in broiler chicks by supplementing the diet with copper.

Copper sulfate was added to the diet of broiler chickens from 1 day to 3 weeks of age at the rate of 0.05% to 0.20% in order to evaluate its influence on the incidence of oral lesions. Both the incidence and severity of oral lesions showed a significant linear increase as the concentration of copper sulfate increased. Adding a level of sulfate equivalent to that produced by the highest level of copper sulfate failed to induce oral lesions. The severity of gizzard erosion also increased as the concentration of copper increased. Dietary copper sulfate supplementation should be considered a possible cause of oral lesions seen during the necropsy of avian species.

Animal Feed↗

[The "Vaccination Reaction" syndrome of broilers after vaccination against Newcastle disease and infectious bronchitis (author's transl)].

In a part of the broiler flocks vaccinated against Newcastle disease (N.C.D) and infectious bronchitis (I.B.), disease symptoms of lingering nature have been observed, generally in the second half of the rearing period. In a practical investigation with weekly examinations of chickens, supplemented by a serological examination of twenty-four animals per flock at the age of six weeks, it was hoped to establish the factors responsible for this "vaccination reaction". In the district under notice the vaccination reaction syndrome had been responsible for widspread abandoning of twice spraying against N.C.D. in the first and fourth week in favour of drinking-water vaccination (generally combined with I.B. vaccination) in the second week and spray-vaccination in the fourth week or of combined drinking-water vaccination in the second week, either with or without N.C.D. drinking-water vaccination in the fourth week. Admittedly the incidence of vaccination reaction in flocks vaccinated exclusively via the drinking water was less frequent (32%) than in flocks in which the second vaccination was administered as a spray (48%), but this difference was largely accounted for by infection with Mycoplasma gallisepticum and/or Mycoplasma synoviae, complicated by infection with Escherichia coli. Of the thirty-three flocks free of mycoplasmosis, 24% exhibited the vaccination reaction, while the incidence to the fifteen infected flocks was 73.4%. In flocks infected with mycoplasmosis the course of E. coli infections was serious in 46.7% of the birds, while this figure was 18.2% in flocks free of mycoplasmosis. In flocks free of mycoplasmosis, the percentage of serious E. coli infections was lower after spray vaccination (14.3%) than after drinking-water vaccination (21%). The strains of E. coli brought in by one-day chicks from the hatchery disappear rapidly and play no role of any significance in the problem of colibacillosis observed at an age of three weeks or older. Of the 310 isolated strains of E. coli, 52 could not be typed and the others belonged to eighty different serotypes. With respect to the effect of infectious bronchitis the investigation does not provide sufficient evidence to permit of drawing conclusions. A significant role in the occurrence of the syndrome was played by coccidiosis and Gumboro's disease. With respect to environmental factors the available data did not allow of drawing conclusions. The authors recommend continuing with all available means to free the breeding animals from M. gallisepticum and M. synoviae, undertaking scientifically based research into the role of infectious bronchitis in the "vaccination reaction" syndrome, an effective programme of hygiene to control E...

Aerosols↗

Vaccination by the non-parenteral route of virus disease in the veterinary field.

After a brief reference to the importance of the non-parenteral route of vaccination of domestic animals in general, the author deals, for each animal species separately, with the most important vaccines utilised by this method of administration. On the basis of bibliographical data, he describes the history of this use, discusses the results of the application in the field and draws the relative conclusions.

Administration, Oral↗

Inoculation experiment of Marek's disease vaccine contaminated with a reticuloendotheliosis virus.

Two-day-old chicks were inoculated with one or ten doses of Marek's disease (MD) vaccine originated from the herpesvirus of turkeys (HVT) and contaminated with a reticuloendotheliosis virus (REV). As a result, they presented such symptoms as abnormality in the vane of remiges, undergrowth, anemia, and leg paralysis. These symptoms were the same as those induced by the same vaccine among chicks in the field. Control chicks which had been placed in the same house as those inoculated with the vaccine exhibited no abnormal signs. A persistent infection with REV was noticed in the vaccine-inoculated group. A horizontal infection with REV was the highest in the control group, which was followed by the group inoculated with one dose and that inoculated with ten doses in the order listed. The antibody response of chicks to HVT and MD virus was also inhibited by REV.

Animals↗