Table 1. Mammalian-type amino acids in the PB2 protein of ostrich isolates.

Virusa	No. of clones	PB2 amino acidb at position:
		591	627	701
Inoculum	50/50	Q	E	D
Brain isolate	35/35	Q	K	D
Trachea isolate	61/73	Q	K	D
	12/73	K	E	D
Lung isolate	33/57	Q	E	D
	24/57	Q	K	D

^aWe intratracheally inoculated A/duck/Vietnam/5001/04 (H5N1) into a 3-week-old ostrich and isolated virus from trachea, lungs, and brain on day 3 post-infection (for more details, see [10]). Viral RNA was isolated, and the PB2 gene was amplified by RT-PCR and cloned. We then sequenced the indicated numbers of PB2 clones. Results for PB2-627 and PB2-701 were already shown in Shinya et al. [10]. We here expanded our analysis to include PB2-591 in this study.

^bMammalian-type amino acids are shown in bold and italics.