Time-related Pathological Changes in Horses Experimentally Inoculated with
Equine Influenza A Virus |
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| Authors: | Masanori MURANAKA Takashi YAMANAKA Yoshinari KATAYAMA Hidekazu NIWA Kazuomi OKU Tomio MATSUMURA Toshifumi OYAMADA |
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| Institution: | 1. Epizootic Research Center, Equine Research Institute, the Japan Racing Association, 1400-4 Shiba, Shimotsuke-shi, Tochigi 329-0412, Japan;2.Racehorse Clinic, Miho Training Center, the Japan Racing Association, Ibaraki 300-0415, Japan;3. Department of Veterinary Pathology, School of Veterinary Medicine, Kitasato University, Aomori 034-8628, Japan |
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| Abstract: | To investigate the pathology of equine influenza, necropsy of 7 horses experimentally
infected with equine influenza A virus (EIV) subtype H3N8 was conducted on post-infection
days (PID) 2, 3, 7, and 14. Histopathologically, rhinitis or tracheitis including
epithelial degeneration or necrosis with loss of ciliated epithelia and a reduction in
goblet cell numbers, was observed in the respiratory tracts on PIDs 2 and 3. Epithelial
hyperplasia or squamous metaplasia and suppurative bronchopneumonia with proliferation of
type II pneumocytes were observed on PIDs 7 and 14. Viral antigen was detected
immunohistochemically in the epithelia of the nasal mucosa, trachea, and bronchi on PIDs 2
and 3. The sodA gene of Streptococcus equi subsp. zooepidemicus, a suspected cause of
suppurative bronchopneumonia, was detected in paraffin-embedded lung tissue sections, but
only on PIDs 7 and 14. These findings suggest that damage caused to ciliated epithelia and
goblet cells by EIV infection results in secondary bacterial bronchopneumonia due to a
reduction in mucociliary clearance. |
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| Keywords: | equine influenza A virus equine respiratory disease experimental infection |
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