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Title: A common mechanism for influenza virus fusion activity and inactivation
Authors: Ramalho-Santos, João 
Nir, Shlomo 
Düzgünes, Nejat 
Carvalho, Arsélio Pato de 
Lima, Maria da Conceição Pedroso de 
Issue Date: Mar-1993
Publisher: American Chemical Society
Citation: Biochemistry. 32:11 (1993) 2771-2779
Abstract: The fusion of influenza virus (A/PR/8/34 strain) with PC- 12 cells was monitored by a fluorescence assay, and the results were analyzed with a mass-action model which could explain and predict the kinetics of fusion. The model accounted explicitly for the reduction in the fusion rate constant upon exposure of the virus to low pH, either for the virus alone in suspension or for the virus bound to the cells. When the pH was lowered without previous viral attachment to cells, an optimal fusion activity was detected at pH 5.2. When the virus was prebound to the cells, however, reduction of pH below 5.2 resulted in enhanced fusion activity at the initial stages. These results were explained by the fact that the rate constants of both fusion and inactivation increased severalfold at pH 4.5 or 4, compared to those at pH 5.2. At pH 5.2, lowering the temperature from 37 to 20 or 4 "C resulted in a decrease in the fusion rate constant by more than 30- or 1000-fold, respectively. Inactivation of the virus when preincubated in the absence of target membranes at pH 5 was found to be rapid and extensive at 37 OC, but was also detected at 0 OC. Our results indicate a strong correlation between fusion and inactivation rate constants, suggesting that the rate-limiting step in viral hemagglutinin (HA)-mediated fusion, that is, rearrangement of viral glycoproteins at the contact points with the target membrane, is similar to that involved in fusion inactivation.
ISSN: 0006-2960
DOI: 10.1021/bi00062a006
Rights: openAccess
Appears in Collections:FMUC Medicina - Artigos em Revistas Internacionais
FCTUC Ciências da Vida - Artigos em Revistas Internacionais

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