Levy J A
Biomedicine. 1981 Feb;34(1):4-8.
Type C RNA viruses have been considered oncogenic because they are found associated with animal tumors and can induce cancers in several animal species. Those viruses that rapidly cause cancer appear to contain an oncogenic gene which resembles genetic sequences present in normal cells. This gene codes for a transforming protein which may be a normal cellular enzyme or a slightly altered cellular product. Its mechanism for transforming a cell is not yet known. Other oncogenic viruses, such as the chronic leukemia viruses, may not produce an oncogenic protein but may affect, by other means, specific target cells so they become malignant. Recent evidence now suggests that the majority of endogenous type C viruses are not transforming agents but inherited in the host to function in other biologic processes. These viruses do not contain transduced cellular genes which are responsible for cancer. Their role probably depends on their expression of other gene products which aid in normal development. These observations suggest that the ultimate control of human cancer may result from the identification of the oncogenic cellular-like genes transduced by some type C viruses even if a true human oncogenic virus is not isolated.
C型RNA病毒一直被认为具有致癌性，因为它们与动物肿瘤有关，并且能在多种动物物种中诱发癌症。那些能迅速引发癌症的病毒似乎含有一个致癌基因，该基因类似于正常细胞中存在的基因序列。这个基因编码一种转化蛋白，它可能是一种正常的细胞酶或略有改变的细胞产物。其转化细胞的机制尚不清楚。其他致癌病毒，如慢性白血病病毒，可能不产生致癌蛋白，但可能通过其他方式影响特定的靶细胞，使其恶变。最近的证据表明，大多数内源性C型病毒不是转化因子，而是在宿主中遗传，在其他生物学过程中发挥作用。这些病毒不包含导致癌症的转导细胞基因。它们的作用可能取决于它们对有助于正常发育的其他基因产物的表达。这些观察结果表明，即使没有分离出真正的人类致癌病毒，人类癌症的最终控制可能也源于对某些C型病毒转导的致癌细胞样基因的识别。
