Herpes Virus Reactivation in Astronauts During Spaceflight

Ultimately, this results in an increased [C]/[D] molar ratio during spaceflight (Figure 2) which potentially indicates immune challenge, and has been linked to immune modulation (Christeff et al., 1997), including the increased inflammatory cytokine response and the TH2 shift observed in earlier spaceflight studies (Mehta et al., 2013a; Crucian B. E. et al., 2014). Recent flight studies (Mehta et al., 2013a; Crucian B. E. et al., 2014; Crucian et al., 2015) have shown that astronauts displayed significant increases in the pro-inflammatory plasma cytokines IL-1α, IL-6, IL-8, IFNγ, IL-4, eotaxin, and IP-10 in samples taken 10 days before launch (L-10), in comparison to their baseline samples taken 180 days before launch (L-180). The results from some of the most recent flight studies suggest a significant decrease in the IFNγ: IL-4 ratio for shedders compared to astronauts who did not shed any viruses during their duty rotation (Mehta et al., 2013a; Crucian B. E. et al., 2014).

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