May 22, 2019 | Updated: 08:18 AM EDT

Astronauts exposed to reactivation of dormant viruses during space flight

Mar 16, 2019 10:45 AM EDT

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Herpes Virus
(Photo : Pixabay)

NASA scientists discover an increase in the virus reactivation rates of astronauts during spaceflight and their findings were published in Frontiers in Microbiology. 

Astronauts were recipients of NASA's rapid viral detection systems and ongoing treatment research, as well as patients who have compromised immune systems. 

Astronauts who are immunocompromised experience reactivation of herpes viruses. 

"NASA astronauts endure weeks or even months exposed to microgravity and cosmic radiation-not to mention the extreme G forces of take-off and re-entry," says senior author Dr. Satish K. Mehta of KBR Wyle at the Johnson Space Center. "This physical challenge is compounded by more familiar stressors like social separation, confinement, and an altered sleep-wake cycle."

Mehta and his team studied the physiological impact of spaceflight by analyzing samples of blood, urine, and saliva from astronauts before, during, and after spaceflight. 

"During spaceflight there is a rise in secretion of stress hormones like cortisol and adrenaline, which are known to suppress the immune system. In keeping with this, we find that astronaut's immune cells-particularly those that normally suppress and eliminate viruses-become less effective during spaceflight and sometimes for up to 60 days after," according to a post from Phys.

Mehta further reiterates, "To date, 47 out of 89 (53%) astronauts on short space shuttle flights, and 14 out of 23 (61%) on longer ISS missions shed herpes viruses in their saliva or urine samples. These frequencies-as well as the quantity-of viral shedding are markedly higher than in samples from before or after flight, or from matched healthy controls."

The study detected four of the eight known human herpes viruses. These include chickenpox and shingles (VZV), oral and genital herpes (HSV). CMV and EBV were also detected and these are related with the "kissing disease."

"Only six astronauts developed any symptoms due to viral reactivation," says Mehta. "All were minor."

The concern is that uninfected and immunocompromised contacts can be affected by the continued virus shedding after a flight. 

"Infectious VZV and CMV were shed in body fluids up to 30 days following return from the International Space Station."

The heightened risk for virus reactivation becomes significant as there are more possibilities of human deep-space missions. 

"The magnitude, frequency, and duration of viral shedding all increase with length of spaceflight."

These deep-space missions depend on the countermeasures developed to viral reactivation.

"The ideal countermeasure is vaccination for astronauts-but this is so far available only against VZV."

"Trials of other herpes virus vaccines show little promise, so our present focus is on developing targeted treatment regimens for individuals suffering the consequences of viral reactivation.

"This research has tremendous clinical relevance for patients on Earth too. Already, our spaceflight-developed technologies for rapid viral detection in saliva have been employed in clinics and hospitals around the world."

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