A serological survey of domestic poultry in the united kingdom for antibody to chicken anaemia agent

A serological survey for antibody to chicken anaemia agent (CAA) was carried out by indirect immunofluorescence. Antibody to CAA was widespread in broiler breeders and in parent and commercial layers in the UK. Antibody to CAA was also detected in five of 11 specific pathogen-free (SPF) chicken flocks tested; positive flocks included those being used for vaccine production or as commercial suppliers of SPF eggs. No antibody to CAA was detected in turkey or duck sera. A longitudinal survey of two broiler breeder flocks showed that maternal antibody to CAA persisted until about 3 weeks of age. Both flocks began to seroconvert to CAA at 8 to 9 weeks and the majority of birds had antibody at 18 to 24 weeks.     

Egg transmission of a respiratory isolate of Mycoplasma synoviae and infection of the chicken embryo

Egg transmission of Mycoplasma synoviae (Ms) was demonstrated in broiler breeder birds of over 40 weeks of age from a commercial flock that had been infected during rearing and in birds experimentally inoculated before onset of lay. Infection of growing birds with Ms did not prevent egg transmission in adult life. The embryonated eggs of experimentally infected hens were less susceptible to infection by inoculation than those of specific pathogen-free birds. Some chicks with maternal antibody were found to be infected at hatching and in these maternal antibody was not mycoplasmacidal. Indeed by protecting the embryo maternal antibody may have promoted hatching of infected chicks.     

Influence of virus dose on experimental anaemia due to chicken anaemia agent

Intramuscular inoculation of susceptible 1-day-old chicks with graded doses of chicken anaemia agent (CAA) showed that the ability of CAA to produce anaemia was related to the dose of virus inoculated. Doses of CAA in excess of 10(5.75) TCID50 invariably produced anaemia but doses below 10(3.3) TCID50 produced anaemia in only a small proportion of inoculated chicks, even though most of these birds seroconverted to CAA and excreted enough virus to infect in-contact chicks. Virus spread from inoculated chicks to in-contact chicks was also less efficient using low doses of CAA. The implications of these findings for testing avian vaccines for contamination with CAA are discussed.     

Preliminary characterisation of isolates of chicken anaemia agent from the United Kingdom

Two isolates of chicken anaemia agent (CAA) were made from livers obtained from broiler flocks with runting stunting syndrome. Following primary isolation in SPF chicks, both isolates were propagated in MDCC-MSB1 cells. Both were resistant to heat and chloroform-treatment, and were antigenically related to the Cux-1 isolate of CAA by cross-immunofluorescence and cross-neutralisation tests. The isolates produced anaemia and characteristic lesions in 100% of experimentally inoculated 1-day-old susceptible chicks, but anaemia was observed in only 15 to 20% of inoculated 7-day-old chicks.     

Chicken anaemia agent: a review

Chicken anaemia agent (CAA) is a small, unclassified, icosahedral DNA virus with a single-stranded, circular genome. It seems to have a worldwide distribution. Only one serotype of CAA has been found, and all isolates investigated so far are pathogenic for young chicks. CAA causes a syndrome in chickens characterised by increased mortality, anaemia associated with atrophy of the haematopoietic tissues in the bone marrow, subcutaneous and intramuscular haemorrhages, and atrophy of the lymphoid system. CAA spreads both vertically and horizontally. Vertical transmission occurs following primary infection of in-lay breeding stock, and results in clinical disease in their progeny around 2 weeks of age. Horizontal spread usually results in subclinical disease. Both clinical and subclinical disease cause economic loss. Current control measures often involve controlled exposure of breeding flocks to CAA during the rearing period. A vaccine is indicated.     

Vertical transmission and clinical signs in broiler breeders and broilers experiencing adenoviral gizzard erosion

The present report documents an outbreak of adenoviral gizzard erosion in 22 broiler flocks in Germany. The clinical picture was characterized by uneven growth of affected broilers that resulted in considerably lower than average weight at slaughtering. Fowl adenovirus serotype 1 (FAdV-1) was isolated from gizzard lesions and histological examinations demonstrated FAdV-1-positive intranuclear inclusion bodies in gizzard epithelial cells of affected broilers by in-situ hybridization. Birds from all affected flocks originated from one broiler breeder farm. During production of affected birds, broiler breeders were between 27 and 32 weeks old. Enzyme-linked immunosorbent assay and specific virus neutralization assay of sera from parent birds demonstrated an acute FAdV-1 infection within the first 5 weeks of the production cycle. Clinically, broiler breeders exhibited a moderate fall in the hatchability of their chicks, while egg production remained normal. No further clinical signs could be observed. Genetically identical FAdV-1 strains were isolated from gizzards of embryos at the lowest point of hatchability and from affected broiler flocks raised on independent farms. For the first time, direct detection of viable FAdV-1 from gizzards of embryos and progenies of one FAdV-1-seropositive broiler breeder farm in the course of an outbreak of adenoviral gizzard erosion could be demonstrated, highlighting the importance of vertical transmission of this disease. Additionally, growth retardation and subsequent reduced average weight at the time of slaughter of broiler chickens underline the economic impact of adenoviral gizzard erosion for poultry production.     

