Figure 4.

L2 is not required for L1 expression but influences L1 location. L1 expression in L2ATGko mutant lesions was mild–moderate and predominately present in the cytoplasm, while the wild-type lesions demonstrated moderate nuclear expression (A, 20×) although a comparative amount of viral DNA was detected (B, 10×). In addition, one of the two tail lesions exhibited viral particles by EM (arrows), although detection required exhaustive searching; wild-type lesions contained far more abundant viral particles (C). The cytoplasm of suprabasal epidermal cells was strongly positive for viral E4 protein in the L2ATGko mutant-induced lesions (D). Biopsies were harvested from lesions induced by the L2ATGko mutant or wild-type MmuPV1 for DNA extraction. No significant difference was found in the DNA copy number from the wild-type lesions and L2ATGko lesions (E, p > 0.05, unpaired Student’s t-test).