TABLE 1. In vitro infectivity of SFV-LacZ and ��-galactosidase protein expression in woodchuck and human HCC-derived cell lines In found order to test if SFV vectors can infect in vivo woodchuck hepatic tumor cells, two chronic WHV carrier woodchucks with HCC were selected, each having three tumors with sizes between 1 and 3 cm in diameter. The first woodchuck received intratumorally 1 �� 109 vp of an SFV vector expressing luciferase (SFV-Luc) into one tumor (tumor 1), whereas the other two tumors (tumors 2 and 3) were left untreated (Fig. (Fig.1A).1A). This woodchuck was euthanized 24 h later, and luciferase activity in the treated and untreated tumors and in surrounding liver tissue was measured. Luciferase activity was detected at high levels only in the treated tumor, demonstrating that transgene expression was mainly confined to the area of injection.

FIG. 1. Infectivity of SFV vectors in chronic WHV carrier woodchucks with HCC. (A) One woodchuck received intratumorally 1 �� 109 vp of SFV-Luc into one tumor with a size of approximately 3 cm in diameter (tumor 1). Two other tumors with sizes between … The second woodchuck received intratumorally 3 �� 109 vp of SFV-Luc into one tumor (tumor 1) and 3 �� 109 vp of an SFV vector expressing murine IL-12 (SFV-enhIL-12) into a second tumor (tumor 2), whereas a third tumor was left untreated (Fig. (Fig.1B).1B). Following euthanasia 24 h later, luciferase activity and IL-12 expression in treated and untreated tumors, adjacent liver tissues, and several other organs were measured, as presented in Fig. 1C and D.

Luciferase activity was elevated in all sections of tumor 1 and was five- to sevenfold higher than in the first woodchuck, which had received a threefold-lower dose of SFV-Luc (Fig. 1A and C). Luciferase activity was low in all other tissues analyzed, with the exception of liver tissue surrounding tumor 1 and spleen tissue. In this woodchuck, IL-12 protein was detected at high concentrations in two sections of tumor 2 treated with SFV-enhIL-12 (Fig. (Fig.1D).1D). Lower IL-12 concentrations were also detected in other sections of tumor 2, in proximal liver tissue, and in tumor 1 treated with SFV-Luc. The SFV-Luc-treated tumor 1 from the first woodchuck was used as an additional negative control, and IL-12 protein was detectable only at background level (Fig. 1A and D).

These results and the additional observation Dacomitinib that IL-12 was detected in serum of the second woodchuck at a concentration of 152 ng/ml (Fig. (Fig.1E)1E) suggest that this cytokine was secreted from neoplastic cells of tumor 2 following infection with SFV-enhIL-12. For establishing a correlation between the dose of SFV-enhIL-12 administered into a hepatic tumor and the IL-12 concentration detected thereafter in serum, a third woodchuck received intratumorally 1.2 �� 1010 vp of SFV-enhIL-12 into one tumor with a size of approximately 0.7 cm in diameter (Fig. (Fig.1E).1E).