RSV loads in RSV infected BALB/c mice BAL and lung supernatant samples measured by PCR vs. plaque assay. RSV loads measured by PCR in BAL samples (▽) remain positive up to 42 days after inoculation, while viral loads measured by plaque assay (□) become negative on day 7 post-inoculation (upper panel). Viral load measured in lung supernatants by the plaque assay also become undetectable by day 7 after inoculation, whereas RSV loads measured by PCR in lung supernatants remain detectable throughout all the time points evaluated (lower panel). All pair-wise multiple comparisons made by One-Way ANOVA. † p < 0.01 between D1 and D5 and *p < 0.05 comparing D1 with D3 and D5.