Responses of specific-pathogen-free chicks to concomitant infections of reovirus (WVU-2937) and infectious bursal disease virus.

Specific-pathogen-free white leghorn chicks concomitantly infected with both infectious bursal disease virus (IBDV) and reovirus (WVU-2937) on day 1 had significantly lower (P less than 0.05) virus-neutralizing- and precipitating-antibody geometric mean titers (GMT) to reovirus than chicks infected with only reovirus on day 1 but had a similar incidence of inflammation of the metatarsal digital flexor tendons. Chicks infected with IBDV on day 7 and reovirus on day 14 had a greater incidence of inflammation of the tarsometatarsal digital flexor tendons and lower neutralizing- and precipitating-antibody GMT to reovirus than chicks infected with only reovirus on day 14. Chicks infected with both viruses on day 1 had a significantly lower (P less than 0.05) neutralizing-antibody GMT to IBDV than chicks infected with only IBDV.

Characterization of an isolate of mycoplasma WVU 907 which possesses common antigens to Mycoplasma gallisepticum.

Antigenic characteristics of an isolate of mycoplasma WVU 907 were compared with Mycoplasma gallisepticum (MG) and Mycoplasma synoviae. Mycoplasma WVU 907 and MG share common agglutinating and precipitin antigens. Although hemagglutinin is an integral part of WVU 907, hemagglutinating-inhibited antibody was not detected in sera of chickens inoculated with WVU 907. The clinical symptoms observed in chickens inoculated with WVU 907 were mild. Viral infections of chickens helped spread WVU 907 to contact controls. WVU 907 was more resistant to tylosin than MG was.

Characterization of avian reoviruses isolated from the synovia and breast blister.

Reoviruses Texas, S 1133, UMI 203, and WVU 2937 induced swelling of the foot pad and inflammatory changes in the synovial membranes when inoculated in the foot pad of 2-week-old gnotobiotic chicks. From differences in virus neutralization as measured with geometric mean (R) value, all four viruses are subtypes of a single serotype. The cell-associated and cell-released virus growth curves were similar, with a lag phase of about 15 hours and a log phase of 15 to 21 hours. Viral RNA synthesis reached a peak in 5 hours and was active at 14 hours but not at 18 hours. In 90 minutes at 60 C the titer of each virus had decreased about 4 logs.

An ultrastructural study of avian synovium infected with an arthrotropic Mycoplasma, Mycoplasma synoviae.

Live Mycoplasma synoviae cells in agar base medium were inoculated intravenously into 10 2-week-old chickens. Joint tissues were collected over a 3-week period for light and transmission electron microscopy. In infected chickens, membrane-bound vacuoles of intact M. synoviae cells were seen in the cytoplasms of adipose cells. Cytoplasmic lipid-containing inclusions had accumulated in enlarged fibroblasts in tendon sheaths and loose connective tissue. Synovial cells had proliferated and contained increased amounts of granular endoplasmic reticulum and lipid inclusions. No abnormalities were seen in control chickens. Infected chickens were positive and control chickens were negative for rheumatoid factor activity by two serological tests: tanned cell hemagglutination and latex agglutination tests.

Ultrastructural study of avian synovium infected with an arthrotropic reovirus.

Three-week-old chicks were inoculated via the foot pad with the avian reovirus (strain WVU 2937) that has been proved to be the causative agent in avian viral arthritis. The initial stages of the avian reovirus infection in the synovium of the hock joint were studied by transmission electron microscopy to shed light on the early virus-host relationship of an arthrotropic virus and synovial tissue. At 48 hours postinoculation (PI), coated, partially coated, and uncoated virus particles were seen in a dense lysosome-like inclusion in the cytoplasm of subsynovial fibroblasts. Virus replication was demonstrated in fibroblasts of the subsynovium 4 days PI. Infiltration of leukocytes into the area of the virus replication was noted at the time of virus replication (4 days PI). By the second week of the infection (11 days PI), the subsynovium was heavily infiltrated with lymphocytes and plasma cells, and proliferative changes had occurred in the synovial lining cells.

Spontaneous spondylolisthesis in embryonic and adult chick.

The incidence of spontaneous avian spondylopathy was maintained between 58 and 66% in the progeny of one flock (Flock A) and less than 40% in the progeny of another (Flock B), by proper selection and breeding for 4 generations. Spondylolisthesis, the major type of spondylopathy present, was observed at the first and sixth vertebral levels. Spondylolisthesis was progressive in nature and consisted of a ventrodorsal rotation of the 1st and/or 6th thoracic vertebrae leading to spinal cord injury and paraplegia or partial crippling in some birds. There was occasionally extensive muscle degeneration and connective tissue proliferation around the distorted vertebrae and the spinous ligaments bridging the defect were stretched and appeared heavier than normal. Spondylopathy was also observed in 20-day chick embryos. Spondylolisthesis was observed in 33% of the embryos examined from Flock A-G2 and the other conditions present consisted of scoliosis and abnormal lordosis and kyphosis. Using a grading scale of +1 (mild) to +3 (severe), all cases of embryonic spondylopathy were graded as +1. The back defects present in Flock B-G2 embryos were entirely due to abnormal kyphosis.

Development of cold agglutinin to chicken red blood cells in Mycoplasma synoviae infection.

