Institut für Immunologie, Friedrich-Loeffler-Institut, Greifswald-Insel Riems.
Abteilung für experimentelle Tierhaltung und Biosicherheit, Friedrich-Loeffler-Institut, Greifswald-Insel Riems.
PLoS Pathog. 2021 Dec 8;17(12):e1010107. doi: 10.1371/journal.ppat.1010107. eCollection 2021 Dec.
In contrast to wild type bovine viral diarhea virus (BVDV) specific double deletion mutants are not able to establish persistent infection upon infection of a pregnant heifer. Our data shows that this finding results from a defect in transfer of the virus from the mother animal to the fetus. Pregnant heifers were inoculated with such a double deletion mutant or the parental wild type virus and slaughtered pairwise on days 6, 9, 10 and 13 post infection. Viral RNA was detected via qRT-PCR and RNAscope analyses in maternal tissues for both viruses from day 6 p.i. on. However, the double deletion mutant was not detected in placenta and was only found in samples from animals infected with the wild type virus. Similarly, high levels of wild type viral RNA were present in fetal tissues whereas the genome of the double deletion mutant was not detected supporting the hypothesis of a specific inhibition of mutant virus replication in the placenta. We compared the induction of gene expression upon infection of placenta derived cell lines with wild type and mutant virus via gene array analysis. Genes important for the innate immune response were strongly upregulated by the mutant virus compared to the wild type in caruncle epithelial cells that establish the cell layer on the maternal side at the maternal-fetal interface in the placenta. Also, trophoblasts which can be found on the fetal side of the interface showed significant induction of gene expression upon infection with the mutant virus although with lower complexity. Growth curves recorded in both cell lines revealed a general reduction of virus replication in caruncular epithelial cells compared to the trophoblasts. Compared to the wild type virus this effect was dramtic for the mutant virus that reached only a TCID50 of 1.0 at 72 hours post infection.
与野生型牛病毒性腹泻病毒（BVDV）不同，特异性双重缺失突变体在感染怀孕母牛时不能建立持续性感染。我们的数据表明，这一发现是由于病毒从母体向胎儿的转移缺陷所致。怀孕母牛用这种双重缺失突变体或亲本野生型病毒接种，并在感染后第 6、9、10 和 13 天成对屠宰。从感染后第 6 天开始，通过 qRT-PCR 和 RNAscope 分析在母体组织中检测两种病毒的 RNA。然而，在胎盘组织中未检测到双重缺失突变体，仅在感染野生型病毒的动物样本中检测到。同样，在胎儿组织中存在高水平的野生型病毒 RNA，而双重缺失突变体的基因组未被检测到，这支持了突变病毒在胎盘内特定复制受到抑制的假说。我们通过基因芯片分析比较了野生型和突变病毒感染胎盘衍生细胞系时基因表达的诱导。与野生型相比，在胎盘的细胞层建立在母体-胎儿界面的母体侧的Caruncle 上皮细胞中，突变病毒强烈地上调了固有免疫反应相关基因的表达。在界面胎儿侧可发现的滋养层细胞中，感染突变病毒后也显示出明显的基因表达诱导，尽管复杂性较低。在两种细胞系中记录的生长曲线显示，在 Caruncle 上皮细胞中病毒复制的总体减少与滋养层细胞相比。与野生型病毒相比，这种效应在突变病毒中更为显著，其在感染后 72 小时的 TCID50 仅为 1.0。
