Epidemiological surveillance of feline morbillivirus infection in the aspects of polymerase chain reaction, indirect elisa and immunohistochemistry

Abstract

Feline morbillivirus (FeMV), a relatively new virus, has been discovered in domestic cats and associated with kidney diseases since 2012 in Hong Kong. The FeMV study gained widely attentions in many countries whereas the pathogenesis remains elusive. These studies aimed to provide the FeMV knowledge in Thai domestic cat by performing the genetic-based, serological-based and pathological-based studies of FeMV-infected in Thai cats. Additionally, the indirect enzyme linked immunosorbent assay (ELISA) and rabbit polyclonal antibody against FeMV matrix (FeMV-M) protein was produced for seroprevalence and viral localization by immunohistochemistry (IHC) techniques, respectively. Our results revealed the FeMV RNA prevalence at 11.9% and seroprevalence at 66.9% in cats derived from shelters and households. The FeMV Thai strains were clustered in FeMV-1A genotype without evidence of viral recombination. Urine sample provided more FeMV positivity rate when compared with blood sample, however the significant correlation between FeMV positive urine and urine characteristics was not observed. To study the localization and distribution of FeMV in two moribund FeMV-positive-PCR cats with history of acute hematuria and, grossly, acute hemorrhagic cystitis, histopathology, IHC, and transmission electron microscopy (TEM) were performed. Microscopically, the prominent lesions revealed scattering intracytoplasmic eosinophilic inclusion bodies (ICIB) in renal epithelial cells locating at corticomedullary junction and renal pelvis. By TEM, the ultrastructural morphology demonstrated the aggregation of electron-dense ribonucleocapsid herringbone-like structure in the cytoplasm of renal tubular epithelial cells, where the inclusion materials were found. Moreover, the immunoreactive signals were also visualized in the ICIB of renal epithelial cells, cytoplasm of tracheal, bronchial, and bronchiolar epitheliums, circulating lymphocytes and infiltrating histiocytes in spleen and mesenteric lymph node, and neuroglial cells in the white matter of brain, suggesting systemic viral infection. Importantly, we proposed that FeMV is a renal epitheliotropic virus, similarly to other morbilliviruses, by existing viral inclusions without integral pathological changes of kidney disease. Furthermore, we have reported the two black leopards (Panthera pardus) which were positive to FeMV-1A genotype and associated with chronic kidney disease. In conclusion, we suggested that domestic and non-domestic felids are susceptible to FeMV infection. However, the association between FeMV and kidney diseases throughout its pathogenesis is needed further investigations.