In vitro study on role of σB protein in avian reovirus pathogenesis

Avian reoviruses, members of Orthoreovirus genus was known to cause diseases like tenosynovitis, runting-stunting syndrome in chickens. Among eight structural proteins, the proteins of S-class are mainly associated with viral arthritis but the significance of σB protein in arthritis is not established till date. In this infection pathological condition together with infection of joints often leads to arthritis because joints consists of cartilage which forms lubricating surface between two bones, and has limited metabolic, replicative and repair capacity. To establish the role of σB protein in arthritis, an in-vitro microarray study was conducted consisting four groups viz. virus infected and control; pDsRed-Express-N1-σB and empty pDs-Red transfected, CEF cells. With cut-off value as FC ≥2, p value <0.05, 6709 and 4026 numbers of DEGs in virus and σB, respectively were identified. The Ingenuity Pathway Analysis gave an idea about the involvement of σB protein in "osteoarthritis pathway", which was activated with z-score with 3.151. The pathway "Role of IL-17A in arthritis pathway" was also enriched with -log (p-value) 1.64. Among total 122 genes involved in osteoarthritis pathway, 28 upregulated and 11 downregulated DEGs were common to both virus and σB treated cells. Moreover, 14 upregulated and 7 downregulated were unique in σB transfected cells. Using qRT-PCR for IL-1B, BMP2, SMAD1, SPP1 genes, the microarray data was validated. We concluded that during ARV infection σB protein, if not fully partially leads to molecular alteration of various genes of host orchestrating the different molecular pattern in joints, leading to tenosynovitis syndrome.