HISTOPATHOLOGICAL CHARACTERIZATION AND PROPOSED PROGNOSTIC PREDICTORS IN EQUINE ARYTENOID CHONDROSIS/CHONDROPATHY P. Bolfa * , M. Dennis * , B. Grevemeyer y , M. Cercone z and N. Ducharme z *Biomedical Sciences, y Clinical Sciences, Ross University School of Veterinary Medicine, St Kitts and z School of Veterinary Medicine, Cornell University, Ithaca, New York, USA Introduction: The aetiology of equine arytenoid chondrosis (chondropathy) is not clear. Trauma or infection/inflammation of the corniculate process and arytenoid cartilage from mucosal damage have been suggested. We aimed to describe the lesion and to develop a grading system that would correlate the size of the affected aryte- noid cartilage with the degree of cartilage loss. This would facilitate a less invasive arytenoidectomy and optimization of the current ther- apy with restoration of a good athletic capacity of the horses. Materials and Methods: Nineteen diseased arytenoids from horses that had previous antibiotic therapy and four controls were sectioned and measured (area) at the same level, caudal to the corniculate pro- cess. All tissues were stained with HE, Safranin O and Alcian blue and evaluated histologically. Total gross area, percentage of cartilage loss and medial growth were assessed and correlated. Results: The lesions were composed of a central area of fibrosis (73.6% of cases) with dropout (47.3%), and for most cases, one or more sinus tracts communicating with the mucosa. Other significant histological features in order of frequency were: muscle involvement (84.2%), epithelial hyperplasia (68.4%), ulceration (26.3%), vascular changes (tortuous blood vessels, 26.3%) or bone metaplasia (10.5%). There was a positive correlation between gross area and medial growth (P !0.05). Cartilage loss correlated positively with epithelial hyperplasia and ulceration (P !0.05). Medial growth correlated positively with presence of pigment (P !0.05). Conclusions: We propose that epithelial hyperplasia, ulceration, medial growth and cartilage loss are accurate predictors of disease severity in equine arytenoid chondropathy and that this will help sur- gical intervention strategies. CRISPR/CAS9: A USEFUL TOOL TO STUDY THE PATHOGENESIS OF THE EQUINE SARCOID? A. Monod * , C. Koch * , S. Rottenberg y , V. Gerber * and K. Hahn y *Swiss Institute of Equine Medicine and y Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, Switzerland Introduction: Equine sarcoids (ESs) account for up to 90% of skin tumours in equids. Bovine papillomavirus (BPV) DNA is frequently associated with these neoplasms, defining BPV as a crucial factor in ES pathogenesis. In this context, the viral genes E2, E5 and E6 are discussed as main BPV oncogenes. Recent studies on human papillo- mavirus (HPV) suggest CRISPR/Cas9 technology as a potential tool for HPV-associated cancer treatment, enabling the knockout of HPV oncogenes. To test this approach in ES we investigated: (1) the appli- cability of the CRISPR/Cas9 system in equine cell lines, and (2) the potential of the CRISPR/Cas9 system to knockout BPV oncogenes. Materials and Methods: We established primary ES (n 5 4) and dermal equine fibroblast (FB) cultures (control; n 5 1) and confirmed BPV infection by PCR and Sanger sequencing. These cell lines were then stably transduced using a lentiviral vector system transferring Cas9 and gRNA targeting vimentin, and BPV genes (long control re- gion, E2, E5 and E6). The efficacy of the knockout was determined using TIDE (Tracking of Indels by DEcomposition) analysis. Results: TIDE analysis and immunofluorescence revealed a success- ful knockout of vimentin in ES and control FB cell lines, resulting in a decreased cell proliferation rate. In contrast, the efficiency of the CRISPR-mediated knockout of BPV oncogenes was low. Conclusions: These experiments outline the CRISPR/Cas9 system as a tool to modify the horse genome, providing the basic to study the interaction of BPV with endogenous host factors. NLRP3 INFLAMMASOME EXPRESSION IN BRAIN AND SKELETAL MUSCLE OF AGED CATTLE D. De Biase * , C. Pirozzi * , F. Prisco * , I. Cimmino * , G. Piegari * , G. Mattace