Space Flight activates sleeping viruses

Detection of infectious herpesviruses in half of all NASA astronauts

The stay in space promotes the reactivation of latent herpesviruses in astronauts. © NASA
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Infectious Aftermath: Staying in space can reactivate sleeping herpes viruses - and make the carriers highly infectious. More than half of all astronauts on space shuttle missions or the International Space Station have detected researchers on their return to reactivated herpesviruses, including Epstein-Barr and chickenpox viruses. Although this was usually symptomless, but especially for longer missions, this would pose a significant health risk, the scientists said.

Astronauts do not have it easy: The extreme G-forces at take-off, the weightlessness, and the burden of cosmic radiation - all this is an enormous burden for the body. Add to that the separation of friends and relatives and a stressful job. The consequences of this are not enough: In addition to muscle and bone atrophy threatening damage to the cardiovascular system, fever and also brain changes and even brain wasting, as studies show.

Herpes simplex virus under the electron microscope. © CDC / Erskine Palmer

Herpesviruses - latent danger

Another danger has now been demonstrated by Bridgette Rooney of GeoControl Systems in Houston and her colleagues at NASA: herpesviruses. This group of viruses are not only the cause of annoying cold sores, they also cause chickenpox, shingles, cytomegalovirus and can promote cancer. Most people carry one or more variants of these herpesviruses in themselves, but these remain mostly inactive.

The problem: If the immune system is weakened - for example due to severe stress or illness - the viruses can become active again and then cause symptoms. And here's where the astronauts come in: "There is growing evidence that the space-based pressures are helping to deliver stress hormones, thereby straining the immune system, " explain Rooney and her team.

Active viruses in more than half of the astronauts

Whether the herpesviruses, which carry 70 to 985 percent of all humans, are reactivated by the astronauts, the researchers have now determined by analysis of blood, saliva and urine samples from a total of 112 NASA astronauts. Ninety-eight of these astronauts were on space-shuttle flights for only a few days, 23 on long-duration missions on the International Space Station. display

The result: 53 percent of the space shuttle astronauts and 61 percent of the ISS astronauts found active infectious herpesviruses in the body fluids during the mission and after the return, "The astronauts released Eppstein-Barr viruses, varicella-zoster viruses and herpes simplex 1 in saliva and cytomegaloviruses in urine, " the researchers report. Thus, four of the eight known herpesvirus species were found in active form in the astronauts.

Increased risk for Lunar and Mars missions

Striking also: The longer the space missions lasted, the more reactivated viruses cavorted in the bodily fluids of the astronauts. The viral load of the rose-rose virus increased from 41 percent in short space shuttle missions to 61 at ISS stops. It was similar to the cytomegalovirus, as Rooney and her team report. Eppstein-Barr increased virus release from 82 to 96 percent.

So far, this virus reactivation seems to go well for most astronauts: "Only six astronauts developed symptoms, " reports co-author Satish Mehta of NASA's Johnson Space Center. Most of these were chickenpox-like skin rashes. But on even longer missions, such as flights to Mars or stays at a future moon station, the reactivated viruses could also trigger serious illnesses, the researchers said.

Virus cocktail strengthens the danger

In addition: Because most people and even astronauts carry several different types of herpesviruses in themselves, their simultaneous reactivation could incriminate the body strengthened and worsen the medical consequences. "The physiological consequences could then add up - it would not only cause skin swelling, but also severe organ failure and permanent loss of sight and senses, " say the researchers.

Scientists in the immune system of the astronauts found the cause for this reactivation of the herpesviruses: Their level of the immuno-inhibiting stress hormones cortisol and adrenaline was increased. "We also found that astronauts' defense cells - especially those that normally fight and suppress viruses - are less effective during spaceflight, " says Mehta. This immune inhibition persisted for up to 60 days after returning to Earth.

Countermeasures are urgently needed

In order not to endanger future space missions by possible viral diseases, it is necessary to prevent this reactivation of the virus as possible. "The ideal countermeasure would be a vaccine for the astronauts - but they are so far only against varicella-zoster viruses, " says Mehta. "Attempts to develop other herpesviral vaccines are currently showing little promise, so our focus must be on targeted treatments." (Frontiers in Microbiology, 2019; doi: 10.3389 / fmicb.2019.00016)

Source: Frontiers

- Nadja Podbregar