Immunohistochemical detection of Mycoplasma gallisepticum antigens in turkey respiratory tissues.

An avidin-biotin-immunoperoxidase diagnostic test was developed to facilitate rapid identification of Mycoplasma gallisepticum in respiratory tissues of turkeys. This procedure used polyclonal primary antibodies produced in rabbits. Turkeys were inoculated into the infraorbital sinus and trachea with the R strain of M. gallisepticum, Mycoplasma synoviae, Mycoplasma meleagridis, or Frey's media. The outer walls of the infraorbital sinuses, lungs, and tracheas were collected and fixed in either 10% neutral formalin or pentanedial methyl glycol at 1, 2, 3, and 4 wk postinoculation. Tissues were subdivided and remained in each fixative for 6 or 24 hr. The avidin-biotin-immunoperoxidase diagnostic test was sufficiently sensitive to detect M. gallisepticum antigen at 1, 2, 3, and 4 wk postinoculation. Staining of M. gallisepticum was significantly more intense on infraorbital sinus epithelium than on respiratory epithelium from the trachea or lung. Statistical analysis indicated that the 6-hr fixation time offered better antigen preservation than 24 hr in a fixative. There was no difference in intensity of M. gallisepticum antigen staining in tissues fixed in methyl pentanedial glycol when compared with tissues fixed in 10% neutral buffered formalin. Significant differences in staining intensity were observed between weeks. Specificity of the avidin-biotin-immunoperoxidase test was not complete. None of the tissues from the M. meleagridis and control groups showed staining. No staining was observed in the ciliated brush border of infraorbital sinus epithelial cells from turkeys infected with M. synoviae. However, weak to moderate staining was observed in several tracheas of turkeys inoculated with M. synoviae. Improved specificity of an avidin-biotin-immunoperoxidase diagnostic test to detect M. gallisepticum in respiratory tissues of turkeys probably will require the use of multiple monoclonal antibodies directed against several different epitopes specific to the cell membrane of M. gallisepticum.

Mutational spectrum in the neurofibromatosis type 2 gene in sporadic and familial schwannomas.

Using a heteroduplex approach and direct sequencing, we have completed the screening of approximately 88% of the neurofibromatosis type 2 (NF2)-coding sequence of DNA extracted from 33 schwannomas from NF2 patients and from 29 patients with sporadic schwannomas. The extensive screening has resulted in the identification of 33 unique mutations. Similarly to other human genes, we have shown that the CpG sites are more highly mutable in the NF2 gene. The frequency, distribution, and types of mutations were shown to differ between the sporadic and familial tumors. The majority of the mutations resulted in protein truncation and were consistent with more severe phenotype, however three missense mutations were identified during this study and were all associated with milder manifestations of the disease.

Safety of ototopical antibiotics.

A prospective randomized study analyzing the safety and efficacy of a single dose of ototopical antibiotics following human middle ear tympanostomy tube insertion was performed. Fifty children undergoing bilateral tympanostomy tube insertion were studied by the placement of 0.5 mL of Cortisporin Otic Suspension (COS; Burroughs Wellcome Co., Research Triangle Park, N.C.) to one middle ear space by random assignment. Preoperative and postoperative audiograms were obtained, and the presence of otorrhea was noted. In one patient sensorineural hearing loss of 6 dB developed bilaterally, which was symmetric in both the treated and the untreated ear. This preliminary study showed no statistical difference in hearing loss or postoperative otorrhea associated with a single application of Cortisporin to the middle ear space.

Outbreak of Mycoplasma iowae infection in commercial turkey poults.

In September 1989, 17-day-old turkey poults were submitted to Iowa State University because of leg weakness and dehydration. These birds were commercial large white toms from a flock of 23,214. Lesions observed at necropsy included chondrodystrophy of the hock joints, clear fluid in hock joint spaces, valgus deformities and shortening of the tarsometatarsal bones, and curled toes. Mycoplasma iowae was isolated and identified from swabs of the air sac, cloaca, hock joint, and large intestine. Approximately 1.4% of the flock was culled between 2 and 8 weeks of age because of leg problems. M. iowae infection did not severely affect overall flock performance. Eighty-seven percent of the flock was marketed at 18 weeks of age with an average per turkey weight of 29.5 pounds.

National survey to determine uniformity of serological test results for avian mycoplasmosis.

A national survey was conducted to address the concern over the uniformity of serological test results for avian mycoplasmosis. The National Veterinary Services Laboratories produced chicken and turkey mycoplasma serum-check test kits. Each kit had a total of 25 sera that consisted of negative and positive sera. Participating laboratories were requested to examine their kits using the serum plate agglutination test with the plate antigens currently being used and the hemagglutination inhibition test with the hemagglutinating antigens provided. A conclusion whether serum plate agglutination-positive sera were positive, negative, or suspicious was based on the hemagglutination inhibition test results. Results in each category were scored on the basis of 100 points. The average scores on the serum plate agglutination test, hemagglutination inhibition test, and conclusion were 95, 71, and 91, respectively, for the chicken serum test kit and 91, 71, and 89, respectively, for the turkey serum test kit. The results indicated a high degree of uniformity among laboratories in reporting serological test results for mycoplasmosis in chickens and turkeys.