Table 2.

Summary of immunohistochemical and histochemical findings referring to the expression of double-stranded ribonucleic acid (dsRNA) in organs of animals lacking USUV antigen expression despite positive qRT-PCR results.

Number (#)	Species (internal ID)	USUV (qRT-PCR) result	Organ	Turnbull blue staining	Detection of USUV antigen	Expression of dsRNA
						9D5	K1	J2
1	Great grey owl (S763/18)	+	Liver	Mild	Marked	Moderate	Marked	Marked
			Spleen	Negative	Moderate	Mild	Mild	Moderate
6	Blackbird (S904/18)	+	Liver	Moderate	Negative	Negative	Negative	Negative
			Spleen	Mild	Mild	Mild	Mild	Mild
7	Blackbird (S939/18)	+	Liver	Mild	Negative	Negative	Moderate	Mild
			Spleen	Negative	Negative	Mild	Moderate	Moderate
9	Blackbird (S1012/18)	+	Liver	Mild	Negative	Negative	Negative	Negative
			Spleen	Negative	Negative	Negative	Moderate	Moderate
14	Blackbird (594/11)	+	Liver	Negative	Negative	Negative	Negative	Negative
23	blackbird (k18/16)	+	Liver	Marked	Negative	Negative	Negative	Negative
			Spleen	Negative	Negative	Negative	Negative	Negative
25	Blackbird (K26/18)	+	Liver	Mild	Negative	Negative	Negative	Negative
			Spleen	Mild	Mild	Negative	Mild	Mild
29	Blackbird (S988/18)	−	Liver	Negative	Negative	Negative	Negative	Negative
			Spleen	Negative	Negative	Negative	Moderate	Moderate

USUV, Usutu virus; dsRNA, double-stranded ribonucleic acid; mild, few positive cells; moderate, moderate numbers of positive cells; marked, high numbers of positive cells; + , positive; -, negative.