Raso * , F. Oriente * , S. Papparella * and O. Paciello * *University of Naples, ‘Federico II’, Naples, Italy Introduction: NLRP3 (NOD-like receptor protein 3) inflammasome is a pattern-recognition receptor responsible for age-related chronic inflammation. Here, we describe the expression of NLRP3 in brains and skeletal muscle of aged cattle. Materials and Methods: Samples of skeletal muscle and hippocam- pus were collected from 42 cattle divided into three groups: aged, adult and young. Immunohistochemistry and double colour immuno- fluorescence were performed on sections of hippocampus to evaluate: (1) the expression of MHC II and NLRP3, and (2) the relationship between NLRP3, SOD1 and autophagy marker Beclin 1. Muscle bi- opsy samples were assessed for morphology and immunohistochem- istry was performed to evaluate the expression of NLRP3, MHC I, MHC II, CD3, CD4, CD8. Western blot analysis for NLRP3 was also performed. Results: Aged brains revealed: (1) a higher expression of MHC II and NLRP3; (2) a negative relationship between inflammasome and Beclin 1; and (3) the co-expression of NLRP3 and SOD1. Aged muscles revealed NLRP3-labelled type II fibres, lymphocytic inflammation and an increased expression of MHC I and II. Western blot analysis showed an 118kDa band in brain and muscle extracted proteins. Conclusions: Upregulation of MHC I and II and NLRP3 in brain and muscle tissues of aged cows indicates the presence of an age- related chronic inflammation, possibly a consequence of the age- related decline of autophagic capacity that leads to increased ROS production and the activation of inflammasome. Our study intro- duces intriguing observations, but it has opened a plethora of research opportunities to investigate the inflammasome and age-related changes in the brain and muscle of animals. PRESENCE OF VISNA/MAEDI VIRUS IN POST- VACCINATION GRANULOMAS IN NATURALLY-INFECTED SHEEP: A NEW FACTOR FOR VIRUS SPREAD? R. de Miguel * , J. As  ın * , I. Echeverr  ıa y , C. G omez-Arrebola y , D. de Andr es y , M. P erez z , R. Reina y and L. Luj an * *Department of Animal Pathology, University of Zaragoza, y Institute of Agrobiotechnology, CSIC-UPNA and z Department of Animal Anatomy, Embryology and Genetics, University of Zaragoza, Spain Introduction: In sheep, post-vaccination granulomas are a constant re- action after inoculation with vaccines containing aluminium-based ad- juvants. These granulomas can be very persistent, sometimes lasting more than 15 months. Presence of multiple post-vaccination granulomas in the same animal can lead to chronic immune system stimulation and to the development of the ovine autoimmune/inflammatory syndrome induced by adjuvants (ASIA syndrome). Small ruminant lentivirus (SRLV) infection is widespread and SRLVs replicate in activated mac- rophages. The objective of this work is to report for the first time the active replication of SRLV in post-vaccination granulomas in sheep. Materials and Methods: Eleven adult, naturally SRLV-infected sheep showing clinical lentiviral arthritis were selected. Eight doses of commer- cial, aluminium-containing vaccines were inoculated over a period of 70 days to all animals. Granulomas were sampled and a study including pa- thology, cell culture (RT activity quantification), PCR and viral sequencing was carried out. SRLV circulating strains in each animal were also evaluated in peripheral blood mononuclear cells and spleen. Results: SRLV could be detected in post-vaccination granulomas in five (45.5%) sheep by cell culture and PCR. Viral sequences be- longed to genotypes A and B and evidenced compartmentalization according to the different tissues analysed including granulomas. Conclusions: Persistent granulomatous inflammatory reactions induced by vaccines allow in-situ SRLV replication. As macrophages from these granulomas can be found in lymph nodes, SRLV may spread throughout the lymphatic system and likely increase the body viral load. The role of post-vaccination granulomas in the spread of sheep SRLV needs to be considered. J. Comp. Path. 2019, Vol. 166, 100e122 ESVP, ESTP and ECVP Proceedings 2017 105