CHARACTERIZATION OF A LIVE, ATTENUATED HUMAN PARAINFLUENZA TYPE-3 VIRUS CANDIDATE VACCINE STRAIN

Characterization of a temperature-sensitive and Live, attenuated human parainfluenza type 3 virus strain (cp45) grown at a permissive temper ature (32 degrees C) suggested that the virus efficiently multiplies i n cell lines and retains antigenic and functional properties of the en velope glycoproteins, When grown at a nonpermissive temperature (39.5 degrees C), the cp45 virus exhibited poor replication; however, shifti ng to a permissive temperature allowed virus growth. Although at a non permissive temperature virus polypeptide synthesis was significantly r educed, the hemagglutinin-neuraminidase and fusion glycoproteins were transported to cell surfaces and retained their characteristic biologi c activities. Studies on mRNA synthesis from the P protein gene sugges ted a poor transcriptional activity of the cp45 virus at a nonpermissi ve temperature. Results from this study indicate that the temperature sensitivity of cp45 virus is related to altered transcriptional activi ty and a marked reduction in virus polypeptide synthesis.