Abstract：
Bovine gammaherpesvirus type 4 (BoHV-4) shows tropism for the endometrium, in which it causes the death of epithelial and stroma cells. Despite having anti-apoptotic genes in its genome, experiments based on immortalized cell lines have shown that BoHV-4 induces cell death by apoptosis. In the present study, we evaluated BoHV-4 replication, pro-apoptotic (Bax) and anti-apoptotic (Bcl-2) mitochondrial genes expression and chromatin condensation in bovine endometrium primary culture cells (BEC) and in the Madin Darby bovine kidney (MDBK) cell line. Results showed that BoHV-4 has a preference for replication in BEC cells over the MDBK cell line, demonstrated by the high viral titer that is consistent with the tropism of the virus. In BEC cells, chromatin condensation was consistent with the values of viral kinetics at the late stage of infection, accompanied with a balance in the mRNA levels of apoptotic mitochondrial proteins. As a consequence, in those cells viral transmission would be enhanced by inhibiting apoptosis in the early stage of virus proliferation, allowing the complete production of viral progeny, and then, the induction of apoptosis in late stages would allow neighboring cells infection. In MDBK cells replication kinetics was coincident with the up-regulation of Bcl-2, which suggests that the productive infection in MDBK is associated with a lytic phase of the virus or another cell death pathway (probably autophagy mechanism) at the late stage of infection. The results agree with the study of nuclear morphology, where a constant chromatin condensation was observed over time. It is clear that the documented BoHV-4 apoptotic responses observed in the cell lines studied above are not valid in cells from primary cultures. The data presented in this study suggest that BoHV-4 could induce apoptosis in BEC cells without a leading role of the mitochondria pathway. Further studies will be necessary to characterize in detail the programmed cell death pathways involved in BoHV-4 infection in the primary cell cultures evaluated.
摘要：
牛γ疱疹病毒4型（BoHV-4）显示子宫内膜的向性，导致上皮细胞和基质细胞死亡。尽管它的基因组中有抗凋亡基因，基于永生化细胞系的实验表明BoHV-4通过凋亡诱导细胞死亡。在本研究中,我们评估了BoHV-4的复制,牛子宫内膜原代培养细胞（BEC）和MadinDarby牛肾（MDBK）细胞系中的促凋亡（Bax）和抗凋亡（Bcl-2）线粒体基因表达和染色质凝聚。结果表明，BoHV-4在BEC细胞中的复制优先于MDBK细胞系，病毒滴度高，与病毒的向性一致。在BEC细胞中,染色质凝聚与感染后期的病毒动力学值一致，伴随着凋亡线粒体蛋白的mRNA水平平衡。因此,在这些细胞中，在病毒增殖的早期阶段通过抑制细胞凋亡来增强病毒传播，允许病毒后代的完整生产，然后,晚期细胞凋亡的诱导将允许邻近细胞感染。在MDBK细胞中，复制动力学与Bcl-2的上调一致，这表明MDBK中的生产性感染与病毒的裂解期或感染后期的另一种细胞死亡途径（可能是自噬机制）有关。结果与核形态学的研究一致，其中随着时间的推移观察到恒定的染色质凝聚。显然,在上述研究的细胞系中观察到的记录的BoHV-4凋亡应答在来自原代培养物的细胞中无效。这项研究中提供的数据表明，BoHV-4可以诱导BEC细胞凋亡，而没有线粒体途径的主导作用。需要进一步的研究来详细表征所评估的原代细胞培养物中BoHV-4感染中涉及的程序性细胞死亡途径。