Dot blot hybridization assay for chicken anemia agent using a cloned DNA probe.

A dot blot hybridization assay capable of detecting chicken anemia agent (CAA)-specific DNA in tissues from infected birds has been developed. The assay uses a 32P-labeled DNA probe prepared from cloned CAA-specific fragments representing the entire virus genome and has a sensitivity limit of between and 1 and 10 pg. DNAs from CAA isolates originating in the Federal Republic of Germany, Japan, the United States, the United Kingdom, and Australia were detected. Investigation of specimens from experimentally infected chicks indicated that virus-specific DNA was detected in the tissues of birds from 5 through 42 days after infection and that greater amounts were usually detected in the thymus than in the spleen, liver, feces, or blood. Tissues from specific-pathogen-free and broiler chicks which had become infected at an older age through contact with experimentally infected anemic chicks also contained CAA-specific DNA detectable by the assay. Thymuses from 1- to 2-week-old chicks from eight commercial broiler flocks which had been showing clinical signs characteristic of anemia-dermatitis syndrome were found positive by the hybridization technique, but thymuses from chicks obtained from broiler flocks which did not show such signs were found negative. Of the 35 positive samples (from 46 samples tested), 19 (54%) contained virus-specific DNA in sufficiently great amounts to permit 4-h autoradiography exposures and sample throughput times of 2 days. When compared with virus isolation, the CAA dot blot hybridization assay is time- and labor-saving.     

Aetiological examination of an outbreak of haemorrhagic syndrome in a broiler flock in Japan

The aetiology of an outbreak of haemorrhagic syndrome (HS) in a commercial broiler flock was examined. At a rearing farm, 596 of 6376 chicks (9.3%) in a flock were culled with depression and increased mortality from 12 to 26 days of age, with a peak at 16 to 19 days of age. Most of the affected chicks examined had haemorrhagic lesions of the muscles, atrophic changes of the lymphoid organs and aplastic bone marrow. Chicken anaemia agent (CAA) was isolated from the livers of all the 21 chicks examined. No fowl adenovirus was isolated. The present field case of HS coincides fairly well with the disease which is produced experimentally by CAA.     

Detection of antibody to chicken anaemia agent: a comparison of three serological tests

A comparison was made between sensitivities of the virus neutralisation (VN) test, indirect fluorescent-antibody (IFA) test and enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies to chicken anaemia agent (CAA). Sera from chickens inoculated with CAA at 11 weeks of age and from specific pathogen-free (SPF) and field breeder chicken flocks were tested. Seroconversion was detected by the three tests in all the inoculated birds at 2 to 3 weeks post-inoculation (pi). Neutralising antibody to CAA was still detectable in all the inoculated birds 37 weeks after infection, the end of the observation period. One of the seven inoculated birds tested by the ELISA gave positive results for the same period whereas the IFA test detected anti-CAA antibody only for 9 weeks. In field sera, the VN test detected many more positive sera than did the ELISA and IFA test. No antibodies to CAA were detected in sera of SPF chickens by the three tests. The IFA test frequently gave false positive results when VN antibody-negative sera were tested at dilutions of 相似文献   

Concurrent cryptosporidiosis and chicken anaemia virus infection in broiler chickens

Concurrent infection with Cryptosporidium baileyi and chicken anaemia virus (CAV) was observed in a flock of 8000 4-week-old broiler chickens. The birds, showing overt symptoms of stunted growth and 25% mortality from hatching to 4 weeks of age, harboured the protozoan in the epithelial cells of the bursa of Fabricius and the urodeal portion of the cloaca. This is the first report on an outbreak of avian cryptosporidiosis associated with CAV.     

Persistence and vertical transmission of chicken anaemia agent in experimentally infected laying hens

Irrespective of route of infection and age of hens at infection chicken anaemia agent (CAA) was excreted via faeces repeatedly during the first 5 weeks postinfection. Eggs, embryos and chicks of hens infected as chicks were free of CAA, but CAA was found in a small number of embryos and hatched chicks of hens infected during the laying period. Re-infection of hens resulted in shedding of CAA via the faeces for a period of 4 days, but no CAA was found in eggs, embryos and chicks. Immunofluorescent and serum neutralization antibody against CAA were demonstrated 2 weeks post-infection. They persisted for at least 6 months. Reinfection with CAA led to a significant increase of both immunofluorescent and serum neutralization antibody titres.     

