engleski

Investigation of TTSuV in nephropathy cases in pigs affacted by PMWS

Introduction Torque teno sus virus (TTSuV) is a member of Anneloviridae family and highly prevalent in the pig population [1]. However, the influence on health status or pathogenesis is still unknown. Some studies indicate that this virus can be co-factor in the pathogenesis of PMWS [2], or in association with PRRSV in case of PDNS [3]. Until now it is known that it can induce lung edema and glomerulonephropathy in gnotobiotic pigs. Novel study indicates that especially TTSuV genogroup 2 can have tropism toward kidneys [4]. The aim of this study was to investigate the possible association of TTSuV in nephropathy in severe PMWS cases. Materials and Methods A total of 14 kidneys with interstitial nephritis and nephroses (Fig 1 a, b, c, d) from PMWS affected pigs were submitted to PCR detection of both TSuV genogroups prevalence according to previously described protocol. The partial ORF2 amplicons were obtained and sequenced. A 41 bp DIG labeled genomic probe to detect TTSuV2 was created based on conservative region of ORF2. Furthermore, TTSuV2 were subjected for viral load detection qPCR. Since some of kidneys were positive by ISH for PCV2, conservative region was specially picked to be more dissimilar than PCV2 sequence. In situ hybridization was performed on tissue fixed in 10% buffered formalin, routinely processed and embedded in paraffin blocks. A final concentration of 0.3 nmol/ml of genomic probe was used. For detection system anti-digoxigenin antibody conjugated with alkaline phosphatase and NBT/X.Phos substrate was used. Tissues were counterstained with fast green. Results Out of 14 kidneys investigated one was positive for TTSuV1 and 10 for TTSuV2 by PCR. TTSuV1 (JQ043191) and TTSuV2 (JQ043197, JQ043199, JQ043204, JQ043202, JQ0431206 sequences were amplified, sequenced and deposited in GeneBank). All those ten samples were positive by qPCR but in only two showed relatively high viral loads (101 and 103 genomic copies per µl) (Table 1). These two kidney samples were also TTSuV2 positive by ISH, showing positive signal in glomerular, epithelial cells, in tubuli and in macrophages of the inflammatory infiltrates (Fig 2a and b). Positive epithelial cells were not associated with sights of atrophy and apoptosis, as in case of PCV2 infection, while PCV2 signal by ISH was absent in glomerular cells at all (Fig 3a and b). Conclusions and Discussion High prevalence of TTSuV2 indicates that infection could be associated with nephropathy cases in pigs. The results of ISH and qPCR are in correlation but expected viral load was higher than detected. The ISH positive signal could mean that TTSuV2 shows tropism toward kidney cells as previously reported [4] but the results and protocol have to be re- evaluated. Low prevalence of TTSuV1 excludes the possible role in the pathogenesis of these lesions. Possible cross-reaction TTSuV2 genomic probe with PCV2 genome can be completely excluded

Torque teno sus virus; nephropathy

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