Immunohistochemical Evaluation of Mx Protein Expression in Canine Encephalitides

Abstract

Mx proteins are a group of interferon-induced GTPases whose expression has been demonstrated in a number of human viral infections and in some idiopathic inflammatory diseases. In this study, the expression of Mx protein was evaluated in known viral, nonviral, and idiopathic encephalitides in the dog via immunohistochemistry using an antibody against human MxA. All 12 cases of confirmed viral encephalitis, including 7 cases of canine distemper, 4 cases of canine herpesvirus, and 1 case of rabies, were Mx positive. In canine distemper cases, staining was particularly strong and a variety of cell types were positive, including astrocytes, macrophages/microglia, and neurons. Immunoreactivity for Mx protein was evident in a few cases of nonviral infectious encephalitis, including neosporosis (1/1), Chagas disease (2/3), aspergillosis (1/2), and encephalitozoonosis (1/1). Consistent staining was observed in most cases of idiopathic encephalitis, including granulomatous meningoencephalomyelitis (7/7), necrotizing meningoencephalitis of pug dogs (6/7), and necrotizing encephalitis of the Yorkshire Terrier (3/3) and Maltese (1/1) breeds. Mx staining was negative in 5 normal dog brains; 3 cases of cryptococcosis; and single cases of blastomycosis, protothecosis, and bacterial meningitis.

Immunogenetic Factors Affecting Susceptibility of Humans and Rodents to Hantaviruses and the Clinical Course of Hantaviral Disease in Humans

“…Because Mx2 is known to limit PUUV replication in humans and in cell cultures [106], and to induce pathological symptoms when overproduced [108,109], Guivier et al [16] analysed the variability of Mx2 gene expression between areas of high and low PUUV seroprevalence in the French Ardennes. Similar results as those observed with Tnf were described.…”

Landscape features and helminth co-infection shape bank vole immunoheterogeneity, with consequences for Puumala virus epidemiology

“…TNF-a and Mx2 are costly immune effectors inducing collateral damage when present at high concentration (Li and Youssoufian, 1997;Wenzel et al, 2005;Porter et al, 2006;Bradley, 2008). Lower levels of expression of the genes encoding these molecules may therefore be considered to constitute a tolerance mechanism, an adaptive process limiting pathologies at the expense of pathogen growth or reproduction (Raberg et al, 2009).…”

“…These molecules limit PUUV replication in humans and in cell cultures (Kanerva et al, 1996;Temonen et al, 1996;Jin et al, 2001). The overproduction of these molecules also leads to pathological symptoms (Li and Youssoufian, 1997;Wenzel et al, 2005;Porter et al, 2006;Bradley, 2008). We analyzed the variability of Tnf-a and Mx2 gene expression between individuals, populations and habitat patches.…”

Slowly progressive lymphohistiocytic meningoencephalomyelitis in 21 adult cats presenting with peculiar neurological signs

“…Non-infectious encephalitides included granulomatous meningoencephalomyelitis, necrotising meningoencephalitis of Pug dogs, and necrotising encephalitis of the Yorkshire Terrier and Maltese breeds. 9 Mx-protein expression in dogs with non-infectious encephalitides was less widespread and intense than in dogs with confirmed viral infection. 9 In the cats described in our study, non-viral organisms were excluded histologically.…”

“…The expression of Mx-protein enables narrowing the panel of immune responses to the action of type I interferons and interferon lambda. 9 In dogs, Mx protein has been identified immunohistochemically in neurons, astrocytes and microglial cells of brains affected by infectious and non-infectious inflammatory encephalitides. The panel of infective aetiologies in canine brains showing Mx protein expression ranged from viruses to fungi.…”