Table 1.

The base change sites and phenotypes of alleles of ALV receptors

Subgroup	Receptor	Alleles	Mutation mechanism	Base changes	Phenotype
ALV-A/K	Tva	Tva	-	-	Sensitive
		Tvar	Base mutation	C/G 168 mRNA	Resistant
		Tvar2	Exon 1 insert 4 bp	284CTGC287	Resistant
		Tvar3	Intron 1 miss 10 bp	507ACCCCGCCCC516	Reduce susceptibility
		Tvar4	Intron 1 miss 5 bp	507ACCCC511	Reduce susceptibility
		Tvar5	Intron 1 miss 10 bp	502CGCTCACCCC511	Reduce susceptibility
		Tvar6	Intron 1 miss 15 bp	502CGCTCACCCCGCCCC516	Reduce susceptibility
ALV-B/D/E	Tvb	Tvbs1	-	-	Sensitive to subgroups B/D/E
		Tvbs3	Base mutation	T/A 184 mRNA	Sensitive to subgroups B/D
		Tvbr	Base mutation	C/T 172 mRNA	Resistant
ALV-C	Tvc	Tvc	-	-	Sensitive
		Tvcr	Base mutation	C/A165 mRNA	Resistant
ALV-J	NHE1	NHE1	-	-	Sensitive
		NHE1∆	Base mutation	W38	Resistant

“-” means no change. The superscript numbers indicate gene loci