RESUMO
Mink astrovirus (MiAstV) is known to play a major role in mink pre-weaning diarrhea, and rotavirus and hepatitis E virus (HEV) are both considered potentially zoonotic agents. These viruses are not monitored in commercial mink, and the role of these viral infections in mink health is not well understood. This study assessed the prevalence of mink astrovirus, rotavirus C, mink HEV and swine HEV in 527 pooled healthy adult female mink and mink kit fecal samples from 50 Canadian mink farms in two seasons over 4 years. Viral RNA was extracted and amplified in RT-PCR to detect mink astrovirus and HEV RdRp genes, swine HEV ORF2, and rotavirus C VP6 gene. At least 26% of all positive samples for each virus was sequenced for phylogenetic analysis. Fourteen percent of samples were astrovirus positive, while 3 and 9% of samples were rotavirus C and mink HEV positive, respectively. One adult female sample was found to be positive by PCR for swine HEV. A significantly higher number of kit samples were astrovirus- and HEV-positive compared to adult female samples (p = 0.01 and p < 0.0001, respectively). Astrovirus was detected in significantly more summer samples from adult females compared to winter samples from adult females (p = 0.001). The detected sequences were closely related to previously reported MiAstV, swine rotavirus C, and mink and swine HEV strains. Two astrovirus sequences were distantly related to all other detected sequences as well as previously reported MiAstVs. These results demonstrate low to moderate prevalence of the three viruses in feces from clinically healthy Canadian commercial mink, and suggest that further monitoring of these viruses may provide a better understanding of how these potentially zoonotic agents may play a role in mink enteritis and overall productivity.
RESUMO
Immunohistochemistry was used to examine the expression of prostaglandin E(2) receptors EP1 and EP4 in sciatic nerves from the rat chronic constriction injury (CCI) model of neuropathic pain. At 21 days post-surgery the CCI rats had developed mechanical hyperalgesia on the operated side, and quantitative image analysis showed a highly significant doubling of the area occupied by EP1- and EP4-positive pixels in sections from CCI nerves when compared to sham-operated controls. Co-localisation studies with the marker ED1 revealed that 73% of the EP1-positive cells and 54% of the EP4-positive cells in the injured nerves represented infiltrating macrophages. Cells negative for ED1 and positive for either EP1 or EP4 were characterised as Schwann cells from their morphology and expression of myelin basic protein and S100 antigens. Similar EP1- and EP4-positive Schwann cell profiles were observed in sections of uninjured control nerves. Low levels of EP receptor expression were found in neurofilament-immunostained axons, but no consistent differences were observed in the levels of axonal EP staining between CCI and control tissue. These data provide further evidence of the importance of prostaglandins in the pathogenesis of neuropathic pain, and suggest that not only infiltrating macrophages but also Schwann cells may be involved in the modulation of these mediators in response to nerve injury.
