Shiro Miura

OCCURRENCE AND SURVIVAL OF SALMONELLA ORGANISMS IN HATCHER CHICK FLUFF FROM COMMERCIAL HATCHERIES

It is well known that contaminated hatcher chick fluff and dust play an important role in transmitting pullorum disease and avian paratyphoid infections in incubators. Lancaster et al. (4) pointed out that three main approaches have recently been devised for the study of hatchery sanitation. One important approach has been bacteriological examination of incubator dust and debris for Salmonella to assess incubator fumigation procedures. It can be considered that examination of hatcher fluff samples from commercial hatcheries for Salmonella will be a useful criterion for determining the contamination of incubators and the effectiveness of disinfection. However, only Gwatkin and Dzenis (2) have reported on this problem. They investigated methods of shipping chick fluff from the commercial hatcheries to the laboratory. Dry chick fluff, infected artificially, was not satisfactory for examination for S. pullorum under their experimental conditions. However, isolation of the organisms appeared to be better when the samples were shipped in broth. They also presented the data obtained from the examination of naturally infected samples applying the latter shipping method. The present paper deals with the frequency of occurrence as well as the survival of Salmonella organisms in hatcher fluff samples from commercial hatcheries which were not satisfactorily disinfected. Dead chick embryos from the same hatcheries were also examined.

Indirect fluorescent antibody technique for the detection of avian encephalomyelitis antibody in chickens.

Attempts (1,2,4,5) have been made to develop more rapid and accurate methods of detecting avian encephalomyelitis (AE) antibody in chickens in place of the virus-neutralization test (VNT) and embryo-susceptibility test. A fluorescent antibody blocking test (FABT) was recently reported by Davis and Lukert (1). They indicated that the test gave 73% sensitive and 72% specific when the FABT results were compared to the VNT. This note describes the use of an indirect fluorescent antibody technique (IDFAT) to examine AE antibody in chickens. 1) Preparation of AE antigen. Susceptible eggs were inoculated (yolk-sac method) with 1000 EID50 AE virus of the Van Roekel embryo-adapted strain after 6 days of incubation, and the cerebrum was removed 12 days later to make slide smears. The smears were fixed with ethanol for 10 minutes. They distinctly indicated AEV antigen by the direct FAT (6) at each test. 2) Serums tested and their diluent. Serums taken from chickens of AE-susceptible flocks, naturally infected flocks, and artificially infected flocks were inactivated at 56 C for 30 minutes. The diluent of the serums was 18-day-old normal chicken embryo brains suspended in 10 volumes of phosphate-buffered saline (PBS) (NaCI 8 g, NaH2PO4 2H20 0.4 g, Na2HP04-12H20 2.5/1000 ml of distilled water, pH 7.4). After sonication for 7 min at 100 V, 150 mA, and the addition of 0.01% merthiolate, the suspension was stored at -20 C, and 2-fold diluent was prepared with PBS before use. This diluent was used for absorption of nonspecific reactant substances

Propagation of non-egg-adapted avian encephalomyelitis virus in chick embryo brain cell culture.

Non-egg-adapted avian encephalomyelitis virus (2 strains and 1 field isolate) multiplied in chick embryo brain monolayer cell cultures. The infection in the cell cultures continued persistently. Initial multiplication of the virus in the cell cultures was slow and variable among the strains and field isolate, but EID50 of about 103 per ml was obtained 14 days after inoculation. The virus activity was neutralized with specific antiserum. Both cytopathic effect and plaque did not occur. Neither the inclusion body nor AEV antigen, stained directly with the fluorescent antibody, was detected in the infected cells.

Avian Encephalomyelitis Virus in Chicken Pancreatic Cell Cultures

Monolayer cell cultures consisting of epithelioid cells were made from pancreatic tissue of 10-to-13-day-old chicks. The maximum virus titer of the cell-culture fluid was obtained 8 days after inoculation with an embryo-adapted avian encephalomyelitis virus (AEV). Virus titers also increased in cell cultures inoculated with a chick-pancreas-passed AEV or a field isolant. Cell cultures inoculated with 3 strains of AEV maintained virus titers of 10(2.9)-10(3.7) 50% embryo-infective doses/ml for 15-20 days. In other cell cultures from pancreatic tissues of chicks preinfected orally with the chick-pancreas-passed AEV or the field isolant, the virus titers decreased for several days after cultivation and thereafter increased and persisted until at least the 25th or 30th day. Neither a cytopathic effect nor any inclusion body was observed in the cell cultures infected with AEV. No AEV-antigen-positive cell was detected by direct fluorescent-antibody technique.