The monkeypox virus is an old acquaintance

We had not finished recovering from the shock caused by SARS-CoV-2 with its different variants when outbreaks of monkeypox have come to remind us that there are more harmful viruses in the world

William Lopez Lluc

GUILLERMO LOPEZ LLUCH Professor of the Cell Biology area. Associate researcher at the Andalusian Center for Developmental Biology. Researcher in metabolism, aging and immune and antioxidant systems, Pablo de Olavide University

We had not finished recovering from the shock caused by SARS-CoV-2 with its different variants and now outbreaks of monkeypox have come to tell us that there are viruses in the world and that they can cause us harm. In case, by any chance, we began to forget about it.

What is striking about this matter is that these outbreaks are not new, as Raúl Rivas González illustrated in his article on this smallpox. Already in 2003, the importation of wild animals into the United States and their relationship with animals from that country caused the monkeypox virus to infect animals used as pets and end up causing this disease in more than 800 people.

In fact, warnings have been raised for some time about the fact that the cessation of vaccination against smallpox in endemic areas of the monkeypox virus has caused an increase in cases of infection by this virus in humans.

Does the story ring a bell? It is quite well known. Viruses affect wild animals, these wild animals interact with humans, infection of humans by viruses that affect other mammals and, finally, health problems in humans. We have just almost come out of a pandemic that should have set off alarm bells about these events.

If you want to know more about the ease with which these zoonoses or infections that pass from their usual organisms to other animals occur, I recommend that you read the book Contagion by David Quammen. Worrying, very worrying.

How does the virus infect cells?

After two years of the pandemic and talking about viruses, mutations and strains almost every day, we should already know that not all viruses are spread in the same way. Essentially because the mechanism they use to enter cells is different. And that makes them affect some cells and not others, in addition to moving between infected and non-infected people differently.

Fortunately, the viruses of the family that causes smallpox, the Orthopoxviruses, are not viruses that are easily dispersed through the air, although they are present in the air droplets that we release when we cough or sneeze. Unlike the aerosols through which coronaviruses are dispersed, smallpox viruses require more direct contact with those infected and with their effluvia. Another advantage is found in the fact that the contagion capacity begins when the first pustules are already present in the mouth and throat, so that an infected person can easily prevent the contagion of other people.

Unlike other viruses, the structure of the viruses in this group is very complex. That allows them to use different mechanisms to infect the cells they invade, including the hemagglutinin used by influenza viruses. Apes and humans are so much alike that a virus that affects apes can certainly affect humans using the same mechanisms. After all, we are nothing more than an evolutionary branch broken off from the common trunk from which our cousins, the apes, also emerge. And furthermore, the variolation used by Edward Jenner to immunize almost all of humanity is based on this principle: the similarity between the cowpox virus and the human one.

As in the case of smallpox, the monkeypox virus targets cells of the immune system. This would explain the swollen glands seen in this infection. The first cells they affect are monocytes, which become macrophages in the tissues and can reach other organs such as the skin, where the pustules are produced.

An interesting feature of these viruses is that they disperse between cells by passing directly from an infected cell to an uninfected cell via bridges generated by the cytoskeleton. In other words, they manipulate the organization of the cytoskeleton to generate bridges that allow viruses to pass from one cell to another without the need to go outside. Staying "hidden" makes them difficult for the antibody-based immune system to detect.

What can we do in the face of this new threat?

To stop outbreaks, the first thing to do is detect those infected, isolate them and prevent any other contagion. Here, finding the zero patient or patients is essential to cut the contagion.

The second challenge is more complex, since it involves eliminating certain practices that are causing these zoonoses to become increasingly serious. What we should do is avoid consuming and distributing animals found in the wild, and especially in the wild in areas rarely frequented by humans. These animals suffer from diseases caused by organisms that could easily pass to us. I think we should have taken note of this by now.

And, obviously, knowing that immunity against smallpox protects against monkeypox, the simplest thing is to use doses of vaccine against smallpox, which we know very well works, and immunize whoever needs to be immunized. In fact, this strategy is the one that the Spanish government seems to have adopted quickly, acquiring thousands of doses of the vaccine. Let's hope we don't have to use them.

This article has been published in 'The Conversation'.

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