Efficacy of vaccination with porcine reproductive and respiratory syndrome virus following challenges with field isolates in Japan.

The objective of this study was to evaluate the influences of genetic and antigenic variations in field isolates of porcine reproductive and respiratory syndrome virus (PRRSV) on vaccine efficacy. Four-week-old pigs were vaccinated with a commercial modified live virus vaccine. Four weeks after vaccination, pigs in both the vaccinated group and the non-vaccinated group were challenged intranasally with 10(7) TCID(50) of PRRSV wt-11 (Experiment 1) or PRRSV wt-7 (Experiment 2).

Virological and serological studies of porcine respiratory coronavirus infection on a Japanese farm.

We detected transmissible gastroenteritis virus (TGEV) antibodies in pig farms in Tochigi prefecture, although the farms had no past record of TGEV vaccination or TGE. Among the farms, Farm A showed a high antibody incidence. We could not confirm if either TGEV or porcine respiratory coronavirus (PRCV) induced the antibodies, since conventional tests failed to discriminate PRCV from TGEV.

Reproduction of adenoviral gizzard erosion by the horizontal transmission of fowl adenovirus serotype 1.

The horizontal transmission ability of fowl adenovirus (FAV) serotype 1 99ZH strain, isolated from chickens exhibiting gizzard erosion, was investigated. Twelve 13-day-old specific pathogen-free chickens were inoculated orally with 10(6) TCID(50)/0.05 ml of the strain.

Comparison of the polymerase chain reaction-restriction fragment length polymorphism pattern of the fiber gene and pathogenicity of serotype-1 fowl adenovirus isolates from gizzard erosions and from feces of clinically healthy chickens in Japan.

The fiber gene sequence and pathogenicity of the serotype-1 fowl adenovirus (FAdV-1) isolated from gizzard erosions and from clinically normal chickens were compared among isolates. The FAdV-99ZH strain, which induced gizzard erosions, had a nucleotide sequence of the long fiber gene that was different from that of the Ote strain, which did not induce gizzard erosions. The differences could be distinguished by use of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis.

An epizootic of subcutaneous tumors associated with subgroup A avian leukosis/sarcoma virus in young layer chickens.

An outbreak of subcutaneous tumors in young layer chickens in a flock in Japan was investigated. Tumors appeared as extensive swelling or bulbous protrusions of the integument and were observed in the head or wing of chickens approximately 9 wk old, with a prevalence of 0.4% (157 of 42,000) in the affected flock.

Pathogenicity of serotype 8 fowl adenovirus isolated from gizzard erosions of slaughtered broiler chickens.

The pathogenicity of serotype 8 fowl adenovirus (FAV), isolated from gizzard erosions of slaughtered broiler chickens, was investigated. In experiment 1, 29 5-day-old specific-pathogen-free (SPF) chickens were inoculated with the isolates of serotype 8 FAV, M013 (group 1) or G0054 (group 2) strain, via an oral route. There were no clinical signs in any of chickens after inoculation, and mild gizzard erosions were observed macroscopically and microscopically in three inoculated chickens of group 2.

Experimental dual infection of pigs with an H1N1 swine influenza virus (A/Sw/Hok/2/81) and Mycoplasma hyopneumoniae.

Dual infection of pigs with swine influenza virus (SIV) and Mycoplasma hyopneumoniae was carried out to compare the clinical and pathological effects of dual infection in caesarian derived and colostrums deprived (CDCD) pigs, with that of a single infection with M. hyopneumoniae. In Experiment 1, 40-day-old CDCD pigs were inoculated only with SIV (A/Sw/Hok/2/81, H1N1).

PCR detection of Porcine circovirus type 2 DNA in whole blood, serum, oropharyngeal swab, nasal swab, and feces from experimentally infected pigs and field cases.

Porcine circovirus type 2 (PCV2) shedding patterns were investigated by polymerase chain reaction (PCR) for the detection of PCV2 DNA, and the diagnostic suitability of a sample for the PCR was examined by using different types of samples. In the experimental infection, sixteen pigs were inoculated intranasally with PCV2. The samples, including oropharyngeal and nasal swabs, feces, whole blood and serum became positive for PCV2 DNA by PCR immediately after the inoculation, and almost all samples remained positive during the observation period, post-inoculation-day 70.