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. 2012 Jan 3;7(1):e29310. doi: 10.1371/journal.pone.0029310

Figure 2. Kinetics of vaccine induced prevention or reduction of viral RNA in blood and nasal secretions.

Figure 2

Viral RNA concentrations, determined by real time RT-PCR, in blood (solid lines) and nasal swab samples (dashed lines). A) High levels of viral RNA were detected in blood soon after challenge in unvaccinated animals (open circles), with nasal secretions becoming RNA positive 5–6 days later. B) No viral RNA, or very low levels in the inconclusive range of the assay, was detected in blood or nasal secretion of animals vaccinated 5 days prior to challenge (filled circles). C) High levels of viral RNA was detected in blood and nasal swab samples of one of the animals vaccinated 3 days prior to challenge with UK2000/7.1. An intermediate level of viral RNA was present in blood of one animal vaccinated 3 days prior to challenge with CBR/93 (open squares), whereas the remaining animals in these groups in both experiments (filled squares) had either a transient low level, or no, viral RNA in blood, and either no or intermediate levels of RNA in nasal secretions. D) Animals vaccinated one day prior to challenge either developed clinical disease and were euthanized by 18 dpc (open triangles) or remained healthy for the duration of the experiment (filled triangles).