Two virus producing cell culture lines, HTG2 and HTG3, were established from a transplantable hamster tumor induced by a murine sarcoma virus (MSV) after 17 and 60 in vivo passages, respectively. HTG2 cells presumably produced only noninfectious sarcoma virions, whereas HTG3 cells yielded both sarcoma and 'helper' viruses. Electron microscopic examination of the original virus induced tumors, of pellets from cells grown in tissue culture, and of tissue culture medium harvested at 24, 48, 72, and 96 hr consistently revealed the same morphologic characteristics: More than 99% of the HTG2 virions retained their electron lucent or 'immature' form, in marked contrast to HTG3 virions or other typical type C viruses, which formed electron dense nucleoids. In addition, a large percentage of both HTG2 and HTG3 particles appeared morphologically incomplete, though completely detached or released from the cells. The inability to form dense nucleoids may be characteristic of noninfectious murine sarcoma viruses.
ASJC Scopus subject areas
- Cancer Research