Table 2.

Results of the pathology of K2p170 compared with the parent strain (K2parent) and commercial live attenuated vaccines (H120 and Ma5) in 1-day-old SPF chickens.

Virusesa	Clinical signs			Histopathologic lesion scores
	Mortality (%)	Respiratory signs	Nephritis	Tracheab					Kidneyb
				Loss of epithelial cilia	Epithelial proliferation	Epithelial degeneration	Exudate	Congestion/Hemorrhage	Epithelial degeneration	Tubulo nephrosis	Interstinal nephritis	Regeneration
K2parent	30	++c	++d	2.2e	1.4	1.8	0.6	0.6	0.8	0	2.4	1.8
K2p170	0	–	–	1.2	0.6	0.8	0.2	0.8	0.6	0	0.4	0.6
H120	0	–	–	1.6	0	0.6	0.2	0.4	0.4	0	1.0	0
Ma5	0	–	–	1.6	0.8	0.8	0	0.2	0.6	0	1.2	0.8
None	0	–	–	0.6	0	0	0	0.4	0.6	0	0.8	0.4

ND: not determined.

^aOne-day-old SPF chicks were inoculated with IBV (10^4.5EID₅₀/bird) via the intraocular route.

^bTwo weeks after challenge, chicks were sacrificed and tissues were collected to observe the histological lesions.

^c++, coughing in more than 30% without dyspnea; –, no coughing.

^dExamined dead chickens only (++, moderate; –, mild).

^eScores of histological lesions: 0, normal; 1, extensively focal; 2, multifocal; 3, diffuse.