Age-dependent development and clinical characteristics of an experimental parrot bornavirus-4 (PaBV-4) infection in cockatiels (Nymphicus hollandicus)

Figures & data

Figure 1. Weight (g) of the adult group of cockatiels after infection with PaBV-4 at different ages. Laying females (A0,1, B0,1, C0,1, E0,1 and F0,1) in colour. Arrows mark the timepoint of the first egg of one clutch. Colour online.

Figure 2. Weight (g) of the juvenile group of cockatiels after infection with PaBV-4 at different ages. Laying females (J3, J4, J7 and J11) as well as the outlier J9 in colour. Arrows mark the timepoint of the first egg of each clutch. Females J3, J4 and J7 were using the same nest, so it was not always possible to know which egg was from which female. The eggs where no assignment to one female was possible are not shown here. Colour online.

Table 1. Clinical findings of cockatiels after infection with PaBV-4 for the different age groups (values are dpi).

				First detection of			First onset of signs
Group	ID	Sex	Age at infection (days)	Anti-PaBV-antibodies (titre)	PaBV-RNA	Reduced general condition/apathy	Bodyweight loss	Polyuria/polydipsia	Gastrointestinal signs	CNS signs	Death	Euthanasia
Adult	A0,1	female	1814	36 (1:640)	36	34	38				–	44
	A1,0	male	2142	57 (1:2560)	48	73	57	157	75	107	–	202
	B0,1	female	668	57 (1: 320)	31		76		83		85	–
	B1,0	male	2043	57 (1:2560)	41	90	69		73		–	92
	C0,1	female	405	71 (1:320)	50						–	230
	C1,0	male	493	50 (1:80)	41	63	62		94	83	–	230
	D0,1	female	629	71 (1:1280)	45						–	231
	D1,0	male	665	36 (1:40)	66	63	59		69	54	80	–
	E0,1	female	422	36 (1:160)	55	48	48		48		–	231
	E1,0	male	417	71 (1:5120)	50		90		73		–	230
	F0,1	female	424	57 (1:1280)	31		92				–	230
Juvenile	J1	male	6	50 (1:320)	36						–	232
	J2	female	5	50 (1:320)	34						–	232
	J3	female	4	36 (1:40)	29						–	233
	J4	female	4	43 (1:80)	31						–	233
	J5	male	3	43 (1:160)	27						–	233
	J6	female	3	57 (1:1280)	27						–	232
	J7	female	1	36 (1:80)	34						–	233
	J8	male	1	99 (1:640)	52						–	232
	J9	female	1	36 (1:40)	27		56				66	–
	J10	male	1	43 (1:80)	29						–	231
	J11	female	1	50 (1:640)	34						–	231

Figure 3. Box plot diagram showing the first detection of anti-PaBV antibodies in cockatiels after infection with PaBV-4 4 in different age groups (juvenile average: 44 dpi, min: 36 dpi, max: 57 dpi; adult average: 54 dpi, min: 36 dpi, max: 71 dpi). The juvenile group seroconverted earlier and more homogenously (P = 0.0502). One outlier in the juvenile group (seroconversion at 99 dpi) was excluded from the diagram.

Figure 4. Anti-PaBV-antibody titre of the adult group of cockatiels after infection with PaBV-4 in different age groups in dpi (Y-axis: 1/titre). Colour online.

Figure 5. Anti-PaBV-antibody titre of the juvenile group of cockatiels after infection with PaBV-4 in different age groups in dpi (Y-axis: 1/titre). Colour online.

Table 2. Post mortem findings of cockatiels after infection with PaBV-4 in different age groups.

				Last detection before death		Post mortem findings
Group	ID	Sex	Age at infection in days	Anti-PaBV-antibody titre	PaBV-RNA (Ct-value) in combined crop and cloacal swabs	PaBV-RNA in organ samples (average Ct-value)	Proventricular dilatation	Death (dpi)	Euthanasia (dpi)
Adult	A0,1	female	1814	1:5120	34.99	24.03	+	–	44
	A1,0	male	2142	1:163,840	22.97	19.97	+++	–	202
	B0,1	female	668	1:40,960	29.24	21.81	+++	85	–
	B1,0	male	2043	1:163,840	30.08	22.35	+++	–	92
	C0,1	female	405	1:81,920	15.65	16.80	–	–	230
	C1,0	male	493	1:40,960	30.32	23.65	+++	–	230
	D0,1	female	629	1:163,840	15.40	17.96	–	–	231
	D1,0	male	665	1:81,920	37.82	27.01	++	80	–
	E0,1	female	422	1:163,840	15.48	18.05	+	–	231
	E1,0	male	417	1:81,920	22.18	18.49	++	–	230
	F0,1	female	424	1:163,840	16.23	16.72	–	–	230
Juvenile	J1	male	6	1:40,960	16.20	16.46	–	–	232
	J2	female	5	1:163,840	15.62	15.37	–	–	232
	J3	female	4	1:40,960	15.15	15.32	–	–	233
	J4	female	4	1:81,920	17.51	14.78	–	–	233
	J5	male	3	1:81,920	13.81	16.97	–	–	233
	J6	female	3	1:163,840	24.30	18.22	–	–	232
	J7	female	1	1:81,920	15.96	16.53	–	–	233
	J8	male	1	1:163,840	15.86	17.53	–	–	232
	J9	female	1	1:20,480	17.47	18.20	–	66	–
	J10	male	1	1:81,920	15.56	15.42	–	–	231
	J11	female	1	1:81,920	15.47	19.58	–	–	231

+++ = severe dilatation; ++ = moderate dilatation; + = mild dilatation; – = no dilatation.

Figure 6. Box plot diagram showing the first detection of PaBV-RNA in combined crop and cloacal swabs of cockatiels after infection with PaBV-4 in different age groups (juvenile average: 31 dpi, min: 27 dpi, max: 36 dpi; adult average: 45 dpi, min: 31 dpi, max: 66 dpi). The juvenile group started shedding earlier and more homogenously, which was highly significant (P = 0.0011). One outlier in the juvenile group (first detection at 52 dpi) was excluded from the diagram.

Table 3. Viral RNA content in the organ samples of cockatiels after infection with PaBV-4 at different ages (Ct-values).