Herpes viruses are reactivated in more than half of the crew members of the Space Shuttle and International Space Station missions, according to a NASA study published in the United States. Frontiers in Microbiology. While only a small proportion develop symptoms, virus reactivation rates increase with the duration of space flight and could pose a significant health risk for missions to Mars and beyond.
NASA's rapid virus detection systems and ongoing research on treatments are beginning to protect astronauts, as well as immunocompromised patients on Earth.
Herpes viruses reactivate in immunocompromised astronauts
"NASA astronauts endure weeks or months of exposure to microgravity and cosmic radiation, not to mention the extreme G forces of take-off and re-entry," said Dr. Satish K. Mehta, lead author KBR Wyle at the Johnson Space Center. "This physical challenge is compounded by more well-known stressors, such as social separation, isolation and a modified sleep-wake cycle."
To study the physiological impact of spaceflight, Mehta and her colleagues analyze samples of saliva, blood and urine taken from astronauts before, during and after spaceflight.
"During spaceflights, the secretion of stress hormones such as cortisol and adrenaline, which are known to suppress the immune system, is increasing, so we find that the immune cells of astronauts , especially those which normally suppress and eliminate viruses, become less effective during spaceflights and sometimes up to 60 days later. "
In the midst of this amnesty caused by stress on viral murders, dormant viruses reactivate and resurface.
"To date, 47 out of 53 (53%) astronauts performing short space shuttle flights and 14 out of 23 (61%) on longer ISS missions have eliminated the herpes virus in their saliva or urine samples, "reports Mehta. "These frequencies, as well as the amount, of viral shedding are significantly higher than in pre-flight or post-flight samples, or in matched healthy controls."
Overall, four of the eight known human herpes viruses have been detected. These include the varieties responsible for oral and genital herpes (HSV), chickenpox and shingles (VZV) – which remain all life in our nerve cells – as well as CMV and EBV. , who reside permanently but without incident in our immune cells during childhood. CMV and EBV are two viruses associated with different strains of mononucleosis or "kissing disease".
The exploration of deep space could depend on effective prevention and treatment
Until now, this viral shedding is usually asymptomatic.
"Only six astronauts have developed symptoms due to viral reactivation," said Mehta. "All were minors."
However, further excretion of the virus after flight could endanger immunocompromised or uninfected contacts on Earth, such as neonates.
"Infectious VZV and CMV were disseminated in body fluids up to 30 days after the return of the International Space Station."
In addition, as we prepare for human missions in the far space beyond the Moon and Mars, the risk that the reactivation of the herpes virus poses to astronauts and their contacts could become more crucial.
"The magnitude, frequency, and duration of viral shedding all increase with the duration of spaceflight."
According to Mehta, the development of countermeasures against viral reactivation is essential to the success of these missions in the deep space.
"The ideal countermeasure is the vaccination of astronauts, but this one is only available against the VZV right now."
"The trials of other herpesvirus vaccines are not promising, so we are focusing on the development of targeted treatment regimens for people suffering from the consequences of viral reactivation.
"This research is also of considerable clinical relevance to patients on Earth, and our spaceborne technologies for rapid detection of viruses in saliva have already been used in clinics and hospitals around the world."
Extended Space Flight Could Degrade the Immune System of Astronauts
Bridgette V. Rooney et al, Reactivation of the herpes virus in astronauts during spaceflight and its application on Earth Frontiers in Microbiology (2019). DOI: 10.3389 / fmicb.2019.00016