Serum from birds chronically infected with Mycoplasma synoviae (MS) evidenced a cold agglutinin (CA) which agglutinated chicken, cat, dog, and guinea pig red blood cells (RBC) but did not agglutinate bovine and sheep RBC. Agglutinin to dog RBC was widespread in serums of birds, whether or not infected with MS.

Use of the agar-gel precipitin test to evaluate broiler breeder and commercial layer flocks for Mycoplasma gallisepticum infection.

In the absence of Mycoplasma gallisepticum (MG) isolation, the importance of agar-gel precipitin (AGP) tests along with microhemagglutination-inhibition (mHI) and serum plate agglutination (SPA) tests for the evaluation of poultry flocks for MG infection was demonstrated. A good correlation between AGP, mHI, and SPA tests for the early confirmation of MG in a flock was observed, except for the breeder flocks from which WVU 907 was isolated. The serums of such breeder flocks were positive for SPA and AGP test but negative for the mHI test. Isolation of MG for confirmation of the status of the flock was unsatisfactory in the later stages of infection or when nonpathogenic organisms were present in appreciable numbers. In the absence of MG or M. synoviae (MS) isolation, demonstration of agglutinin, precipitin, and/or mHI antibodies in the serums of such flocks were confirmatory for MG or MS infection. The new isolate WVU 907 gave positive reactions on the SPA and AGP tests with MG antiserum. The isolate hemagglutinated chicken red blood cells (RBC) and induced low HI antibody levels (less than or equal to 1:20) when inoculated into chickens. Like MG, WVU 907 precipitin antigen was partially denatured by urea, Triton x-100, and sodium dodecyl sulfate treatment.

Efficacy of chlortetracycline against Mycoplasma synoviae isolated in two periods.

Isolates obtained in 1954-55 were generally more pathogenic for the synovial membranes than those obtained in 1969-73. All isolates were capable of producing synovitis when inoculated into the foot pad. Chlortetracycline was effective in controlling signs of infectious synovitis at the 100-g/ton concentration. The 50-g concentration prevented mortality and reduced morbidity. All concentrations of chlortetracycline used (50, 100, or 200 g/ton of feed) reduced immune response, positive agglutination tests, and isolation of MS below that of inoculated untreated birds. Chlortetracycline at all concentrations prevented the spread of MS in contact controls. Chlortetracycline was more effective against the 1954-55 isolates than the 1969-73 isolates when measured by gross lesions, development of agglutinins, and isolation of mycoplasma. No difference in efficacy was found in mortality, weight gain, and feed efficiency.

Evaluation of broiler breeder flocks for nonspecific Mycoplasma synoviae reaction.

Serums from 65 broiler breeder flocks were evaluated for mycoplasma synoviae (MS) and Mycoplasma gallisepticum (MG) antibodies by serum plate agglutination (SPA), micro hemagglutination-inhibition (HI), and agar gel precipitin (AGP) tests. The nonspecific SPA reaction in serum from breeder flocks was eliminated by diluting the serum 1:5 in phosphate-buffered saline (PBS), pH 7.2, before testing provided that the MS antigen reacted with 1:10 dilution of the MS antiserums. The nonspecific SPA reaction was confirmed by negative HI and AGP reactions. Wehn specific MS reactions occurred, the serums showed a micro HI titer of 1:80 or greater and an AGP line, and MS was isolated from the upper respiratory tract of infected birds. Serums from experimental birds on Aureomycin, 200 g/ton of feed, were positive on the SPA test but were negative for micro HI and AGP tests. MS was isolated from these birds. Nonspecific SPA MG reaction occurred in many of the flocks which were negative by MG HI and AGP tests.

Comparison of the characteristics of avian reoviruses isolated from the digestive and respiratory tract, with viruses isolated from the synovia.

Two-week-old gnotobiotic chicks were inoculated in the foot pad with viruses isolated from synovia and synovial membrane-WVU 1464-29H, WVU 1675, WVU 2937, WVU 2986, and WVU 71-212; from digestive tract-reoviruses 24, 25, and 59; or from respiratory tract-reovirus Fahey-Crawley (FC). All viruses induced swelling of the foot pad and inflammatory changes of synovial membrane. Serum from virus-infected chicks had a common agar gel precipitin (AGP) line. On the basis of the plaque-reduction test in primary chicken kidney (PCK) cells, the viruses were classified into 4 major serotypes. All viruses produced cytopathic effects (CPE) in primary chicken tissue cultures. Other than reovirus FC and WVU 1464-29H, all viruses produced CPE in the Vero cell line.

Avian viral arthritis: antigenic types and immune response.

Serums from broiler breeders of an integrated broiler operator were examined for precipitin antibodies using antigens prepared from preliminary reovirus serotypes represented by WVU-2937, Reo-25, Reo-59, and Fahey-Crawley virus. The precipitin antibodies were present in most of the flocks. Virus neutralization tests indicated that the reovirus responsible for viral arthritis represented by WVU-2937 was not present in the breeder flocks, but antibodies to Reo-25, Reo-59, and the Fahey-Crawley viruses were present.

Hemagglutination-inhibition versus serum plate agglutination in detecting Mycoplasma gallisepticum in broiler flocks.

Sera from 43,040 broilers in 36 flocks were tested for antibodies to Mycoplasma gallisepticum by serum plate agglutination (SPA) and hemagglutination-inhibition (HI) tests. The importance of testing SPA-negative samples for HI antibodies was demonstrated.