Supplementary Fig. S1. A range of concentrations of an affinity-purified IgG fraction from a rabbit anti-GIF serum (horizontally hatched bars) was incubated with partially purified rGIF-BPSV pre-bound to 96-well plates. Specific binding was demonstrated by a reduced level of binding when the antiserum was pre-incubated with conditioned medium containing 20–50 µg ml⁻¹ of rGIF PCPV (shaded bars) or rGIF ORFV (filled bars). No significant reduction in binding was observed when the antiserum was pre-incubated with medium taken from untransfected CHO cells (empty bars). *P<0.001 compared with the rGIF-ORFV control.

Supplementary Fig. S2. Northern blots of RNA isolated from PCPV-infected (lane 3) and BPSV-infected (lane 1, V660; lane 2, A599) cells 24 h post-infection. Panel (a) was probed with ³²P-labelled PCPV GIF cDNA, whilst panel (b) was probed with ³²P-labelled BPSV (V660) GIF cDNA. A smear representative of poxvirus late mRNA transcripts is visible in lane 3, panel (a), and lanes 1 and 2, panel (b).

Supplementary Fig. S3. Northern blots of RNA isolated from CHO cells transfected with either PCPV or BPSV (V660) GIF cDNA in expression plasmid pEE14. RNA was isolated 24 h post-transfection. Panel (a) was probed with ³²P-labelled PCPV GIF cDNA, whilst panel (b) was probed with ³²P-labelled BPSV (V660) GIF cDNA. A single, discrete mRNA of approximately 1.5 kb in length was visualized in lane 1, panel (a) and lane 2, panel (b).