Systemic expression of rat soluble retinal antigen induces resistance to experimental autoimmune uveoretinitis.

To assess the role of sequestration in the maintenance of the immune privilege of the retina, retrovirally mediated gene transfer was used to express a defined, specific retinal autoantigen, rat soluble retinal Ag (S-Ag), in a systemic, nonsequestered manner. In this study we report the stable, long term transduction of rat retinal S-Ag into PBMC. Tolerance to S-Ag was assayed by challenging the S-Ag chimeric animals with S-Ag peptides in CFA and monitoring the time course and severity of experimental autoimmune uveoretinitis (EAU). The resulting data showed a correlation between the incidence of S-Ag chimerism and the loss of susceptibility to EAU. The development of resistance to EAU induction supports the hypothesis that Ag sequestration contributes to retinal immune privilege.

Retinal expression of a neo-self antigen, beta-galactosidase, is not tolerogenic and creates a target for autoimmune uveoretinitis.

Recent studies revealing active mechanisms of immune privilege in neural tissues have diminished the putative role of passive tolerance. To examine the significance of Ag localization in the retina on immune privilege, the immune responses of transgenic mice expressing high and low levels of beta-galactosidase (beta-gal) in the photoreceptor cells of the retina were compared with those of normal mice and those of mice expressing moderate levels of beta-gal systemically. Immunization with beta-gal induced experimental autoimmune uveoretinitis indistinguishable from that induced by known photoreceptor cell autoantigens, including destruction of photoreceptor cells, in transgenic mice with high level retinal expression. Retinal expression had no apparent effect on the immune responses to beta-gal, showing that tolerance was not elicited by levels of retinal beta-gal sufficient to serve as a target for autoimmune disease. Mice with systemic expression exhibited reduced lymphoproliferative responses following immunization with beta-gal and did not develop autoimmune disease. T cells prepared from normal mice immunized with beta-gal transferred experimental autoimmune uveoretinitis to the transgenic mice with high level retinal beta-gal expression, but no disease was found in mice with systemic transgene expression under these conditions. The results of our experiments are most consistent with sequestration being the primary mechanism of retinal immune privilege. The results also show that beta-gal can serve as an immunopathogenic neural autoantigen, and that T cells raised by immunization of normal mice with a foreign Ag can be immunopathogenic in certain transgenic recipients.

Molecular cloning and characterization of the DNA of two papillomaviruses from monkeys.

Benign and malignant lesions from monkeys were analyzed for the presence of papillomavirus (PV) DNA. By hybridization with different PV DNA probes under conditions of lowered stringency, two tumors were found to contain PV-specific DNA sequences: (1) a cutaneous papilloma from a Colobus monkey; and, (2) a lymph node metastasis of a squamous cell carcinoma of the penis from a Rhesus monkey. Analysis of the DNA of the papilloma from the Colobus monkey indicated the presence of extrachromosomal DNA whereas analysis of DNA from the Rhesus tumor suggested the presence of integrated viral DNA. The physical size (7.8 and 8.1 kb), colinear alignment to HPV-5, and cross-hybridization with other PV types under low stringency indicate that the two genomic DNA clones represent new PV types that have been tentatively designated as Rhesus papillomavirus type 1 (RhPV 1) and Colobus guereza papillomavirus type 2 (CgPV 2). A putative viral-host DNA junction fragment was also isolated from the Rhesus genomic library. Nucleotide sequences very closely related to RhPV 1 were observed by in situ hybridization in a laryngeal carcinoma from the Colobus guereza monkey. This report communicates the finding of novel papillomaviruses associated with a benign cutaneous tumor and genital and laryngeal malignancies in non-human primates which may have significance as a putative system for the study of papillomavirus-induced genital and laryngeal malignancies in humans.

Prevalence of antibodies to seven viruses in a flock of ewes in Minnesota.

Blood samples were collected from a flock of healthy ewes at a University of Minnesota research station. Sera from these blood samples were tested for antibodies against 7 viruses, using 3 tests (eg, virus-neutralization test for bovine viral diarrhea virus, infectious bovine rhinotracheitis virus, bovine adenovirus type 3, and bovine respiratory syncytial virus; hemagglutination inhibition test for parainfluenza virus type 3; and agar-gel immunodiffusion test for lentivirus of ovine progressive interstitial pneumonia and bluetongue virus). The number of seropositive ewes for each antibody type were 1 of 377 (0.3%) for bovine viral diarrhea virus, 2 of 377 (0.5%) for infectious bovine rhinotracheitis virus, 29 of 378 (7.6%) for bovine adenovirus type 3, 200 of 378 (52.5%) for bovine respiratory syncytial virus, 273 of 373 (71.7%) for parainfluenza virus type 3, and 210 of 379 (55%) for ovine progressive pneumonia virus. All ewes were seronegative for bluetongue virus antibodies.

Comparison of three serotests for the detection of pseudorabies antibodies in pigs.

The serum-neutralization test (SN), enzyme-linked immunosorbent assay (ELISA) and the radial immunodiffusion enzyme assay (RIDEA) were compared for the detection of pseudorabies (PRV) antibodies in swine sera. A total of 1285 serum samples were tested. All three tests were considered useful in determining the PRV antibody status of swine on a herd basis, but available evidence supports the continued use of SN as the definitive test because of possible false positive reactions associated with ELISA and RIDEA.