Green M P, Spate L D, Bixby J A, Ealy A D, Roberts R M
Department of Animal Sciences, University of Missouri, Columbia, Missouri 65211, USA.
Biol Reprod. 2005 Dec;73(6):1087-93. doi: 10.1095/biolreprod.105.043406. Epub 2005 Aug 3.
Interferon tau (IFNT) is secreted by the trophectoderm of ruminant conceptuses during the peri-implantation period and serves an anti-luteolytic function. The question as to whether IFNT is superior as an anti-luteolytic agent to closely related Type I IFNs, such as IFN alpha (IFNA), which have a different function, remains unanswered. Thus, the aim of this study was to determine whether equivalent antiviral (AV) units of ovIFNA and ovIFNT are equipotent in extending estrous cycle length. Four distinct ovIFNA mRNA (ovIFNA1-4) were cloned from ovine lymphocytes. Recombinant ovine IFNs (ovIFNT4 and ovIFNA1) were prepared in the yeast Pichia pastoris. The AV activity of the purified IFNs was determined on a bovine cell line (MDBK) and on transformed ovine luminal uterine epithelial cells. Indwelling uterine catheters were fitted into crossbred ewes on Day 3 postestrus (Day 0 = estrus). Between Days 10 and 18 postestrus, ewes received twice-daily infusions of 0.7 x 10(7) IU of either ovIFNA1 or T4, plus serum albumin. Control ewes received serum albumin only. Daily blood samples were collected for progesterone determination, and ewes were monitored twice daily for estrus. Both ovIFNA (P = 0.04) and ovIFNT (P = 0.01) caused estrous cycle extension in nonpregnant ewes compared to controls when administered at equivalent AV doses. In conclusion, the uniqueness of IFNT as an anti-luteolytic agent most likely resides in its unique expression pattern rather than its special biopotency.
干扰素τ（IFNT）在反刍动物胚胎着床前期由滋养外胚层分泌，具有抗黄体溶解功能。IFNT作为一种抗黄体溶解剂是否优于功能不同但密切相关的I型干扰素，如干扰素α（IFNA），这个问题仍未得到解答。因此，本研究的目的是确定等量抗病毒（AV）单位的绵羊IFNA和绵羊IFNT在延长发情周期长度方面是否具有同等效力。从绵羊淋巴细胞中克隆出四种不同的绵羊IFNA mRNA（ovIFNA1 - 4）。在毕赤酵母中制备重组绵羊干扰素（ovIFNT4和ovIFNA1）。在牛细胞系（MDBK）和转化的绵羊子宫腔上皮细胞上测定纯化干扰素的AV活性。在发情后第3天（第0天 = 发情期）将留置子宫导管插入杂交母羊体内。在发情后第10至18天，母羊每天接受两次0.7×10⁷ IU的ovIFNA1或T4输注，加血清白蛋白。对照母羊仅接受血清白蛋白。每天采集血样测定孕酮，并每天对母羊进行两次发情监测。当以等效AV剂量给药时，与对照组相比，ovIFNA（P = 0.04）和ovIFNT（P = 0.01）均使未怀孕母羊的发情周期延长。总之，IFNT作为抗黄体溶解剂的独特性很可能在于其独特的表达模式而非其特殊的生物效能。
