Kinetic modeling of Sendai virus fusion with PC-12 cells. Effect of pH and temperature on fusion and viral inactivation

• Autor(a) principal: Lima, Maria da Conceição Pedroso de
• Data de Publicação: 1992
• Outros Autores: Ramalho-Santos, João, Martins, Maria de Fátima, Carvalho, Arsélio Pato de, Bairos, Vasco, Nir, Shlomo
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10316/8436; https://doi.org/10.1111/j.1432-1033.1992.tb16766.x

We have studied the fusion activity of Sendai virus, a lipid-enveloped paramyxovirus, towards a line of adherent cells designated PC-12. Fusion was monitored by the dequenching of octadecylrhodamine, a fluorescent non-exchangeable probe. The results were analysed with a mass action kinetic model which could explain and predict the kinetics of virus2013cell fusion. When the temperature was lowered from 37°C to 25°C, a sharp inhibition of the fusion process was observed, probably reflecting a constraint in the movement of viral glycoproteins at low temperatures. The rate constants of adhesion and fusion were reduced 3.5-fold and 7-fold, respectively, as the temperature was lowered from 37°C to 25°C. The fusion process seemed essentially pH-independent, unlike the case of liposomes and erythrocyte ghosts. Preincubation of the virus in the absence of target cell membranes at neutral and alkaline pH (37°C, 30 min) did not affect the fusion process. However, a similar preincubation of the virus at pH = 5.0 resulted in marked, though slow, inhibition in fusion with the fusion rate constant being reduced 8-fold. Viral preincubation for 5 min in the same acidic conditions yielded a mild inhibition of fusogenic activity, while preincubation in the cold (4°C, 30 min) did not alter viral fusion activity. These acid-induced inhibitory effects could not be fully reversed by further viral preincubation at pH = 7.4 (37°C, 30 min). Changes in internal pH as well as endocytic activity of PC-12 cells had small effect on the fusion process, thus indicating that Sendai virus fuses primarily with the plasma membranes.