Could nanoparticles reactivate latent herpes infections?

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Carbon nanoparticles, such as those from combustions engines, appear to reactivate herpesviruses that are latent in lung tissue cells, according to new research from Helmholtz Zentrum München (Neuherberg, Germany).

Previously, it has been reported that both inhalation of environmental nanoparticles and persistent herpesvirus infections are linked with chronic lung disease. The team therefore hypothesized that nanoparticle exposure could disrupt immune control of latent viruses, leading to inflammation and tissue damage.

The study, published recently in Particle and Fibre Toxicology, tested the impact of nanoparticles in a mouse model and in human cells in vitro. The researchers, led by Tobias Stöger and Heiko Adler, both from the Helmholtz Zentrum München, demonstrated that exposure of persistently herpesvirus-infected cells to nanoparticles restored the molecular signature of active viral infection.

The team applied different nanoparticles to mice latently infected with murine gammaherpesvirus 68. In mice treated with these particles the scientists detected a significant increase in lytic viral proteins, which are only observed during active infection. “Metabolic and gene expression analyses also revealed patterns resembling acute infection,” commented author Philippe Schmitt-Kopplin (Helmholtz Zentrum München).

In addition, the researchers investigated the effect of nanoparticles in in vitro herpesvirus-infected human cells, discovering that exposure to nanoparticles induced expression of viral lytic gene ORF50.

This study indicates that in persistently-infected herpesvirus cells exposure to nanoparticles can restore the molecular signature typically seen in acute viral infection, subsequently causing inflammation in the lungs.

Stöger explained: “A particle inhalation triggered production of lytic viral proteins, in addition to the pro-inflammatory effect of the particles themselves; the viral reactivation may enhance the inflammatory response in the lung such that the combination might finally result in tissue damage and pathological alterations.

“This might particularly be worrying for repeated exposure scenarios such as at work places or episodes of high pollution.

“We however need to stress here, that our current study is only a first step and used very high dose rates. Future studies will have to test whether more realistic exposures such as observed under inhalation conditions also trigger this kind of boosts production of lytic viral proteins.”

“In addition,” Stöger concluded, “in long-term studies we would like to investigate to what extent repeated nanoparticle exposure with corresponding virus reactivation leads to chronic inflammatory and remodeling processes in the lung.”

Sources:  Sattler C, Moritz F, Chen S et al. Nanoparticle exposure reactivates latent herpesvirus and restores a signature of acute infection, Part Fibre Toxicol. 14 (2) (2017) https://www.helmholtz-muenchen.de/en/news/latest-news/press-information-news/article/37450/index.html

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