“Every cloud has a silver lining” – that’s what people sometimes say. But they are not thinking about HSV at the time. HSV or Herpes Simplex Virus could be unpleasant, yet the viruses that set it off and other related diseases may have a benefit. At least in mice, they provide bacterial resistance against diseases like the bubonic plague.
Herpes is just one of several itchy, blistering infections, caused by the virus group aptly named as herpes viruses. Eight members of the virus group infect humans and result in various illnesses including chickenpox, shingles, glandular fever, and, indeed, herpes itself.
Nearly everybody contracts one of these viruses during their childhood. But the virus group will stay in the body permanently; not just for the holidays. After your immune system combats the primary infection, the virus goes into an inactive phase called “latency.” It stays hidden, showing no apparent symptoms. But it is likely to reactivate at any time.
In this manner, herpes viruses are like life-long parasites, guaranteeing their own survival and causing damage to their host’s health. In extreme instances, latent viruses can cause chronic inflammation, which in return can result in autoimmune diseases or a few forms of cancer.
But there’s a bright side to herpes as well. Washington University Medical School’s Erik Barton and colleagues discovered that once infected, mice went into the latent phase and became shockingly resistant to particular types of bacteria. Different from their susceptible and uninfected peers, they are even able to fight off the fatal plague bug, Yersinia pestis.
In mice at least, latent herpes viruses develop into paying tenants instead of freeloading squatters – resistance to the bacteria is their rent. The latent phase is vital to the effect of resistance, and Barton discovered that a mutant herpes virus infects yet provides nothing in return to its host.
The viruses function by placing the immune system on alert. The effect is just like raising a terror alert, causing an intensified security level where the body is ready to ward off any threats. The viruses activate the release of cytokines in high levels. Cytokines are immune system chemicals. These molecules – counting IFN-g (interferon-gamma) and TNF-a (tumor necrosis factor alpha) – aid to coordinate the defense against infections.
These chemicals trigger macrophages – a white blood cell. These cellular slayers consume invading bacteria and digest them. They’re activated in large quantities in mice infected by herpes viruses at the latent stage. This sequence is just how the immune system protects us against various bacterial invaders. However, in Barton’s study, the protection was initiated by viruses instead and persisted for longer than usual. Good for the mice.
What do we gain from these viruses? Will it have the same effect on us as the mice? Barton thinks so. In his research, two different strains – gHV68 (murine gammaherpesvirus 68) and MCMV (murine cytomegalovirus) – had a similar effect. He thinks that giving bacterial resistance is a universal characteristic of all herpes viruses.