Table 3.

Pathogenicity of H9N2 AIV to SPF chickens ^a

Virus	Lethality	Virus titers in trachea (log 10 EID 50 /gram ± SD)	Virus titers in lung (log 10 EID 50 /gram ± SD)	Seroconversion (HI titers)
rSD01	None	5.83 ± 0.29	5.33 ± 0.34	64, 128
r01/NASS	None	3.72 ± 0.35*	3.61 ± 0.26*	64, 64
r01/NAHB	None	5.67 ± 0.34	5.21 ± 0.18	128, 64
r01/NA381	None	4.17 ± 0.29*	3.56 ± 0.10*	128, 64

^aSPF chickens (n = 5) were inoculated intranasally 10⁷ EID₅₀ of each virus. Clarified homogenates of tracheas and lungs from three animals collected on 5 dpi were titrated for virus infectivity in SPF embryonated chicken eggs from initial dilutions of 1:10. Virus titers were expressed as mean log₁₀EID₅₀/g wet tissues ± standard deviation (SD). Two chickens were observed for signs of lethality, and seroconversion was confirmed by hemagglutination inhibition (HI) assay on 14 dpi. *P < 0.05 compared with rSD01.