Virus World

Little is known on the landscape of viruses that reside within our cells, nor on the interplay with the host imperative for their persistence. Yet, a lifetime of interactions conceivably have an imprint on our physiology and immune phenotype. In this work, we revealed the genetic make-up and unique composition of the known eukaryotic human DNA virome in nine organs (colon, liver, lung, heart, brain, kidney, skin, blood, hair) of 31 Finnish individuals. By integration of quantitative (qPCR) and qualitative (hybrid-capture sequencing) analysis, we identified the DNAs of 17 species, primarily herpes-, parvo-, papilloma- and anello-viruses (>80% prevalence), typically persisting in low copies (mean 540 copies/ million cells).

We assembled in total 70 viral genomes (>90% breadth coverage), distinct in each of the individuals, and identified high sequence homology across the organs. Moreover, we detected variations in virome composition in two individuals with underlying malignant conditions. Our findings reveal unprecedented prevalences of viral DNAs in human organs and provide a fundamental ground for the investigation of disease correlates. Our results from post-mortem tissues call for investigation of the crosstalk between human DNA viruses, the host, and other microbes, as it predictably has a significant impact on our health.

Published (April 24, 2023)in Nucleic Acids Research:

https://doi.org/10.1093/nar/gkad199 

Latent herpes virus reactivation has been documented in more than half of astronauts during space shuttle and International Space Station missions, and according to a recent study funded by NASA, the cause is stress.“Herpes virus is a broad category of viruses, beyond the small subset that cause sexually transmitted diseases.Most humans become infected early in life with one or more, and never fully clear these viruses,” Satish Mehta, PhD, senior scientist in the immunology/virology lab at the Johnson Space Center in Houston, told Infectious Disease News.

Results showed that 47 out of 89 (53%) astronauts on short space shuttle flights, and 14 out of 23 (61%) on longer space station missions shed herpes viruses in their saliva or urine samples. According to the study, astronauts shed four of the eight major human herpes viruses: Epstein-Barr, varicella-zoster and herpes simplex-1 in saliva and cytomegalovirus in urine. The researchers said most astronauts were asymptomatic, with only six developing symptoms.

“Larger quantities and increased frequencies for these viruses were found during spaceflight as compared to before or after flight samples and their matched healthy controls,” Mehta and colleagues wrote.  Mehta explained why: “[The] short answer is stress. In people with reduced immunity, such as the elderly or stressed individuals, these viruses can awaken and cause disease,” he said.

“Although NASA believes there is no clinical risk to astronauts during orbital spaceflight, there is concern that during deep space exploration missions, there may be clinical risks related to viral shedding. Although we do not have a serious clinical problem related to herpes viruses, their reactivation is an excellent ‘flag,’ or biomarker, for stress and reduced immunity.”

In the study, Mehta and colleagues noted that continued viral shedding after a flight can pose a potential risk for crew who may encounter infants, seronegative adults or immunocompromised people, so protocols have been put in place. 

The study was published in February 2019  in Frontiers in Microbiology - Virology:

https://doi.org/10.3389/fmicb.2019.00016