FIG. 4.

Stability of internalized particles. The cytoplasmic fraction prepared at 4 hpi was fractionated through a sucrose gradient as described for Fig. 2b. (a) Vp1 in odd-numbered fractions was detected immunologically as described for Fig. 2c. (b) Viral DNA in even-numbered fractions was detected by semiquantitative PCR, generating a 2.2-kbp fragment, followed by Southern blotting with ³²P-labeled SV40 DNA as a probe. Wt, wild type.