The human parainfluenza virus type-1 prototypic strain contains a heat-labile hemagglutinin-neuraminidase protein.
The virus yield of human parainfluenza virus type-1 (hPIV-1) in cultured cells at 38 degrees C is reduced more than 100-fold compared to 34 degrees C, while the virus yield of Sendai virus (SV, Enders strain), a murine parainfluenza virus type-1 with high homology to hPIV-1 was almost equal at both temperatures. To understand the basis for the differences in the temperature growth characteristics of the two viruses, we examined the heat-stability of hPIV-1 and SV glycoproteins expressed from cDNAs by pulse-chase experiments. The hemagglutinin-neuraminidase (HN) protein of hPIV-1 was stable after a 6-h chase at 34 degrees C, while at 38 degrees C prominent protein degradation was observed starting at 3 h chase and by 6 h HN was reduced by 65%. In contrast, SV HN protein was stable at both 34 and 38 degrees C. The other hPIV-1 glycoprotein, the fusion (F) protein was stable at both temperatures. To identify the amino acids which are responsible for the heat-lability of hPIV-1 HN, mutant HN proteins were constructed by site-directed mutagenesis. Mutant hPIV-1 HN which had substitutions at positions 461 and 462 became heat-stable at 38 degrees C. These data indicate amino acids around 461 are responsible for the heat-lability of the wild type hPIV-1 HN protein and the reduced yield of the virus at 38 degrees C.
Takimoto
T
T
Department of Virology and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38101-0318.
Portner
A
A
D000595:Amino Acid Sequence; D002478:Cells, Cultured; D015707:HN Protein / Q000737:chemistry / Q000302:isolation & purification*; D006358:Hot Temperature; D006801:Humans; D008969:Molecular Sequence Data; D010222:Parainfluenza Virus 1, Human / Q000737:chemistry* / Q000502:physiology; D011489:Protein Denaturation; D014779:Virus Replication
D015707:HN Protein