... cells, making manufacture of these vaccines commercially feasible. In the present study,two new rHPIV1 viruses containing single att mutations in L, L 17 10 11 and L Y942A, were generated and ... to the level of temperature sensitivity in vitro and attenuation in vivo. The rHPIV1 mutant bearing the indi-vidual att mutation L 17 10 11 (rHPIV1-CR84G L 17 10 11 ) alsoTable 1: Summary of ... J, Collins PL,Zoon KC, Murphy BR, Skiadopoulos MH, Bartlett EJ: Attenuating mutations in the P/C gene of human parainfluenza virus type 1 (HPIV1) vaccine candidates abrogate the inhibition of...