Acute bovine viral diarrhoea virus infection inhibits expression of interferon tau-stimulated genes in bovine endometrium

Abstract

Bovine viral diarrhea virus (BVDV) can evade host detection by downregulation of interferon signaling pathways. Infection of cows with noncytopathic (ncp) BVDV can cause early embryonic mortality. Upregulation of type I interferon stimulated genes (ISGs) by blastocyst-secreted interferon tau (IFNT) is a crucial component of the maternal recognition of pregnancy (MRP) in ruminants. This study investigated the potential of acute BVDV infection to disrupt MRP by modulating endometrial ISG expression. Endometrial cells from 10 BVDV-free cows were cultured and treated with 0 or 100 ng/ml IFNT for 24 h in the absence or presence of ncpBVDV infection to yield four treatment groups: CONT, ncpBVDV, IFNT, or ncpBVDV+IFNT. ncpBVDV infection alone only upregulated TRIM56, but reduced mRNA expression of ISG15, MX2, BST2, and the proinflammatory cytokine IL1B. As anticipated, IFNT treatment alone significantly increased expression of all 17 ISGs tested. In contrast to the limited effect of ncpBVDV alone, the virus markedly inhibited IFNT-stimulated expression of 15 ISGs tested (ISG15, HERC5, USP18, DDX58, IFIH1, IFIT1, IFIT3, BST2, MX1, MX2, RSAD2, OAS1Y, SAMD9, GBP4, and PLAC8), together with ISG15 secreted protein. Only TRIM56 and IFI27 expression was unaltered. IL1B expression was reduced by the combined treatment. These results indicate that acute ncpBVDV infection may decrease uterine immunity and lead to MRP failure through inhibition of IFNT-stimulated endometrial ISG production. This in turn could reduce fertility and predispose cows to uterine disease, while evasion of the normal uterine immune response by ncpBVDV may contribute to maintenance and spreading of this economically important disease.

Bovine Viral Diarrhoea Virus Infection Disrupts Uterine Interferon Stimulated Gene Regulatory Pathways During Pregnancy Recognition in Cows

“…In support of this, our recent studies using an in vitro model of PR illustrated that BVDV inhibited bovine uterine defence systems to facilitate its own survival [23,24]. As expected, IFNT treatment alone significantly stimulated ISG expression in endometrial cell cultures, but concurrent BVDV infection significantly inhibited this stimulatory effect for 15 of the 17 ISGs tested (ISG15, HERC5, USP18, DDX58, IFIH1, IFIT1, IFIT3, BST2, MX1, MX2, RSAD2, OAS1Y, SAMD9, GBP4 and PLAC8) [24]. This suggests a potential mechanism by which BVDV infection impairs PR and reproductive performance.…”

“…Once acquired, the virus has a broad tissue tropism, and can replicate in many tissues, including the female reproductive system [20,22]. In support of this, our recent studies using an in vitro model of PR illustrated that BVDV inhibited bovine uterine defence systems to facilitate its own survival [23,24]. As expected, IFNT treatment alone significantly stimulated ISG expression in endometrial cell cultures, but concurrent BVDV infection significantly inhibited this stimulatory effect for 15 of the 17 ISGs tested (ISG15, HERC5, USP18, DDX58, IFIH1, IFIT1, IFIT3, BST2, MX1, MX2, RSAD2, OAS1Y, SAMD9, GBP4 and PLAC8) [24].…”

“…The uteri from 10 BVDV-free cows were selected for the experiments. Uterine endometrial cells (a mixture of primary epithelial and stromal cells) were isolated and cultured using the methods established in our laboratory [23,24]. Briefly, strips of intercaruncular endometrium were dissected and put into Dulbecco's Modified Eagle's Medium/Nutrient Mixture F-12 Ham (DMEM/F12 medium) (Sigma).…”

Importance of Viral Disease in Dairy Cow Fertility

“…This early innate response is crucial to avoid the development of uterine disease; nevertheless, many dairy cows do develop metritis and/or endometritis (estimated at around 40% and 20% of all animals, respectively) [38]. In cultured bovine endometrial cells, experimental infection with ncp BVDV inhibited a variety of immune pathways normally activated in response to a challenge with bacterial lipopolysaccharide (LPS), including downregulation of many interferon-stimulated genes (ISGs), which are an important part of uterine defense mechanisms [40,41]. Infection with ncp BVDV was also able to switch endometrial prostaglandin production from prostaglandin (PG)F 2a to PGE 2 [42].…”

“…Acute infection with ncp BVDV alone has been shown to have a limited influence on endometrial gene expression in vitro [40]. However, infection did interfere with the ISG regulatory IRF-STAT1 and STAT2 pathways to inhibit IFNT-induced ISG expression including ISG15, HERC5, USP18 (involved in protein modification via ISGylation), DDX58, IFIH1 (cytosolic detection of viral RNA) and IFIT3, MX2, RSAD2, and SAMD9 (immune regulators with antiviral activity) [41]. Upregulation of the endometrial ISGylation pathway is an important process in early pregnancy that is conserved across mammalian species [55].…”