Herpesvirus saliva DNA increases dramatically during spaceflight

In All, Chronic Fatigue Syndrome, Latest Scientific News by Kristin Loomis

A number of astronauts have complained about herpesvirus reactivations during flight, and several developed shingles. Investigators at NASA determined that space flight increases herpesvirus shedding in saliva, compared to levels before and after their missions.

61% of astronauts shed CMV in their urine during and after space flight, compared to the complete absence of CMV DNA in urine samples taken 6 months before the flight. Varicella virus was found in the saliva of 65% of astronauts spending time at the space station, compared to none before their departures.

Previous studies have shown that significant immune dysregulation accompanies the viral reactivation, with substantial reductions in cell-mediated immunity in astronauts with herpesvirus reactivations. CD4+, CD8+ T-cell and NK cell function falls during flight. NK cell function is especially affected because there is a decreased production of the enzymes perforin and granzyme B, which are required for NK cells to function. Additionally, the body does not seem to overcome this dysfunction over time; rather, viral load in body fluids only increases as the astronauts spend more time in space. The reactivation of these viruses, especially in combination, could lead to a host of clinical problems, ranging from rashes to vision loss and organ damage. Furthermore, the immune impairment lasts up to 60 days post-flight, which, the authors of this study note, could put very young children or immunocompromised individuals who come into contact with the astronauts at risk of infection back on Earth.

Astronauts with viral reactivation also experience a significant increase in pro-inflammatory plasma cytokines such as IL-6, IL-8, TNF alpha, IL-4 and eotaxin in comparison to baselines.

In addition to stress, astronauts are subject to variable gravitational forces, cosmic radiation, social separation, circadian rhythm disruption, and microgravity, which are all thought to contribute to dysregulation of the immune and endocrine systems.

The astronauts’ salivary cortisol was higher before and during each flight, but the basal cortisol, or early morning cortisol level, was lower.

Unfortunately, HHV-6A/B/7 were not tested in this study.

To read the full paper: Rooney 2019