Relationship between mortality, clinical signs and tracheal pathology in infectious laryngotracheitis

Figures & data

Table 1.  Details of the ILTV strains used in this study and comparisons of RFLP patterns generated by restriction digestion of PCR products of selected genes

Strain	Year of isolation	Origin	Pattern combination^a	Class^b
N3-04	2004	Broiler	BBBBB	2
S2-04	2004	Layer	BBACB	3
Q1-96	1996	Unknown	AAAAA	1
V1-99	1999	Layer	BBBBB	2
CSW	1970	Layer	BBCCB	4
SA2	c1966	Vaccine	AAAAA	1
A20	1983	Vaccine	AAAAA	1
^aCombination of RFLP patterns for genes gG, TK, ICP4, ICP18.5 and ORFB-TK.
^bClasses of ILTV strains according to their pattern combination.

Table 2.  Percentage weight gain of 3-week-old chickens at 4 days post-inoculation with different strains of ILTV

Group	Percentage weight gain^a
Negative control	38.3^A±10.3
N3-04	22.5^AB±35.8
S2-04	14.3^B±5.8
Q1-96	−14.4^C±19.9
V1-99	14.9^B±17.0
CSW	19.5^B±18.4
SA2	11.9^B±16.6
A20	13.3^B±10.4
Data presented as the mean±standard deviation.
^aSignificantly different data are shown by different superscript letters.

Table 3.  Scores for the median (range) clinical signs of 3-week-old chickens at 4 days post-inoculation with different strains of ILTV

	Median^a (range)
Group	Breathing	Conjunctiva	Demeanour	Sum
Negative control	0^A (0 to 0)	0^A (0 to 0)	0^B (0 to 0)	0^A (0 to 0)
N3-04	1^B (0 to 2)	0^AB (0 to 2)	0^AB (0 to 1)	2^B (1 to 3)
S2-04	1^B (0 to 4)	0.5^A (0 to 1)	0^B (0 to 0)	2^B (0 to 5)
Q1-96	0^A (0 to 1)	1^B (0 to 2)	1^A (0 to 2)	2^B (0 to 4)
V1-99	1^B (0 to 3)	0^A (0 to 0)	0^B (0 to 1)	1^B (0 to 3)
CSW	1^B (0 to 2)	0^A (0 to 2)	0^AB (0 to 2)	1^B (1 to 4)
SA2	1^B (0 to 2)	0^A (0 to 0)	0^B (0 to 1)	1^B (0 to 3)
A20	1^B (0 to 4)	0^A (0 to 2)	0^AB (0 to 1)	2^B (1 to 4)
^aSignificantly different data are shown by different superscript letters.

Table 4.  Scores for the median (range) microscopic tracheal lesions for the upper trachea, lower trachea and total trachea of 3-week-old chickens at 3 days post-inoculation with different strains of ILTV

	Median^a (range)
Group	Upper trachea	Lower trachea	Total trachea
Negative control	0.0^A (0.0 to 0.3)	0.0^A (0.0 to 0.0)	0.0^A (0.0 to 0.3)
N3-04	2.8^BC (0.0 to 5.0)	0.0^AB (0.0 to 4.5)	2.8^BC (0.0 to 9.5)
S2-04	0.5^BC (0.0 to 5.0)	0.0^AB (0.0 to 5.0)	0.5^AC (0.0 to 9.5)
Q1-96	2.3^B (0.0 to 3.0)	0.0^A (0.0 to 2.0)	2.3^AC (0.0 to 4.5)
V1-99	3.0^BC (0.0 to 4.0)	0.0^A (0.0 to 2.5)	3.0^BC (0.0 to 6.0)
CSW	4.0^C (2.5 to 5.0)	0.0^A (0.0 to 2.0)	4.3^BC (2.5 to 6.0)
SA2	3.0^C (2.0 to 4.0)	0.8^AB (0.0 to 3.0)	4.3^BC (2.0 to 7.0)
A20	3.5^C (1.0 to 4.0)	2.5^B (0.0 to 2.5)	6.0^B (1 to 6.5)
^a Significantly different data are shown by different superscript letters.

Table 5.  Median and range of viral copy numbers (determined by quantitative PCR) in trachea of 3-week-old chickens at 4 days post-inoculation with different strains of ILTV

Group	Median^a	Range
Negative control	1^A	1 to 1
N3-04	1^AB	1 to 8863
S2-04	10^BD	1 to 16 411
Q1-96	238^BE	1 to 5916
V1-99	1028^B	1 to 5394
CSW	1498^CDEF	321 to 38 361
SA2	2615^BFG	221 to 7760
A20	7596^EG	616 to 22 481
^aSignificantly different data are shown by different superscript letters.

Figure 1.  Mortalities of chickens after inoculation with different ILTV strains or sterile PBS. The data represent birds found dead as well as birds culled before termination of experiment (21 days post inoculation) due to severe clinical signs.