Differentiation-Dependent Interpentameric Disulfide Bond Stabilizes Native Human Papillomavirus Type 16
Figure 8
Relative stabilities of 20-day wild-type versus mutant virions.
20-day wild-type (WT), C428S, C175S, C185S, and C175,185S viruses were Optiprep-fractionated. Fractions were assayed by a SYBR green-based DNA encapsidation assay to detect total endonuclease-resistant genomes per fraction. As a measure of capsid stability, the sum of genomes in the uppermost gradient fractions (fractions #1 through #4) was described as “unstable” (US), which were genomes either not associated or disassociated from an intact capsid during ultracentrifugation. The sum of genomes flanking highly infectious fractions (fractions #6 through #9) was described as “stable” (S) since they were associated with intact capsids. Relative capsid stability is described by the ratio US/S, whereby higher values indicate more unstable virions [23].