title: Parainfluenza 3 virus: plaque-type variants lacking neuraminidase activity.
abstract: Virus clones lacking detectable neuraminidase activity (SC-YN and M-YN) as well as those possessing it (LT-910N and LT-YN) were isolated from bovine strains of parainfluenza 3 virus. LT-910N and LT-YN viruses produced large turbid plaques in MDBK cells, and SC-YN virus produced small clear plaques. Incorporation of a bacterial neuraminidase in agar overlay medium made SC-YN virus form large turbid plaques, whereas it made M-YN virus form large clear plaques. However, M-YN virus formed only pinhole plaques or no plaques in the absence of neuraminidase. The exogenous neuraminidase had little effect on the plaque formation of LT-910N and LT-YN viruses. M-YN virus induced extensive syncytial formation, and SC-YN virus produced less extensive syncytial formation. The exogenous neuraminidase enhanced replication of SC-YN and M-YN viruses and reduced syncytial formation by these viruses. The enzyme had little effect on replication and cytopathic effect of LT-910N and LT-YN viruses. The reason for these effects of the exogenous neuraminidase is discussed.
mesh_terms: D000818:Animals; D002460:Cell Line; D003470:Culture Media; D004285:Dogs; D014644:Genetic Variation; D009439:Neuraminidase / Q000378:metabolism / Q000494:pharmacology*; D010224:Parainfluenza Virus 3, Human / Q000032:analysis / Q000201:enzymology / Q000254:growth & development*; D018108:Respirovirus / Q000254:growth & development*; D010948:Viral Plaque Assay; D014764:Viral Proteins / Q000032:analysis
chemical_list: D003470:Culture Media; D014764:Viral Proteins; D009439:Neuraminidase