Table 1.

Temperature sensitivity and subgroup identity ofwt rAB chimeric RSV and derivatives containing attenuating mutationsa

Table 1.
  • a The A2-derived mutations contained in the various rAB derivatives have been described previously and were derived from two different biologically derived viruses,cpts248/404 (16) and cpts530/1030 (41). The mutations were as follows: the cpgenotype consists of five amino acid substitutions in the N (V267I), F (E218A, T523I), and L (C319Y, H1690Y) proteins, which are employed as a set and confer a non-ts attenuated phenotype (8,42). Here, because of the replacement of the F gene,cp involves only the changes in N and L. The 248 and 1030 mutations involve amino acid substitution Q831L and Y1321N, respectively, in the L protein, each of which confers the tsand attenuation phenotypes (40, 41). The 404 genotype involves an amino acid substitution in L, D1183E, which is not associated with the ts or attenuation phenotype, and a nucleotide substitution in the GS signal of the M2 gene, with confers the ts and attenuation phenotypes (40). The ΔSH mutation involves deletion of the SH gene, which confers a modest attenuation phenotype in vivo (2).

  • b Shut-off temperature is defined as the lowest restrictive temperature at which a 100-fold or greater reduction of titer is observed. The virus titers at the shut-off temperature are boxed.

  • c Infected cell monolayers were immunostained with either RSV F monoclonal antibody (MAb) 92-11C (subgroup A specific) or 102-10B (subgroup B specific) and scored visually for staining. +, staining; −, nonstaining.

  • d Pinpoint plaque size.