Pathogenicity and growth characteristics of selected infectious laryngotracheitis virus strains from the United States

Figures & data

Figure 1.  Total clinical sign scores recorded daily for chickens infected with (1a) isolates IV-A and IV-B, (1b) isolates V-A and V-B, and (1c) isolates VI-A and VI-B as compared with clinical signs induced by the CEO vaccine.

Figure 2.  Average GCN log₁₀ value detected per sample by ReTi-PCR (quantitative PCR). (2a) Conjunctiva, (2b) sinuses and (2c) trachea of chickens inoculated with isolates IV-A, IV-B, V-A, V-B, VI-A and VI-B and CEO vaccine.

Figure 3.  Average GCN log₁₀ value detected per sample by ReTi-PCR (quantitative PCR). (3a) Trigeminal ganglia (TG) thymus (TH) and (3b) caecal tonsils (To) and cloaca (Cl) of chickens inoculated with isolates IV-A, IV-B, V-A, V-B, VI-A and VI-B and CEO vaccine.

Table 1.  Virus isolation results on adult CK cells

Isolate	Conjunctiva^a	Sinus^a	Trachea^a	Thymus^b
IV-A	3^c/14	1^c/14	0/14	0/8
IV-B	3^c/14	3^c/14	0/14	0/8
V-A	1^d/14	3^d/14	2^d/14	0/8
V-B	2^e/14	4^e/14	2^e/14	0/8
VI-A	4^c/14	1^c/14	3^c/14	2^c/8
VI-B	6^f/14	5^f/14	2^f/14	2^f/8
CEO	5^g/14	4^g/14	0/14	0/8
^aNumber of positive virus isolation samples/total number collected 2, 4, 5, 7, 9, 11, and 14 d.p.i. ^bNumber of virus isolation-positive samples/total thymus collected 5, 7, and 9 d.p.i. ^c4 and 5 d.p.i. ^d7 and 9 d.p.i. ^e4, 5, and 7 d.p.i. ^f2, 4, 5, and 7 d.p.i. ^g2, 4, and 5 d.p.i.

Figure 4.  Average plaque diameter in LMH cells for ILTV isolates. The average diameters in micrometers of 100 plaques±standard deviation was calculated for each isolate, CEO vaccine, and the USDA strain. Different uppercase letters represent significant size differences at P ≤ 0.05.