"To date, 47 out of 89 (53%) astronauts on short flights and 14 out of 23 (61%) on longer ISS missions scour herpes virus in their saliva or urine samples, "says lead study author Satish K. Mehta at the Johnson Space Center. These frequencies – as well as the amount – of viral shedding are significantly higher than in pre- or post-flight samples, or from matched healthy controls. "
Shedding is when a virus is reactivated.
In both short and long term space flights, astronauts send gravity exposure, cosmic radiation and extreme G forces during start and re-entry. In addition, confinement in small spaces, social separation from family and friends and a changed sleep cycle, the researchers say.
Spaceflight creates a stressful environment for astronauts that awaken sleeping viruses.
Four of the eight human herpes viruses were detected, including oral and genital herpes, chickenpox and shingles. Because the herpes viruses reside in nerve and immune cells, they are never completely gone, so they can "wake up".
But fortunately for the astronauts, re-activation of viruses does not necessarily mean that the symptoms return.
"Only six astronauts developed symptoms due to viral reactivation," said Mehta. "Everyone was small."
But the implication of infecting others when the astronauts return to earth is very real, especially those with compromised immune systems or newborns.
Evidence of infectious chickenpox and shingles was still evident in body fluids up to 30 days after the astronauts returned.
The researchers also look forward to future space missions that will take them on long-term trips to the moon and Mars through deep spaces. A round trip mission to Mars could take up to three years.
"The size, frequency and duration of viral shedding all increase with the length of spaceflight," said Mehta. "The ideal countermeasure is vaccination for astronauts – but so far only available to chickenpox."
The samples from other herpes virus vaccines show little lie, so the researchers focus on developing targeted treatment regimens for people suffering from the consequences of viral reactivation.
"This research also has great clinical relevance for patients on Earth. Already today, our space-engineered saliva viral detection technologies have been employed in clinics and hospitals worldwide," said Mehta.
What happens to immune systems in the room
"Cancer is a major risk to astronauts during very long spaceflight missions due to exposure to radiation," said Richard Simpson, senior research writer and University of Arizona professor of nutritional sciences. "[NK-cells] is also very important to kill virus-infected cells. When you are in the space station, it is a very sterile environment – you are not inclined to pick up flu or rhinovirus or any community infections – but the infections that are a problem are the viruses already in your body. These are mostly viruses that cause things like shingles, mononucleosis or cold sores; They remain in your body for the rest of your life and they reactivate when you are stressed. "
During the study, the researchers studied blood samples from eight astronauts who spent time in the space station and compared them to healthy people who did not endure space flight. Astronaut blood samples were taken before, during and after spaceflight.
Compared to the healthy controls and how they were before the flight, the astronauts' NK cell function was weakened during and after spaceflight. On day 90 of their stay at the space station, samples of NK cell activity against leukemia cells in cultured dishes were reduced by 50% in crew members.
The effect was even greater in astronauts who went to space for the first time compared to those who had previously flown missions.
"I don't think there is any doubt that the NK cell function falls into the spaceflight environment when it is analyzed in a cell culture system," Simpson said.
But what caused this to happen? As in the new study, the researchers in this study believe that it could be stress-induced. The first-time astronauts were also younger than the spacecraft and found their first experience more stressful, which could exacerbate their cellular response.
The study does not imply that astronauts are more susceptible to cancer. On that question, future studies can tell.
"The next question would be how do we mitigate these effects? How do we prevent the immune system from falling into space?" Said simpson "To do that, first find out what causes the decline: Is it stress? Is it microgravity? Is it radiation? Is it an abundance of things? When we count on it, we can try to find ways targeting these factors directly and mitigating them. "
Researchers at the Johnson Space Center are working on possible countermeasures, including exercise, nutritional and pharmacological, to keep the astronauts healthy in space. These could all increase the immune response.