Welcome back, and excuse my absence.

I realized that we have never faced a topic, that of viruses. Even if the idea had touched me some time ago, I resisted it, because objectively, we haven’t had good experiences with viruses in the last year and a half. CoVid 19 continues to give us no respite and certainly we have to pay attention.

However, this is one of the most used words in the last year, at least I think, and it deserves to be understood.

Viruses are infectious genetic elements that can be present in 2 different phases: outside and inside the host (cell).

Outside the host, the genetic material of the virus is enclosed in a protein envelope (capsid), which allows it to resist in the extracellular environment. This particle is called Virion (with RNA or DNA depending on the genetic material that characterizes it), and cannot reproduce itsef.

And it is precisely inside the cell that the virus, whatever it is, finds a way to spread.

Depending on the organisms that a virus is able to infect, we can distinguish those that infect bacteria (called bacteriophages), and others capable of infecting plants, animals (including humans).

In the case of infections involving animals, we can distinguish:

• Lytic infection, in which host cells support viral replication until the viral progeny leads to irreversible damage to the cell itself (orthomyxovirus: influenza virus);

• Chronic persistent infection, in which viral replication is extremely slow allowing the virus to remain in the host for a long time before generating symptoms (hepatitis);

• Persistent latent type infection, in which the virus genome is present in the host cell but is not active or is only minimally active, since the host cell does not prove to be permissive (oral and genital herpes);

• Chronic transforming-type infection, related to the onset of tumors. In fact, about 15% of human cancers have been shown to be related to viral infection. Obviously, it must certainly be said that it is not only the viral infection that triggers tumorigenic growth but that it can be one of the triggering factors along with a number of other determining factors.

It seems that this hasn’t correlation with the sea. Obviously this is not the case.

Viruses are the most numerous biological entities in the ocean with an average density of 10⁷ viral particles for each ml (not considering, for example, the variability given by the trophic state of the waters).

The role of viruses proves to be important in the ocean, modulating and modifying the species composition of bacterial communities. Another important role is that of participating in the recycling of organic matter through the so-called viral shunt (reintroduction into the environment of important components that allow the growth of the microorganisms themselves). Both by infecting phytoplankton and bacteria, with lysis, there is the reintroduction and remineralization of elements fundamental to the sustenance of small organisms (and therefore also of the most “important” ones in terms of size).

Furthermore, through the process of transduction (mixing of genes), viruses can favor recombination phenomena and the acquisition of new genetic and phenotypic characteristics in the host. And therefore they allow the evolution of bacteria.

Vibrio cholerae itself (marine bacterium) has undergone transduction by a bacteriophage (the lysogenic phage called CTXφ) which has given it pathogenicity, so much so as to generate many of the pandemics that have affected the human species for hundreds of years (cholera). In fact, the real factors determining the pathogenicity are not intrinsic to Vibrio cholerae, but it acquired them through a viral infection, which gave it greater “competitiveness” compared to other bacterial species given the ease of propagation and reproduction following the gene exchange occurred.

Due to the seclusion of recent times, other viruses that generate self-replicating thoughts have increasingly depopulated: cultural viruses. Well yes guys, let’s lighten the situation. We will talk about the Meme.

Richard Dawkins, in 1976 invented the term Meme, as the cultural equivalent of the term gene. For this reason, the cultural unit of information present within a memetic pool has been defined. Memes give life to thoughts that may or may not survive for a variable amount of time. They can appear in the same way in behavioral patterns, such as the way they dress, dance, talk and even determine the birth of some subcultures.

The study of memes, which by spreading in mass culture become famous, describes in a “light” way how they are similar to viruses and bacteria. They pass, they upset, they leave behind the aftermath.

But remember, they end.

Maria Bruno