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Experimental Vaccine Against Mink Astrovirus Infection Reduces the Incidence of Brain Lesions
J. Comp. Path. 2017, Vol. 156, 54e141
ESVP and ECVP Proceedings 2016
EXPERIMENTAL VACCINE AGAINST MINK ASTROVIRUS INFECTION REDUCES THE INCIDENCE OF BRAIN LESIONS M.S. Hansen *, C. Baule z, K. Ullman x, T.H. Jensen {, ely G. Larsen x and M. Chri *Section for Bacteriology, Pathology and Parasitology, National Veterinary Institute, Technical University of Denmark, ySection for Public Sector Service and Commercial Diagnostics, National Veterinary Institute, Technical University of Denmark, Denmark, zQuantum BioTechnologies Lda, Maputo, Mozambique, xDepartment of Microbiology, National Veterinary Institute, Uppsala, Sweden and {Aalborg Zoo/Aalborg University, Aalborg, Denmark Introduction: Astrovirus infection in mink is associated with the ‘greasy kits’ syndrome that causes diarrhoea and results in major losses, and with a ‘shaking mink’ syndrome, where the mink experiences uncoordinated movements. Therefore, there is great interest in developing vaccines that can reduce the disease burden and the associated economic losses. Materials and Methods: Two astrovirus vaccines, based on the full-length (C1) and the truncated (C4) capsid proteins, were tested. Fifteen pregnant mink dams were either non-immunized (group 1), or immunized with C4 (group 2) or C1 (group 3) and their kits were subsequently inoculated with astrovirus to evaluate the induction of immune responses, viral shedding, development of clinical signs and tissue lesions. This study focuses on the histopathology. The kits were killed at 7e8 weeks of age. Samples from brain, intestines and spleen were fixed in formalin and processed by standard histological methods. Results: At necropsy examination one kit had hydrocephalus. By histology, 33%, 38% and 29% of the kits in groups 1e3, respectively, had one or more intestinal lesions. The lesions were mainly flattening of intestinal villi, often seen together with dilated crypts containing cellular debris. In the brain 53%, 8% and 0% of the kits in groups 1e3, respectively, had lesions of non-suppurative encephalitis in the grey matter, non-suppurative cuffing and/or focal non-suppurative leptomeningitis. Spleens were without lesions. Conclusions: The immunizations and in particular the C1 vaccine reduced the incidence of histological brain lesions, and also reduced the duration and severity of clinical signs and viral shedding.
113
FATAL SYSTEMIC USUTU VIRUS INFECTION IN TWO JUVENILE GREAT GREY OWLS (STRIX NEBULOSA) FROM A GERMAN ZOOLOGICAL GARDEN C. Schulze *, U. Ziegler y, P. Schlieben *, C. Fast y, S. Bock *, A. Sch€ ule z and A. Ochsz *BerlineBrandenburg State Laboratory, yFriedrich-Loeffler-Institut, Federal Research Institute for Animal Health and zZoo Berlin, Germany Introduction: Usutu virus (USUV), an African arbovirus within the genus Flavivirus, was introduced into Italy in 1996 and afterwards spread north causing epizootics among wild and captive birds in different European countries. In Germany, USUV was initially recovered from carcasses of wild birds from the upper Rhine Valley in 2011. Materials and Methods: Necropsy examination was performed on two 3-month-old great grey owls from Berlin Zoo, which suffered from a hyperacute fatal disease. Native tissues were screened for USUV by RT-qPCR. Formalin-fixed and paraffin wax-embedded tissues were investigated by HE staining and immunohistochemistry using a polyclonal rabbit antiserum. In addition, the virus was isolated in cell culture and further characterized by molecular methods. Results: Main gross findings in both owls were multiple foci of necrosis in liver and spleen. Additionally, several other organs including the brain, kidney, lung, bone marrow, heart and skeletal muscle contained necrosis of different degrees. The USUV RT-qPCR was positive in tissue pools from both birds. By immunohistochemistry, USUV antigen was detected in vascular endothelium, parenchymal and reticulohistiocytic cells, mainly associated with the necrotic foci. Molecular phylogeny revealed that the birds were infected by a new USUV strain, provisionally named USUV-Berlin, of Africa 2 lineage. Conclusions: The reported outbreak represents the third independent USUV introduction to Germany and its northernmost occurrence in Europe. Great grey owls seem to be suitable sentinel animals for the indication of the presence of the virus in a formerly unaffected region.
