Table 1.

Summary of the mutations introduced into the rHPIV1 genome^a.

Gene	Mutationb	ORF	nt changes wt → mutant c	Type of mutation	Codon position	Amino acid change	# nt changes for reversion to wt
P/C	R84G	C	AGA → GGA	point	84	R → G	1
		P	GAG → GGG	point	87	E → G	1
	Δ170d	C	AGG GAT TTC → AGC	deletion	168–170	RDF → S (D deletion; 3 nt deletions in the flanking R-F codons results in a S substitution)	6 (insertions)d
		P	GGA TTT→ deletion	deletion	172–173	GF deletion	6 (insertions)
HN	T553A	HN	ACC → GCC	point	553	T → A	1
L	Y942Ae	L	TAT→ GCG	point	942	Y → A	3e
	Δ1710–11d	L	GCT GAG→ deletion	deletion	1710–11	AE deletion	6 (insertions)d

^a HPIV1 strain Washington/1964, GenBank accession no. NC_003461.

^b The nomenclature used to describe each mutation indicates the wt amino acid, the codon position and the new amino acid, or the position of the deletion (Δ), with respect to the C, HN or L protein.

^c The nucleotides (nt) affected by substitution or deletion are shown underlined and in bold type.

^d Designed for increased genetic stability by use of a deletion. Deletions involved six nt to conform to the rule of six [20].

^e Designed for increased genetic stability by the use of a codon that differs by three nucleotides from codons yielding a wild type assignment.