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MARÍA ÁNGELES GARCÍA Y COLS. AN. R. ACAD. NAC. FARM.

vectors, although there was a trend of slightly higher tumour reduc-
tion in mice inoculated with the viral vectors expressing PKR. The
virus titers at the tumour site remain elevated in animals inoculated
with VV-Luc compared to animals inoculated with VV-PKR. At day 5
after the administration of two doses of virus by i.p. inoculation, the
mean virus titers in 3 mice were 3.9x106 pfu/gr tissue in the tumours
of VV-LUC compared to less then 102 in VV-PKR.

Previously, it has been shown that virus lacking TK improves the
oncolytic activity of VACV (3). Our results showing that VV-PKR ex-
hibits reduced replication in tissues compared to either VV-LUC or
VV-PKR(K296R), together with the fact that tumours were reduced
similarly by VV-PKR as for the other two vectors, indicate that
VV-PKR is a self-limited replication vector with oncolytic activity.

Figure 3. Antibody response against different VACV recombinants. Detection of
antibodies against vaccinia virus (by ELISA) in serum obtained 23 days post-infec-
tion from mice, four per group, inoculated i.p. twice (days 0 and 3) with 5x107 pfu
per mouse of each recombinant viruses VVLUC, VV-PKR, VV-K296R or PBS. 96-well
plates were fixed with 1 µg/well of soluble cell extract from VACV-infected BSC-40
cells. A single serum dilution of 1:400 was used for all samples. Absorbance of serum
dilution from each mouse is shown.

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