Egg penetration by Campylobacter jejuni

Hens eggs were immersed in suspensions of Campylobacter jejuni (4 strains) and examined for penetration and infection. Penetration was demonstrated using an egg moulding technique and by culture. C. jejuni was recovered from shell membranes, but not from the albumin or yolk. Embryonic deaths were not significantly greater in test than control eggs. Unlike a strain of Salmonella virchow, which was used as a control, the C. jejuni strains did not survive for more than 6 hours after penetration. It is concluded that transmission of C. jejuni to broiler birds via eggs is highly improbable.     

Viral aetiology of haemangiosarcoma outbreaks among layer hens

Outbreaks of neoplastic disease defined as haemangiosarcoma occurred among layer flocks of chickens in Israel. The disease caused bleeding tumours in the skin and internal organs of young layers, followed by anaemia, cessation of egg production and high mortality up to 20%. Avian leukosis virus was isolated from tumour cells which contain several viral DNA copies integrated in the cell genome. The isolated virus induced haemangiosarcomas in more than 30% of birds inoculated on the day of hatching. Congenital transmission of viruses from tumour-bearing hens to their offspring was observed.     

Persistence of maternal antibody to chicken anaemia agent and its effect on the susceptibility of young chickens

Based on the incidence of anaemia, chicks derived from immune dams were shown to resist the parenteral challenge with chicken anaemia agent (CAA) until 14 days of age. Judging from thymic atrophy induced by the CAA-challenge, maternally-derived immunity of chicks against CAA infection persisted up to at least day 21. A very low level of maternal anti-CAA antibody seemed to be efficacious to the CAA-challenge. These results are discussed in relation to the significance of CAA anaemia under field conditions.     

Molecular characterization of the chicken anaemia viruses isolated from broiler farms of west Azerbaijan,Iran

Chicken anaemia virus (CAV) is an economically important pathogen of chickens with worldwide distribution. CAV is the causative agent of chicken anaemia disease, causing severe anaemia, lymphoid atrophy and immunosuppression in young birds. In the present study, the genetic variation of circulating CAVs in west Azerbaijan broiler farms was investigated and compared with CAVs from other countries. Extracted viral DNA from livers of chickens positive for CAV (46 out of 100) was used and a fragment of the VP1 gene 1390 base pairs in size was amplified. The purified products were subjected to restriction fragment-length polymorphism (RFLP) using HinfI endonuclease and nucleotide sequencing. Four different RFLP patterns were identified from all examined CAV DNAs. Sequence analysis of the VP1 gene of isolated CAV viruses revealed a high genetic distance (0.5 to 4.7%) among CAV isolates. Phylogenetic analysis showed that CAVs isolated from Iranian poultry farms clustered with CAVs isolated from different parts of the world. It was concluded that the circulating CAVs in broiler farms of west Azerbaijan had a high genomic variation.     

Blue wing disease of chickens: Experimental infection with a Swedish isolate of chicken anaemia agent and an avian reovirus

Isolates of an avian reovirus and chicken anaemia agent (CAA) from a field case of blue wing disease (BWD) in Sweden were inoculated into groups of SPF, one-day-old chicks as follows: Expt 1, an organ suspension from the field case; Expt 2, a selected non-purified reovirus isolate grown in chicken embryo liver cells. Expt 3, a plaque-purified reovirus strain; Expt 4, the CAA isolate from the organ suspension and Expt 5, a combination of reovirus (from Expt 3) and CAA (from Expt 4). The inoculations were given intraperitoneally.In a sixth experiment the isolates were given intramuscularly. The chicks in Expts 1, 2, 5 and 6 became ill after two weeks, and several birds died or were killed when moribund between 13 and 22 days of age. These birds had lesions similar to those found in field cases of BWD, i.e., atrophy of the thymus and the bursa of Fabricius and petechial haemorrhages in the skin. All of them had atrophie bone marrow. The chicks inoculated with the cloned reovirus strain (Expt 3) or CAA alone (Expt 4), did not show any apparent signs of disease. In Expt 4, lesions were found in the thymus, bursa of Fabricius, and bone marrow but to a less severe degree. In Expts 1, 2 and 5 both the reovirus and the CAA were successfully reisolated.     

