Table 1.

Pathogenesis of A/Panama/2007/99 (H3N2) and A/Thailand/16/04 (H5N1) viruses in ferrets inoculated intranasally or by aerosols

			Number of animals
			Clinical signs up to 14 dpi						Virus detection at 3 dpi
Virus	Method of inoculation	Dose range*	Weight loss (%)†	RII	Diarrhea	Dyspnea	Neurological‡	Lethality (MDT)	Lung§	NT	Liver	Brain¶	OB	Spleen	Int**
PN99	IN	High	7.4	1.2	0/5	0/5	0/5	0/5	0/3	3/3	0/3	3/3	2/3	0/3	0/3
PN99	AR	High	3.6	1.0	0/2	0/2	0/2	0/2	0/3	3/3	0/3	1/3	1/3	0/3	0/3
TH16	IN	Low	12.6	2.1	2/2	0/2	0/2	2/2 (6.0)	N.d.	N.d.	N.d.	N.d.	N.d.	N.d.	N.d.
TH16	IN	Intermediate	12.3	2.0	0/2	0/2	1/2	2/2 (6.0)	N.d.	N.d.	N.d.	N.d.	N.d.	N.d.	N.d.
TH16	IN	High	15.8	2.2	4/5	3/5	3/5	5/5 (6.2)	2/3	1/3	3/3	1/3	2/3	3/3	3/3
TH16	AR	Low	13.0	2.4	2/2	1/2	2/2	2/2 (6.0)	N.d.	N.d.	N.d.	N.d.	N.d.	N.d.	N.d.
TH16	AR	Intermediate	18.9	2.1	3/3	3/3	2/3	3/3 (6.3)	N.d.	N.d.	N.d.	N.d.	N.d.	N.d.	N.d.
TH16	AR	High	16.7	2.6	4/6	6/6	6/6	6/6 (6.3)	3/3	3/3	3/3	2/3	2/3	2/3	0/3

AR, inoculation by aerosol; MDT, mean time to death in days; IN, intranasal inoculation; N.d., not determined; NT, nasal turbinates; OB, olfactory bulb region of the brain; RII, relative inactivity index.

*Dose range (FID₅₀ based on pfu): for PN99, high IN (100–227), high AR (74–526); for TH16, low IN (1.2), intermediate IN (12), high IN (62–115), low AR (1.5–1.8), intermediate AR (12–22), high AR (60–87).

^†Percent mean maximum weight loss is shown.

^‡Neurological clinical signs include hind limb paresis, torticollis, seizures.

^§All lobes sampled and pooled.

^¶Including posterior and anterior regions of brain.

**Intestinal duodenum, jejunum, and descending colon sampled and pooled.