Viral kinetics of fetal infection over 21 days plotted from three separate studies.

<p>43 pregnant guinea pigs were inoculated by subcutaneous injection with 4×10³ PFU of pathogenic stock IVP8 at day 21 gestation and sacrificed at 1, 3, 7, 11, 15, and 21 days post-infection. Each glyph (dot) represents the proportion of infected fetuses, with the size of the glyph proportional to the litter size. The solid lines represent the proportion of infected fetuses in a litter from a beta-binomial model fit to all three cohorts. The dashed segment of each line is extrapolated beyond the cohort data and is model based. See statistical section in methods for more details.