ESVP and ECVP Proceedings 2016
EXPERIMENTAL VACCINE AGAINST MINK ASTROVIRUS INFECTION REDUCES THE INCIDENCE OF BRAIN LESIONS M.S. Hansen *, C. Baule z, K. Ullman x, T.H. Jensen {, ely G. Larsen x and M. Chri *Section for Bacteriology, Pathology and Parasitology, National Veterinary Institute, Technical University of Denmark, ySection for Public Sector Service and Commercial Diagnostics, National Veterinary Institute, Technical University of Denmark, Denmark, zQuantum BioTechnologies Lda, Maputo, Mozambique, xDepartment of Microbiology, National Veterinary Institute, Uppsala, Sweden and {Aalborg Zoo/Aalborg University, Aalborg, Denmark Introduction: Astrovirus infection in mink is associated with the ‘greasy kits’ syndrome that causes diarrhoea and results in major losses, and with a ‘shaking mink’ syndrome, where the mink experiences uncoordinated movements. Therefore, there is great interest in developing vaccines that can reduce the disease burden and the associated economic losses. Materials and Methods: Two astrovirus vaccines, based on the full-length (C1) and the truncated (C4) capsid proteins, were tested. Fifteen pregnant mink dams were either non-immunized (group 1), or immunized with C4 (group 2) or C1 (group 3) and their kits were subsequently inoculated with astrovirus to evaluate the induction of immune responses, viral shedding, development of clinical signs and tissue lesions. This study focuses on the histopathology. The kits were killed at 7e8 weeks of age. Samples from brain, intestines and spleen were fixed in formalin and processed by standard histological methods. Results: At necropsy examination one kit had hydrocephalus. By histology, 33%, 38% and 29% of the kits in groups 1e3, respectively, had one or more intestinal lesions. The lesions were mainly flattening of intestinal villi, often seen together with dilated crypts containing cellular debris. In the brain 53%, 8% and 0% of the kits in groups 1e3, respectively, had lesions of non-suppurative encephalitis in the grey matter, non-suppurative cuffing and/or focal non-suppurative leptomeningitis. Spleens were without lesions. Conclusions: The immunizations and in particular the C1 vaccine reduced the incidence of histological brain lesions, and also reduced the duration and severity of clinical signs and viral shedding.
113
FATAL SYSTEMIC USUTU VIRUS INFECTION IN TWO JUVENILE GREAT GREY OWLS (STRIX NEBULOSA) FROM A GERMAN ZOOLOGICAL GARDEN C. Schulze *, U. Ziegler y, P. Schlieben *, C. Fast y, S. Bock *, A. Sch€ ule z and A. Ochsz *BerlineBrandenburg State Laboratory, yFriedrich-Loeffler-Institut, Federal Research Institute for Animal Health and zZoo Berlin, Germany Introduction: Usutu virus (USUV), an African arbovirus within the genus Flavivirus, was introduced into Italy in 1996 and afterwards spread north causing epizootics among wild and captive birds in different European countries. In Germany, USUV was initially recovered from carcasses of wild birds from the upper Rhine Valley in 2011. Materials and Methods: Necropsy examination was performed on two 3-month-old great grey owls from Berlin Zoo, which suffered from a hyperacute fatal disease. Native tissues were screened for USUV by RT-qPCR. Formalin-fixed and paraffin wax-embedded tissues were investigated by HE staining and immunohistochemistry using a polyclonal rabbit antiserum. In addition, the virus was isolated in cell culture and further characterized by molecular methods. Results: Main gross findings in both owls were multiple foci of necrosis in liver and spleen. Additionally, several other organs including the brain, kidney, lung, bone marrow, heart and skeletal muscle contained necrosis of different degrees. The USUV RT-qPCR was positive in tissue pools from both birds. By immunohistochemistry, USUV antigen was detected in vascular endothelium, parenchymal and reticulohistiocytic cells, mainly associated with the necrotic foci. Molecular phylogeny revealed that the birds were infected by a new USUV strain, provisionally named USUV-Berlin, of Africa 2 lineage. Conclusions: The reported outbreak represents the third independent USUV introduction to Germany and its northernmost occurrence in Europe. Great grey owls seem to be suitable sentinel animals for the indication of the presence of the virus in a formerly unaffected region.