Experimental infection of broiler breeder hens with the intestinal spirochaete Brachyspira ( Serpulina ) pilosicoli causes reduced egg production

The pathogenic potential of the anaerobic intestinal spirochaetes Brachyspira ( Serpulina ) pilosicoli and Brachyspira innocens was evaluated in adult chickens. Thirty 17-week-old Cobb broiler breeder hens were individually caged in three groups of 10 birds. Control birds (group A) were sham inoculated with sterile broth medium. Birds in the other two groups (groups B and C) were inoculated, respectively, with an isolate of B. innocens or of B. pilosicoli . Birds were monitored daily, and killed at 41 weeks of age. Infection had no consistent effect on body weight gain, but inoculation with B. pilosicoli resulted in a transient increase in faecal water content. B. innocens infection had no effect on egg production, but B. pilosicoli infection caused a delayed onset of laying, and a highly significant reduction in egg production over the first 11 weeks of lay. This study confirms that B. pilosicoli can cause serious egg production losses in adult chickens, while B. innocens is not obviously pathogenic.     

Prevalence and disease association of intestinal spirochaetes in chickens in eastern Australia

Faecal samples (n = 1786) from chickens in broiler breeder (n = 28), layer (n = 22) or broiler (n = 19) flocks in the eastern states of Australia were cultured for intestinal spirochaetes. Overall, birds in 42.9% of broiler breeder and 68.2% of layer flocks were colonized with spirochaetes, but no birds in broiler flocks were infected. Colonization rates in infected flocks ranged from 10 to 100% of birds sampled. Faeces from colonized flocks were on average 14% wetter than those from non-colonized flocks. There was a highly significant association between colonization with spirochaetes and the occurrence of wet litter and/or reduced production. A subset of 57 spirochaete isolates from birds in 16 flocks were identified to the species level using a panel of polymerase chain reaction tests. Isolates from nine (56%) of these flocks were spirochaetes that are known to be pathogens of poultry: Serpulina pilosicoli was isolated from birds from five flocks, birds from two flocks were infected with Serpulina intermedia, and in two other flocks both species were identified. Isolates from the other seven flocks belonged to other Serpulina species, which are currently of unknown pathogenicity. This study indicates that infections with intestinal spirochaetes are a common but currently under-diagnosed cause of wet litter and/or reduced egg production in broiler breeder and layer flocks in Australia.     

A myopathy associated with protozoan schizonts in chickens in commercial farms in peninsular Malaysia

A myopathy associated with elongated intramuscular protozoan schizonts of uncertain classification was observed in chickens in commercial farms. Of 152 affected fowls originating from 21 flocks in 12 farms, 149 were 24 weeks of age or older and 136 were broiler breeder birds. Both sexes were affected. The disease was only observed during the months of October, November and December, 1976 and 1977. The monthly mortality rate in affected adult flocks rose by 0.5% to 4% and the egg production declined by 5% to 15% during this period. Most affected birds were in good body condition or overweight. Gross lesions were usually present in all skeletal muscles and the cardiac muscle. They resembled nutritional myopathy, sarcosporidiosis, leucocytozoonosis or haemorrhagic syndrome. Microscopically visible elongated schizonts were demonstrated in skeletal muscles and the cardiac muscle in 49 of 55 birds examined histologically. The possible aetiology with respect to known parasites of muscles in fowls is discussed.     

Evaluation of the egg transmission and pathogenicity of Mycoplasma gallisepticum isolates genotyped as ts-11

Live Mycoplasma gallisepticum vaccines are used for the control of respiratory disease, egg production losses and egg transmission associated with M. gallisepticum infection in long-lived poultry. The first field case of apparent increased virulence and vertical transmission of ts-11, a live M. gallisepticum vaccine, has been reported. In that study a M. gallisepticum isolate from the broiler progeny of ts-11-vaccinated breeders was genotyped as ts-11 by sequence analysis of four different genetic targets and Random Amplified Polymorphic DNA and found to be significantly more virulent than ts-11 vaccine. The objective of the current study was to evaluate the rate of egg transmission and pathogenicity of ts-11 vaccine and isolates recovered from ts-11-vaccinated breeders (K6222B) and their broiler progeny (K6216D) which had been genotyped as ts-11. Groups of 28-week-old specific pathogen-free chickens at 87% average weekly egg production were inoculated with sterile broth media (negative controls), ts-11 vaccine, K6222B, K6216D or R strain (positive controls) by eye-drop and aerosol. K6216D transmitted via the egg at an average rate of 4.0% in the third and fourth weeks post-infection, while egg transmission of K6222B and ts-11 vaccine was not detected. M. gallisepticum was isolated from the air sacs, ovaries and oviducts of hens infected with K6216D and K6222B, but not from those infected with ts-11 vaccine. K6216D and K6222B both induced respiratory signs and significantly more tracheal colonization and more severe tracheal and air sac lesions than ts-11 vaccine (P ≤ 0.05). There were no substantial differences in the egg production of ts-11, K6216D and K6222B infected groups. These results provide the first conclusive evidence of transovarian transmission of an isolate genotyped as ts-11 and indicate that isolates genotyed as ts-11 vary in their virulence and ability to transmit via the egg.