Table 2.

Neutralizing index and antigenic relatedness of Spanish field isolates Spain/99/319 (Genotype I) and Spain/99/325 (Genotype IV) field isolates and the main reference IBV European serotypes

Virus 1	Virus 2	Neutralizing index virus 1a	Neutralizing index virus 2b	Antigenic relatedness (%)
Spain/99/325c	M41	0.6	0.6	23.2
	D274	0.84	0.6	33.0
	D1466	0.6	0.6	24.3
	4/91	0.8	0.6	26.3
	Spain/00/337e	2.8	1.98	67.5
	Spain/99/319	0.8	1.7	47.3
	Spain/99/325	2.9	2.9	100.0
Spain/99/319d	M41	0.6	0.6	27.3
	D274	1.2	0.6	46.3
	D1466	0.84	0.6	33.8
	4/91	3	0.6	59.8
	Spain/00/337	1.4	1.2	43.6
	Spain/99/325	1.7	0.8	47.3
	Spain/99/319	2.1	2.1	100.0

Maximum antigenic relatedness obtained for each isolate is indicated in bold letters.

^aNeutralizing index obtained from antisera of virus 1 against virus 2.

^bNeatruazing index obtained from antisera of virus 2 against virus 1.

^cSpanish isolate representative from Genotype IV.

^dSpanish isolate representative from Genotype I (4/91 Spanish isolate).

^eSpanish field isolate previously demonstrated to belong to Italy 02 serotype (Dolz et al., 2006).