It is generally accepted that a virophage is a viral agent that infects other larger viruses. It is a dsDNA virus which utilizes the replication factories of other viruses to reproduce itself. Virophages are essentially parasitic in nature, much in the same way as traditional satellite viruses. It is not without controversy that distinctions between satellite viruses and virophages are described. The difference between the two often seem more semantic than factual and more supported by conjecture than observation. Not to say there is no room for agreement. The primary and notable distinction between a satellite virus and a virophage is that virophages to one degree or another inhibit the replication of their host “helper” virus (HHV) progeny
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The first virophage to be discovered is Sputnik virophage. It was found accidentally while examining Mamavirus with an electron microscope. The Acanthamoeba that contained Mamavirus was found in a water cooling tower in Paris. Sputnik depends upon the co-infection of host cells by larger viruses known as Mamavirus and alone is incapable of infecting the host amoeba cell [9]. A versatile virophage capable of interacting with all three lineages of Mimivirus, Sputnik virophage reproduce by using the viral factories of the Mamavirus and in turn inhibit the replication of Mamavirus progeny. In addition to disrupting replication, Sputnik also causes a percentage of Mamavirus progeny to be deformed and not viable. It is notable as the amoebal host cell is indirectly helped by Sputnik because the abnormal Mamavirus particles produced render it less infective to the host cell. It is fascinating that the Sputnik virophage is aiding the host amoebal cell by moderating host virus activities.
After Sputnik, the second virophage discovered is Mavirus virophage. Mavirus uses the second subfamily of Mimiviridae, Cafeteria roenbergensis virus (CroV) as its HHV. An interesting feature of Mavirus is that it is capable of entering the host cell, C. roenbergensis, independently …show more content…
Real-time PCR was performed with a LightCycler FastStart DNA Master SYBR Green I™ kit in a standard PCR reaction, as described by the manufacturer (Roche Diagnostics, Mannheim Germany). Each reaction contained 3 mM MgCl2, 1 µM of each primer (primers for Mamavirus polymerase, Marseillevirus capsid, or Sputnik ORF20; table 1), and 5 µl of template DNA in a 20-µl PCR mixture. The amplification started with an initial denaturation step at 95° for 10 min, followed by 40 cycles of 95°for 15s, 57° for 5s, and 72° for 8s, with a temperature transition rate of 2°/s. Fluorescence signals were measured once in each cycle at the end of the extension step. After PCR amplification, Tm curve analysis was performed. For each sample, the CT (Cycle Threshold) was given. The CT corresponds to the PCR cycle number at which the fluorescence reaches a threshold value of 10 times the standard deviation of the baseline emission. The CT values are inversely proportional to the starting amount of target
The first virophage to be discovered is Sputnik virophage. It was found accidentally while examining Mamavirus with an electron microscope. The Acanthamoeba that contained Mamavirus was found in a water cooling tower in Paris. Sputnik depends upon the co-infection of host cells by larger viruses known as Mamavirus and alone is incapable of infecting the host amoeba cell [9]. A versatile virophage capable of interacting with all three lineages of Mimivirus, Sputnik virophage reproduce by using the viral factories of the Mamavirus and in turn inhibit the replication of Mamavirus progeny. In addition to disrupting replication, Sputnik also causes a percentage of Mamavirus progeny to be deformed and not viable. It is notable as the amoebal host cell is indirectly helped by Sputnik because the abnormal Mamavirus particles produced render it less infective to the host cell. It is fascinating that the Sputnik virophage is aiding the host amoebal cell by moderating host virus activities.
After Sputnik, the second virophage discovered is Mavirus virophage. Mavirus uses the second subfamily of Mimiviridae, Cafeteria roenbergensis virus (CroV) as its HHV. An interesting feature of Mavirus is that it is capable of entering the host cell, C. roenbergensis, independently …show more content…
Real-time PCR was performed with a LightCycler FastStart DNA Master SYBR Green I™ kit in a standard PCR reaction, as described by the manufacturer (Roche Diagnostics, Mannheim Germany). Each reaction contained 3 mM MgCl2, 1 µM of each primer (primers for Mamavirus polymerase, Marseillevirus capsid, or Sputnik ORF20; table 1), and 5 µl of template DNA in a 20-µl PCR mixture. The amplification started with an initial denaturation step at 95° for 10 min, followed by 40 cycles of 95°for 15s, 57° for 5s, and 72° for 8s, with a temperature transition rate of 2°/s. Fluorescence signals were measured once in each cycle at the end of the extension step. After PCR amplification, Tm curve analysis was performed. For each sample, the CT (Cycle Threshold) was given. The CT corresponds to the PCR cycle number at which the fluorescence reaches a threshold value of 10 times the standard deviation of the baseline emission. The CT values are inversely proportional to the starting amount of target