Table 1.

The characterized chicken ASLV receptor alleles including the genetic defects and phenotypes of the known ASLV receptor resistance alleles.

Allele	Chicken Line	Mutation	Phenotype	Ref.
tvas	Line H6 Line 0	Wild type	Tva receptor conferring susceptibility to ASLV(A) infection.	[57]
tvar	Line C Line Rh-C	Single nucleotide mutation in tvas resulting in a Cys40Trp substitution.	Structural change in Tva due to alteration of the disulfide bond pattern. Drastically lowered binding affinity for ASLV(A) envelope glycoproteins.
tvar2	Line 72	Four-nucleotide insertion in tvas changing reading frame.	Predicted to lead to a complete absence of the Tva protein.
tvbs1	Line 15B1	Wild type	TvbS1 receptor conferring susceptibility to ASLV subgroups B, D, and E.	[49,58]
tvbs3	Line 0	Single nucleotide mutation in tvbs1 resulting in a Cys62Ser substitution.	Structural change in TvbS1 due to alteration of the disulfide bond pattern. Drastically lower binding affinity for only ASLV(E) envelope glycoproteins.	[49,58]
tvbr	Line 72	Single nucleotide mutation in tvbs1 resulting in a premature stop codon.	Predicted to lead to the production of a severely truncated protein at amino acid 57 of the TvbS1 protein.	[58]
tvbr2	Line M	Single nucleotide mutation in tvbs1 resulting in a Cys125Ser substitution.	Structural change in TvbS1 due to alteration of the disulfide bond pattern. Lowered binding affinity for ASLV(B) and ASLV(D), and drastically lower binding affinity for ASLV(E) glycoproteins.	[52]
tvcs	Line H6	Wild type	Tvc receptor conferring susceptibility to ASLV(C) infection.	[54]
tvcr	Line 15 Line 15I5	Single nucleotide mutation in tvcs resulting in a premature stop codon.	Predicted to lead to the production of a severely truncated protein at amino acid 55 of the Tvc protein.