Efficient Multiplication of Human Metapneumovirus in Vero Cells Expressing the Transmembrane Serine Protease TMPRSS2

Abstract

Human metapneumovirus (HMPV) is a major causative agent of severe bronchiolitis and pneumonia. Its fusion (F) protein must be cleaved by host proteases to cause membrane fusion, a critical step for virus infection. By generating Vero cells constitutively expressing the transmembrane serine protease TMPRSS2 and green fluorescent protein-expressing recombinant HMPV, we show that TMPRSS2, which is expressed in the human lung epithelium, cleaves the HMPV F protein efficiently and supports HMPV multiplication. The results indicate that TMPRSS2 is a possible candidate protease involved in the development of lower respiratory tract illness in HMPV-infected patients.

The SI Strain of Measles Virus Derived from a Patient with Subacute Sclerosing Panencephalitis Possesses Typical Genome Alterations and Unique Amino Acid Changes That Modulate Receptor Specificity and Reduce Membrane Fusion Activity

“…The resulting full-length genome plasmid was designated pHHRz-SI-AcGFP. BHK/T7-9 cells, which represent a baby hamster kidney (BHK) cell-derived clone constitutively expressing T7 RNA polymerase (20) (kindly provided by M. Sugiyama and N. Ito), has been shown to be highly potent for initiating the replication cycles of other negativestrand RNA viruses from cloned cDNAs (20,48). By the use of previously reported methods of studies employing BHK/T7-9 cells (48), the cDNAs of the N, P, and L genes of MV were inserted into the pCITE vector; the resulting plasmids were termed pCITE-IC-N, pCITE-IC-P⌬C, and pCITEko-9301B-L, respectively.…”

In vitro characterization of TMPRSS2 inhibition in IPEC-J2 cells

“…Development of synthetic inhibitors of TMPRSS2 can offer also possibilities in the therapy of human metapneumovirus (HMPV) infections by reduction in cleavage of the fusion protein F 25,26 or in the treatment of severe acute respiratory syndrome coronavirus, where TMPRSS2 is involved in the spike protein S activation 27,28 . Calu-3 cells infected with H1N1 or H3N2 influenza viruses were treated with I-432 and related TMPRSS2 inhibitors at 50 mM for 48 h incubation time and it was found that the viral replication was significantly reduced.…”

Residues of the Human Metapneumovirus Fusion (F) Protein Critical for Its Strain-Related Fusion Phenotype: Implications for the Virus Replication Cycle

“…Cleavage takes place at a mono-or multibasic cleavage site immediately upstream of a hydrophobic fusion peptide, generating two polypeptide chains (F2 N-terminally located to F1) that remain covalently linked by at least one disulfide bond. It has been reported that the hMPV F protein has a monobasic cleavage site that can be recognized by trypsin (30,32) or by TMPRSS2 (35), a transmembrane serine protease present in the human airway epithelium. The ectodomain of paramyxovirus F proteins also contains two conserved heptad repeat (HR) regions, designated HRA and HRB, which are located downstream of the fusion peptide and upstream of the transmembrane (TM) domain, respectively.…”