Experimental infection of highly pathogenic avian influenza virus H5N1 in black-headed gulls ( Chroicocephalus ridibundus )

Table 3 Histological lesions (HE) and presence of antigen (IHC) in tissues of H5N1-inoculated gulls during the course of the experiment

	Number of birds positive/number of birds examined per day
	2 dpi		4 dpi		5 dpi		6 dpi		7 dpi		12 dpi
Tissue	HE¹	IHC²	HE	IHC	HE	IHC	HE	IHC	HE	IHC	HE	IHC
Thymus	0/4	2/4	0/5	0/5	0/2	0/2	0/2	0/2	0/1	0/1	0/2	0/2
Adrenal	1/4	1/4	0/5	0/5	0/2	0/2	1/2	1/2	0/1	0/1	0/2	0/2
Lung/Trachea	0/4	3/4	1/5	0/5	1/2	0/2	1/2	0/2	0/1	0/1	0/2	0/2
Air sacs	4/4	4/4	5/5	5/5	2/2	1/2	1/2	1/2	0/1	0/1	1/2	1/2
Pancreas	0/4	0/4	2/5	2/5	1/2	1/2	2/2	2/2	1/1	1/1	1/2	0/2
CNS	0/4	0/4	5/5	5/5	2/2	2/2	2/2	2/2	1/1	1/1	1/2	0/2

¹HE: presence of histological lesions by examination of hematoxylin-and-eosin-stained tissue sections.
²IHC: presence of viral antigen by examination of tissue sections stained by immunohistochemical technique.