Comparison of influenza virus recovery in conjunctival wash samples following ocular inoculation of ferrets.

Ferrets were inoculated by the ocular route with 10⁶ EID₅₀/ml of each virus shown. Viral titers were measured in conjunctival washes (CW) collected on indicated days following serial titration in eggs; endpoint titers are expressed as mean log₁₀ EID₅₀/ml plus standard deviation (left y-axis and bars). Relative viral RNA copy number in conjunctival washes was determined by real-time PCR using a universal M1 primer and extrapolated using a standard curve based on samples of known virus (right y-axis and lines). The limit of virus detection was 10^1.5 EID₅₀/ml. †, no ferrets survived until day 9 p.i. R-squared values are shown for those viruses where a statistically significant (p<0.05) correlation between viral titer and viral RNA copy number exists. NS, not significant.