A single amino acid mutation at position 170 of human parainfluenza virus type 1 fusion glycoprotein induces obvious syncytium formation and caspase-3-dependent cell death

Abstract

An escape mutant of human parainfluenza virus type 1 (hPIV1), which was selected by serial passage in the presence of a sialidase inhibitor, 4-O-thiocarbamoylmethyl-2-deoxy-2,3-didehydro-N-acetylneur-aminic acid (TCM-Neu5Ac2en), exhibited remarkable syncytium formation and virus-induced cell death in LLC-MK2 cells but no difference in susceptibility for the sialidase inhibitor TCM-Neu5Ac2en from that of wild-type hPIV1 strain C35 (WT). The mutant virus also had higher replication and plaque formation abilities. The mutant virus acquired two amino acid mutations, Glu to Gly at position 170 and Ala to Glu 442 in fusion (F) glycoprotein, but no mutations in haemaggulutinin-neuraminidase (HN) glycoprotein. Using cells co-expressing F and HN genes with site-specific mutagenesis, we demonstrated that a point mutation of Glu to Gly at position 170, which was estimated to be located in hPIV1 F glycoprotein heptad repeat 1, was required for obvious syncytium formation and caspase-3-dependent cell death. In contrast, wild-type F glycoprotein induced no synctium formation or cell death. The findings suggest that a single amino acid mutation of hPIV1 F glycoprotein promotes syncytium formation that is followed by caspase-3-dependent cell death.

A study of genetic variability of human parainfluenza virus type 1 in Croatia, 2011–2014

“…Literature data showed that substitution of one amino acid in HPIV1 proteins could significantly influence their biological features (Bartlett et al, 2007;Bousse et al, 1995Bousse et al, , 2006Takaguchi et al, 2011).…”

Consecutive oral administration of Bifidobacterium longum MM‐2 improves the defense system against influenza virus infection by enhancing natural killer cell activity in a murine model

“…For detection of IFV‐induced cell death, DNA fragmentation in cells derived from BALF was analyzed by flow cytometry . In brief, cells in BALF were collected by centrifugation (200 g , 9 min, 4°C) and fixed with 70% ethanol for 15 min at 4 °C.…”

A I131V Substitution in the Fusion Glycoprotein of Human Parainfluenza Virus Type 1 Enhances Syncytium Formation and Virus Growth

“…6,7) The F glycoprotein is a common spike protein in paramyxovirus and mediates both membrane fusion between the virus and cell (virus-cell fusion) and membrane fusion between cells (cell-cell fusion). 8) Nascent HN and F glycoproteins are abundantly expressed on the cell surface membrane of paramyxovirus-infected cells. The F glycoprotein on the cell surface membrane induces cell-cell membrane fusion between virus-infected cells and their neighboring non-infected cells, resulting in multinucleated giant cell formation, called syncytium formation.…”

“…9) Syncytium formation has been reported to be associated with paramyxovirus growth. 8,10) Remarkable syncytium formation can be seen in cells infected with some paramyxoviruses such as Sendai virus (SeV), respiratory syncytial virus, and human parainfluenza virus type 3 (hPIV3). 11,12) hPIV1 shows little syncytium formation during virus growth in vitro.…”

“…11,12) hPIV1 shows little syncytium formation during virus growth in vitro. 8,13) We previously established a hPIV1 plaque formation assay. 14) In the present study, we isolated an hPIV1 variant (Vr) that had acquired enhanced syncytium formation ability compared with wild-type C35 strain (WT) of hPIV1 by our plaque formation assay.…”