Jaffredo T, Molina R M, al Moustafa A E, Gautier R, Cosset F L, Verdier G, Dieterlen-Lièvre F
Institut d'Embryologie Cellulaire et Moléculaire du CNRS et du Collège de France.
Cell Adhes Commun. 1993 Sep;1(2):119-32. doi: 10.3109/15419069309095688.
We previously demonstrated that Avian Leukemia Viruses (ALV) carrying the v-myc gene specifically induce two types of tumors, cardiomyocytic tumors when the virus is injected before embryonic day 3 (E3), skin tumors when the virus is injected at E3 or E5. Aiming to elucidate the mechanisms which determine this time-dependent change in target, we infected chick and quail embryos at E3 and E5 with replication-deficient, lacZ gene-carrying, ALV-based viruses produced by a packaging cell line. Three constructs driven by 3 different Long Terminal Repeats (LTRs) were tested and yielded similar results. When the constructs were inoculated at E3 and the lacZ gene product revealed 5 days later, around 70% of the embryos carried lacZ+ clones in the heart, around 50% had positive clones in the skin anywhere on the body, while a few embryos displayed clones in internal organs (liver, stomach, lungs). Immunocytological identification of the heart cell type(s) expressing the virus revealed that the only cells infected were cardiomyocytes. When the constructs were inoculated at E5, no lacZ+ clones appeared in the heart but all were located in the cephalic skin. In order to examine the relationship between viral integration and expression, DNA of different organs or tissues from lacZ stained embryos was analyzed by PCR. A tight correlation between integration and expression in the heart and in the skin was revealed in most cases. In contrast, a significant PCR signal was often detected in the liver or the stomach despite weak or absent expression as revealed by lacZ+ clones. We then investigated the influence of envelope glycoprotein subgroups on the tropism of these constructs. The lacZ vector driven by RAV-2 LTRs was packaged as subgroups A, B or E viral particles. The A subgroup, used in the part of the study described above, infects both chick and quail while the B and E subgroups are specific for chick or quail respectively. These B and E subgroups induced lacZ+ clones in the heart (after E3 injection) while no clones or only a few were detected in the skin either after E3 or E5 injection. The following conclusions can be drawn: 1) cardiomyocytes are at E3 the major target for integration and expression of ALV-derived viruses in vivo; 2) targets change rapidly with embryonic age; and 3) tissue-specific infections depend on the envelope subgroup, thus presumably on the presence of the cognate receptor.(ABSTRACT TRUNCATED AT 400 WORDS)
我们之前证明，携带v-myc基因的禽白血病病毒（ALV）能特异性诱导两种类型的肿瘤，在胚胎第3天（E3）之前注射病毒时会诱导心肌细胞瘤，在E3或E5注射病毒时会诱导皮肤肿瘤。为了阐明决定这种靶标随时间变化的机制，我们在E3和E5时用包装细胞系产生的复制缺陷型、携带lacZ基因的基于ALV的病毒感染鸡和鹌鹑胚胎。测试了由3种不同的长末端重复序列（LTR）驱动的三种构建体，结果相似。当在E3接种构建体并在5天后检测lacZ基因产物时，约70%的胚胎心脏中有lacZ+克隆，约50%的胚胎身体任何部位的皮肤中有阳性克隆，而少数胚胎的内部器官（肝脏、胃、肺）中有克隆。对表达病毒的心脏细胞类型进行免疫细胞鉴定发现，唯一被感染的细胞是心肌细胞。当在E5接种构建体时，心脏中未出现lacZ+克隆，所有克隆都位于头部皮肤。为了研究病毒整合与表达之间的关系，通过PCR分析了来自lacZ染色胚胎的不同器官或组织的DNA。在大多数情况下，心脏和皮肤中的整合与表达之间存在紧密的相关性。相比之下，尽管lacZ+克隆显示表达较弱或无表达，但在肝脏或胃中经常检测到显著的PCR信号。然后我们研究了包膜糖蛋白亚组对这些构建体嗜性的影响。由RAV-2 LTR驱动的lacZ载体被包装成A、B或E亚组病毒颗粒。在上述研究部分中使用的A亚组既能感染鸡也能感染鹌鹑，而B和E亚组分别对鸡或鹌鹑具有特异性。这些B和E亚组在心脏中诱导出lacZ+克隆（在E3注射后），而在E3或E5注射后，在皮肤中未检测到克隆或仅检测到少数克隆。可以得出以下结论：1）在体内，E3时心肌细胞是ALV衍生病毒整合和表达的主要靶标；2）靶标随胚胎年龄迅速变化；3）组织特异性感染取决于包膜亚组，因此可能取决于同源受体的存在。（摘要截断于400字）
