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The occurrence of equine arteritis virus (EAV) induced equine abortions was studied with different laboratory methods during a 3-year period. Tissue samples from 96 aborted equine foetuses or newborn foals were collected from 57 farms located in different parts of Hungary. Virus isolation, polymerase chain reaction (PCR), immunohistochemistry and serology were used for the detection of EAV infection. The overall seroprevalence of EAV infection in mares was 65%. EAV induced abortion was diagnosed in eight (8.3%) cases from six (10.5%) herds. Abortion was sporadic in all herds except for one, where epidemic abortion happened. Fetal serology in six (75%) cases, the virus isolation in one (12.5%) case whereas PCR in all of the four investigated cases were positive. The virus could be observed with immunohistochemistry in seven (87.5%) cases mostly in the spleen followed by other organs and the allantochorion. In conclusion, PCR and immunohistochemistry seem to be the most sensitive and useful tests for the diagnosis of EAV induced equine abortion.

Oral administration of autoantigens can delay or suppress clinical disease in experimental autoimmune disorders. However, repeated feeding of large tolerogen amounts is required over long periods and is only partially effective in animals systemically sensitized to the ingested antigen. The cholera toxin B subunit adjuvant (CTB) when linked to autoantigen epitopes acts as a strong adjuvant to enhance suppression of inflammatory Th1 cell reactivity in both naive and immune animals. Enhanced suppression of inflammatory Th1 cell reactivity was demonstrated in both naive and immune NOD mice following oral inoculation with islet autoantigens coupled to CTB. To stimulate adjuvant-autoantigen fusion protein biosynthesis in the gut mucosae, we evaluated oral inoculation of juvenile NOD mice with recombinant vaccinia virus (rVV) expressing fusion genes encoding CTB linked to the pancreatic islet autoantigens proinsulin (INS) and a 55 kDa peptide from glutamate decarboxylase (GAD55). Oral inoculation with rVV significantly reduced pancreatic insulitis. Hyperglycemia in NOD mice inoculated with CTB::GAD fusion protein was reduced by 40% in comparison with rVV-GAD inoculated mice. Measurement of antibody isotype titers in rVV infected mice suggested activation of autoantigen specific Th2 lymphocytes. These experiments demonstrate the feasibility of vaccinia virus mediated delivery of adjuvanted autoantigens to the mucosae of prediabetic mice for suppression of autoimmune diabetes.

Live vaccinia viruses (VV) are promising vectors of gene delivery for gene- and immuno-therapy of various human diseases. Safety concerns have initiated development of safer VV strains. We explore an attenuation strategy by further weakening of the Lister vaccine strain via virus-mediated blockade of IFN-dependent cell protection mechanism. Previously, we constructed a Lister vaccine derivative (VVr/g) expressing fused Renilla luciferase and jellyfish GFP reporters, which enable non-invasive monitoring of virus dissemination in live animals. Recently, a VVr/g derivative was constructed (VVr/g8) lacking both IFN-α/β and IFN-γ receptor homologs, and retaining propagation potential in vitro. The safety of the new virus vector was investigated by survival assay and biodistribution in nude mice. High dose (3 × 108 plaque-forming units/animal) of VVr/g8 inoculated into mice showed less pronounced virus dissemination, improved weight gain, and increased survival rate as compared with the VVr/g strain. The data indicate a significant increase in attenuation of the VVr/g8 virus. Immunogenicity of viruses was tested in immunocompetent mice by measuring humoral and cell-mediated immune responses utilizing three different methods. Various versions of virus neutralization assay were applied, and none of them showed significant differences between parental Lister, VVr/g and VVr/g8 strains. Quantification of virus-induced 3H-thymidine incorporation, mitogen-induced IFN-γ production, and T lymphocyte subsets by flow cytometry demonstrated similar or greater levels of leukocyte activation in the spleen, confirming that the constructed Lister derivatives were as immunogenic as the parental virus. Thus, it appears likely that the constructed VVr/g8 virus is a safer VV vector candidate for gene therapy, immunotherapy or vaccination of humans.