Isolation of haemagglutinating adeno-like virus related to virus 127 from an Australian poultry flock with an egg drop syndrome

Studies on the persistence and excretion of egg drop syndrome 1976 virus in chickens

EDS virus strain 127 did not induce clinical signs or gross lesions in susceptible chicks of various age groups and in adult cocks. Virus persistence in various internal organs and the rate of excretion of virus by experimentally-infected chicken declined rapidly with increasing age. Virus 127 was detectable in organs of young chicks up to 5 weeks post-infection and in their faeces up to 2 weeks post-infection. In adult birds virus 127 persisted in tissues for about 3 weeks and was excreted with faeces for only 1 week post-infection. Vaccination of adult cocks with an inactivated vaccine resulted in intermittent shedding of virus only within the first 4 days post-challenge; thus, in comparison to non-vaccinated chickens, vaccination reduced virus excretion in faeces to a major extent.

The experimental production of big liver and spleen disease in broiler breeder hens

Big liver and spleen disease (BLS) was reproduced experimentally by intravenous (IV) and oral (PO) administration of BLS inocula to susceptible broiler breeder hens 34 to 36 weeks of age. Serological and pathological signs of BLS similar to those seen in the natural disease occurred in inoculated and in-contact birds. Splenomegaly was the earliest and often the only necropsy finding, with hepatomegaly and kidney enlargement occurring in some birds later in the course of the disease. After IV administration, serum antigen was detected between 2 and 4 weeks, and antibody between 3 and 5 weeks. After PO administration, antigen was detected between 2 and 4 weeks, and antibody between 3 and 6 weeks. Antibody persisted in all birds to the end of the experiment (6 weeks), and horizontal transmission probably occurred since in-contact birds developed BLS. Liver probably contained the highest concentration of BLS agent because it had the highest infectivity.

Epidemiological and clinical investigations into big liver and spleen disease of broiler breeder hens

The epidemiological and clinical features of big liver and spleen disease (BLS) in flocks on two broiler breeder farms were investigated by serology and gross pathology. The most common necropsy findings on farm 1 were splenomegaly and hepatomegaly, with kidney enlargement in some birds. In one flock (farm 1), a decline in egg production began at 40 weeks of age and lasted for 9 weeks. Seroconversion to BLS antigen was first detected at 45 weeks (3.1% of birds) and increased to 72% at 50 weeks, which coincided with clinical recovery in the flock. Antigen was detected before antibody at 44 weeks and persisted at low incidence (< 15%). Farm egg production statistics and serology indicated that the disease affected all flocks on the farm. In three of eight flocks, seroconversion was detected in birds before peak production. The birds in the remaining sheds did not seroconvert or become sick until after peak production. On the second farm, sampling began within a flock already experiencing BLS. Clinical signs and pathology were similar to those seen in flocks on farm 1. However, the lesions that were seen in the pancreas in 15% of birds have not been reported previously. BLS antibody was detected in 78%, and circulating antigen in 14%, of sick birds.

Biological characterisation of an Indian isolate of egg drop syndrome-76 virus

An isolate of egg drop syndrome-76 virus replicated best in primary chicken embryo liver cells and less well in duck embryo liver cells, duck embryo fibroblast cells and chicken embryo kidney cells. The cytopathic effect in chicken embryo liver cells was marked by the presence of round and refractile cells and detachment of cells from the glass surface. The intranuclear eosinophilic inclusion bodies were observed by 24 to 48 hours after infection. No virus multiplication was observed in primary quail embryo fibroblast cells, chicken embryo fibroblast cells or mammalian cells like Vero, BHK-21 and MDBK. Duck embryos supported the maximum growth of the virus, with allantoic fluid having the highest haemagglutinin titre, followed in order by chorioallantoic membrane, skin and internal organs. Chicken and quail embryos did not support the growth of the virus.

Purification and hemagglutinating properties of egg drop syndrome 1976 virus

We purified three populations of virus particles, F7, F9 and F17, with buoyant densities of 1.34, 1.33 and 1.29 g/ml, respectively, in CsCl equilibrium density gradients from cultures of chick embryo liver cells infected with the H-162 strain of the virus of egg drop syndrome 1976. F9 particles were infectious complete virions and most F17 particles were empty particles. F7 particles were less infectious, and had little capacity of hemagglutination (HA). HA titers were the same at 4 degrees and 37 degrees C and maximal between pH 6.4 and 8.4 and ionic strength from 0.14 to 0.54 M of NaCl. HA titer was inversely proportional to erythrocyte concentration. Potassium periodate destroyed markedly the infectivity of the virus and partially its HA activity at 37 degrees C. HA activity was stable at 56 degrees C or lower temperatures and destroyed at 80 degrees C. Trypsin, alpha-chymotrypsin, papain, ficin and neuraminidase had no effect on HA activity. Alpha-chymotrypsin destroyed the receptor for the virus on chicken erythrocytes, whereas trypsin and neuraminidase did not affect the receptor.

A survey of disease in five commercial flocks of meat breeder chickens

Causes of sickness and death in approximately 30,000 chickens in 5 meat breeder flocks were investigated between May 1979 and April 1980. Approximately 23% of disease was due to neoplasms; 81% of these were Marek's disease despite vaccination against this infection. Other frequent diagnoses included cellulitis (15%), respiratory disease (14%), lesions of the reproductive tract (11%) and tenosynovitis/arthritis (9%). Antibodies to Mycoplasma gallisepticium, avian adenovirus, infectious bursal disease virus and reticuloendotheliosis virus were present in all flocks. Antibody to Newcastle disease virus (NDV) was found in 2 flocks but titres were not considered protective against a virulent NDV challenge. Antibody to egg drop syndrome 1976 virus was found in 2 flocks comprised of the same breed of bird.