Figure 4
IAV detection in oral-pharyngeal and cloacal swabs of H9N2-infected SPF chickens by pan-IAV FRET-PCR and virus isolation.
Three-week-old specific pathogen-free (SPF) White Leghorn chickens (n = 10) were inoculated intranasally with 106 EID50 of IAV H9N2 in a 0.2 ml volume. Oral-pharyngeal and cloacal swabs were collected from chickens at 5, 7 and 9 dpi and resuspended in 1 ml PBS for total nucleic acids extraction followed by FRET-PCR and for virus isolation in the allantoic cavities of 10-day-old embryonated chicken eggs. The pan-IAV FRET-PCR determined the presence of IAV RNA in 8 oral-pharyngeal swabs and 3 cloacal swabs at day-5 pi and 7 oral-pharyngeal swabs at day-7 pi. In a contrast, virus isolation for H9N2 was positive in 6 oral-pharyngeal swabs and 2 cloacal swabs of chickens at day-5 pi and 3 oral-pharyngeal swabs at day-7 pi. IAV was not detected in the cloacal swabs of day-7 pi and both types of swabs of day-9 pi by the pan-IAV FRET-PCR and virus isolation. Swabs determined to be positive by virus isolation were all positive detected by the pan-IAV FRET-PCR in animal experiment.
