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Inside the Lifestyle of the Virophage

2010; Karger Publishers; Volume: 53; Issue: 5 Linguagem: Inglês

10.1159/000312914

1423-0100

Christelle Desnues, Didier Raoult,

Vibrio bacteria research studies

<i>Objective(s):</i> We sought to better characterize Sputnik, the first isolated virophage, and to analyze its parasitic lifestyle during co-infection with Marseillevirus (a new giant virus) in <i>Acanthamoeba castellanii</i>. <i>Methods:</i> A combination of electron microscopy, immunofluorescence microscopy, and real-time PCR was used to characterize the kinetics of the viral replication cycle. RT-PCR was performed to detect RNAs inside the Sputnik virions. <i>Results:</i> Sputnik is a new viral entity carrying an almost complete ready-to-use set of viral RNAs (20 out of 21). Sputnik does not replicate with Marseillevirus but delays its replication cycle. While Marseillevirus is successfully internalized by <i>A. castellanii</i> following co-infections with Mamavirus and Sputnik, it does not initiate a replication cycle. In contrast, both Marseillevirus and Mamavirus can replicate in the amoeba in case of co-infection, but the development of one is exclusive from the other inside a single amoeba cell. <i>Conclusions:</i> This work provides new insight into the Sputnik replication cycle with another giant virus and confirms that Sputnik is a virophage. It shows new dimensions of the interactions existing among giant viruses.