A 3D illustration of a group of herpes visruses. Credit: Location South / Alamy Stock Photo
Researchers have identified specific herpes simplex viruses that can evade the host’s immune system, remain latent and cause recurrent infections without destroying host cells1.
The research team found two new and several previously reported mutations in a viral gene that helped the viruses to develop resistance to a common antiviral drug used to treat herpes infections.
These findings show the need to screen new antivirals against such viruses, the researchers say.
The herpes simplex virus type-1 (HSV-1) spreads predominantly through oral contact, causing painful blisters or ulcers at the site of the infection. It can spread from the mouth to the genitals.
Scientists at the Indian Institute of Chemical Biology in Kolkata collected oral or genital swabs from 18 patients who reported painful, recurrent herpes infections despite treatment with the antiviral drug acyclovir.
The researchers, led by Subhajit Biswas, wanted to characterise the viruses by growing them in specific lung and kidney epithelial cell lines. HSV-1 infected the cells but showed no cytopathic effects, which meant it could proliferate inside host cells without killing them.
Expression of viral genes and low levels of viral proteins in these cells indicated the presence of slowly multiplying viruses.
By replicating slowly, the viruses possibly avoid being cleared from patients’ bodies, causing recurrent herpes infections.
The researchers think HSV-1 is evolving to morph into a ‘cryptic’ form – a strategy which will allow it evade the host immune system and establish chronic infection in patients.
