Hijacking A Virus

–Viperae

Few days ago, I've read a post that proposes what if viruses can attack other pathogen such as bacteria and that is possible because some viruses are only species specific pathogen and they are called BACTERIOPHAGE. But what if a virus attacks a virus instead of bacteria? At first glance, I admitted that I laughed but that got me curious at the same time thus I spent my time and to take a little break from COVID-19 updates to research if it is really possible. So it is possible?

The answer is YES and it is possible.

When we think of viral infections, most of us thinks a virus infecting the cells of bacteria, plants, or animals, that's the norm in nature. The idea of one virus acting as a parasite towards another one rarely comes to mind not unlike a virus acting as a parasite to some bacterium species. Scientists have discovered an ocurrence of large and small viruses in marine microorganisms and the nature of their interactions with another species has not been clearly defined. In a Nature article, French scientists observed that a small virus can actually be parasitic to a larger one which is rare to see. Due to the parallels with bacteriophages, where a virus infects bacteria, they coined the term VIROPHAGE for this tiny virus.

In 2008, the first virophage identified was isolated from a water tower in Paris and named Sputnik because it was found along side a giant virus, by the way giant viruses sometimes resembles of a bacteria or bigger than them hence sometimes it is often mistaken. The giant virus named Mamavirus. The virophage is acting as a satellite virus like in a simple analogy of Earth and Moon. Sputnik contains a mere 21 genes compared to the humongous mamavirus that encodes more than 900 genes. Mamavirus is the second found Acanthamoeba polyphaga mimivirus (AMPV), the largest known viruses, it was named mamavirus because it is slightly bigger than known mimiviruses. Here’s the cool part: when the mamavirus infects an amoeba it uses its 900 protein-encoding genes to build a viral factory for replication that works within the amoeba – Sputnik hijacks this factory and uses it to replicate, therefore lowering the replication of the mamavirus particles making the virus less infective. You can say virophage are like script kiddies in real life hacking, giant viruses are the developers of the tool and virophages use it for their own.

When La Scola et al. looked further into Sputnik’s genome they found that 3 of the 21 genes shared homology with mamavirus proteins! They not only hijack the mamavirus viral factory, but they might have picked up mamavirus viral particles or genes while using its factory.

After the discovery of Sputnik, a new virophage is found in Antarctica in Organic Lake, named Organic Lake Virophage (OLV). OLV preys on phycodnaviruses (big viruses) that infect prasinophytes (algae found in Organic Lake). In Organic Lake (and in nearby lake, Ace Lake and two tropical lakes in the Galapagos) phycodnaviruses infect algae with intent to kill & OLV comes to save the day by inhibiting the viral production of phycodnavirsus by hijacking its already set up viral factory in the algae, therefore letting algae live to see another day. They determined that the this new virophage affects the entire microbial community and marine environment by “reducing overall mortality of the host and increasing frequency of blooms during polar summer light periods”. Although Organic Lake isn’t 4,000 meters under ice, it is 6,000 years old and has proven to harbor some pretty amazing biodiversity.

With these newly found discoveries of virophages, some scientists at present are now questioning again the definition of life which is til now it is not applicable to viruses.

What do you think of virophages? Can we use them for future medical advancements?

Photo:

An immunofluorescence labeling of an amoeba (A. castellannii) infected with a mixture of mamavirus and Sputnik.

Red – mamavirus, Green – Sputnik, Blue – nucleic acids (DAPI).

A) Sputnik virions entering cytoplasm 30 minutes after infection.

B) 4 hours after infection, the first viral factories were seen as distinct, stongly stained patches (Red/yellow).

C) 6 hours after infection the viral factories expanded and were strongly stained with DAPI (blue = DNA, because of viral replication).

D) 8 hours after infection, mamavirus production observed.

E) 12 hours after infection.

F) 16 hours after infection

#EnigmaReaders