Productive replication of peste des petits ruminants virus Nigeria 75/1 vaccine strain in vero cells correlates with inefficiency of maturation of the viral fusion protein

• Published in: Virus research 2019-08, Vol.269, p.197634-197634, Article 197634
• Main Authors: Osman, Nussieba A., Portugal, Raquel, Giesow, Katrin, Keil, Günther M.
• Format: Article
• Language: English
• Subjects: Fusion protein; Haemagglutinin; Peste des petits ruminants virus; PPRV Kurdistan 2011 strain; PPRV Nigeria 75/1 vaccine strain; Protein expression
• ISSN: 0168-1702; 1872-7492
• DOI: 10.1016/j.virusres.2019.05.012

•PPRV Nigeria 75/1 vaccine and Kurdistan 2011 strains induce syncytia in Vero-dogSLAM cells only.•Failure to induce syncytia is beneficial for the productive replication of PPRV Nigeria 75/1 vaccine strain in Vero cells.•At low MOI infection, intracellular transport and cleavage of F0 is impaired in VeroMontpellier cells.•After high MOI infection, cleavage of F0 is efficacious only in Vero-dogSLAM cells. Peste des petits ruminants virus (PPRV), a member of the genus Morbillivirus, in the family Paramyxoviridae expresses two membrane glycoproteins, the fusion (F) and haemagglutinin (H) glycoproteins which mediate virus-to-cell fusion and cell-to-cell fusion leading to the induction of syncytia in PPRV infected cells. In the context of the characterization of the virulent lineage IV strain PPRV Kurdistan 2011, isolated from wild goats from the Kurdistan region in Iraq, we observed that both PPRV Kurdistan 2011 and the PPRV Nigeria 75/1 vaccine strain led to induction of large syncytia in Vero-dogSLAM cells within 48 h whereas both failed to induce detectable cell-cell fusion events in two Vero cell lines of differing passage histories. We were unable to detect syncytium formation in transiently transfected cells expressing PPRV F or H alone whereas co-expression of F and H induced large syncytia – in Vero-dogSLAM cells only. In VeroMontpellier cells expressing PPRV F and H, fused cells were rarely detectable indicating that PPRV mediated cell fusion activity is impaired in this cell line. Surprisingly, on Vero-dogSLAM cells the vaccine strain grew to titers of 105.25 TCID50/ml, whereas infectious virus yield was about 200-fold higher on VeroMontpellier and Vero-76 cells. In contrast, the virulent Kurdistan 2011 strain grew to a maximum titer of 107.0 TCID50/ml on Vero-dogSLAM cells and only 104.5 TCID50/ml on normal Vero cells. This was as expected since Vero cells lacking the SLAM receptor for PPRV are regarded as not so permissive for infection. To elucidate the divergent productive replication behaviour of PPRV Nigeria 75/1 vaccine strain on Vero vs Vero-dogSLAM cells, we examined whether intracellular transport and/or maturation of the viral envelope glycoproteins F and H might be implicated with this phenomenon. The results indicate that F in contrast to the H glycoprotein matures inefficiently during intracellular transport in VeroMontpellier cells, thus leading to an absence of detectable syncytia formation. However, in the case of the PPRV Nigeria 75