Differences in bovine parainfluenza 3 virus variants studied by sequencing of the genes of viral envelope proteins.
By determining gene nucleotide sequences we compared the primary structures of the membrane (M), fusion (F), and hemagglutinin-neuraminidase (HN) proteins of bovine parainfluenza 3 virus strains, M, SC, and MR which are substrains derived from a wild strain YN. The M and SC viruses are indistinguishable in having very weak hemagglutination (HA) and neuraminidase (NA) activities, but M virus' syncytium-inducing (SI) activity is considerably higher than that of the SC virus. However, the results showed that the amino acid sequence of the F protein was identical in M and SC viruses, demonstrating that M virus' high SI activity was not due to alteration of its F protein. Two differences in M and SC viruses' other proteins then seemed to be important, although their significance in the SI activity is not clear at present; the first being the 70th amino acid residue of the M protein, which was Asp in the M virus and Gly in the SC virus, and the other being the 539th residue of the HN protein, which was Tyr in the M virus and His in the SC virus. The nucleocapsid proteins of both M and SC viruses were identical. The MR virus, which is a variant derived from the M virus and has high HA and NA activities but very weak SI activity, was different from the M virus at only one site throughout the M, F, and HN proteins; the 193rd amino acid residue of the HN protein was Leu in the MR virus and Phe in the M virus. This result strongly suggested that the substitution of Leu with Phe at this particular site was closely linked to the drastic reduction in both HA and NA activities.
Shioda
T
T
Department of Viral Infection, University of Tokyo, Japan.
Wakao
S
S
Suzu
S
S
Shibuta
H
H
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002213:Capsid / Q000235:genetics; D002417:Cattle / Q000382:microbiology; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D005796:Genes; D005814:Genes, Viral; D015707:HN Protein; D010224:Parainfluenza Virus 3, Human / Q000235:genetics*; D018108:Respirovirus / Q000235:genetics*; D014758:Viral Core Proteins / Q000235:genetics; D014759:Viral Envelope Proteins / Q000235:genetics*; D014760:Viral Fusion Proteins / Q000235:genetics; D014763:Viral Matrix Proteins / Q000235:genetics
D015707:HN Protein; D014758:Viral Core Proteins; D014759:Viral Envelope Proteins; D014760:Viral Fusion Proteins; D014763:Viral Matrix Proteins; D004247:DNA