A method for infection of cultured myogenic cells with Rous sarcoma virus using polybrene

A method for efficiently infecting primary myogenic cultures with a temperature-sensitive variant of the Prague strain of Rous sarcoma virus (RSV, tsLA24) to obtain a high yield of transformed myogenic cells is reported. It incorporates the use of an amorphous polymer of polycations, Polybrene, to enhance the absorption of the virus by the muscle cells. In addition, other steps which were shown to be important were a) to allow cell attachment before infection, b) to infect at 35 degrees C in low protein medium, c) to use a density of 1 to 1.5 X 10(6) cells/60-mm dish, d) gentle agitation during infection, and e) to minimize the number of passages after infection. The use of the temperature-sensitive virus provided a means of confirming the presence of myogenic cells in transformed cultures. When infected cells were maintained at 35 degrees C (the permissive temperature for virus activity) they exhibited the characteristics of transformed cells. These characteristics included altered cell morphology, the absence of contact-inhibited growth, growth in semisolid medium, and expression of the src oncogene. In contrast, when infected cells were maintained at 41 degrees C (the nonpermissive temperature for virus activity) they do not express src and showed normal myogenic development and ultimately formed myotubes.