Immune System May Protect Against CMV-Induced Hearing Loss, Study Finds

patient being inspected by doctor
March 31, 2019

The best weapon for curing herpes-induced hearing loss may be in our own bodies, a recent study found.

The findings, published in PLOS Pathogen, suggest that immune system cells, referred to as “natural killers” (NK), may play a protective role against hearing loss caused by cytomegalovirus (CMV).

CMV is a strain of the herpes virus that can exist as a latent virus in the body. It’s a common virus, but the majority of people do not know they have it. This is because, under normal circumstances, the immune system is able to control it. CMV can cause complications, but it is particularly dangerous for people who are pregnant or are otherwise immunocompromised. Bodily fluid is the normal medium of transmission for CMV, and it is most commonly transferred from mother to unborn child during pregnancy.

The study showed that NK cells, which destroy infected cells to control viral infections, can interact with the CMV protein (m157) at the surface of infected cells. The National CMV Association estimates that difficulties with hearing occur in up to 75% of babies with symptomatic congenital CMV.

Symptoms of CMV don’t happen every often, but if they do occur they typically take the following form:
  • Fever
  • Night sweats
  • Fatigue and feelings of anxiety
  • Sore throat
  • Swollen glands
  • Joint and muscle pain
  • Low appetite and unintentional weight loss

The findings could be significant for people suffering from CMV-induced hearing loss. According to the American Academy of Pediatrics, congenital CMV infection occurs in about 0.5% to 1.0% of all newborns in the US during the prenatal period. About one-third of all children below the age of five have been infected with CMV, and 10% of children with CMV experience hearing loss.

An earlier study published in PLOS Pathogen described the characteristics of CMV-induced hearing loss among children: Delayed onset, hearing loss that is progressive, and unilateral hearing loss.

Beyond hearing loss, children with congenital CMV may be born with certain birth defects and developmental issues, including:
  • Impairment of vision
  • Lack of coordination
  • Mental disabilities
  • Microcephaly
  • Seizures
  • Sensory difficulties
  • Irregular sleeping behavior
  • Cerebral Palsy

The study was conducted with mice, so more comprehensive testing with human participants will prove to be key in better understanding of NK cell activity in utero and in newborns.

“The study demonstrates the importance of the innate immune response in controlling CMV-induced hearing loss,” said Albert Park, MD, the study’s senior author. “We expect that further characterization of this response will ultimately lead to identification of novel effective clinical interventions.”